Add mentions for v2 group chats.

app/src/main/java/org/thoughtcrime/securesms/BindableConversationItem.java

@@ -47,7 +47,7 @@ public interface BindableConversationItem extends Unbindable {
     void onMessageSharedContactClicked(@NonNull List<Recipient> choices);
     void onInviteSharedContactClicked(@NonNull List<Recipient> choices);
     void onReactionClicked(@NonNull View reactionTarget, long messageId, boolean isMms);
-    void onGroupMemberAvatarClicked(@NonNull RecipientId recipientId, @NonNull GroupId groupId);
+    void onGroupMemberClicked(@NonNull RecipientId recipientId, @NonNull GroupId groupId);
     void onMessageWithErrorClicked(@NonNull MessageRecord messageRecord);
   }
 }

app/src/main/java/org/thoughtcrime/securesms/components/ComposeText.java

@@ -5,6 +5,7 @@ import android.content.res.Configuration;
 import android.graphics.Canvas;
 import android.os.Build;
 import android.os.Bundle;
+import android.text.Annotation;
 import android.text.Editable;
 import android.text.InputType;
 import android.text.Spannable;
@@ -13,7 +14,6 @@ import android.text.SpannableStringBuilder;
 import android.text.Spanned;
 import android.text.TextUtils;
 import android.text.TextUtils.TruncateAt;
-import android.text.method.QwertyKeyListener;
 import android.text.style.RelativeSizeSpan;
 import android.util.AttributeSet;
 import android.view.inputmethod.EditorInfo;
@@ -21,7 +21,6 @@ import android.view.inputmethod.InputConnection;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.core.os.BuildCompat;
 import androidx.core.view.inputmethod.EditorInfoCompat;
 import androidx.core.view.inputmethod.InputConnectionCompat;
 import androidx.core.view.inputmethod.InputContentInfoCompat;
@@ -30,18 +29,26 @@ import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.TransportOption;
 import org.thoughtcrime.securesms.components.emoji.EmojiEditText;
 import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
+import org.thoughtcrime.securesms.components.mention.MentionDeleter;
 import org.thoughtcrime.securesms.components.mention.MentionRendererDelegate;
+import org.thoughtcrime.securesms.components.mention.MentionValidatorWatcher;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.logging.Log;
+import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.util.FeatureFlags;
+import org.thoughtcrime.securesms.util.StringUtil;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
+import org.thoughtcrime.securesms.util.ThemeUtil;
 
-import java.util.UUID;
+import java.util.List;
+
+import static org.thoughtcrime.securesms.database.MentionUtil.MENTION_STARTER;
 
 public class ComposeText extends EmojiEditText {
 
-  private CharSequence            hint;
+  private CharSequence            combinedHint;
-  private SpannableString         subHint;
   private MentionRendererDelegate mentionRendererDelegate;
+  private MentionValidatorWatcher mentionValidatorWatcher;
 
   @Nullable private InputPanel.MediaListener      mediaListener;
   @Nullable private CursorPositionChangedListener cursorPositionChangedListener;
@@ -62,47 +69,63 @@ public class ComposeText extends EmojiEditText {
     initialize();
   }
 
-  public String getTextTrimmed(){
+  /**
-    return getText().toString().trim();
+   * Trims and returns text while preserving potential spans like {@link MentionAnnotation}.
+   */
+  public @NonNull CharSequence getTextTrimmed() {
+    Editable text = getText();
+    if (text == null) {
+      return "";
+    }
+    return StringUtil.trimSequence(text);
   }
 
   @Override
   protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
     super.onLayout(changed, left, top, right, bottom);
 
-    if (!TextUtils.isEmpty(hint)) {
+    if (!TextUtils.isEmpty(combinedHint)) {
-      if (!TextUtils.isEmpty(subHint)) {
+      setHint(combinedHint);
-        setHint(new SpannableStringBuilder().append(ellipsizeToWidth(hint))
-                                            .append("\n")
-                                            .append(ellipsizeToWidth(subHint)));
-      } else {
-        setHint(ellipsizeToWidth(hint));
-      }
     }
   }
 
   @Override
-  protected void onSelectionChanged(int selStart, int selEnd) {
+  protected void onSelectionChanged(int selectionStart, int selectionEnd) {
-    super.onSelectionChanged(selStart, selEnd);
+    super.onSelectionChanged(selectionStart, selectionEnd);
 
-    if (FeatureFlags.mentions()) {
+    if (FeatureFlags.mentions() && getText() != null) {
-      if (selStart == selEnd) {
+      boolean selectionChanged = changeSelectionForPartialMentions(getText(), selectionStart, selectionEnd);
-        doAfterCursorChange();
+      if (selectionChanged) {
+        return;
+      }
+
+      if (selectionStart == selectionEnd) {
+        doAfterCursorChange(getText());
       } else {
         updateQuery("");
       }
     }
 
     if (cursorPositionChangedListener != null) {
-      cursorPositionChangedListener.onCursorPositionChanged(selStart, selEnd);
+      cursorPositionChangedListener.onCursorPositionChanged(selectionStart, selectionEnd);
     }
   }
 
   @Override
   protected void onDraw(Canvas canvas) {
-    if (FeatureFlags.mentions() && getText() != null && getLayout() != null) {
+    if (getText() != null && getLayout() != null) {
       int checkpoint = canvas.save();
+
+      // Clip using same logic as TextView drawing
+      int   maxScrollY = getLayout().getHeight() - getBottom() - getTop() - getCompoundPaddingBottom() - getCompoundPaddingTop();
+      float clipLeft   = getCompoundPaddingLeft() + getScrollX();
+      float clipTop    = (getScrollY() == 0) ? 0 : getExtendedPaddingTop() + getScrollY();
+      float clipRight  = getRight() - getLeft() - getCompoundPaddingRight() + getScrollX();
+      float clipBottom = getBottom() - getTop() + getScrollY() - ((getScrollY() == maxScrollY) ? 0 : getExtendedPaddingBottom());
+
+      canvas.clipRect(clipLeft - 10, clipTop, clipRight + 10, clipBottom);
       canvas.translate(getTotalPaddingLeft(), getTotalPaddingTop());
+
       try {
         mentionRendererDelegate.draw(canvas, getText(), getLayout());
       } finally {
@@ -120,25 +143,25 @@ public class ComposeText extends EmojiEditText {
   }
 
   public void setHint(@NonNull String hint, @Nullable CharSequence subHint) {
-    this.hint = hint;
-
     if (subHint != null) {
-      this.subHint = new SpannableString(subHint);
+      Spannable subHintSpannable = new SpannableString(subHint);
-      this.subHint.setSpan(new RelativeSizeSpan(0.5f), 0, subHint.length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
+      subHintSpannable.setSpan(new RelativeSizeSpan(0.5f), 0, subHintSpannable.length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
+
+      combinedHint = new SpannableStringBuilder().append(ellipsizeToWidth(hint))
+                                                 .append("\n")
+                                                 .append(ellipsizeToWidth(subHintSpannable));
     } else {
-      this.subHint = null;
+      combinedHint = ellipsizeToWidth(hint);
     }
 
-    if (this.subHint != null) {
+    super.setHint(combinedHint);
-      super.setHint(new SpannableStringBuilder().append(ellipsizeToWidth(this.hint))
-                                                .append("\n")
-                                                .append(ellipsizeToWidth(this.subHint)));
-    } else {
-      super.setHint(ellipsizeToWidth(this.hint));
-    }
   }
 
   public void appendInvite(String invite) {
+    if (getText() == null) {
+      return;
+    }
+
     if (!TextUtils.isEmpty(getText()) && !getText().toString().equals(" ")) {
       append(" ");
     }
@@ -155,13 +178,18 @@ public class ComposeText extends EmojiEditText {
     this.mentionQueryChangedListener = listener;
   }
 
+  public void setMentionValidator(@Nullable MentionValidatorWatcher.MentionValidator mentionValidator) {
+    if (FeatureFlags.mentions()) {
+      mentionValidatorWatcher.setMentionValidator(mentionValidator);
+    }
+  }
+
   private boolean isLandscape() {
     return getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE;
   }
 
   public void setTransport(TransportOption transport) {
     final boolean useSystemEmoji = TextSecurePreferences.isSystemEmojiPreferred(getContext());
-    final boolean isIncognito    = TextSecurePreferences.isIncognitoKeyboardEnabled(getContext());
 
     int imeOptions = (getImeOptions() & ~EditorInfo.IME_MASK_ACTION) | EditorInfo.IME_ACTION_SEND;
     int inputType  = getInputType();
@@ -201,19 +229,59 @@ public class ComposeText extends EmojiEditText {
     this.mediaListener = mediaListener;
   }
 
+  public boolean hasMentions() {
+    Editable text = getText();
+    if (text != null) {
+      return !MentionAnnotation.getMentionAnnotations(text).isEmpty();
+    }
+    return false;
+  }
+
+  public @NonNull List<Mention> getMentions() {
+    return MentionAnnotation.getMentionsFromAnnotations(getText());
+  }
+
   private void initialize() {
     if (TextSecurePreferences.isIncognitoKeyboardEnabled(getContext())) {
       setImeOptions(getImeOptions() | 16777216);
     }
 
+    mentionRendererDelegate = new MentionRendererDelegate(getContext(), ThemeUtil.getThemedColor(getContext(), R.attr.conversation_mention_background_color));
+
     if (FeatureFlags.mentions()) {
-      mentionRendererDelegate = new MentionRendererDelegate(getContext());
+      addTextChangedListener(new MentionDeleter());
+      mentionValidatorWatcher = new MentionValidatorWatcher();
+      addTextChangedListener(mentionValidatorWatcher);
     }
   }
 
-  private void doAfterCursorChange() {
+  private boolean changeSelectionForPartialMentions(@NonNull Spanned spanned, int selectionStart, int selectionEnd) {
-    Editable text = getText();
+    Annotation[] annotations = spanned.getSpans(0, spanned.length(), Annotation.class);
-    if (text != null && enoughToFilter(text)) {
+    for (Annotation annotation : annotations) {
+      if (MentionAnnotation.isMentionAnnotation(annotation)) {
+        int spanStart = spanned.getSpanStart(annotation);
+        int spanEnd   = spanned.getSpanEnd(annotation);
+
+        boolean startInMention = selectionStart > spanStart && selectionStart < spanEnd;
+        boolean endInMention   = selectionEnd > spanStart && selectionEnd < spanEnd;
+
+        if (startInMention || endInMention) {
+          if (selectionStart == selectionEnd) {
+            setSelection(spanEnd, spanEnd);
+          } else {
+            int newStart = startInMention ? spanStart : selectionStart;
+            int newEnd   = endInMention ? spanEnd : selectionEnd;
+            setSelection(newStart, newEnd);
+          }
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  private void doAfterCursorChange(@NonNull Editable text) {
+    if (enoughToFilter(text)) {
       performFiltering(text);
     } else {
       updateQuery("");
@@ -241,7 +309,7 @@ public class ComposeText extends EmojiEditText {
     return end - findQueryStart(text, end) >= 1;
   }
 
-  public void replaceTextWithMention(@NonNull String displayName, @NonNull UUID uuid) {
+  public void replaceTextWithMention(@NonNull String displayName, @NonNull RecipientId recipientId) {
     Editable text = getText();
     if (text == null) {
       return;
@@ -251,14 +319,12 @@ public class ComposeText extends EmojiEditText {
 
     int    end      = getSelectionEnd();
     int    start    = findQueryStart(text, end) - 1;
-    String original = TextUtils.substring(text, start, end);
 
-    QwertyKeyListener.markAsReplaced(text, start, end, original);
+    text.replace(start, end, createReplacementToken(displayName, recipientId));
-    text.replace(start, end, createReplacementToken(displayName, uuid));
   }
 
-  private @NonNull CharSequence createReplacementToken(@NonNull CharSequence text, @NonNull UUID uuid) {
+  private @NonNull CharSequence createReplacementToken(@NonNull CharSequence text, @NonNull RecipientId recipientId) {
-    SpannableStringBuilder builder = new SpannableStringBuilder("@");
+    SpannableStringBuilder builder = new SpannableStringBuilder().append(MENTION_STARTER);
     if (text instanceof Spanned) {
       SpannableString spannableString = new SpannableString(text + " ");
       TextUtils.copySpansFrom((Spanned) text, 0, text.length(), Object.class, spannableString, 0);
@@ -267,7 +333,7 @@ public class ComposeText extends EmojiEditText {
       builder.append(text).append(" ");
     }
 
-    builder.setSpan(MentionAnnotation.mentionAnnotationForUuid(uuid), 0, builder.length() - 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    builder.setSpan(MentionAnnotation.mentionAnnotationForRecipientId(recipientId), 0, builder.length() - 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
     return builder;
   }
@@ -278,11 +344,11 @@ public class ComposeText extends EmojiEditText {
     }
 
     int delimiterSearchIndex = inputCursorPosition - 1;
-    while (delimiterSearchIndex >= 0 && (text.charAt(delimiterSearchIndex) != '@' && text.charAt(delimiterSearchIndex) != ' ')) {
+    while (delimiterSearchIndex >= 0 && (text.charAt(delimiterSearchIndex) != MENTION_STARTER && text.charAt(delimiterSearchIndex) != ' ')) {
       delimiterSearchIndex--;
     }
 
-    if (delimiterSearchIndex >= 0 && text.charAt(delimiterSearchIndex) == '@') {
+    if (delimiterSearchIndex >= 0 && text.charAt(delimiterSearchIndex) == MENTION_STARTER) {
       return delimiterSearchIndex + 1;
     }
     return inputCursorPosition;
@@ -300,7 +366,7 @@ public class ComposeText extends EmojiEditText {
 
     @Override
     public boolean onCommitContent(InputContentInfoCompat inputContentInfo, int flags, Bundle opts) {
-      if (BuildCompat.isAtLeastNMR1() && (flags & InputConnectionCompat.INPUT_CONTENT_GRANT_READ_URI_PERMISSION) != 0) {
+      if (Build.VERSION.SDK_INT >= 25 && (flags & InputConnectionCompat.INPUT_CONTENT_GRANT_READ_URI_PERMISSION) != 0) {
         try {
           inputContentInfo.requestPermission();
         } catch (Exception e) {

app/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java

@@ -2,10 +2,8 @@ package org.thoughtcrime.securesms.components;
 
 import android.animation.Animator;
 import android.animation.ValueAnimator;
-import android.annotation.TargetApi;
 import android.content.Context;
 import android.net.Uri;
-import android.os.Build;
 import android.text.format.DateUtils;
 import android.util.AttributeSet;
 import android.view.KeyEvent;
@@ -94,7 +92,6 @@ public class InputPanel extends LinearLayout
     super(context, attrs);
   }
 
-  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
   public InputPanel(Context context, AttributeSet attrs, int defStyleAttr) {
     super(context, attrs, defStyleAttr);
   }
@@ -160,7 +157,7 @@ public class InputPanel extends LinearLayout
   public void setQuote(@NonNull GlideRequests glideRequests,
                        long id,
                        @NonNull Recipient author,
-                       @NonNull String body,
+                       @NonNull CharSequence body,
                        @NonNull SlideDeck attachments)
   {
     this.quoteView.setQuote(glideRequests, id, author, body, false, attachments);
@@ -228,7 +225,7 @@ public class InputPanel extends LinearLayout
 
   public Optional<QuoteModel> getQuote() {
     if (quoteView.getQuoteId() > 0 && quoteView.getVisibility() == View.VISIBLE) {
-      return Optional.of(new QuoteModel(quoteView.getQuoteId(), quoteView.getAuthor().getId(), quoteView.getBody(), false, quoteView.getAttachments()));
+      return Optional.of(new QuoteModel(quoteView.getQuoteId(), quoteView.getAuthor().getId(), quoteView.getBody().toString(), false, quoteView.getAttachments(), quoteView.getMentions()));
     } else {
       return Optional.absent();
     }

app/src/main/java/org/thoughtcrime/securesms/components/QuoteView.java

@@ -23,6 +23,8 @@ import com.bumptech.glide.load.engine.DiskCacheStrategy;
 
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.attachments.Attachment;
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.mms.DecryptableStreamUriLoader.DecryptableUri;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 import org.thoughtcrime.securesms.mms.Slide;
@@ -55,7 +57,7 @@ public class QuoteView extends FrameLayout implements RecipientForeverObserver {
 
   private long          id;
   private LiveRecipient author;
-  private String        body;
+  private CharSequence  body;
   private TextView      mediaDescriptionText;
   private TextView      missingLinkText;
   private SlideDeck     attachments;
@@ -147,7 +149,7 @@ public class QuoteView extends FrameLayout implements RecipientForeverObserver {
   public void setQuote(GlideRequests glideRequests,
                        long id,
                        @NonNull Recipient author,
-                       @Nullable String body,
+                       @Nullable CharSequence body,
                        boolean originalMissing,
                        @NonNull SlideDeck attachments)
   {
@@ -196,7 +198,7 @@ public class QuoteView extends FrameLayout implements RecipientForeverObserver {
     mainView.setBackgroundColor(author.getColor().toQuoteBackgroundColor(getContext(), outgoing));
   }
 
-  private void setQuoteText(@Nullable String body, @NonNull SlideDeck attachments) {
+  private void setQuoteText(@Nullable CharSequence body, @NonNull SlideDeck attachments) {
     if (!TextUtils.isEmpty(body) || !attachments.containsMediaSlide()) {
       bodyView.setVisibility(VISIBLE);
       bodyView.setText(body == null ? "" : body);
@@ -280,11 +282,15 @@ public class QuoteView extends FrameLayout implements RecipientForeverObserver {
     return author.get();
   }
 
-  public String getBody() {
+  public CharSequence getBody() {
     return body;
   }
 
   public List<Attachment> getAttachments() {
     return attachments.asAttachments();
   }
+
+  public @NonNull List<Mention> getMentions() {
+    return MentionAnnotation.getMentionsFromAnnotations(body);
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/components/emoji/EmojiTextView.java

@@ -2,12 +2,17 @@ package org.thoughtcrime.securesms.components.emoji;
 
 import android.content.Context;
 import android.content.res.TypedArray;
+import android.graphics.Canvas;
 import android.graphics.drawable.Drawable;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.core.content.ContextCompat;
 import androidx.core.widget.TextViewCompat;
 import androidx.appcompat.widget.AppCompatTextView;
+
+import android.text.Annotation;
 import android.text.SpannableStringBuilder;
+import android.text.Spanned;
 import android.text.TextUtils;
 import android.util.AttributeSet;
 import android.util.TypedValue;
@@ -15,10 +20,15 @@ import android.util.TypedValue;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.components.emoji.EmojiProvider.EmojiDrawable;
 import org.thoughtcrime.securesms.components.emoji.parsing.EmojiParser;
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
+import org.thoughtcrime.securesms.components.mention.MentionRendererDelegate;
+import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 import org.thoughtcrime.securesms.util.Util;
 import org.whispersystems.libsignal.util.guava.Optional;
 
+import java.util.List;
+
 
 public class EmojiTextView extends AppCompatTextView {
 
@@ -35,6 +45,9 @@ public class EmojiTextView extends AppCompatTextView {
   private int          maxLength;
   private CharSequence overflowText;
   private CharSequence previousOverflowText;
+  private boolean      renderMentions;
+
+  private MentionRendererDelegate mentionRendererDelegate;
 
   public EmojiTextView(Context context) {
     this(context, null);
@@ -48,14 +61,33 @@ public class EmojiTextView extends AppCompatTextView {
     super(context, attrs, defStyleAttr);
 
     TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.EmojiTextView, 0, 0);
-    scaleEmojis = a.getBoolean(R.styleable.EmojiTextView_scaleEmojis, false);
+    scaleEmojis    = a.getBoolean(R.styleable.EmojiTextView_scaleEmojis, false);
-    maxLength   = a.getInteger(R.styleable.EmojiTextView_emoji_maxLength, -1);
+    maxLength      = a.getInteger(R.styleable.EmojiTextView_emoji_maxLength, -1);
-    forceCustom = a.getBoolean(R.styleable.EmojiTextView_emoji_forceCustom, false);
+    forceCustom    = a.getBoolean(R.styleable.EmojiTextView_emoji_forceCustom, false);
+    renderMentions = a.getBoolean(R.styleable.EmojiTextView_emoji_renderMentions, true);
     a.recycle();
 
     a = context.obtainStyledAttributes(attrs, new int[]{android.R.attr.textSize});
     originalFontSize = a.getDimensionPixelSize(0, 0);
     a.recycle();
+
+    if (renderMentions) {
+      mentionRendererDelegate = new MentionRendererDelegate(getContext(), ContextCompat.getColor(getContext(), R.color.transparent_black_20));
+    }
+  }
+
+  @Override
+  protected void onDraw(Canvas canvas) {
+    if (renderMentions && getText() instanceof Spanned && getLayout() != null) {
+      int checkpoint = canvas.save();
+      canvas.translate(getTotalPaddingLeft(), getTotalPaddingTop());
+      try {
+        mentionRendererDelegate.draw(canvas, (Spanned) getText(), getLayout());
+      } finally {
+        canvas.restoreToCount(checkpoint);
+      }
+    }
+    super.onDraw(canvas);
   }
 
   @Override public void setText(@Nullable CharSequence text, BufferType type) {
@@ -115,7 +147,19 @@ public class EmojiTextView extends AppCompatTextView {
   private void ellipsizeAnyTextForMaxLength() {
     if (maxLength > 0 && getText().length() > maxLength + 1) {
       SpannableStringBuilder newContent = new SpannableStringBuilder();
-      newContent.append(getText().subSequence(0, maxLength)).append(ELLIPSIS).append(Optional.fromNullable(overflowText).or(""));
+
+      CharSequence shortenedText = getText().subSequence(0, maxLength);
+      if (shortenedText instanceof Spanned) {
+        Spanned          spanned            = (Spanned) shortenedText;
+        List<Annotation> mentionAnnotations = MentionAnnotation.getMentionAnnotations(spanned, maxLength - 1, maxLength);
+        if (!mentionAnnotations.isEmpty()) {
+          shortenedText = shortenedText.subSequence(0, spanned.getSpanStart(mentionAnnotations.get(0)));
+        }
+      }
+
+      newContent.append(shortenedText)
+                .append(ELLIPSIS)
+                .append(Util.emptyIfNull(overflowText));
 
       EmojiParser.CandidateList newCandidates = EmojiProvider.getInstance(getContext()).getCandidates(newContent);
 

app/src/main/java/org/thoughtcrime/securesms/components/mention/MentionAnnotation.java

@@ -2,16 +2,26 @@ package org.thoughtcrime.securesms.components.mention;
 
 
 import android.text.Annotation;
+import android.text.Spannable;
+import android.text.Spanned;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
-import java.util.UUID;
+import com.annimon.stream.Stream;
+
+import org.thoughtcrime.securesms.database.model.Mention;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+
+import java.util.Collections;
+import java.util.List;
 
 /**
- * Factory for creating mention annotation spans.
+ * This wraps an Android standard {@link Annotation} so it can leverage the built in
+ * span parceling for copy/paste. The annotation span contains the mentioned recipient's
+ * id (in numerical form).
  *
- * Note: This wraps creating an Android standard {@link Annotation} so it can leverage the built in
+ * Note: Do not extend Annotation or the parceling behavior will be lost.
- * span parceling for copy/paste. Do not extend Annotation or this will be lost.
  */
 public final class MentionAnnotation {
 
@@ -20,7 +30,45 @@ public final class MentionAnnotation {
   private MentionAnnotation() {
   }
 
-  public static Annotation mentionAnnotationForUuid(@NonNull UUID uuid) {
+  public static Annotation mentionAnnotationForRecipientId(@NonNull RecipientId id) {
-    return new Annotation(MENTION_ANNOTATION, uuid.toString());
+    return new Annotation(MENTION_ANNOTATION, idToMentionAnnotationValue(id));
+  }
+
+  public static String idToMentionAnnotationValue(@NonNull RecipientId id) {
+    return String.valueOf(id.toLong());
+  }
+
+  public static boolean isMentionAnnotation(@NonNull Annotation annotation) {
+    return MENTION_ANNOTATION.equals(annotation.getKey());
+  }
+
+  public static void setMentionAnnotations(Spannable body, List<Mention> mentions) {
+    for (Mention mention : mentions) {
+      body.setSpan(MentionAnnotation.mentionAnnotationForRecipientId(mention.getRecipientId()), mention.getStart(), mention.getStart() + mention.getLength(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+  }
+
+  public static @NonNull List<Mention> getMentionsFromAnnotations(@Nullable CharSequence text) {
+    if (text instanceof Spanned) {
+      Spanned spanned = (Spanned) text;
+      return Stream.of(getMentionAnnotations(spanned))
+                   .map(annotation -> {
+                     int spanStart  = spanned.getSpanStart(annotation);
+                     int spanLength = spanned.getSpanEnd(annotation) - spanStart;
+                     return new Mention(RecipientId.from(annotation.getValue()), spanStart, spanLength);
+                   })
+                   .toList();
+    }
+    return Collections.emptyList();
+  }
+
+  public static @NonNull List<Annotation> getMentionAnnotations(@NonNull Spanned spanned) {
+    return getMentionAnnotations(spanned, 0, spanned.length());
+  }
+
+  public static @NonNull List<Annotation> getMentionAnnotations(@NonNull Spanned spanned, int start, int end) {
+    return Stream.of(spanned.getSpans(start, end, Annotation.class))
+                 .filter(MentionAnnotation::isMentionAnnotation)
+                 .toList();
   }
 }

app/src/main/java/org/thoughtcrime/securesms/components/mention/MentionDeleter.java

@@ -0,0 +1,50 @@
+package org.thoughtcrime.securesms.components.mention;
+
+import android.text.Annotation;
+import android.text.Editable;
+import android.text.Spanned;
+import android.text.TextWatcher;
+
+import androidx.annotation.Nullable;
+
+import static org.thoughtcrime.securesms.database.MentionUtil.MENTION_STARTER;
+
+/**
+ * Detects if some part of the mention is being deleted, and if so, deletes the entire mention and
+ * span from the text view.
+ */
+public class MentionDeleter implements TextWatcher {
+
+  @Nullable private Annotation toDelete;
+
+  @Override
+  public void beforeTextChanged(CharSequence sequence, int start, int count, int after) {
+    if (count > 0 && sequence instanceof Spanned) {
+      Spanned text = (Spanned) sequence;
+
+      for (Annotation annotation : MentionAnnotation.getMentionAnnotations(text, start, start + count)) {
+        if (text.getSpanStart(annotation) < start && text.getSpanEnd(annotation) > start) {
+          toDelete = annotation;
+          return;
+        }
+      }
+    }
+  }
+
+  @Override
+  public void afterTextChanged(Editable editable) {
+    if (toDelete == null) {
+      return;
+    }
+
+    int toDeleteStart = editable.getSpanStart(toDelete);
+    int toDeleteEnd   = editable.getSpanEnd(toDelete);
+    editable.removeSpan(toDelete);
+    toDelete = null;
+
+    editable.replace(toDeleteStart, toDeleteEnd, String.valueOf(MENTION_STARTER));
+  }
+
+  @Override
+  public void onTextChanged(CharSequence sequence, int start, int before, int count) { }
+}

app/src/main/java/org/thoughtcrime/securesms/components/mention/MentionRendererDelegate.java

@@ -9,11 +9,11 @@ import android.text.Spanned;
 
 import androidx.annotation.ColorInt;
 import androidx.annotation.NonNull;
+import androidx.annotation.Px;
 import androidx.core.content.ContextCompat;
 
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.util.DrawableUtil;
-import org.thoughtcrime.securesms.util.ThemeUtil;
 import org.thoughtcrime.securesms.util.ViewUtil;
 
 /**
@@ -28,42 +28,32 @@ public class MentionRendererDelegate {
   private final MentionRenderer multi;
   private final int             horizontalPadding;
 
-  public MentionRendererDelegate(@NonNull Context context) {
+  public MentionRendererDelegate(@NonNull Context context, @ColorInt int tint) {
-    //noinspection ConstantConditions
+    this.horizontalPadding = ViewUtil.dpToPx(2);
-    this(ViewUtil.dpToPx(2),
-         ViewUtil.dpToPx(2),
-         ContextCompat.getDrawable(context, R.drawable.mention_text_bg),
-         ContextCompat.getDrawable(context, R.drawable.mention_text_bg_left),
-         ContextCompat.getDrawable(context, R.drawable.mention_text_bg_mid),
-         ContextCompat.getDrawable(context, R.drawable.mention_text_bg_right),
-         ThemeUtil.getThemedColor(context, R.attr.conversation_mention_background_color));
-  }
 
-  public MentionRendererDelegate(int horizontalPadding,
+    Drawable drawable     = ContextCompat.getDrawable(context, R.drawable.mention_text_bg);
-                                 int verticalPadding,
+    Drawable drawableLeft = ContextCompat.getDrawable(context, R.drawable.mention_text_bg_left);
-                                 @NonNull Drawable drawable,
+    Drawable drawableMid  = ContextCompat.getDrawable(context, R.drawable.mention_text_bg_mid);
-                                 @NonNull Drawable drawableLeft,
+    Drawable drawableEnd  = ContextCompat.getDrawable(context, R.drawable.mention_text_bg_right);
-                                 @NonNull Drawable drawableMid,
+
-                                 @NonNull Drawable drawableEnd,
+    //noinspection ConstantConditions
-                                 @ColorInt int tint)
+    single = new MentionRenderer.SingleLineMentionRenderer(horizontalPadding,
-  {
+                                                           0,
-    this.horizontalPadding = horizontalPadding;
+                                                           DrawableUtil.tint(drawable, tint));
-    single                 = new MentionRenderer.SingleLineMentionRenderer(horizontalPadding,
+    //noinspection ConstantConditions
-                                                                           verticalPadding,
+    multi = new MentionRenderer.MultiLineMentionRenderer(horizontalPadding,
-                                                                           DrawableUtil.tint(drawable, tint));
+                                                         0,
-    multi                  = new MentionRenderer.MultiLineMentionRenderer(horizontalPadding,
+                                                         DrawableUtil.tint(drawableLeft, tint),
-                                                                          verticalPadding,
+                                                         DrawableUtil.tint(drawableMid, tint),
-                                                                          DrawableUtil.tint(drawableLeft, tint),
+                                                         DrawableUtil.tint(drawableEnd, tint));
-                                                                          DrawableUtil.tint(drawableMid, tint),
-                                                                          DrawableUtil.tint(drawableEnd, tint));
   }
 
   public void draw(@NonNull Canvas canvas, @NonNull Spanned text, @NonNull Layout layout) {
-    Annotation[] spans = text.getSpans(0, text.length(), Annotation.class);
+    Annotation[] annotations = text.getSpans(0, text.length(), Annotation.class);
-    for (Annotation span : spans) {
+    for (Annotation annotation : annotations) {
-      if (MentionAnnotation.MENTION_ANNOTATION.equals(span.getKey())) {
+      if (MentionAnnotation.isMentionAnnotation(annotation)) {
-        int spanStart = text.getSpanStart(span);
+        int spanStart = text.getSpanStart(annotation);
-        int spanEnd   = text.getSpanEnd(span);
+        int spanEnd   = text.getSpanEnd(annotation);
         int startLine = layout.getLineForOffset(spanStart);
         int endLine   = layout.getLineForOffset(spanEnd);
 

app/src/main/java/org/thoughtcrime/securesms/components/mention/MentionValidatorWatcher.java

@@ -0,0 +1,58 @@
+package org.thoughtcrime.securesms.components.mention;
+
+import android.text.Annotation;
+import android.text.Editable;
+import android.text.Spanned;
+import android.text.TextWatcher;
+
+import androidx.annotation.Nullable;
+
+import java.util.List;
+
+/**
+ * Provides a mechanism to validate mention annotations set on an edit text. This enables
+ * removing invalid mentions if the user mentioned isn't in the group.
+ */
+public class MentionValidatorWatcher implements TextWatcher {
+
+  @Nullable private List<Annotation> invalidMentionAnnotations;
+  @Nullable private MentionValidator mentionValidator;
+
+  @Override
+  public void onTextChanged(CharSequence sequence, int start, int before, int count) {
+    if (count > 1 && mentionValidator != null && sequence instanceof Spanned) {
+      Spanned span = (Spanned) sequence;
+
+      List<Annotation> mentionAnnotations = MentionAnnotation.getMentionAnnotations(span, start, start + count);
+
+      if (mentionAnnotations.size() > 0) {
+        invalidMentionAnnotations = mentionValidator.getInvalidMentionAnnotations(mentionAnnotations);
+      }
+    }
+  }
+
+  @Override
+  public void afterTextChanged(Editable editable) {
+    if (invalidMentionAnnotations == null) {
+      return;
+    }
+
+    List<Annotation> invalidMentions = invalidMentionAnnotations;
+    invalidMentionAnnotations = null;
+
+    for (Annotation annotation : invalidMentions) {
+      editable.removeSpan(annotation);
+    }
+  }
+
+  public void setMentionValidator(@Nullable MentionValidator mentionValidator) {
+    this.mentionValidator = mentionValidator;
+  }
+
+  @Override
+  public void beforeTextChanged(CharSequence sequence, int start, int count, int after) { }
+
+  public interface MentionValidator {
+    List<Annotation> getInvalidMentionAnnotations(List<Annotation> mentionAnnotations);
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java

@@ -41,6 +41,8 @@ import android.provider.Browser;
 import android.provider.ContactsContract;
 import android.provider.Telephony;
 import android.text.Editable;
+import android.text.Spannable;
+import android.text.SpannableString;
 import android.text.TextWatcher;
 import android.view.Gravity;
 import android.view.KeyEvent;
@@ -72,6 +74,7 @@ import androidx.core.content.pm.ShortcutManagerCompat;
 import androidx.core.graphics.drawable.IconCompat;
 import androidx.lifecycle.ViewModelProviders;
 
+import com.annimon.stream.Collectors;
 import com.annimon.stream.Stream;
 import com.bumptech.glide.load.engine.DiskCacheStrategy;
 import com.bumptech.glide.request.target.CustomTarget;
@@ -111,6 +114,7 @@ import org.thoughtcrime.securesms.components.emoji.EmojiStrings;
 import org.thoughtcrime.securesms.components.emoji.MediaKeyboard;
 import org.thoughtcrime.securesms.components.identity.UnverifiedBannerView;
 import org.thoughtcrime.securesms.components.location.SignalPlace;
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
 import org.thoughtcrime.securesms.components.reminder.ExpiredBuildReminder;
 import org.thoughtcrime.securesms.components.reminder.Reminder;
 import org.thoughtcrime.securesms.components.reminder.ReminderView;
@@ -124,6 +128,7 @@ import org.thoughtcrime.securesms.contactshare.ContactShareEditActivity;
 import org.thoughtcrime.securesms.contactshare.ContactUtil;
 import org.thoughtcrime.securesms.contactshare.SimpleTextWatcher;
 import org.thoughtcrime.securesms.conversation.ConversationGroupViewModel.GroupActiveState;
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.conversation.ui.error.SafetyNumberChangeDialog;
 import org.thoughtcrime.securesms.conversation.ui.mentions.MentionsPickerViewModel;
 import org.thoughtcrime.securesms.conversationlist.model.MessageResult;
@@ -136,12 +141,14 @@ import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.database.IdentityDatabase;
 import org.thoughtcrime.securesms.database.IdentityDatabase.IdentityRecord;
 import org.thoughtcrime.securesms.database.IdentityDatabase.VerifiedStatus;
-import org.thoughtcrime.securesms.database.MessagingDatabase.MarkedMessageInfo;
+import org.thoughtcrime.securesms.database.MentionUtil;
+import org.thoughtcrime.securesms.database.MentionUtil.UpdatedBodyAndMentions;
 import org.thoughtcrime.securesms.database.MmsSmsColumns.Types;
 import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.RecipientDatabase.RegisteredState;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
 import org.thoughtcrime.securesms.database.identity.IdentityRecordList;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.database.model.MmsMessageRecord;
 import org.thoughtcrime.securesms.database.model.ReactionRecord;
@@ -196,7 +203,6 @@ import org.thoughtcrime.securesms.mms.Slide;
 import org.thoughtcrime.securesms.mms.SlideDeck;
 import org.thoughtcrime.securesms.mms.StickerSlide;
 import org.thoughtcrime.securesms.mms.VideoSlide;
-import org.thoughtcrime.securesms.notifications.MarkReadReceiver;
 import org.thoughtcrime.securesms.notifications.NotificationChannels;
 import org.thoughtcrime.securesms.permissions.Permissions;
 import org.thoughtcrime.securesms.profiles.GroupShareProfileView;
@@ -221,6 +227,7 @@ import org.thoughtcrime.securesms.stickers.StickerLocator;
 import org.thoughtcrime.securesms.stickers.StickerManagementActivity;
 import org.thoughtcrime.securesms.stickers.StickerPackInstallEvent;
 import org.thoughtcrime.securesms.stickers.StickerSearchRepository;
+import org.thoughtcrime.securesms.util.Base64;
 import org.thoughtcrime.securesms.util.BitmapUtil;
 import org.thoughtcrime.securesms.util.CharacterCalculator.CharacterState;
 import org.thoughtcrime.securesms.util.CommunicationActions;
@@ -248,10 +255,12 @@ import org.whispersystems.libsignal.util.Pair;
 import org.whispersystems.libsignal.util.guava.Optional;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
+import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
@@ -648,6 +657,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
       boolean    initiating     = threadId == -1;
       QuoteModel quote          = result.isViewOnce() ? null : inputPanel.getQuote().orNull();
       SlideDeck  slideDeck      = new SlideDeck();
+      List<Mention> mentions    = new ArrayList<>(result.getMentions());
 
       for (Media mediaItem : result.getNonUploadedMedia()) {
         if (MediaUtil.isVideoType(mediaItem.getMimeType())) {
@@ -669,6 +679,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
                        quote,
                        Collections.emptyList(),
                        Collections.emptyList(),
+                       mentions,
                        expiresIn,
                        result.isViewOnce(),
                        subscriptionId,
@@ -1373,7 +1384,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
   private ListenableFuture<Boolean> initializeDraft() {
     final SettableFuture<Boolean> result = new SettableFuture<>();
 
-    final String         draftText        = getIntent().getStringExtra(TEXT_EXTRA);
+    final CharSequence   draftText        = getIntent().getCharSequenceExtra(TEXT_EXTRA);
     final Uri            draftMedia       = getIntent().getData();
     final String         draftContentType = getIntent().getType();
     final MediaType      draftMediaType   = MediaType.from(draftContentType);
@@ -1437,19 +1448,34 @@ public class ConversationActivity extends PassphraseRequiredActivity
   private ListenableFuture<Boolean> initializeDraftFromDatabase() {
     SettableFuture<Boolean> future = new SettableFuture<>();
 
-    new AsyncTask<Void, Void, List<Draft>>() {
+    new AsyncTask<Void, Void, Pair<Drafts, CharSequence>>() {
       @Override
-      protected List<Draft> doInBackground(Void... params) {
+      protected Pair<Drafts, CharSequence> doInBackground(Void... params) {
-        DraftDatabase draftDatabase = DatabaseFactory.getDraftDatabase(ConversationActivity.this);
+        Context       context       = ConversationActivity.this;
-        List<Draft> results         = draftDatabase.getDrafts(threadId);
+        DraftDatabase draftDatabase = DatabaseFactory.getDraftDatabase(context);
+        Drafts        results       = draftDatabase.getDrafts(threadId);
+        Draft         mentionsDraft = results.getDraftOfType(Draft.MENTION);
+        Spannable     updatedText   = null;
+
+        if (mentionsDraft != null) {
+          String                 text     = results.getDraftOfType(Draft.TEXT).getValue();
+          List<Mention>          mentions = MentionUtil.bodyRangeListToMentions(context, Base64.decodeOrThrow(mentionsDraft.getValue()));
+          UpdatedBodyAndMentions updated  = MentionUtil.updateBodyAndMentionsWithDisplayNames(context, text, mentions);
+
+          updatedText = new SpannableString(updated.getBody());
+          MentionAnnotation.setMentionAnnotations(updatedText, updated.getMentions());
+        }
 
         draftDatabase.clearDrafts(threadId);
 
-        return results;
+        return new Pair<>(results, updatedText);
       }
 
       @Override
-      protected void onPostExecute(List<Draft> drafts) {
+      protected void onPostExecute(Pair<Drafts, CharSequence> draftsWithUpdatedMentions) {
+        Drafts       drafts      = Objects.requireNonNull(draftsWithUpdatedMentions.first());
+        CharSequence updatedText = draftsWithUpdatedMentions.second();
+
         if (drafts.isEmpty()) {
           future.set(false);
           updateToggleButtonState();
@@ -1473,7 +1499,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
           try {
             switch (draft.getType()) {
               case Draft.TEXT:
-                composeText.setText(draft.getValue());
+                composeText.setText(updatedText == null ? draft.getValue() : updatedText);
                 listener.onSuccess(true);
                 break;
               case Draft.LOCATION:
@@ -1874,8 +1900,9 @@ public class ConversationActivity extends PassphraseRequiredActivity
     MentionsPickerViewModel mentionsViewModel = ViewModelProviders.of(this, new MentionsPickerViewModel.Factory()).get(MentionsPickerViewModel.class);
 
     recipient.observe(this, mentionsViewModel::onRecipientChange);
+
     composeText.setMentionQueryChangedListener(query -> {
-      if (getRecipient().isGroup()) {
+      if (getRecipient().isPushV2Group()) {
         if (!mentionsSuggestions.resolved()) {
           mentionsSuggestions.get();
         }
@@ -1883,12 +1910,26 @@ public class ConversationActivity extends PassphraseRequiredActivity
       }
     });
 
+    composeText.setMentionValidator(annotations -> {
+      if (!getRecipient().isPushV2Group()) {
+        return annotations;
+      }
+
+      Set<String> validRecipientIds = Stream.of(getRecipient().getParticipants())
+                                            .map(r -> MentionAnnotation.idToMentionAnnotationValue(r.getId()))
+                                            .collect(Collectors.toSet());
+
+      return Stream.of(annotations)
+                   .filterNot(a -> validRecipientIds.contains(a.getValue()))
+                   .toList();
+    });
+
     mentionsViewModel.getSelectedRecipient().observe(this, recipient -> {
       String replacementDisplayName = recipient.getDisplayName(this);
       if (replacementDisplayName.equals(recipient.getDisplayUsername())) {
         replacementDisplayName = recipient.getUsername().or(replacementDisplayName);
       }
-      composeText.replaceTextWithMention(replacementDisplayName, recipient.requireUuid());
+      composeText.replaceTextWithMention(replacementDisplayName, recipient.getId());
     });
   }
 
@@ -2073,7 +2114,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
     long       expiresIn      = recipient.get().getExpireMessages() * 1000L;
     boolean    initiating     = threadId == -1;
 
-    sendMediaMessage(isSmsForced(), "", attachmentManager.buildSlideDeck(), null, contacts, Collections.emptyList(), expiresIn, false, subscriptionId, initiating, false);
+    sendMediaMessage(isSmsForced(), "", attachmentManager.buildSlideDeck(), null, contacts, Collections.emptyList(), Collections.emptyList(), expiresIn, false, subscriptionId, initiating, false);
   }
 
   private void selectContactInfo(ContactData contactData) {
@@ -2097,7 +2138,11 @@ public class ConversationActivity extends PassphraseRequiredActivity
     Drafts drafts = new Drafts();
 
     if (!Util.isEmpty(composeText)) {
-      drafts.add(new Draft(Draft.TEXT, composeText.getTextTrimmed()));
+      drafts.add(new Draft(Draft.TEXT, composeText.getTextTrimmed().toString()));
+      List<Mention> draftMentions = composeText.getMentions();
+      if (!draftMentions.isEmpty()) {
+        drafts.add(new Draft(Draft.MENTION, Base64.encodeBytes(MentionUtil.mentionsToBodyRangeList(draftMentions).toByteArray())));
+      }
     }
 
     for (Slide slide : attachmentManager.buildSlideDeck().getSlides()) {
@@ -2187,7 +2232,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
   }
 
   private void calculateCharactersRemaining() {
-    String          messageBody     = composeText.getTextTrimmed();
+    String          messageBody     = composeText.getTextTrimmed().toString();
     TransportOption transportOption = sendButton.getSelectedTransport();
     CharacterState  characterState  = transportOption.calculateCharacters(messageBody);
 
@@ -2270,7 +2315,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
   }
 
   private String getMessage() throws InvalidMessageException {
-    String rawText = composeText.getTextTrimmed();
+    String rawText = composeText.getTextTrimmed().toString();
 
     if (rawText.length() < 1 && !attachmentManager.isAttachmentPresent())
       throw new InvalidMessageException(getString(R.string.ConversationActivity_message_is_empty_exclamation));
@@ -2339,6 +2384,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
                                        recipient.isGroup()                     ||
                                        recipient.getEmail().isPresent()        ||
                                        inputPanel.getQuote().isPresent()       ||
+                                       composeText.hasMentions()               ||
                                        linkPreviewViewModel.hasLinkPreview()   ||
                                        needsSplit;
 
@@ -2369,9 +2415,10 @@ public class ConversationActivity extends PassphraseRequiredActivity
   private void sendMediaMessage(@NonNull MediaSendActivityResult result) {
     long                 expiresIn     = recipient.get().getExpireMessages() * 1000L;
     QuoteModel           quote         = result.isViewOnce() ? null : inputPanel.getQuote().orNull();
+    List<Mention>        mentions      = new ArrayList<>(result.getMentions());
     boolean              initiating    = threadId == -1;
-    OutgoingMediaMessage message       = new OutgoingMediaMessage(recipient.get(), new SlideDeck(), result.getBody(), System.currentTimeMillis(), -1, expiresIn, result.isViewOnce(), distributionType, quote, Collections.emptyList(), Collections.emptyList());
+    OutgoingMediaMessage message       = new OutgoingMediaMessage(recipient.get(), new SlideDeck(), result.getBody(), System.currentTimeMillis(), -1, expiresIn, result.isViewOnce(), distributionType, quote, Collections.emptyList(), Collections.emptyList(), mentions);
-    OutgoingMediaMessage secureMessage = new OutgoingSecureMediaMessage(message                                                                                                                                                                                      );
+    OutgoingMediaMessage secureMessage = new OutgoingSecureMediaMessage(message);
 
     ApplicationContext.getInstance(this).getTypingStatusSender().onTypingStopped(threadId);
 
@@ -2395,7 +2442,18 @@ public class ConversationActivity extends PassphraseRequiredActivity
       throws InvalidMessageException
   {
     Log.i(TAG, "Sending media message...");
-    sendMediaMessage(forceSms, getMessage(), attachmentManager.buildSlideDeck(), inputPanel.getQuote().orNull(), Collections.emptyList(), linkPreviewViewModel.getActiveLinkPreviews(), expiresIn, viewOnce, subscriptionId, initiating, true);
+    sendMediaMessage(forceSms,
+                     getMessage(),
+                     attachmentManager.buildSlideDeck(),
+                     inputPanel.getQuote().orNull(),
+                     Collections.emptyList(),
+                     linkPreviewViewModel.getActiveLinkPreviews(),
+                     composeText.getMentions(),
+                     expiresIn,
+                     viewOnce,
+                     subscriptionId,
+                     initiating,
+                     true);
   }
 
   private ListenableFuture<Void> sendMediaMessage(final boolean forceSms,
@@ -2404,6 +2462,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
                                                   QuoteModel quote,
                                                   List<Contact> contacts,
                                                   List<LinkPreview> previews,
+                                                  List<Mention> mentions,
                                                   final long expiresIn,
                                                   final boolean viewOnce,
                                                   final int subscriptionId,
@@ -2424,7 +2483,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
       }
     }
 
-    OutgoingMediaMessage outgoingMessageCandidate = new OutgoingMediaMessage(recipient.get(), slideDeck, body, System.currentTimeMillis(), subscriptionId, expiresIn, viewOnce, distributionType, quote, contacts, previews);
+    OutgoingMediaMessage outgoingMessageCandidate = new OutgoingMediaMessage(recipient.get(), slideDeck, body, System.currentTimeMillis(), subscriptionId, expiresIn, viewOnce, distributionType, quote, contacts, previews, mentions);
 
     final SettableFuture<Void> future  = new SettableFuture<>();
     final Context              context = getApplicationContext();
@@ -2543,7 +2602,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
   private void updateLinkPreviewState() {
     if (TextSecurePreferences.isLinkPreviewsEnabled(this) && !sendButton.getSelectedTransport().isSms() && !attachmentManager.isAttachmentPresent()) {
       linkPreviewViewModel.onEnabled();
-      linkPreviewViewModel.onTextChanged(this, composeText.getTextTrimmed(), composeText.getSelectionStart(), composeText.getSelectionEnd());
+      linkPreviewViewModel.onTextChanged(this, composeText.getTextTrimmed().toString(), composeText.getSelectionStart(), composeText.getSelectionEnd());
     } else {
       linkPreviewViewModel.onUserCancel();
     }
@@ -2611,7 +2670,20 @@ public class ConversationActivity extends PassphraseRequiredActivity
         SlideDeck  slideDeck      = new SlideDeck();
         slideDeck.addSlide(audioSlide);
 
-        sendMediaMessage(forceSms, "", slideDeck, inputPanel.getQuote().orNull(), Collections.emptyList(), Collections.emptyList(), expiresIn, false, subscriptionId, initiating, true).addListener(new AssertedSuccessListener<Void>() {
+        ListenableFuture<Void> sendResult = sendMediaMessage(forceSms,
+                                                             "",
+                                                             slideDeck,
+                                                             inputPanel.getQuote().orNull(),
+                                                             Collections.emptyList(),
+                                                             Collections.emptyList(),
+                                                             composeText.getMentions(),
+                                                             expiresIn,
+                                                             false,
+                                                             subscriptionId,
+                                                             initiating,
+                                                             true);
+
+        sendResult.addListener(new AssertedSuccessListener<Void>() {
           @Override
           public void onSuccess(Void nothing) {
             new AsyncTask<Void, Void, Void>() {
@@ -2700,7 +2772,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
 
   @Override
   public void onCursorPositionChanged(int start, int end) {
-    linkPreviewViewModel.onTextChanged(this, composeText.getTextTrimmed(), start, end);
+    linkPreviewViewModel.onTextChanged(this, composeText.getTextTrimmed().toString(), start, end);
   }
 
   @Override
@@ -2740,7 +2812,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
 
     slideDeck.addSlide(stickerSlide);
 
-    sendMediaMessage(transport.isSms(), "", slideDeck, null, Collections.emptyList(), Collections.emptyList(), expiresIn, false, subscriptionId, initiating, clearCompose);
+    sendMediaMessage(transport.isSms(), "", slideDeck, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList(), expiresIn, false, subscriptionId, initiating, clearCompose);
   }
 
   private void silentlySetComposeText(String text) {
@@ -2969,7 +3041,9 @@ public class ConversationActivity extends PassphraseRequiredActivity
   }
 
   @Override
-  public void handleReplyMessage(MessageRecord messageRecord) {
+  public void handleReplyMessage(ConversationMessage conversationMessage) {
+    MessageRecord messageRecord = conversationMessage.getMessageRecord();
+
     Recipient author;
 
     if (messageRecord.isOutgoing()) {
@@ -3005,7 +3079,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
       inputPanel.setQuote(GlideApp.with(this),
                           messageRecord.getDateSent(),
                           author,
-                          messageRecord.getBody(),
+                          conversationMessage.getDisplayBody(this),
                           slideDeck);
     } else {
       SlideDeck slideDeck = messageRecord.isMms() ? ((MmsMessageRecord) messageRecord).getSlideDeck() : new SlideDeck();
@@ -3019,7 +3093,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
       inputPanel.setQuote(GlideApp.with(this),
                           messageRecord.getDateSent(),
                           author,
-                          messageRecord.getBody(),
+                          conversationMessage.getDisplayBody(this),
                           slideDeck);
     }
 
@@ -3186,6 +3260,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
                      quote,
                      Collections.emptyList(),
                      Collections.emptyList(),
+                     composeText.getMentions(),
                      expiresIn,
                      false,
                      subscriptionId,
@@ -3244,7 +3319,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
     }
   }
 
-  private class QuoteRestorationTask extends AsyncTask<Void, Void, MessageRecord> {
+  private class QuoteRestorationTask extends AsyncTask<Void, Void, ConversationMessage> {
 
     private final String                  serialized;
     private final SettableFuture<Boolean> future;
@@ -3255,20 +3330,27 @@ public class ConversationActivity extends PassphraseRequiredActivity
     }
 
     @Override
-    protected MessageRecord doInBackground(Void... voids) {
+    protected ConversationMessage doInBackground(Void... voids) {
       QuoteId quoteId = QuoteId.deserialize(ConversationActivity.this, serialized);
 
-      if (quoteId != null) {
+      if (quoteId == null) {
-        return DatabaseFactory.getMmsSmsDatabase(getApplicationContext()).getMessageFor(quoteId.getId(), quoteId.getAuthor());
+        return null;
       }
 
-      return null;
+      Context context = getApplicationContext();
+
+      MessageRecord messageRecord = DatabaseFactory.getMmsSmsDatabase(context).getMessageFor(quoteId.getId(), quoteId.getAuthor());
+      if (messageRecord == null) {
+        return null;
+      }
+
+      return ConversationMessageFactory.createWithUnresolvedData(context, messageRecord);
     }
 
     @Override
-    protected void onPostExecute(MessageRecord messageRecord) {
+    protected void onPostExecute(ConversationMessage conversationMessage) {
-      if (messageRecord != null) {
+      if (conversationMessage != null) {
-        handleReplyMessage(messageRecord);
+        handleReplyMessage(conversationMessage);
         future.set(true);
       } else {
         Log.e(TAG, "Failed to restore a quote from a draft. No matching message record.");

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java

@@ -4,14 +4,17 @@ import android.content.Context;
 import android.database.ContentObserver;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.paging.DataSource;
 import androidx.paging.PositionalDataSource;
 
 import com.annimon.stream.Stream;
 
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.database.DatabaseContentProviders;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.MmsSmsDatabase;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.util.concurrent.SignalExecutors;
@@ -19,7 +22,11 @@ import org.thoughtcrime.securesms.util.paging.Invalidator;
 import org.thoughtcrime.securesms.util.paging.SizeFixResult;
 
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedList;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.Executor;
 
 /**
@@ -66,19 +73,24 @@ class ConversationDataSource extends PositionalDataSource<ConversationMessage> {
     int                 totalCount     = db.getConversationCount(threadId);
     int                 effectiveCount = params.requestedStartPosition;
 
+    MentionHelper mentionHelper = new MentionHelper();
+
     try (MmsSmsDatabase.Reader reader = db.readerFor(db.getConversation(threadId, params.requestedStartPosition, params.requestedLoadSize))) {
       MessageRecord record;
       while ((record = reader.getNext()) != null && effectiveCount < totalCount && !isInvalid()) {
         records.add(record);
+        mentionHelper.add(record);
         effectiveCount++;
       }
     }
 
+    mentionHelper.fetchMentions(context);
+
     if (!isInvalid()) {
       SizeFixResult<MessageRecord> result = SizeFixResult.ensureMultipleOfPageSize(records, params.requestedStartPosition, params.pageSize, totalCount);
 
       List<ConversationMessage> items = Stream.of(result.getItems())
-                                              .map(ConversationMessage::new)
+                                              .map(m -> ConversationMessageFactory.createWithUnresolvedData(context, m, mentionHelper.getMentions(m.getId())))
                                               .toList();
 
       callback.onResult(items, params.requestedStartPosition, result.getTotal());
@@ -92,24 +104,48 @@ class ConversationDataSource extends PositionalDataSource<ConversationMessage> {
   public void loadRange(@NonNull LoadRangeParams params, @NonNull LoadRangeCallback<ConversationMessage> callback) {
     long start = System.currentTimeMillis();
 
-    MmsSmsDatabase      db      = DatabaseFactory.getMmsSmsDatabase(context);
+    MmsSmsDatabase      db            = DatabaseFactory.getMmsSmsDatabase(context);
-    List<MessageRecord> records = new ArrayList<>(params.loadSize);
+    List<MessageRecord> records       = new ArrayList<>(params.loadSize);
+    MentionHelper       mentionHelper = new MentionHelper();
 
     try (MmsSmsDatabase.Reader reader = db.readerFor(db.getConversation(threadId, params.startPosition, params.loadSize))) {
       MessageRecord record;
       while ((record = reader.getNext()) != null && !isInvalid()) {
         records.add(record);
+        mentionHelper.add(record);
       }
     }
 
+    mentionHelper.fetchMentions(context);
+
     List<ConversationMessage> items = Stream.of(records)
-                                            .map(ConversationMessage::new)
+                                            .map(m -> ConversationMessageFactory.createWithUnresolvedData(context, m, mentionHelper.getMentions(m.getId())))
                                             .toList();
     callback.onResult(items);
 
     Log.d(TAG, "[Update] " + (System.currentTimeMillis() - start) + " ms | thread: " + threadId + ", start: " + params.startPosition + ", size: " + params.loadSize + (isInvalid() ? " -- invalidated" : ""));
   }
 
+  private static class MentionHelper {
+
+    private Collection<Long>         messageIds          = new LinkedList<>();
+    private Map<Long, List<Mention>> messageIdToMentions = new HashMap<>();
+
+    void add(MessageRecord record) {
+      if (record.isMms()) {
+        messageIds.add(record.getId());
+      }
+    }
+
+    void fetchMentions(Context context) {
+      messageIdToMentions = DatabaseFactory.getMentionDatabase(context).getMentionsForMessages(messageIds);
+    }
+
+    @Nullable List<Mention> getMentions(long id) {
+      return messageIdToMentions.get(id);
+    }
+  }
+
   static class Factory extends DataSource.Factory<Integer, ConversationMessage> {
 
     private final Context             context;

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationFragment.java

@@ -18,6 +18,8 @@ package org.thoughtcrime.securesms.conversation;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
+import android.content.ClipData;
+import android.content.ClipboardManager;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
@@ -25,7 +27,7 @@ import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Build;
 import android.os.Bundle;
-import android.text.ClipboardManager;
+import android.text.SpannableStringBuilder;
 import android.text.TextUtils;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -72,6 +74,7 @@ import org.thoughtcrime.securesms.contactshare.ContactUtil;
 import org.thoughtcrime.securesms.contactshare.SharedContactDetailsActivity;
 import org.thoughtcrime.securesms.conversation.ConversationAdapter.ItemClickListener;
 import org.thoughtcrime.securesms.conversation.ConversationAdapter.StickyHeaderViewHolder;
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.MessagingDatabase;
 import org.thoughtcrime.securesms.database.RecipientDatabase;
@@ -128,7 +131,6 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
@@ -595,33 +597,25 @@ public class ConversationFragment extends LoggingFragment {
   }
 
   private void handleCopyMessage(final Set<ConversationMessage> conversationMessages) {
-    List<MessageRecord> messageList = Stream.of(conversationMessages).map(ConversationMessage::getMessageRecord).toList();
+    List<ConversationMessage> messageList = new ArrayList<>(conversationMessages);
-    Collections.sort(messageList, new Comparator<MessageRecord>() {
+    Collections.sort(messageList, (lhs, rhs) -> Long.compare(lhs.getMessageRecord().getDateReceived(), rhs.getMessageRecord().getDateReceived()));
-      @Override
-      public int compare(MessageRecord lhs, MessageRecord rhs) {
-        if      (lhs.getDateReceived() < rhs.getDateReceived())  return -1;
-        else if (lhs.getDateReceived() == rhs.getDateReceived()) return 0;
-        else                                                     return 1;
-      }
-    });
 
-    StringBuilder    bodyBuilder = new StringBuilder();
+    SpannableStringBuilder bodyBuilder = new SpannableStringBuilder();
-    ClipboardManager clipboard   = (ClipboardManager) getActivity().getSystemService(Context.CLIPBOARD_SERVICE);
+    ClipboardManager       clipboard   = (ClipboardManager) requireActivity().getSystemService(Context.CLIPBOARD_SERVICE);
 
-    for (MessageRecord messageRecord : messageList) {
+    for (ConversationMessage message : messageList) {
-      String body = messageRecord.getDisplayBody(requireContext()).toString();
+      CharSequence body = message.getDisplayBody(requireContext());
       if (!TextUtils.isEmpty(body)) {
-        bodyBuilder.append(body).append('\n');
+        if (bodyBuilder.length() > 0) {
+          bodyBuilder.append('\n');
+        }
+        bodyBuilder.append(body);
       }
     }
-    if (bodyBuilder.length() > 0 && bodyBuilder.charAt(bodyBuilder.length() - 1) == '\n') {
+
-      bodyBuilder.deleteCharAt(bodyBuilder.length() - 1);
+    if (!TextUtils.isEmpty(bodyBuilder)) {
+      clipboard.setPrimaryClip(ClipData.newPlainText(null, bodyBuilder));
     }
-
-    String result = bodyBuilder.toString();
-
-    if (!TextUtils.isEmpty(result))
-        clipboard.setText(result);
   }
 
   private void handleDeleteMessages(final Set<ConversationMessage> conversationMessages) {
@@ -746,8 +740,7 @@ public class ConversationFragment extends LoggingFragment {
   }
 
   private void handleForwardMessage(ConversationMessage conversationMessage) {
-    MessageRecord message = conversationMessage.getMessageRecord();
+    if (conversationMessage.getMessageRecord().isViewOnce()) {
-    if (message.isViewOnce()) {
       throw new AssertionError("Cannot forward a view-once message.");
     }
 
@@ -755,10 +748,10 @@ public class ConversationFragment extends LoggingFragment {
 
     SimpleTask.run(getLifecycle(), () -> {
       Intent composeIntent = new Intent(getActivity(), ShareActivity.class);
-      composeIntent.putExtra(Intent.EXTRA_TEXT, message.getDisplayBody(requireContext()).toString());
+      composeIntent.putExtra(Intent.EXTRA_TEXT, conversationMessage.getDisplayBody(requireContext()));
 
-      if (message.isMms()) {
+      if (conversationMessage.getMessageRecord().isMms()) {
-        MmsMessageRecord mediaMessage = (MmsMessageRecord) message;
+        MmsMessageRecord mediaMessage = (MmsMessageRecord) conversationMessage.getMessageRecord();
         boolean          isAlbum      = mediaMessage.containsMediaSlide()                      &&
                                         mediaMessage.getSlideDeck().getSlides().size() > 1     &&
                                         mediaMessage.getSlideDeck().getAudioSlide() == null    &&
@@ -788,7 +781,7 @@ public class ConversationFragment extends LoggingFragment {
                                       Optional.fromNullable(attachment.getCaption()),
                                       Optional.absent()));
             }
-          };
+          }
 
           if (!mediaList.isEmpty()) {
             composeIntent.putExtra(ConversationActivity.MEDIA_EXTRA, mediaList);
@@ -835,7 +828,7 @@ public class ConversationFragment extends LoggingFragment {
       ((AppCompatActivity) getActivity()).getSupportActionBar().collapseActionView();
     }
 
-    listener.handleReplyMessage(message.getMessageRecord());
+    listener.handleReplyMessage(message);
   }
 
   private void handleSaveAttachment(final MediaMmsMessageRecord message) {
@@ -875,7 +868,7 @@ public class ConversationFragment extends LoggingFragment {
     if (getListAdapter() != null) {
       clearHeaderIfNotTyping(getListAdapter());
       setLastSeen(0);
-      getListAdapter().addFastRecord(new ConversationMessage(messageRecord));
+      getListAdapter().addFastRecord(ConversationMessageFactory.createWithResolvedData(messageRecord, messageRecord.getDisplayBody(requireContext()), message.getMentions()));
       list.post(() -> list.scrollToPosition(0));
     }
 
@@ -888,7 +881,7 @@ public class ConversationFragment extends LoggingFragment {
     if (getListAdapter() != null) {
       clearHeaderIfNotTyping(getListAdapter());
       setLastSeen(0);
-      getListAdapter().addFastRecord(new ConversationMessage(messageRecord));
+      getListAdapter().addFastRecord(ConversationMessageFactory.createWithResolvedData(messageRecord));
       list.post(() -> list.scrollToPosition(0));
     }
 
@@ -1017,7 +1010,7 @@ public class ConversationFragment extends LoggingFragment {
 
   public interface ConversationFragmentListener {
     void setThreadId(long threadId);
-    void handleReplyMessage(MessageRecord messageRecord);
+    void handleReplyMessage(ConversationMessage conversationMessage);
     void onMessageActionToolbarOpened();
     void onForwardClicked();
     void onMessageRequest(@NonNull MessageRequestViewModel viewModel);
@@ -1306,7 +1299,7 @@ public class ConversationFragment extends LoggingFragment {
     }
 
     @Override
-    public void onGroupMemberAvatarClicked(@NonNull RecipientId recipientId, @NonNull GroupId groupId) {
+    public void onGroupMemberClicked(@NonNull RecipientId recipientId, @NonNull GroupId groupId) {
       if (getContext() == null) return;
 
       RecipientBottomSheetDialogFragment.create(recipientId, groupId).show(requireFragmentManager(), "BOTTOM");

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationItem.java

@@ -26,6 +26,7 @@ import android.graphics.PorterDuff;
 import android.graphics.Rect;
 import android.graphics.Typeface;
 import android.net.Uri;
+import android.text.Annotation;
 import android.text.Spannable;
 import android.text.SpannableString;
 import android.text.SpannableStringBuilder;
@@ -71,6 +72,7 @@ import org.thoughtcrime.securesms.components.QuoteView;
 import org.thoughtcrime.securesms.components.SharedContactView;
 import org.thoughtcrime.securesms.components.BorderlessImageView;
 import org.thoughtcrime.securesms.components.emoji.EmojiTextView;
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
 import org.thoughtcrime.securesms.contactshare.Contact;
 import org.thoughtcrime.securesms.database.AttachmentDatabase;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
@@ -552,7 +554,7 @@ public class ConversationItem extends LinearLayout implements BindableConversati
     } else if (isCaptionlessMms(messageRecord)) {
       bodyText.setVisibility(View.GONE);
     } else {
-      Spannable styledText = linkifyMessageBody(messageRecord.getDisplayBody(getContext()), batchSelected.isEmpty());
+      Spannable styledText = linkifyMessageBody(conversationMessage.getDisplayBody(getContext()), batchSelected.isEmpty());
       styledText = SearchUtil.getHighlightedSpan(locale, () -> new BackgroundColorSpan(Color.YELLOW), styledText, searchQuery);
       styledText = SearchUtil.getHighlightedSpan(locale, () -> new ForegroundColorSpan(Color.BLACK), styledText, searchQuery);
 
@@ -855,7 +857,7 @@ public class ConversationItem extends LinearLayout implements BindableConversati
 
     contactPhoto.setOnClickListener(v -> {
       if (eventListener != null) {
-        eventListener.onGroupMemberAvatarClicked(recipientId, conversationRecipient.get().requireGroupId());
+        eventListener.onGroupMemberClicked(recipientId, conversationRecipient.get().requireGroupId());
       }
     });
 
@@ -879,6 +881,12 @@ public class ConversationItem extends LinearLayout implements BindableConversati
         messageBody.setSpan(new LongClickCopySpan(urlSpan.getURL()), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
       }
     }
+
+    List<Annotation> mentionAnnotations = MentionAnnotation.getMentionAnnotations(messageBody);
+    for (Annotation annotation : mentionAnnotations) {
+      messageBody.setSpan(new MentionClickableSpan(RecipientId.from(annotation.getValue())), messageBody.getSpanStart(annotation), messageBody.getSpanEnd(annotation), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+
     return messageBody;
   }
 
@@ -901,7 +909,7 @@ public class ConversationItem extends LinearLayout implements BindableConversati
       }
       Quote quote = ((MediaMmsMessageRecord)current).getQuote();
       //noinspection ConstantConditions
-      quoteView.setQuote(glideRequests, quote.getId(), Recipient.live(quote.getAuthor()).get(), quote.getText(), quote.isOriginalMissing(), quote.getAttachment());
+      quoteView.setQuote(glideRequests, quote.getId(), Recipient.live(quote.getAuthor()).get(), quote.getDisplayText(), quote.isOriginalMissing(), quote.getAttachment());
       quoteView.setVisibility(View.VISIBLE);
       quoteView.getLayoutParams().width = ViewGroup.LayoutParams.WRAP_CONTENT;
 
@@ -1405,6 +1413,24 @@ public class ConversationItem extends LinearLayout implements BindableConversati
     }
   }
 
+  private class MentionClickableSpan extends ClickableSpan {
+    private final RecipientId mentionedRecipientId;
+
+    MentionClickableSpan(RecipientId mentionedRecipientId) {
+      this.mentionedRecipientId = mentionedRecipientId;
+    }
+
+    @Override
+    public void onClick(@NonNull View widget) {
+      if (eventListener != null && !Recipient.resolved(mentionedRecipientId).isLocalNumber()) {
+        eventListener.onGroupMemberClicked(mentionedRecipientId, conversationRecipient.get().requireGroupId());
+      }
+    }
+
+    @Override
+    public void updateDrawState(@NonNull TextPaint ds) { }
+  }
+
   private void handleMessageApproval() {
     final int title;
     final int message;

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationMessage.java

@@ -1,27 +1,58 @@
 package org.thoughtcrime.securesms.conversation;
 
-import androidx.annotation.NonNull;
+import android.content.Context;
+import android.text.SpannableString;
 
+import androidx.annotation.AnyThread;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
+import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.MentionUtil;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.util.Conversions;
 
 import java.security.MessageDigest;
+import java.util.Collections;
+import java.util.List;
 
 /**
  * A view level model used to pass arbitrary message related information needed
  * for various presentations.
  */
 public class ConversationMessage {
-  private final MessageRecord messageRecord;
+  @NonNull  private final MessageRecord   messageRecord;
+  @NonNull  private final List<Mention>   mentions;
+  @Nullable private final SpannableString body;
 
-  public ConversationMessage(@NonNull MessageRecord messageRecord) {
+  private ConversationMessage(@NonNull MessageRecord messageRecord) {
+    this(messageRecord, null, null);
+  }
+
+  private ConversationMessage(@NonNull MessageRecord messageRecord,
+                              @Nullable CharSequence body,
+                              @Nullable List<Mention> mentions)
+  {
     this.messageRecord = messageRecord;
+    this.body          = body != null ? SpannableString.valueOf(body) : null;
+    this.mentions      = mentions != null ? mentions : Collections.emptyList();
+
+    if (!this.mentions.isEmpty() && this.body != null) {
+      MentionAnnotation.setMentionAnnotations(this.body, this.mentions);
+    }
   }
 
   public @NonNull MessageRecord getMessageRecord() {
     return messageRecord;
   }
 
+  public @NonNull List<Mention> getMentions() {
+    return mentions;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;
@@ -41,4 +72,74 @@ public class ConversationMessage {
 
     return Conversions.byteArrayToLong(bytes);
   }
+
+  public @NonNull SpannableString getDisplayBody(Context context) {
+    if (mentions.isEmpty() || body == null) {
+      return messageRecord.getDisplayBody(context);
+    }
+    return body;
+  }
+
+  /**
+   * Factory providing multiple ways of creating {@link ConversationMessage}s.
+   */
+  public static class ConversationMessageFactory {
+
+    /**
+     * Creates a {@link ConversationMessage} wrapping the provided MessageRecord. No database or
+     * heavy work performed as the message is assumed to not have any mentions.
+     */
+    @AnyThread
+    public static @NonNull ConversationMessage createWithResolvedData(@NonNull MessageRecord messageRecord) {
+      return new ConversationMessage(messageRecord);
+    }
+
+    /**
+     * Creates a {@link ConversationMessage} wrapping the provided MessageRecord, potentially annotated body, and
+     * list of actual mentions. No database or heavy work performed as the body and mentions are assumed to be
+     * fully updated with display names.
+     *
+     * @param body     Contains appropriate {@link MentionAnnotation}s and is updated with actual profile names.
+     * @param mentions List of actual mentions (i.e., not placeholder) matching annotation ranges in body.
+     */
+    @AnyThread
+    public static @NonNull ConversationMessage createWithResolvedData(@NonNull MessageRecord messageRecord, @Nullable CharSequence body, @Nullable List<Mention> mentions) {
+      if (messageRecord.isMms() && mentions != null && !mentions.isEmpty()) {
+        return new ConversationMessage(messageRecord, body, mentions);
+      }
+      return createWithResolvedData(messageRecord);
+    }
+
+    /**
+     * Creates a {@link ConversationMessage} wrapping the provided MessageRecord and will update and modify the provided
+     * mentions from placeholder to actual. This method may perform database operations to resolve mentions to display names.
+     *
+     * @param mentions List of placeholder mentions to be used to update the body in the provided MessageRecord.
+     */
+    @WorkerThread
+    public static @NonNull ConversationMessage createWithUnresolvedData(@NonNull Context context, @NonNull MessageRecord messageRecord, @Nullable List<Mention> mentions) {
+      if (messageRecord.isMms() && mentions != null && !mentions.isEmpty()) {
+        MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithDisplayNames(context, messageRecord, mentions);
+        return new ConversationMessage(messageRecord, updated.getBody(), updated.getMentions());
+      }
+      return createWithResolvedData(messageRecord);
+    }
+
+    /**
+     * Creates a {@link ConversationMessage} wrapping the provided MessageRecord, and will query for potential mentions. If mentions
+     * are found, the body of the provided message will be updated and modified to match actual mentions. This will perform
+     * database operations to query for mentions and then to resolve mentions to display names.
+     */
+    @WorkerThread
+    public static @NonNull ConversationMessage createWithUnresolvedData(@NonNull Context context, @NonNull MessageRecord messageRecord) {
+      if (messageRecord.isMms()) {
+        List<Mention> mentions = DatabaseFactory.getMentionDatabase(context).getMentionsForMessage(messageRecord.getId());
+        if (!mentions.isEmpty()) {
+          MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithDisplayNames(context, messageRecord, mentions);
+          return new ConversationMessage(messageRecord, updated.getBody(), updated.getMentions());
+        }
+      }
+      return createWithResolvedData(messageRecord);
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/conversation/ui/mentions/MentionViewHolder.java

@@ -16,20 +16,24 @@ public class MentionViewHolder extends MappingViewHolder<MentionViewState> {
 
   private final AvatarImageView avatar;
   private final TextView        name;
+  private final TextView        username;
+
   @Nullable private final MentionEventsListener mentionEventsListener;
 
   public MentionViewHolder(@NonNull View itemView, @Nullable MentionEventsListener mentionEventsListener) {
     super(itemView);
     this.mentionEventsListener = mentionEventsListener;
 
-    avatar = findViewById(R.id.mention_recipient_avatar);
+    avatar   = findViewById(R.id.mention_recipient_avatar);
-    name   = findViewById(R.id.mention_recipient_name);
+    name     = findViewById(R.id.mention_recipient_name);
+    username = findViewById(R.id.mention_recipient_username);
   }
 
   @Override
   public void bind(@NonNull MentionViewState model) {
     avatar.setRecipient(model.getRecipient());
     name.setText(model.getName(context));
+    username.setText(model.getUsername());
     itemView.setOnClickListener(v -> {
       if (mentionEventsListener != null) {
         mentionEventsListener.onMentionClicked(model.getRecipient());

app/src/main/java/org/thoughtcrime/securesms/conversation/ui/mentions/MentionViewState.java

@@ -7,6 +7,7 @@ import androidx.annotation.NonNull;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.util.MappingModel;
+import org.thoughtcrime.securesms.util.Util;
 
 import java.util.Objects;
 
@@ -26,6 +27,10 @@ public final class MentionViewState implements MappingModel<MentionViewState> {
     return recipient;
   }
 
+  @NonNull String getUsername() {
+    return Util.emptyIfNull(recipient.getDisplayUsername());
+  }
+
   @Override
   public boolean areItemsTheSame(@NonNull MentionViewState newItem) {
     return recipient.getId().equals(newItem.recipient.getId());

app/src/main/java/org/thoughtcrime/securesms/conversation/ui/mentions/MentionsPickerFragment.java

@@ -27,13 +27,15 @@ public class MentionsPickerFragment extends LoggingFragment {
   private RecyclerView              list;
   private BottomSheetBehavior<View> behavior;
   private MentionsPickerViewModel   viewModel;
+  private int                       defaultPeekHeight;
 
   @Override
   public @Nullable View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
     View view = inflater.inflate(R.layout.mentions_picker_fragment, container, false);
 
-    list     = view.findViewById(R.id.mentions_picker_list);
+    list              = view.findViewById(R.id.mentions_picker_list);
-    behavior = BottomSheetBehavior.from(view.findViewById(R.id.mentions_picker_bottom_sheet));
+    behavior          = BottomSheetBehavior.from(view.findViewById(R.id.mentions_picker_bottom_sheet));
+    defaultPeekHeight = view.getContext().getResources().getDimensionPixelSize(R.dimen.mentions_picker_peek_height);
 
     return view;
   }
@@ -72,13 +74,16 @@ public class MentionsPickerFragment extends LoggingFragment {
     if (mappingModels.isEmpty()) {
       updateBottomSheetBehavior(0);
     }
+    list.scrollToPosition(0);
   }
 
   private void updateBottomSheetBehavior(int count) {
     if (count > 0) {
       if (behavior.getPeekHeight() == 0) {
-        behavior.setPeekHeight(ViewUtil.dpToPx(240), true);
+        behavior.setPeekHeight(defaultPeekHeight, true);
         behavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
+      } else {
+        list.scrollToPosition(0);
       }
     } else {
       behavior.setState(BottomSheetBehavior.STATE_COLLAPSED);

app/src/main/java/org/thoughtcrime/securesms/conversation/ui/mentions/MentionsPickerRepository.java

@@ -0,0 +1,51 @@
+package org.thoughtcrime.securesms.conversation.ui.mentions;
+
+import android.content.Context;
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.WorkerThread;
+
+import com.annimon.stream.Stream;
+
+import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.RecipientDatabase;
+import org.thoughtcrime.securesms.groups.ui.GroupMemberEntry;
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+
+import java.util.Collections;
+import java.util.List;
+
+final class MentionsPickerRepository {
+
+  private final RecipientDatabase recipientDatabase;
+
+  MentionsPickerRepository(@NonNull Context context) {
+    recipientDatabase = DatabaseFactory.getRecipientDatabase(context);
+  }
+
+  @WorkerThread
+  @NonNull List<Recipient> search(MentionQuery mentionQuery) {
+    if (TextUtils.isEmpty(mentionQuery.query)) {
+      return Collections.emptyList();
+    }
+
+    List<RecipientId> recipientIds = Stream.of(mentionQuery.members)
+                                           .filterNot(m -> m.getMember().isLocalNumber())
+                                           .map(m -> m.getMember().getId())
+                                           .toList();
+
+    return recipientDatabase.queryRecipientsForMentions(mentionQuery.query, recipientIds);
+  }
+
+  static class MentionQuery {
+    private final String                            query;
+    private final List<GroupMemberEntry.FullMember> members;
+
+    MentionQuery(@NonNull String query, @NonNull List<GroupMemberEntry.FullMember> members) {
+      this.query   = query;
+      this.members = members;
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/conversation/ui/mentions/MentionsPickerViewModel.java

@@ -1,7 +1,5 @@
 package org.thoughtcrime.securesms.conversation.ui.mentions;
 
-import android.text.TextUtils;
-
 import androidx.annotation.NonNull;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
@@ -11,6 +9,7 @@ import androidx.lifecycle.ViewModelProvider;
 
 import com.annimon.stream.Stream;
 
+import org.thoughtcrime.securesms.conversation.ui.mentions.MentionsPickerRepository.MentionQuery;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.groups.LiveGroup;
@@ -20,7 +19,6 @@ import org.thoughtcrime.securesms.util.MappingModel;
 import org.thoughtcrime.securesms.util.SingleLiveEvent;
 import org.thoughtcrime.securesms.util.livedata.LiveDataUtil;
 
-import java.util.Collections;
 import java.util.List;
 
 public class MentionsPickerViewModel extends ViewModel {
@@ -28,17 +26,18 @@ public class MentionsPickerViewModel extends ViewModel {
   private final SingleLiveEvent<Recipient>      selectedRecipient;
   private final LiveData<List<MappingModel<?>>> mentionList;
   private final MutableLiveData<LiveGroup>      group;
-  private final MutableLiveData<CharSequence>   liveQuery;
+  private final MutableLiveData<String>         liveQuery;
 
-  MentionsPickerViewModel() {
+  MentionsPickerViewModel(@NonNull MentionsPickerRepository mentionsPickerRepository) {
     group             = new MutableLiveData<>();
     liveQuery         = new MutableLiveData<>();
     selectedRecipient = new SingleLiveEvent<>();
 
-    // TODO [cody] [mentions] simple query support implement for building UI/UX, to be replaced with better search before launch
+    LiveData<List<FullMember>> fullMembers  = Transformations.distinctUntilChanged(Transformations.switchMap(group, LiveGroup::getFullMembers));
-    LiveData<List<FullMember>> members = Transformations.distinctUntilChanged(Transformations.switchMap(group, LiveGroup::getFullMembers));
+    LiveData<String>           query        = Transformations.distinctUntilChanged(liveQuery);
+    LiveData<MentionQuery>     mentionQuery = LiveDataUtil.combineLatest(query, fullMembers, MentionQuery::new);
 
-    mentionList = LiveDataUtil.combineLatest(Transformations.distinctUntilChanged(liveQuery), members, this::filterMembers);
+    mentionList = LiveDataUtil.mapAsync(mentionQuery, q -> Stream.of(mentionsPickerRepository.search(q)).<MappingModel<?>>map(MentionViewState::new).toList());
   }
 
   @NonNull LiveData<List<MappingModel<?>>> getMentionList() {
@@ -54,7 +53,7 @@ public class MentionsPickerViewModel extends ViewModel {
   }
 
   public void onQueryChange(@NonNull CharSequence query) {
-    liveQuery.setValue(query);
+    liveQuery.setValue(query.toString());
   }
 
   public void onRecipientChange(@NonNull Recipient recipient) {
@@ -65,22 +64,11 @@ public class MentionsPickerViewModel extends ViewModel {
     }
   }
 
-  private @NonNull List<MappingModel<?>> filterMembers(@NonNull CharSequence query, @NonNull List<FullMember> members) {
-    if (TextUtils.isEmpty(query)) {
-      return Collections.emptyList();
-    }
-
-    return Stream.of(members)
-                 .filter(m -> m.getMember().getDisplayName(ApplicationDependencies.getApplication()).toLowerCase().replaceAll("\\s", "").startsWith(query.toString()))
-                 .<MappingModel<?>>map(m -> new MentionViewState(m.getMember()))
-                 .toList();
-  }
-
   public static final class Factory implements ViewModelProvider.Factory {
     @Override
     public @NonNull <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
       //noinspection ConstantConditions
-      return modelClass.cast(new MentionsPickerViewModel());
+      return modelClass.cast(new MentionsPickerViewModel(new MentionsPickerRepository(ApplicationDependencies.getApplication())));
     }
   }
 }

app/src/main/java/org/thoughtcrime/securesms/database/DatabaseFactory.java

@@ -63,6 +63,7 @@ public class DatabaseFactory {
   private final KeyValueDatabase        keyValueDatabase;
   private final MegaphoneDatabase       megaphoneDatabase;
   private final RemappedRecordsDatabase remappedRecordsDatabase;
+  private final MentionDatabase         mentionDatabase;
 
   public static DatabaseFactory getInstance(Context context) {
     synchronized (lock) {
@@ -165,6 +166,10 @@ public class DatabaseFactory {
     return getInstance(context).remappedRecordsDatabase;
   }
 
+  public static MentionDatabase getMentionDatabase(Context context) {
+    return getInstance(context).mentionDatabase;
+  }
+
   public static SQLiteDatabase getBackupDatabase(Context context) {
     return getInstance(context).databaseHelper.getReadableDatabase();
   }
@@ -214,6 +219,7 @@ public class DatabaseFactory {
     this.keyValueDatabase        = new KeyValueDatabase(context, databaseHelper);
     this.megaphoneDatabase       = new MegaphoneDatabase(context, databaseHelper);
     this.remappedRecordsDatabase = new RemappedRecordsDatabase(context, databaseHelper);
+    this.mentionDatabase         = new MentionDatabase(context, databaseHelper);
   }
 
   public void onApplicationLevelUpgrade(@NonNull Context context, @NonNull MasterSecret masterSecret,

app/src/main/java/org/thoughtcrime/securesms/database/DraftDatabase.java

@@ -4,6 +4,8 @@ import android.content.ContentValues;
 import android.content.Context;
 import android.database.Cursor;
 import android.net.Uri;
+
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import net.sqlcipher.database.SQLiteDatabase;
@@ -73,14 +75,11 @@ public class DraftDatabase extends Database {
     db.delete(TABLE_NAME, null, null);
   }
 
-  public List<Draft> getDrafts(long threadId) {
+  public Drafts getDrafts(long threadId) {
-    SQLiteDatabase db   = databaseHelper.getReadableDatabase();
+    SQLiteDatabase db      = databaseHelper.getReadableDatabase();
-    List<Draft> results = new LinkedList<>();
+    Drafts         results = new Drafts();
-    Cursor cursor       = null;
-
-    try {
-      cursor = db.query(TABLE_NAME, null, THREAD_ID + " = ?", new String[] {threadId+""}, null, null, null);
 
+    try (Cursor cursor = db.query(TABLE_NAME, null, THREAD_ID + " = ?", new String[] {threadId+""}, null, null, null)) {
       while (cursor != null && cursor.moveToNext()) {
         String type  = cursor.getString(cursor.getColumnIndexOrThrow(DRAFT_TYPE));
         String value = cursor.getString(cursor.getColumnIndexOrThrow(DRAFT_VALUE));
@@ -89,9 +88,6 @@ public class DraftDatabase extends Database {
       }
 
       return results;
-    } finally {
-      if (cursor != null)
-        cursor.close();
     }
   }
 
@@ -102,6 +98,7 @@ public class DraftDatabase extends Database {
     public static final String AUDIO    = "audio";
     public static final String LOCATION = "location";
     public static final String QUOTE    = "quote";
+    public static final String MENTION  = "mention";
 
     private final String type;
     private final String value;
@@ -133,7 +130,7 @@ public class DraftDatabase extends Database {
   }
 
   public static class Drafts extends LinkedList<Draft> {
-    private Draft getDraftOfType(String type) {
+    public @Nullable Draft getDraftOfType(String type) {
       for (Draft draft : this) {
         if (type.equals(draft.getType())) {
           return draft;
@@ -142,7 +139,7 @@ public class DraftDatabase extends Database {
       return null;
     }
 
-    public String getSnippet(Context context) {
+    public @NonNull String getSnippet(Context context) {
       Draft textDraft = getDraftOfType(Draft.TEXT);
       if (textDraft != null) {
         return textDraft.getSnippet(context);

app/src/main/java/org/thoughtcrime/securesms/database/MentionDatabase.java

@@ -0,0 +1,112 @@
+package org.thoughtcrime.securesms.database;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+
+import net.sqlcipher.database.SQLiteDatabase;
+
+import org.thoughtcrime.securesms.database.helpers.SQLCipherOpenHelper;
+import org.thoughtcrime.securesms.database.model.Mention;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+import org.thoughtcrime.securesms.util.CursorUtil;
+import org.thoughtcrime.securesms.util.SqlUtil;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+public class MentionDatabase extends Database {
+
+  private static final String TABLE_NAME = "mention";
+
+  private static final String ID           = "_id";
+  private static final String THREAD_ID    = "thread_id";
+  private static final String MESSAGE_ID   = "message_id";
+  private static final String RECIPIENT_ID = "recipient_id";
+  private static final String RANGE_START  = "range_start";
+  private static final String RANGE_LENGTH = "range_length";
+
+  public static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + "(" + ID           + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
+                                                                                 THREAD_ID    + " INTEGER, " +
+                                                                                 MESSAGE_ID   + " INTEGER, " +
+                                                                                 RECIPIENT_ID + " INTEGER, " +
+                                                                                 RANGE_START  + " INTEGER, " +
+                                                                                 RANGE_LENGTH + " INTEGER)";
+
+  public static final String[] CREATE_INDEXES = new String[] {
+    "CREATE INDEX IF NOT EXISTS mention_message_id_index ON " + TABLE_NAME + " (" + MESSAGE_ID + ");",
+    "CREATE INDEX IF NOT EXISTS mention_recipient_id_thread_id_index ON " + TABLE_NAME + " (" + RECIPIENT_ID + ", " + THREAD_ID + ");"
+  };
+
+  public MentionDatabase(@NonNull Context context, @NonNull SQLCipherOpenHelper databaseHelper) {
+    super(context, databaseHelper);
+  }
+
+  public void insert(long threadId, long messageId, @NonNull Collection<Mention> mentions) {
+    SQLiteDatabase db = databaseHelper.getWritableDatabase();
+
+    db.beginTransaction();
+    try {
+      for (Mention mention : mentions) {
+        ContentValues values = new ContentValues();
+        values.put(THREAD_ID, threadId);
+        values.put(MESSAGE_ID, messageId);
+        values.put(RECIPIENT_ID, mention.getRecipientId().toLong());
+        values.put(RANGE_START, mention.getStart());
+        values.put(RANGE_LENGTH, mention.getLength());
+        db.insert(TABLE_NAME, null, values);
+      }
+
+      db.setTransactionSuccessful();
+    } finally {
+      db.endTransaction();
+    }
+  }
+
+  public @NonNull List<Mention> getMentionsForMessage(long messageId) {
+    SQLiteDatabase db       = databaseHelper.getReadableDatabase();
+    List<Mention>  mentions = new LinkedList<>();
+
+    try (Cursor cursor = db.query(TABLE_NAME, null, MESSAGE_ID + " = ?", SqlUtil.buildArgs(messageId), null, null, null)) {
+      while (cursor != null && cursor.moveToNext()) {
+        mentions.add(new Mention(RecipientId.from(CursorUtil.requireLong(cursor, RECIPIENT_ID)),
+                                 CursorUtil.requireInt(cursor, RANGE_START),
+                                 CursorUtil.requireInt(cursor, RANGE_LENGTH)));
+      }
+    }
+
+    return mentions;
+  }
+
+  public @NonNull Map<Long, List<Mention>> getMentionsForMessages(@NonNull Collection<Long> messageIds) {
+    SQLiteDatabase           db       = databaseHelper.getReadableDatabase();
+    Map<Long, List<Mention>> mentions = new HashMap<>();
+
+    String ids = TextUtils.join(",", messageIds);
+
+    try (Cursor cursor = db.query(TABLE_NAME, null, MESSAGE_ID + " IN (" + ids + ")", null, null, null, null)) {
+      while (cursor != null && cursor.moveToNext()) {
+        long          messageId       = CursorUtil.requireLong(cursor, MESSAGE_ID);
+        List<Mention> messageMentions = mentions.get(messageId);
+
+        if (messageMentions == null) {
+          messageMentions = new LinkedList<>();
+          mentions.put(messageId, messageMentions);
+        }
+
+        messageMentions.add(new Mention(RecipientId.from(CursorUtil.requireLong(cursor, RECIPIENT_ID)),
+                                        CursorUtil.requireInt(cursor, RANGE_START),
+                                        CursorUtil.requireInt(cursor, RANGE_LENGTH)));
+      }
+    }
+
+    return mentions;
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/database/MentionUtil.java

@@ -0,0 +1,166 @@
+package org.thoughtcrime.securesms.database;
+
+import android.content.Context;
+import android.text.SpannableStringBuilder;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+
+import com.annimon.stream.Stream;
+import com.annimon.stream.function.Function;
+import com.google.protobuf.InvalidProtocolBufferException;
+
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.database.RecipientDatabase.MentionSetting;
+import org.thoughtcrime.securesms.database.model.Mention;
+import org.thoughtcrime.securesms.database.model.MessageRecord;
+import org.thoughtcrime.securesms.database.model.databaseprotos.BodyRangeList;
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+import org.whispersystems.signalservice.api.util.UuidUtil;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public final class MentionUtil {
+
+  public static final char   MENTION_STARTER     = '@';
+         static final String MENTION_PLACEHOLDER = "\uFFFC";
+
+  private MentionUtil() { }
+
+  @WorkerThread
+  public static @NonNull CharSequence updateBodyWithDisplayNames(@NonNull Context context, @NonNull MessageRecord messageRecord) {
+    return updateBodyWithDisplayNames(context, messageRecord, messageRecord.getDisplayBody(context));
+  }
+
+  @WorkerThread
+  public static @NonNull CharSequence updateBodyWithDisplayNames(@NonNull Context context, @NonNull MessageRecord messageRecord, @NonNull CharSequence body) {
+    if (messageRecord.isMms()) {
+      List<Mention> mentions = DatabaseFactory.getMentionDatabase(context).getMentionsForMessage(messageRecord.getId());
+      CharSequence  updated  = updateBodyAndMentionsWithDisplayNames(context, body, mentions).getBody();
+      if (updated != null) {
+        return updated;
+      }
+    }
+    return body;
+  }
+
+  @WorkerThread
+  public static @NonNull UpdatedBodyAndMentions updateBodyAndMentionsWithDisplayNames(@NonNull Context context, @NonNull MessageRecord messageRecord, @NonNull List<Mention> mentions) {
+    return updateBodyAndMentionsWithDisplayNames(context, messageRecord.getDisplayBody(context), mentions);
+  }
+
+  @WorkerThread
+  public static @NonNull UpdatedBodyAndMentions updateBodyAndMentionsWithDisplayNames(@NonNull Context context, @NonNull CharSequence body, @NonNull List<Mention> mentions) {
+    return update(body, mentions, m -> MENTION_STARTER + Recipient.resolved(m.getRecipientId()).getDisplayName(context));
+  }
+
+  public static @NonNull UpdatedBodyAndMentions updateBodyAndMentionsWithPlaceholders(@Nullable CharSequence body, @NonNull List<Mention> mentions) {
+    return update(body, mentions, m -> MENTION_PLACEHOLDER);
+  }
+
+  private static @NonNull UpdatedBodyAndMentions update(@Nullable CharSequence body, @NonNull List<Mention> mentions, @NonNull Function<Mention, CharSequence> replacementTextGenerator) {
+    if (body == null || mentions.isEmpty()) {
+      return new UpdatedBodyAndMentions(body, mentions);
+    }
+
+    SpannableStringBuilder updatedBody     = new SpannableStringBuilder();
+    List<Mention>          updatedMentions = new ArrayList<>();
+
+    Collections.sort(mentions);
+
+    int bodyIndex = 0;
+
+    for (Mention mention : mentions) {
+      updatedBody.append(body.subSequence(bodyIndex, mention.getStart()));
+      CharSequence replaceWith    = replacementTextGenerator.apply(mention);
+      Mention      updatedMention = new Mention(mention.getRecipientId(), updatedBody.length(), replaceWith.length());
+
+      updatedBody.append(replaceWith);
+      updatedMentions.add(updatedMention);
+
+      bodyIndex = mention.getStart() + mention.getLength();
+    }
+
+    if (bodyIndex < body.length()) {
+      updatedBody.append(body.subSequence(bodyIndex, body.length()));
+    }
+
+    return new UpdatedBodyAndMentions(updatedBody.toString(), updatedMentions);
+  }
+
+  public static @Nullable BodyRangeList mentionsToBodyRangeList(@Nullable List<Mention> mentions) {
+    if (mentions == null || mentions.isEmpty()) {
+      return null;
+    }
+
+    BodyRangeList.Builder builder = BodyRangeList.newBuilder();
+
+    for (Mention mention : mentions) {
+      String uuid = Recipient.resolved(mention.getRecipientId()).requireUuid().toString();
+      builder.addRanges(BodyRangeList.BodyRange.newBuilder()
+                                               .setMentionUuid(uuid)
+                                               .setStart(mention.getStart())
+                                               .setLength(mention.getLength()));
+    }
+
+    return builder.build();
+  }
+
+  public static @NonNull List<Mention> bodyRangeListToMentions(@NonNull Context context, @Nullable byte[] data) {
+    if (data != null) {
+      try {
+        return Stream.of(BodyRangeList.parseFrom(data).getRangesList())
+                     .filter(bodyRange -> bodyRange.getAssociatedValueCase() == BodyRangeList.BodyRange.AssociatedValueCase.MENTIONUUID)
+                     .map(mention -> {
+                       RecipientId id = Recipient.externalPush(context, UuidUtil.parseOrThrow(mention.getMentionUuid()), null, false).getId();
+                       return new Mention(id, mention.getStart(), mention.getLength());
+                     })
+                     .toList();
+      } catch (InvalidProtocolBufferException e) {
+        return Collections.emptyList();
+      }
+    } else {
+      return Collections.emptyList();
+    }
+  }
+
+  public static @NonNull String getMentionSettingDisplayValue(@NonNull Context context, @NonNull MentionSetting mentionSetting) {
+    switch (mentionSetting) {
+      case GLOBAL:
+        return context.getString(SignalStore.notificationSettings().isMentionNotifiesMeEnabled() ? R.string.GroupMentionSettingDialog_default_notify_me
+                                                                                                 : R.string.GroupMentionSettingDialog_default_dont_notify_me);
+      case ALWAYS_NOTIFY:
+        return context.getString(R.string.GroupMentionSettingDialog_always_notify_me);
+      case DO_NOT_NOTIFY:
+        return context.getString(R.string.GroupMentionSettingDialog_dont_notify_me);
+    }
+    throw new IllegalArgumentException("Unknown mention setting: " + mentionSetting);
+  }
+
+  public static class UpdatedBodyAndMentions {
+    @Nullable private final CharSequence  body;
+    @NonNull  private final List<Mention> mentions;
+
+    public UpdatedBodyAndMentions(@Nullable CharSequence body, @NonNull List<Mention> mentions) {
+      this.body     = body;
+      this.mentions = mentions;
+    }
+
+    public @Nullable CharSequence getBody() {
+      return body;
+    }
+
+    public @NonNull List<Mention> getMentions() {
+      return mentions;
+    }
+
+    @Nullable String getBodyAsString() {
+      return body != null ? body.toString() : null;
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/database/MmsDatabase.java

@@ -47,10 +47,12 @@ import org.thoughtcrime.securesms.database.documents.NetworkFailure;
 import org.thoughtcrime.securesms.database.documents.NetworkFailureList;
 import org.thoughtcrime.securesms.database.helpers.SQLCipherOpenHelper;
 import org.thoughtcrime.securesms.database.model.MediaMmsMessageRecord;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.database.model.NotificationMmsMessageRecord;
 import org.thoughtcrime.securesms.database.model.Quote;
 import org.thoughtcrime.securesms.database.model.ReactionRecord;
+import org.thoughtcrime.securesms.database.model.databaseprotos.BodyRangeList;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.jobs.TrimThreadJob;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
@@ -68,6 +70,7 @@ import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.revealable.ViewOnceExpirationInfo;
 import org.thoughtcrime.securesms.revealable.ViewOnceUtil;
+import org.thoughtcrime.securesms.util.CursorUtil;
 import org.thoughtcrime.securesms.util.JsonUtils;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 import org.thoughtcrime.securesms.util.Util;
@@ -109,9 +112,11 @@ public class MmsDatabase extends MessagingDatabase {
           static final String QUOTE_BODY       = "quote_body";
           static final String QUOTE_ATTACHMENT = "quote_attachment";
           static final String QUOTE_MISSING    = "quote_missing";
+          static final String QUOTE_MENTIONS   = "quote_mentions";
 
           static final String SHARED_CONTACTS = "shared_contacts";
           static final String LINK_PREVIEWS   = "previews";
+          static final String MENTIONS_SELF   = "mentions_self";
 
   public  static final String VIEW_ONCE       = "reveal_duration";
 
@@ -163,6 +168,7 @@ public class MmsDatabase extends MessagingDatabase {
                                                                                   QUOTE_BODY             + " TEXT, " +
                                                                                   QUOTE_ATTACHMENT       + " INTEGER DEFAULT -1, " +
                                                                                   QUOTE_MISSING          + " INTEGER DEFAULT 0, " +
+                                                                                  QUOTE_MENTIONS         + " BLOB DEFAULT NULL," +
                                                                                   SHARED_CONTACTS        + " TEXT, " +
                                                                                   UNIDENTIFIED           + " INTEGER DEFAULT 0, " +
                                                                                   LINK_PREVIEWS          + " TEXT, " +
@@ -170,7 +176,8 @@ public class MmsDatabase extends MessagingDatabase {
                                                                                   REACTIONS              + " BLOB DEFAULT NULL, " +
                                                                                   REACTIONS_UNREAD       + " INTEGER DEFAULT 0, " +
                                                                                   REACTIONS_LAST_SEEN    + " INTEGER DEFAULT -1, " +
-                                                                                  REMOTE_DELETED         + " INTEGER DEFAULT 0);";
+                                                                                  REMOTE_DELETED         + " INTEGER DEFAULT 0, " +
+                                                                                  MENTIONS_SELF          + " INTEGER DEFAULT 0);";
 
   public static final String[] CREATE_INDEXS = {
     "CREATE INDEX IF NOT EXISTS mms_thread_id_index ON " + TABLE_NAME + " (" + THREAD_ID + ");",
@@ -193,9 +200,9 @@ public class MmsDatabase extends MessagingDatabase {
       MESSAGE_SIZE, STATUS, TRANSACTION_ID,
       BODY, PART_COUNT, RECIPIENT_ID, ADDRESS_DEVICE_ID,
       DELIVERY_RECEIPT_COUNT, READ_RECEIPT_COUNT, MISMATCHED_IDENTITIES, NETWORK_FAILURE, SUBSCRIPTION_ID,
-      EXPIRES_IN, EXPIRE_STARTED, NOTIFIED, QUOTE_ID, QUOTE_AUTHOR, QUOTE_BODY, QUOTE_ATTACHMENT, QUOTE_MISSING,
+      EXPIRES_IN, EXPIRE_STARTED, NOTIFIED, QUOTE_ID, QUOTE_AUTHOR, QUOTE_BODY, QUOTE_ATTACHMENT, QUOTE_MISSING, QUOTE_MENTIONS,
       SHARED_CONTACTS, LINK_PREVIEWS, UNIDENTIFIED, VIEW_ONCE, REACTIONS, REACTIONS_UNREAD, REACTIONS_LAST_SEEN,
-      REMOTE_DELETED,
+      REMOTE_DELETED, MENTIONS_SELF,
       "json_group_array(json_object(" +
           "'" + AttachmentDatabase.ROW_ID + "', " + AttachmentDatabase.TABLE_NAME + "." + AttachmentDatabase.ROW_ID + ", " +
           "'" + AttachmentDatabase.UNIQUE_ID + "', " + AttachmentDatabase.TABLE_NAME + "." + AttachmentDatabase.UNIQUE_ID + ", " +
@@ -805,6 +812,7 @@ public class MmsDatabase extends MessagingDatabase {
       throws MmsException, NoSuchMessageException
   {
     AttachmentDatabase attachmentDatabase = DatabaseFactory.getAttachmentDatabase(context);
+    MentionDatabase    mentionDatabase    = DatabaseFactory.getMentionDatabase(context);
     Cursor             cursor             = null;
 
     try {
@@ -812,6 +820,7 @@ public class MmsDatabase extends MessagingDatabase {
 
       if (cursor != null && cursor.moveToNext()) {
         List<DatabaseAttachment> associatedAttachments = attachmentDatabase.getAttachmentsForMessage(messageId);
+        List<Mention>            mentions              = mentionDatabase.getMentionsForMessage(messageId);
 
         long             outboxType         = cursor.getLong(cursor.getColumnIndexOrThrow(MESSAGE_BOX));
         String           body               = cursor.getString(cursor.getColumnIndexOrThrow(BODY));
@@ -830,6 +839,7 @@ public class MmsDatabase extends MessagingDatabase {
         String            quoteText          = cursor.getString(cursor.getColumnIndexOrThrow(QUOTE_BODY));
         boolean           quoteMissing       = cursor.getInt(cursor.getColumnIndexOrThrow(QUOTE_MISSING)) == 1;
         List<Attachment>  quoteAttachments   = Stream.of(associatedAttachments).filter(Attachment::isQuote).map(a -> (Attachment)a).toList();
+        List<Mention>     quoteMentions      = parseQuoteMentions(cursor);
         List<Contact>     contacts           = getSharedContacts(cursor, associatedAttachments);
         Set<Attachment>   contactAttachments = new HashSet<>(Stream.of(contacts).map(Contact::getAvatarAttachment).filter(a -> a != null).toList());
         List<LinkPreview> previews           = getLinkPreviews(cursor, associatedAttachments);
@@ -846,7 +856,7 @@ public class MmsDatabase extends MessagingDatabase {
         QuoteModel                quote           = null;
 
         if (quoteId > 0 && quoteAuthor > 0 && (!TextUtils.isEmpty(quoteText) || !quoteAttachments.isEmpty())) {
-          quote = new QuoteModel(quoteId, RecipientId.from(quoteAuthor), quoteText, quoteMissing, quoteAttachments);
+          quote = new QuoteModel(quoteId, RecipientId.from(quoteAuthor), quoteText, quoteMissing, quoteAttachments, quoteMentions);
         }
 
         if (!TextUtils.isEmpty(mismatchDocument)) {
@@ -866,12 +876,12 @@ public class MmsDatabase extends MessagingDatabase {
         }
 
         if (body != null && (Types.isGroupQuit(outboxType) || Types.isGroupUpdate(outboxType))) {
-          return new OutgoingGroupUpdateMessage(recipient, new MessageGroupContext(body, Types.isGroupV2(outboxType)), attachments, timestamp, 0, false, quote, contacts, previews);
+          return new OutgoingGroupUpdateMessage(recipient, new MessageGroupContext(body, Types.isGroupV2(outboxType)), attachments, timestamp, 0, false, quote, contacts, previews, mentions);
         } else if (Types.isExpirationTimerUpdate(outboxType)) {
           return new OutgoingExpirationUpdateMessage(recipient, timestamp, expiresIn);
         }
 
-        OutgoingMediaMessage message = new OutgoingMediaMessage(recipient, body, attachments, timestamp, subscriptionId, expiresIn, viewOnce, distributionType, quote, contacts, previews, networkFailures, mismatches);
+        OutgoingMediaMessage message = new OutgoingMediaMessage(recipient, body, attachments, timestamp, subscriptionId, expiresIn, viewOnce, distributionType, quote, contacts, previews, mentions, networkFailures, mismatches);
 
         if (Types.isSecureType(outboxType)) {
           return new OutgoingSecureMediaMessage(message);
@@ -1000,10 +1010,15 @@ public class MmsDatabase extends MessagingDatabase {
 
     if (retrieved.getQuote() != null) {
       contentValues.put(QUOTE_ID, retrieved.getQuote().getId());
-      contentValues.put(QUOTE_BODY, retrieved.getQuote().getText());
+      contentValues.put(QUOTE_BODY, retrieved.getQuote().getText().toString());
       contentValues.put(QUOTE_AUTHOR, retrieved.getQuote().getAuthor().serialize());
       contentValues.put(QUOTE_MISSING, retrieved.getQuote().isOriginalMissing() ? 1 : 0);
 
+      BodyRangeList mentionsList = MentionUtil.mentionsToBodyRangeList(retrieved.getQuote().getMentions());
+      if (mentionsList != null) {
+        contentValues.put(QUOTE_MENTIONS, mentionsList.toByteArray());
+      }
+
       quoteAttachments = retrieved.getQuote().getAttachments();
     }
 
@@ -1012,7 +1027,7 @@ public class MmsDatabase extends MessagingDatabase {
       return Optional.absent();
     }
 
-    long messageId = insertMediaMessage(retrieved.getBody(), retrieved.getAttachments(), quoteAttachments, retrieved.getSharedContacts(), retrieved.getLinkPreviews(), contentValues, null);
+    long messageId = insertMediaMessage(threadId, retrieved.getBody(), retrieved.getAttachments(), quoteAttachments, retrieved.getSharedContacts(), retrieved.getLinkPreviews(), retrieved.getMentions(), contentValues, null);
 
     if (!Types.isExpirationTimerUpdate(mailbox)) {
       DatabaseFactory.getThreadDatabase(context).incrementUnread(threadId, 1);
@@ -1158,15 +1173,23 @@ public class MmsDatabase extends MessagingDatabase {
     List<Attachment> quoteAttachments = new LinkedList<>();
 
     if (message.getOutgoingQuote() != null) {
+      MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithPlaceholders(message.getOutgoingQuote().getText(), message.getOutgoingQuote().getMentions());
+
       contentValues.put(QUOTE_ID, message.getOutgoingQuote().getId());
       contentValues.put(QUOTE_AUTHOR, message.getOutgoingQuote().getAuthor().serialize());
-      contentValues.put(QUOTE_BODY, message.getOutgoingQuote().getText());
+      contentValues.put(QUOTE_BODY, updated.getBodyAsString());
       contentValues.put(QUOTE_MISSING, message.getOutgoingQuote().isOriginalMissing() ? 1 : 0);
 
+      BodyRangeList mentionsList = MentionUtil.mentionsToBodyRangeList(updated.getMentions());
+      if (mentionsList != null) {
+        contentValues.put(QUOTE_MENTIONS, mentionsList.toByteArray());
+      }
+
       quoteAttachments.addAll(message.getOutgoingQuote().getAttachments());
     }
 
-    long messageId = insertMediaMessage(message.getBody(), message.getAttachments(), quoteAttachments, message.getSharedContacts(), message.getLinkPreviews(), contentValues, insertListener);
+    MentionUtil.UpdatedBodyAndMentions updatedBodyAndMentions = MentionUtil.updateBodyAndMentionsWithPlaceholders(message.getBody(), message.getMentions());
+    long messageId = insertMediaMessage(threadId, updatedBodyAndMentions.getBodyAsString(), message.getAttachments(), quoteAttachments, message.getSharedContacts(), message.getLinkPreviews(), updatedBodyAndMentions.getMentions(), contentValues, insertListener);
 
     if (message.getRecipient().isGroup()) {
       OutgoingGroupUpdateMessage outgoingGroupUpdateMessage = (message instanceof OutgoingGroupUpdateMessage) ? (OutgoingGroupUpdateMessage) message : null;
@@ -1197,17 +1220,22 @@ public class MmsDatabase extends MessagingDatabase {
     return messageId;
   }
 
-  private long insertMediaMessage(@Nullable String body,
+  private long insertMediaMessage(long threadId,
+                                  @Nullable String body,
                                   @NonNull List<Attachment> attachments,
                                   @NonNull List<Attachment> quoteAttachments,
                                   @NonNull List<Contact> sharedContacts,
                                   @NonNull List<LinkPreview> linkPreviews,
+                                  @NonNull List<Mention> mentions,
                                   @NonNull ContentValues contentValues,
                                   @Nullable SmsDatabase.InsertListener insertListener)
       throws MmsException
   {
-    SQLiteDatabase     db            = databaseHelper.getWritableDatabase();
+    SQLiteDatabase     db              = databaseHelper.getWritableDatabase();
-    AttachmentDatabase partsDatabase = DatabaseFactory.getAttachmentDatabase(context);
+    AttachmentDatabase partsDatabase   = DatabaseFactory.getAttachmentDatabase(context);
+    MentionDatabase    mentionDatabase = DatabaseFactory.getMentionDatabase(context);
+
+    boolean mentionsSelf = Stream.of(mentions).filter(m -> Recipient.resolved(m.getRecipientId()).isLocalNumber()).findFirst().isPresent();
 
     List<Attachment> allAttachments     = new LinkedList<>();
     List<Attachment> contactAttachments = Stream.of(sharedContacts).map(Contact::getAvatarAttachment).filter(a -> a != null).toList();
@@ -1219,11 +1247,14 @@ public class MmsDatabase extends MessagingDatabase {
 
     contentValues.put(BODY, body);
     contentValues.put(PART_COUNT, allAttachments.size());
+    contentValues.put(MENTIONS_SELF, mentionsSelf ? 1 : 0);
 
     db.beginTransaction();
     try {
       long messageId = db.insert(TABLE_NAME, null, contentValues);
 
+      mentionDatabase.insert(threadId, messageId, mentions);
+
       Map<Attachment, AttachmentId> insertedAttachments = partsDatabase.insertAttachmentsForMessage(messageId, allAttachments, quoteAttachments);
       String                        serializedContacts  = getSerializedSharedContacts(insertedAttachments, sharedContacts);
       String                        serializedPreviews  = getSerializedLinkPreviews(insertedAttachments, linkPreviews);
@@ -1468,6 +1499,12 @@ public class MmsDatabase extends MessagingDatabase {
     }
   }
 
+  private @NonNull List<Mention> parseQuoteMentions(Cursor cursor) {
+    byte[] raw = cursor.getBlob(cursor.getColumnIndexOrThrow(QUOTE_MENTIONS));
+
+    return MentionUtil.bodyRangeListToMentions(context, raw);
+  }
+
   public void beginTransaction() {
     databaseHelper.getWritableDatabase().beginTransaction();
   }
@@ -1542,6 +1579,16 @@ public class MmsDatabase extends MessagingDatabase {
     public MessageRecord getCurrent() {
       SlideDeck slideDeck = new SlideDeck(context, message.getAttachments());
 
+      CharSequence  quoteText     = message.getOutgoingQuote() != null ? message.getOutgoingQuote().getText() : null;
+      List<Mention> quoteMentions = message.getOutgoingQuote() != null ? message.getOutgoingQuote().getMentions() : Collections.emptyList();
+
+      if (quoteText != null && !quoteMentions.isEmpty()) {
+        MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithDisplayNames(context, quoteText, quoteMentions);
+
+        quoteText     = updated.getBody();
+        quoteMentions = updated.getMentions();
+      }
+
       return new MediaMmsMessageRecord(id,
                                        message.getRecipient(),
                                        message.getRecipient(),
@@ -1564,14 +1611,16 @@ public class MmsDatabase extends MessagingDatabase {
                                        message.getOutgoingQuote() != null ?
                                            new Quote(message.getOutgoingQuote().getId(),
                                                      message.getOutgoingQuote().getAuthor(),
-                                                     message.getOutgoingQuote().getText(),
+                                                     quoteText,
                                                      message.getOutgoingQuote().isOriginalMissing(),
-                                                     new SlideDeck(context, message.getOutgoingQuote().getAttachments())) :
+                                                     new SlideDeck(context, message.getOutgoingQuote().getAttachments()),
+                                                     quoteMentions) :
                                            null,
                                        message.getSharedContacts(),
                                        message.getLinkPreviews(),
                                        false,
                                        Collections.emptyList(),
+                                       false,
                                        false);
     }
   }
@@ -1665,6 +1714,7 @@ public class MmsDatabase extends MessagingDatabase {
       boolean              isViewOnce           = cursor.getLong(cursor.getColumnIndexOrThrow(MmsDatabase.VIEW_ONCE))   == 1;
       boolean              remoteDelete         = cursor.getLong(cursor.getColumnIndexOrThrow(MmsDatabase.REMOTE_DELETED))   == 1;
       List<ReactionRecord> reactions            = parseReactions(cursor);
+      boolean              mentionsSelf         = CursorUtil.requireBoolean(cursor, MENTIONS_SELF);
 
       if (!TextSecurePreferences.isReadReceiptsEnabled(context)) {
         readReceiptCount = 0;
@@ -1686,7 +1736,7 @@ public class MmsDatabase extends MessagingDatabase {
                                        threadId, body, slideDeck, partCount, box, mismatches,
                                        networkFailures, subscriptionId, expiresIn, expireStarted,
                                        isViewOnce, readReceiptCount, quote, contacts, previews, unidentified, reactions,
-                                       remoteDelete);
+                                       remoteDelete, mentionsSelf);
     }
 
     private List<IdentityKeyMismatch> getMismatchedIdentities(String document) {
@@ -1724,14 +1774,22 @@ public class MmsDatabase extends MessagingDatabase {
     private @Nullable Quote getQuote(@NonNull Cursor cursor) {
       long                       quoteId          = cursor.getLong(cursor.getColumnIndexOrThrow(MmsDatabase.QUOTE_ID));
       long                       quoteAuthor      = cursor.getLong(cursor.getColumnIndexOrThrow(MmsDatabase.QUOTE_AUTHOR));
-      String                     quoteText        = cursor.getString(cursor.getColumnIndexOrThrow(MmsDatabase.QUOTE_BODY));
+      CharSequence               quoteText        = cursor.getString(cursor.getColumnIndexOrThrow(MmsDatabase.QUOTE_BODY));
       boolean                    quoteMissing     = cursor.getInt(cursor.getColumnIndexOrThrow(MmsDatabase.QUOTE_MISSING)) == 1;
+      List<Mention>              quoteMentions    = parseQuoteMentions(cursor);
       List<DatabaseAttachment>   attachments      = DatabaseFactory.getAttachmentDatabase(context).getAttachment(cursor);
       List<? extends Attachment> quoteAttachments = Stream.of(attachments).filter(Attachment::isQuote).toList();
       SlideDeck                  quoteDeck        = new SlideDeck(context, quoteAttachments);
 
       if (quoteId > 0 && quoteAuthor > 0) {
-        return new Quote(quoteId, RecipientId.from(quoteAuthor), quoteText, quoteMissing, quoteDeck);
+        if (quoteText != null && !quoteMentions.isEmpty()) {
+          MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithDisplayNames(context, quoteText, quoteMentions);
+
+          quoteText     = updated.getBody();
+          quoteMentions = updated.getMentions();
+        }
+
+        return new Quote(quoteId, RecipientId.from(quoteAuthor), quoteText, quoteMissing, quoteDeck, quoteMentions);
       } else {
         return null;
       }

app/src/main/java/org/thoughtcrime/securesms/database/MmsSmsDatabase.java

@@ -82,6 +82,7 @@ public class MmsSmsDatabase extends Database {
                                               MmsDatabase.QUOTE_BODY,
                                               MmsDatabase.QUOTE_MISSING,
                                               MmsDatabase.QUOTE_ATTACHMENT,
+                                              MmsDatabase.QUOTE_MENTIONS,
                                               MmsDatabase.SHARED_CONTACTS,
                                               MmsDatabase.LINK_PREVIEWS,
                                               MmsDatabase.VIEW_ONCE,
@@ -89,7 +90,8 @@ public class MmsSmsDatabase extends Database {
                                               MmsSmsColumns.REACTIONS,
                                               MmsSmsColumns.REACTIONS_UNREAD,
                                               MmsSmsColumns.REACTIONS_LAST_SEEN,
-                                              MmsSmsColumns.REMOTE_DELETED};
+                                              MmsSmsColumns.REMOTE_DELETED,
+                                              MmsDatabase.MENTIONS_SELF};
 
   public MmsSmsDatabase(Context context, SQLCipherOpenHelper databaseHelper) {
     super(context, databaseHelper);
@@ -408,6 +410,7 @@ public class MmsSmsDatabase extends Database {
                               MmsDatabase.QUOTE_BODY,
                               MmsDatabase.QUOTE_MISSING,
                               MmsDatabase.QUOTE_ATTACHMENT,
+                              MmsDatabase.QUOTE_MENTIONS,
                               MmsDatabase.SHARED_CONTACTS,
                               MmsDatabase.LINK_PREVIEWS,
                               MmsDatabase.VIEW_ONCE,
@@ -415,7 +418,8 @@ public class MmsSmsDatabase extends Database {
                               MmsSmsColumns.REACTIONS_UNREAD,
                               MmsSmsColumns.REACTIONS_LAST_SEEN,
                               MmsSmsColumns.DATE_SERVER,
-                              MmsSmsColumns.REMOTE_DELETED };
+                              MmsSmsColumns.REMOTE_DELETED,
+                              MmsDatabase.MENTIONS_SELF };
 
     String[] smsProjection = {SmsDatabase.DATE_SENT + " AS " + MmsSmsColumns.NORMALIZED_DATE_SENT,
                               SmsDatabase.DATE_RECEIVED + " AS " + MmsSmsColumns.NORMALIZED_DATE_RECEIVED,
@@ -440,6 +444,7 @@ public class MmsSmsDatabase extends Database {
                               MmsDatabase.QUOTE_BODY,
                               MmsDatabase.QUOTE_MISSING,
                               MmsDatabase.QUOTE_ATTACHMENT,
+                              MmsDatabase.QUOTE_MENTIONS,
                               MmsDatabase.SHARED_CONTACTS,
                               MmsDatabase.LINK_PREVIEWS,
                               MmsDatabase.VIEW_ONCE,
@@ -447,7 +452,8 @@ public class MmsSmsDatabase extends Database {
                               MmsSmsColumns.REACTIONS_UNREAD,
                               MmsSmsColumns.REACTIONS_LAST_SEEN,
                               MmsSmsColumns.DATE_SERVER,
-                              MmsSmsColumns.REMOTE_DELETED };
+                              MmsSmsColumns.REMOTE_DELETED,
+                              MmsDatabase.MENTIONS_SELF };
 
     SQLiteQueryBuilder mmsQueryBuilder = new SQLiteQueryBuilder();
     SQLiteQueryBuilder smsQueryBuilder = new SQLiteQueryBuilder();
@@ -493,6 +499,7 @@ public class MmsSmsDatabase extends Database {
     mmsColumnsPresent.add(MmsDatabase.QUOTE_BODY);
     mmsColumnsPresent.add(MmsDatabase.QUOTE_MISSING);
     mmsColumnsPresent.add(MmsDatabase.QUOTE_ATTACHMENT);
+    mmsColumnsPresent.add(MmsDatabase.QUOTE_MENTIONS);
     mmsColumnsPresent.add(MmsDatabase.SHARED_CONTACTS);
     mmsColumnsPresent.add(MmsDatabase.LINK_PREVIEWS);
     mmsColumnsPresent.add(MmsDatabase.VIEW_ONCE);
@@ -500,6 +507,7 @@ public class MmsSmsDatabase extends Database {
     mmsColumnsPresent.add(MmsDatabase.REACTIONS_UNREAD);
     mmsColumnsPresent.add(MmsDatabase.REACTIONS_LAST_SEEN);
     mmsColumnsPresent.add(MmsDatabase.REMOTE_DELETED);
+    mmsColumnsPresent.add(MmsDatabase.MENTIONS_SELF);
 
     Set<String> smsColumnsPresent = new HashSet<>();
     smsColumnsPresent.add(MmsSmsColumns.ID);

app/src/main/java/org/thoughtcrime/securesms/database/RecipientDatabase.java

@@ -119,13 +119,13 @@ public class RecipientDatabase extends Database {
   private static final String PROFILE_GIVEN_NAME       = "signal_profile_name";
   private static final String PROFILE_FAMILY_NAME      = "profile_family_name";
   private static final String PROFILE_JOINED_NAME      = "profile_joined_name";
+  private static final String MENTION_SETTING          = "mention_setting";
 
   public  static final String SEARCH_PROFILE_NAME      = "search_signal_profile";
   private static final String SORT_NAME                = "sort_name";
   private static final String IDENTITY_STATUS          = "identity_status";
   private static final String IDENTITY_KEY             = "identity_key";
 
-
   private static final String[] RECIPIENT_PROJECTION = new String[] {
       UUID, USERNAME, PHONE, EMAIL, GROUP_ID, GROUP_TYPE,
       BLOCKED, MESSAGE_RINGTONE, CALL_RINGTONE, MESSAGE_VIBRATE, CALL_VIBRATE, MUTE_UNTIL, COLOR, SEEN_INVITE_REMINDER, DEFAULT_SUBSCRIPTION_ID, MESSAGE_EXPIRATION_TIME, REGISTERED,
@@ -136,7 +136,8 @@ public class RecipientDatabase extends Database {
       UNIDENTIFIED_ACCESS_MODE,
       FORCE_SMS_SELECTION,
       UUID_CAPABILITY, GROUPS_V2_CAPABILITY,
-      STORAGE_SERVICE_ID, DIRTY
+      STORAGE_SERVICE_ID, DIRTY,
+      MENTION_SETTING
   };
 
   private static final String[] ID_PROJECTION              = new String[]{ID};
@@ -146,6 +147,8 @@ public class RecipientDatabase extends Database {
                                                                    .map(columnName -> TABLE_NAME + "." + columnName)
                                                                    .toList().toArray(new String[0]);
 
+  private static final String[] MENTION_SEARCH_PROJECTION  = new String[]{ID, removeWhitespace("COALESCE(" + nullIfEmpty(SYSTEM_DISPLAY_NAME) + ", " + nullIfEmpty(PROFILE_JOINED_NAME) + ", " + nullIfEmpty(PROFILE_GIVEN_NAME) + ", " + nullIfEmpty(USERNAME) + ", " + nullIfEmpty(PHONE) + ")") + " AS " + SORT_NAME};
+
   private static final String[] RECIPIENT_FULL_PROJECTION = ArrayUtils.concat(
       new String[] { TABLE_NAME + "." + ID },
       TYPED_RECIPIENT_PROJECTION,
@@ -275,6 +278,24 @@ public class RecipientDatabase extends Database {
     }
   }
 
+  public enum MentionSetting {
+    GLOBAL(0), ALWAYS_NOTIFY(1), DO_NOT_NOTIFY(2);
+
+    private final int id;
+
+    MentionSetting(int id) {
+      this.id = id;
+    }
+
+    int getId() {
+      return id;
+    }
+
+    public static MentionSetting fromId(int id) {
+      return values()[id];
+    }
+  }
+
   public static final String CREATE_TABLE =
       "CREATE TABLE " + TABLE_NAME + " (" + ID                       + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                                             UUID                     + " TEXT UNIQUE DEFAULT NULL, " +
@@ -314,7 +335,8 @@ public class RecipientDatabase extends Database {
                                             UUID_CAPABILITY          + " INTEGER DEFAULT " + Recipient.Capability.UNKNOWN.serialize() + ", " +
                                             GROUPS_V2_CAPABILITY     + " INTEGER DEFAULT " + Recipient.Capability.UNKNOWN.serialize() + ", " +
                                             STORAGE_SERVICE_ID       + " TEXT UNIQUE DEFAULT NULL, " +
-                                            DIRTY                    + " INTEGER DEFAULT " + DirtyState.CLEAN.getId() + ");";
+                                            DIRTY                    + " INTEGER DEFAULT " + DirtyState.CLEAN.getId() + ", " +
+                                            MENTION_SETTING          + " INTEGER DEFAULT " + MentionSetting.GLOBAL.getId() + ");";
 
   private static final String INSIGHTS_INVITEE_LIST = "SELECT " + TABLE_NAME + "." + ID +
       " FROM " + TABLE_NAME +
@@ -1078,6 +1100,7 @@ public class RecipientDatabase extends Database {
     int     uuidCapabilityValue        = CursorUtil.requireInt(cursor, UUID_CAPABILITY);
     int     groupsV2CapabilityValue    = CursorUtil.requireInt(cursor, GROUPS_V2_CAPABILITY);
     String  storageKeyRaw              = CursorUtil.requireString(cursor, STORAGE_SERVICE_ID);
+    int     mentionSettingId           = CursorUtil.requireInt(cursor, MENTION_SETTING);
 
     Optional<String>  identityKeyRaw    = CursorUtil.getString(cursor, IDENTITY_KEY);
     Optional<Integer> identityStatusRaw = CursorUtil.getInt(cursor, IDENTITY_STATUS);
@@ -1145,7 +1168,7 @@ public class RecipientDatabase extends Database {
                                  Recipient.Capability.deserialize(uuidCapabilityValue),
                                  Recipient.Capability.deserialize(groupsV2CapabilityValue),
                                  InsightsBannerTier.fromId(insightsBannerTier),
-                                 storageKey, identityKey, identityStatus);
+                                 storageKey, identityKey, identityStatus, MentionSetting.fromId(mentionSettingId));
   }
 
   public BulkOperationsHandle beginBulkSystemContactUpdate() {
@@ -1299,6 +1322,14 @@ public class RecipientDatabase extends Database {
     }
   }
 
+  public void setMentionSetting(@NonNull RecipientId id, @NonNull MentionSetting mentionSetting) {
+    ContentValues values = new ContentValues();
+    values.put(MENTION_SETTING, mentionSetting.getId());
+    if (update(id, values)) {
+      Recipient.live(id).refresh();
+    }
+  }
+
   /**
    * Updates the profile key.
    * <p>
@@ -1902,6 +1933,29 @@ public class RecipientDatabase extends Database {
     return databaseHelper.getReadableDatabase().query(TABLE_NAME, SEARCH_PROJECTION, selection, args, null, null, null);
   }
 
+  public @NonNull List<Recipient> queryRecipientsForMentions(@NonNull String query, @NonNull List<RecipientId> recipientIds) {
+    if (TextUtils.isEmpty(query) || recipientIds.isEmpty()) {
+      return Collections.emptyList();
+    }
+
+    query = buildCaseInsensitiveGlobPattern(query);
+
+    String ids = TextUtils.join(",", Stream.of(recipientIds).map(RecipientId::serialize).toList());
+
+    String   selection = BLOCKED + " = 0 AND " +
+                         ID + " IN (" + ids + ") AND " +
+                         SORT_NAME  + " GLOB ?";
+
+    List<Recipient> recipients = new ArrayList<>();
+    try (RecipientDatabase.RecipientReader reader = new RecipientReader(databaseHelper.getReadableDatabase().query(TABLE_NAME, MENTION_SEARCH_PROJECTION, selection, SqlUtil.buildArgs(query), null, null, SORT_NAME))) {
+      Recipient recipient;
+      while ((recipient = reader.getNext()) != null) {
+        recipients.add(recipient);
+      }
+    }
+    return recipients;
+  }
+
   /**
    * Builds a case-insensitive GLOB pattern for fuzzy text queries. Works with all unicode
    * characters.
@@ -2384,6 +2438,10 @@ public class RecipientDatabase extends Database {
     return "NULLIF(" + column + ", '')";
   }
 
+  private static @NonNull String removeWhitespace(@NonNull String column) {
+    return "REPLACE(" + column + ", ' ', '')";
+  }
+
   public interface ColorUpdater {
     MaterialColor update(@NonNull String name, @Nullable String color);
   }
@@ -2427,6 +2485,7 @@ public class RecipientDatabase extends Database {
     private final byte[]                          storageId;
     private final byte[]                          identityKey;
     private final IdentityDatabase.VerifiedStatus identityStatus;
+    private final MentionSetting                  mentionSetting;
 
     RecipientSettings(@NonNull RecipientId id,
                       @Nullable UUID uuid,
@@ -2465,7 +2524,8 @@ public class RecipientDatabase extends Database {
                       @NonNull InsightsBannerTier insightsBannerTier,
                       @Nullable byte[] storageId,
                       @Nullable byte[] identityKey,
-                      @NonNull IdentityDatabase.VerifiedStatus identityStatus)
+                      @NonNull IdentityDatabase.VerifiedStatus identityStatus,
+                      @NonNull MentionSetting mentionSetting)
     {
       this.id                     = id;
       this.uuid                   = uuid;
@@ -2505,6 +2565,7 @@ public class RecipientDatabase extends Database {
       this.storageId              = storageId;
       this.identityKey            = identityKey;
       this.identityStatus         = identityStatus;
+      this.mentionSetting         = mentionSetting;
     }
 
     public RecipientId getId() {
@@ -2661,6 +2722,10 @@ public class RecipientDatabase extends Database {
     public @NonNull IdentityDatabase.VerifiedStatus getIdentityStatus() {
       return identityStatus;
     }
+
+    public @NonNull MentionSetting getMentionSetting() {
+      return mentionSetting;
+    }
   }
 
   public static class RecipientReader implements Closeable {

app/src/main/java/org/thoughtcrime/securesms/database/ThreadBodyUtil.java

@@ -66,7 +66,7 @@ public final class ThreadBodyUtil {
       return context.getString(R.string.ThreadRecord_media_message);
     } else {
       Log.w(TAG, "Got a media message with a body of a type we were not able to process. [contains media slide]:" + record.containsMediaSlide());
-      return record.getBody();
+      return getBody(context, record);
     }
   }
   
@@ -75,10 +75,10 @@ public final class ThreadBodyUtil {
   }
 
   private static @NonNull String getBodyOrDefault(@NonNull Context context, @NonNull MessageRecord record, @StringRes int defaultStringRes) {
-    if (TextUtils.isEmpty(record.getBody())) {
+    return TextUtils.isEmpty(record.getBody()) ? context.getString(defaultStringRes) : getBody(context, record);
-      return context.getString(defaultStringRes);
+  }
-    } else {
+
-      return record.getBody();
+  private static @NonNull String getBody(@NonNull Context context, @NonNull MessageRecord record) {
-    }
+    return MentionUtil.updateBodyWithDisplayNames(context, record, record.getBody()).toString();
   }
 }

app/src/main/java/org/thoughtcrime/securesms/database/helpers/SQLCipherOpenHelper.java

@@ -22,6 +22,7 @@ import net.sqlcipher.database.SQLiteDatabaseHook;
 import net.sqlcipher.database.SQLiteOpenHelper;
 
 import org.thoughtcrime.securesms.contacts.avatars.ContactColorsLegacy;
+import org.thoughtcrime.securesms.database.MentionDatabase;
 import org.thoughtcrime.securesms.database.RemappedRecordsDatabase;
 import org.thoughtcrime.securesms.profiles.AvatarHelper;
 import org.thoughtcrime.securesms.profiles.ProfileName;
@@ -139,8 +140,9 @@ public class SQLCipherOpenHelper extends SQLiteOpenHelper {
   private static final int QUOTE_CLEANUP                    = 65;
   private static final int BORDERLESS                       = 66;
   private static final int REMAPPED_RECORDS                 = 67;
+  private static final int MENTIONS                         = 68;
 
-  private static final int    DATABASE_VERSION = 67;
+  private static final int    DATABASE_VERSION = 68;
   private static final String DATABASE_NAME    = "signal.db";
 
   private final Context        context;
@@ -184,6 +186,7 @@ public class SQLCipherOpenHelper extends SQLiteOpenHelper {
     db.execSQL(StorageKeyDatabase.CREATE_TABLE);
     db.execSQL(KeyValueDatabase.CREATE_TABLE);
     db.execSQL(MegaphoneDatabase.CREATE_TABLE);
+    db.execSQL(MentionDatabase.CREATE_TABLE);
     executeStatements(db, SearchDatabase.CREATE_TABLE);
     executeStatements(db, JobDatabase.CREATE_TABLE);
     executeStatements(db, RemappedRecordsDatabase.CREATE_TABLE);
@@ -198,6 +201,7 @@ public class SQLCipherOpenHelper extends SQLiteOpenHelper {
     executeStatements(db, GroupReceiptDatabase.CREATE_INDEXES);
     executeStatements(db, StickerDatabase.CREATE_INDEXES);
     executeStatements(db, StorageKeyDatabase.CREATE_INDEXES);
+    executeStatements(db, MentionDatabase.CREATE_INDEXES);
 
     if (context.getDatabasePath(ClassicOpenHelper.NAME).exists()) {
       ClassicOpenHelper                      legacyHelper = new ClassicOpenHelper(context);
@@ -970,6 +974,23 @@ public class SQLCipherOpenHelper extends SQLiteOpenHelper {
                                                   "new_id INTEGER)");
       }
 
+      if (oldVersion < MENTIONS) {
+        db.execSQL("CREATE TABLE mention (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
+                                         "thread_id INTEGER, " +
+                                         "message_id INTEGER, " +
+                                         "recipient_id INTEGER, " +
+                                         "range_start INTEGER, " +
+                                         "range_length INTEGER)");
+
+        db.execSQL("CREATE INDEX IF NOT EXISTS mention_message_id_index ON mention (message_id)");
+        db.execSQL("CREATE INDEX IF NOT EXISTS mention_recipient_id_thread_id_index ON mention (recipient_id, thread_id);");
+
+        db.execSQL("ALTER TABLE mms ADD COLUMN quote_mentions BLOB DEFAULT NULL");
+        db.execSQL("ALTER TABLE mms ADD COLUMN mentions_self INTEGER DEFAULT 0");
+
+        db.execSQL("ALTER TABLE recipient ADD COLUMN mention_setting INTEGER DEFAULT 0");
+      }
+
       db.setTransactionSuccessful();
     } finally {
       db.endTransaction();

app/src/main/java/org/thoughtcrime/securesms/database/model/MediaMmsMessageRecord.java

@@ -45,6 +45,7 @@ public class MediaMmsMessageRecord extends MmsMessageRecord {
   private final static String TAG = MediaMmsMessageRecord.class.getSimpleName();
 
   private final int     partCount;
+  private final boolean mentionsSelf;
 
   public MediaMmsMessageRecord(long id,
                                Recipient conversationRecipient,
@@ -71,19 +72,26 @@ public class MediaMmsMessageRecord extends MmsMessageRecord {
                                @NonNull List<LinkPreview> linkPreviews,
                                boolean unidentified,
                                @NonNull List<ReactionRecord> reactions,
-                               boolean remoteDelete)
+                               boolean remoteDelete,
+                               boolean mentionsSelf)
   {
     super(id, body, conversationRecipient, individualRecipient, recipientDeviceId, dateSent,
           dateReceived, dateServer, threadId, Status.STATUS_NONE, deliveryReceiptCount, mailbox, mismatches, failures,
           subscriptionId, expiresIn, expireStarted, viewOnce, slideDeck,
           readReceiptCount, quote, contacts, linkPreviews, unidentified, reactions, remoteDelete);
-    this.partCount = partCount;
+    this.partCount    = partCount;
+    this.mentionsSelf = mentionsSelf;
   }
 
   public int getPartCount() {
     return partCount;
   }
 
+  @Override
+  public boolean hasSelfMention() {
+    return mentionsSelf;
+  }
+
   @Override
   public boolean isMmsNotification() {
     return false;

app/src/main/java/org/thoughtcrime/securesms/database/model/Mention.java

@@ -0,0 +1,90 @@
+package org.thoughtcrime.securesms.database.model;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+
+import java.util.Objects;
+
+public class Mention implements Comparable<Mention>, Parcelable {
+  private final RecipientId recipientId;
+  private final int         start;
+  private final int         length;
+
+  public Mention(@NonNull RecipientId recipientId, int start, int length) {
+    this.recipientId = recipientId;
+    this.start       = start;
+    this.length      = length;
+  }
+
+  protected Mention(Parcel in) {
+    recipientId = in.readParcelable(RecipientId.class.getClassLoader());
+    start       = in.readInt();
+    length      = in.readInt();
+  }
+
+  public @NonNull RecipientId getRecipientId() {
+    return recipientId;
+  }
+
+  public int getStart() {
+    return start;
+  }
+
+  public int getLength() {
+    return length;
+  }
+
+  @Override
+  public int compareTo(Mention other) {
+    return Integer.compare(start, other.start);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(recipientId, start, length);
+  }
+
+  @Override
+  public boolean equals(@Nullable Object object) {
+    if (this == object) {
+      return true;
+    }
+
+    if (object == null || getClass() != object.getClass()) {
+      return false;
+    }
+
+    Mention that = (Mention) object;
+    return recipientId.equals(that.recipientId) && start == that.start && length == that.length;
+  }
+
+  @Override
+  public void writeToParcel(Parcel dest, int flags) {
+    dest.writeParcelable(recipientId, flags);
+    dest.writeInt(start);
+    dest.writeInt(length);
+  }
+
+  @Override
+  public int describeContents() {
+    return 0;
+  }
+
+  public static final Creator<Mention> CREATOR = new Creator<Mention>() {
+    @Override
+    public Mention createFromParcel(Parcel in) {
+      return new Mention(in);
+    }
+
+    @Override
+    public Mention[] newArray(int size) {
+      return new Mention[size];
+    }
+  };
+}

app/src/main/java/org/thoughtcrime/securesms/database/model/MessageRecord.java

@@ -374,4 +374,8 @@ public abstract class MessageRecord extends DisplayRecord {
   public @NonNull List<ReactionRecord> getReactions() {
     return reactions;
   }
+
+  public boolean hasSelfMention() {
+    return false;
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/database/model/Quote.java

@@ -1,26 +1,42 @@
 package org.thoughtcrime.securesms.database.model;
 
+import android.text.SpannableString;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
 import org.thoughtcrime.securesms.mms.SlideDeck;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 
+import java.util.List;
+
 public class Quote {
 
-  private final long        id;
+  private final long          id;
-  private final RecipientId author;
+  private final RecipientId   author;
-  private final String      text;
+  private final CharSequence  text;
-  private final boolean     missing;
+  private final boolean       missing;
-  private final SlideDeck   attachment;
+  private final SlideDeck     attachment;
+  private final List<Mention> mentions;
 
-  public Quote(long id, @NonNull RecipientId author, @Nullable String text, boolean missing, @NonNull SlideDeck attachment) {
+  public Quote(long id,
-    this.id         = id;
+               @NonNull RecipientId author,
-    this.author     = author;
+               @Nullable CharSequence text,
-    this.text       = text;
+               boolean missing,
-    this.missing    = missing;
+               @NonNull SlideDeck attachment,
-    this.attachment = attachment;
+               @NonNull List<Mention> mentions)
+  {
+    this.id                = id;
+    this.author            = author;
+    this.missing           = missing;
+    this.attachment        = attachment;
+    this.mentions          = mentions;
+
+    SpannableString spannable = new SpannableString(text);
+    MentionAnnotation.setMentionAnnotations(spannable, mentions);
+
+    this.text = spannable;
   }
 
   public long getId() {
@@ -31,7 +47,7 @@ public class Quote {
     return author;
   }
 
-  public @Nullable String getText() {
+  public @Nullable CharSequence getDisplayText() {
     return text;
   }
 

app/src/main/java/org/thoughtcrime/securesms/groups/GroupManagerV1.java

@@ -149,7 +149,7 @@ final class GroupManagerV1 {
       avatarAttachment = new UriAttachment(avatarUri, MediaUtil.IMAGE_PNG, AttachmentDatabase.TRANSFER_PROGRESS_DONE, avatar.length, null, false, false, false, null, null, null, null, null);
     }
 
-    OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(groupRecipient, groupContext, avatarAttachment, System.currentTimeMillis(), 0, false, null, Collections.emptyList(), Collections.emptyList());
+    OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(groupRecipient, groupContext, avatarAttachment, System.currentTimeMillis(), 0, false, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
     long                      threadId        = MessageSender.send(context, outgoingMessage, -1, false, null);
 
     return new GroupActionResult(groupRecipient, threadId, newMemberCount, Collections.emptyList());
@@ -241,6 +241,7 @@ final class GroupManagerV1 {
                                                       false,
                                                       null,
                                                       Collections.emptyList(),
+                                                      Collections.emptyList(),
                                                       Collections.emptyList()));
   }
 }

app/src/main/java/org/thoughtcrime/securesms/groups/GroupManagerV2.java

@@ -519,6 +519,7 @@ final class GroupManagerV2 {
                                                                                        false,
                                                                                        null,
                                                                                        Collections.emptyList(),
+                                                                                       Collections.emptyList(),
                                                                                        Collections.emptyList());
 
     if (plainGroupChange != null && DecryptedGroupUtil.changeIsEmptyExceptForProfileKeyChanges(plainGroupChange)) {

app/src/main/java/org/thoughtcrime/securesms/groups/GroupV1MessageProcessor.java

@@ -240,7 +240,7 @@ public final class GroupV1MessageProcessor {
         MmsDatabase                mmsDatabase     = DatabaseFactory.getMmsDatabase(context);
         RecipientId                recipientId     = DatabaseFactory.getRecipientDatabase(context).getOrInsertFromGroupId(GroupId.v1orThrow(group.getGroupId()));
         Recipient                  recipient       = Recipient.resolved(recipientId);
-        OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(recipient, storage, null, content.getTimestamp(), 0, false, null, Collections.emptyList(), Collections.emptyList());
+        OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(recipient, storage, null, content.getTimestamp(), 0, false, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
         long                       threadId        = DatabaseFactory.getThreadDatabase(context).getThreadIdFor(recipient);
         long                       messageId       = mmsDatabase.insertMessageOutbox(outgoingMessage, threadId, false, null);
 

app/src/main/java/org/thoughtcrime/securesms/groups/ui/managegroup/ManageGroupFragment.java

@@ -51,6 +51,7 @@ import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.recipients.ui.bottomsheet.RecipientBottomSheetDialogFragment;
 import org.thoughtcrime.securesms.recipients.ui.notifications.CustomNotificationsDialogFragment;
 import org.thoughtcrime.securesms.util.DateUtils;
+import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.LifecycleCursorWrapper;
 import org.thoughtcrime.securesms.util.views.LearnMoreTextView;
 
@@ -99,6 +100,8 @@ public class ManageGroupFragment extends LoggingFragment {
   private TextView                           muteNotificationsUntilLabel;
   private TextView                           customNotificationsButton;
   private View                               customNotificationsRow;
+  private View                               mentionsRow;
+  private TextView                           mentionsValue;
   private View                               toggleAllMembers;
 
   private final Recipient.FallbackPhotoProvider fallbackPhotoProvider = new Recipient.FallbackPhotoProvider() {
@@ -156,6 +159,8 @@ public class ManageGroupFragment extends LoggingFragment {
     muteNotificationsRow        = view.findViewById(R.id.group_mute_notifications_row);
     customNotificationsButton   = view.findViewById(R.id.group_custom_notifications_button);
     customNotificationsRow      = view.findViewById(R.id.group_custom_notifications_row);
+    mentionsRow                 = view.findViewById(R.id.group_mentions_row);
+    mentionsValue               = view.findViewById(R.id.group_mentions_value);
     toggleAllMembers            = view.findViewById(R.id.toggle_all_members);
 
     groupV1Indicator.setOnLinkClickListener(v -> GroupsLearnMoreBottomSheetDialogFragment.show(requireFragmentManager()));
@@ -317,7 +322,6 @@ public class ManageGroupFragment extends LoggingFragment {
 
     customNotificationsRow.setVisibility(View.VISIBLE);
 
-    //noinspection CodeBlock2Expr
     if (NotificationChannels.supported()) {
       viewModel.hasCustomNotifications().observe(getViewLifecycleOwner(), hasCustomNotifications -> {
         customNotificationsButton.setText(hasCustomNotifications ? R.string.ManageGroupActivity_on
@@ -325,6 +329,10 @@ public class ManageGroupFragment extends LoggingFragment {
       });
     }
 
+    mentionsRow.setVisibility(FeatureFlags.mentions() && groupId.isV2() ? View.VISIBLE : View.GONE);
+    mentionsRow.setOnClickListener(v -> viewModel.handleMentionNotificationSelection());
+    viewModel.getMentionSetting().observe(getViewLifecycleOwner(), value -> mentionsValue.setText(value));
+
     viewModel.getSnackbarEvents().observe(getViewLifecycleOwner(), this::handleSnackbarEvent);
     viewModel.getInvitedDialogEvents().observe(getViewLifecycleOwner(), this::handleInvitedDialogEvent);
 

app/src/main/java/org/thoughtcrime/securesms/groups/ui/managegroup/ManageGroupRepository.java

@@ -12,6 +12,7 @@ import org.signal.storageservice.protos.groups.local.DecryptedGroup;
 import org.thoughtcrime.securesms.ContactSelectionListFragment;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.GroupDatabase;
+import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
 import org.thoughtcrime.securesms.groups.GroupAccessControl;
 import org.thoughtcrime.securesms.groups.GroupChangeException;
@@ -152,6 +153,13 @@ final class ManageGroupRepository {
     });
   }
 
+  void setMentionSetting(RecipientDatabase.MentionSetting mentionSetting) {
+    SignalExecutors.BOUNDED.execute(() -> {
+      RecipientId recipientId = Recipient.externalGroup(context, groupId).getId();
+      DatabaseFactory.getRecipientDatabase(context).setMentionSetting(recipientId, mentionSetting);
+    });
+  }
+
   static final class GroupStateResult {
 
     private final long      threadId;

app/src/main/java/org/thoughtcrime/securesms/groups/ui/managegroup/ManageGroupViewModel.java

@@ -22,6 +22,8 @@ import org.thoughtcrime.securesms.ExpirationDialog;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.contacts.ContactsCursorLoader;
 import org.thoughtcrime.securesms.database.MediaDatabase;
+import org.thoughtcrime.securesms.database.MentionUtil;
+import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.loaders.MediaLoader;
 import org.thoughtcrime.securesms.database.loaders.ThreadMediaLoader;
 import org.thoughtcrime.securesms.groups.GroupAccessControl;
@@ -31,6 +33,7 @@ import org.thoughtcrime.securesms.groups.ui.GroupChangeFailureReason;
 import org.thoughtcrime.securesms.groups.ui.GroupErrors;
 import org.thoughtcrime.securesms.groups.ui.GroupMemberEntry;
 import org.thoughtcrime.securesms.groups.ui.addmembers.AddMembersActivity;
+import org.thoughtcrime.securesms.groups.ui.managegroup.dialogs.GroupMentionSettingDialog;
 import org.thoughtcrime.securesms.notifications.NotificationChannels;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
@@ -75,6 +78,7 @@ public class ManageGroupViewModel extends ViewModel {
   private final LiveData<Boolean>                           canLeaveGroup;
   private final LiveData<Boolean>                           canBlockGroup;
   private final LiveData<Boolean>                           showLegacyIndicator;
+  private final LiveData<String>                            mentionSetting;
 
   private ManageGroupViewModel(@NonNull Context context, @NonNull ManageGroupRepository manageGroupRepository) {
     this.context               = context;
@@ -114,6 +118,8 @@ public class ManageGroupViewModel extends ViewModel {
                                                          recipient -> recipient.getNotificationChannel() != null || !NotificationChannels.supported());
     this.canLeaveGroup             = liveGroup.isActive();
     this.canBlockGroup             = Transformations.map(this.groupRecipient, recipient -> !recipient.isBlocked());
+    this.mentionSetting            = Transformations.distinctUntilChanged(Transformations.map(this.groupRecipient,
+                                                                                              recipient -> MentionUtil.getMentionSettingDisplayValue(context, recipient.getMentionSetting())));
   }
 
   @WorkerThread
@@ -207,6 +213,10 @@ public class ManageGroupViewModel extends ViewModel {
     return canLeaveGroup;
   }
 
+  LiveData<String> getMentionSetting() {
+    return mentionSetting;
+  }
+
   void handleExpirationSelection() {
     manageGroupRepository.getRecipient(groupRecipient ->
                                          ExpirationDialog.show(context,
@@ -250,6 +260,10 @@ public class ManageGroupViewModel extends ViewModel {
     memberListCollapseState.setValue(CollapseState.OPEN);
   }
 
+  void handleMentionNotificationSelection() {
+    manageGroupRepository.getRecipient(r -> GroupMentionSettingDialog.show(context, r.getMentionSetting(), mentionSetting -> manageGroupRepository.setMentionSetting(mentionSetting)));
+  }
+
   private void onBlockAndLeaveConfirmed() {
     SimpleProgressDialog.DismissibleDialog dismissibleDialog = SimpleProgressDialog.showDelayed(context);
 

app/src/main/java/org/thoughtcrime/securesms/groups/ui/managegroup/dialogs/GroupMentionSettingDialog.java

@@ -0,0 +1,90 @@
+package org.thoughtcrime.securesms.groups.ui.managegroup.dialogs;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.CheckedTextView;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.appcompat.app.AlertDialog;
+import androidx.core.util.Consumer;
+
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.database.RecipientDatabase.MentionSetting;
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
+
+public final class GroupMentionSettingDialog {
+
+  public static void show(@NonNull Context context, @NonNull MentionSetting mentionSetting, @Nullable Consumer<MentionSetting> callback) {
+    SelectionCallback selectionCallback = new SelectionCallback(mentionSetting, callback);
+
+    new AlertDialog.Builder(context)
+                   .setTitle(R.string.GroupMentionSettingDialog_notify_me_for_mentions)
+                   .setView(getView(context, mentionSetting, selectionCallback))
+                   .setPositiveButton(android.R.string.ok, selectionCallback)
+                   .setNegativeButton(android.R.string.cancel, null)
+                   .show();
+  }
+
+  @SuppressLint("InflateParams")
+  private static View getView(@NonNull Context context, @NonNull MentionSetting mentionSetting, @NonNull SelectionCallback selectionCallback) {
+    View            root          = LayoutInflater.from(context).inflate(R.layout.group_mention_setting_dialog, null, false);
+    CheckedTextView defaultOption = root.findViewById(R.id.group_mention_setting_default);
+    CheckedTextView alwaysNotify  = root.findViewById(R.id.group_mention_setting_always_notify);
+    CheckedTextView dontNotify    = root.findViewById(R.id.group_mention_setting_dont_notify);
+
+    defaultOption.setText(SignalStore.notificationSettings().isMentionNotifiesMeEnabled() ? R.string.GroupMentionSettingDialog_default_notify_me
+                                                                                          : R.string.GroupMentionSettingDialog_default_dont_notify_me);
+
+    View.OnClickListener listener = (v) -> {
+      defaultOption.setChecked(defaultOption == v);
+      alwaysNotify.setChecked(alwaysNotify == v);
+      dontNotify.setChecked(dontNotify == v);
+
+      if      (defaultOption.isChecked()) selectionCallback.selection = MentionSetting.GLOBAL;
+      else if (alwaysNotify.isChecked())  selectionCallback.selection = MentionSetting.ALWAYS_NOTIFY;
+      else if (dontNotify.isChecked())    selectionCallback.selection = MentionSetting.DO_NOT_NOTIFY;
+    };
+
+    defaultOption.setOnClickListener(listener);
+    alwaysNotify.setOnClickListener(listener);
+    dontNotify.setOnClickListener(listener);
+
+    switch (mentionSetting) {
+      case GLOBAL:
+        listener.onClick(defaultOption);
+        break;
+      case ALWAYS_NOTIFY:
+        listener.onClick(alwaysNotify);
+        break;
+      case DO_NOT_NOTIFY:
+        listener.onClick(dontNotify);
+        break;
+    }
+
+    return root;
+  }
+
+  private static class SelectionCallback implements DialogInterface.OnClickListener {
+
+    @NonNull  private final MentionSetting           previousMentionSetting;
+    @NonNull  private       MentionSetting           selection;
+    @Nullable private final Consumer<MentionSetting> callback;
+
+    public SelectionCallback(@NonNull MentionSetting previousMentionSetting, @Nullable Consumer<MentionSetting> callback) {
+      this.previousMentionSetting = previousMentionSetting;
+      this.selection              = previousMentionSetting;
+      this.callback               = callback;
+    }
+
+    @Override
+    public void onClick(DialogInterface dialog, int which) {
+      if (callback != null && selection != previousMentionSetting) {
+        callback.accept(selection);
+      }
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/v2/processing/GroupsV2StateProcessor.java

@@ -232,6 +232,7 @@ public final class GroupsV2StateProcessor {
                                                                                           false,
                                                                                           null,
                                                                                           Collections.emptyList(),
+                                                                                          Collections.emptyList(),
                                                                                           Collections.emptyList());
 
       try {
@@ -397,7 +398,7 @@ public final class GroupsV2StateProcessor {
           MmsDatabase                mmsDatabase     = DatabaseFactory.getMmsDatabase(context);
           RecipientId                recipientId     = recipientDatabase.getOrInsertFromGroupId(groupId);
           Recipient                  recipient       = Recipient.resolved(recipientId);
-          OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(recipient, decryptedGroupV2Context, null, timestamp, 0, false, null, Collections.emptyList(), Collections.emptyList());
+          OutgoingGroupUpdateMessage outgoingMessage = new OutgoingGroupUpdateMessage(recipient, decryptedGroupV2Context, null, timestamp, 0, false, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
           long                       threadId        = DatabaseFactory.getThreadDatabase(context).getThreadIdFor(recipient);
           long                       messageId       = mmsDatabase.insertMessageOutbox(outgoingMessage, threadId, false, null);
 

app/src/main/java/org/thoughtcrime/securesms/jobs/PushGroupSendJob.java

@@ -286,6 +286,7 @@ public final class PushGroupSendJob extends PushSendJob {
     Optional<SignalServiceDataMessage.Sticker> sticker            = getStickerFor(message);
     List<SharedContact>                        sharedContacts     = getSharedContactsFor(message);
     List<Preview>                              previews           = getPreviewsFor(message);
+    List<SignalServiceDataMessage.Mention>     mentions           = getMentionsFor(message.getMentions());
     List<SignalServiceAddress>                 addresses          = Stream.of(destinations).map(this::getPushAddress).toList();
     List<Attachment>                           attachments        = Stream.of(message.getAttachments()).filterNot(Attachment::isSticker).toList();
     List<SignalServiceAttachment>              attachmentPointers = getAttachmentPointersFor(attachments);
@@ -352,6 +353,7 @@ public final class PushGroupSendJob extends PushSendJob {
                                                      .withSticker(sticker.orNull())
                                                      .withSharedContacts(sharedContacts)
                                                      .withPreviews(previews)
+                                                     .withMentions(mentions)
                                                      .build();
 
       Log.i(TAG, JobLogger.format(this, "Beginning message send."));

app/src/main/java/org/thoughtcrime/securesms/jobs/PushProcessMessageJob.java

@@ -42,6 +42,7 @@ import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.SmsDatabase;
 import org.thoughtcrime.securesms.database.StickerDatabase;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.database.model.MmsMessageRecord;
 import org.thoughtcrime.securesms.database.model.ReactionRecord;
@@ -123,6 +124,7 @@ import org.whispersystems.signalservice.api.messages.multidevice.ViewOnceOpenMes
 import org.whispersystems.signalservice.api.messages.shared.SharedContact;
 import org.whispersystems.signalservice.api.push.SignalServiceAddress;
 import org.whispersystems.signalservice.api.push.exceptions.PushNetworkException;
+import org.whispersystems.signalservice.api.util.UuidUtil;
 
 import java.io.IOException;
 import java.security.SecureRandom;
@@ -133,6 +135,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
+import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
 public final class PushProcessMessageJob extends BaseJob {
@@ -341,7 +344,7 @@ public final class PushProcessMessageJob extends BaseJob {
 
       if (content.getDataMessage().isPresent()) {
         SignalServiceDataMessage message        = content.getDataMessage().get();
-        boolean                  isMediaMessage = message.getAttachments().isPresent() || message.getQuote().isPresent() || message.getSharedContacts().isPresent() || message.getPreviews().isPresent() || message.getSticker().isPresent();
+        boolean                  isMediaMessage = message.getAttachments().isPresent() || message.getQuote().isPresent() || message.getSharedContacts().isPresent() || message.getPreviews().isPresent() || message.getSticker().isPresent() || message.getMentions().isPresent();
         Optional<GroupId>        groupId        = GroupUtil.idFromGroupContext(message.getGroupContext());
         boolean                  isGv2Message   = groupId.isPresent() && groupId.get().isV2();
 
@@ -729,6 +732,7 @@ public final class PushProcessMessageJob extends BaseJob {
                                                                    Optional.absent(),
                                                                    Optional.absent(),
                                                                    Optional.absent(),
+                                                                   Optional.absent(),
                                                                    Optional.absent());
 
       database.insertSecureDecryptedMessageInbox(mediaMessage, -1);
@@ -1029,6 +1033,7 @@ public final class PushProcessMessageJob extends BaseJob {
       Optional<QuoteModel>        quote          = getValidatedQuote(message.getQuote());
       Optional<List<Contact>>     sharedContacts = getContacts(message.getSharedContacts());
       Optional<List<LinkPreview>> linkPreviews   = getLinkPreviews(message.getPreviews(), message.getBody().or(""));
+      Optional<List<Mention>>     mentions       = getMentions(message.getMentions());
       Optional<Attachment>        sticker        = getStickerAttachment(message.getSticker());
       IncomingMediaMessage        mediaMessage   = new IncomingMediaMessage(RecipientId.fromHighTrust(content.getSender()),
                                                                             message.getTimestamp(),
@@ -1044,6 +1049,7 @@ public final class PushProcessMessageJob extends BaseJob {
                                                                             quote,
                                                                             sharedContacts,
                                                                             linkPreviews,
+                                                                            mentions,
                                                                             sticker);
 
       insertResult = database.insertSecureDecryptedMessageInbox(mediaMessage, -1);
@@ -1109,6 +1115,7 @@ public final class PushProcessMessageJob extends BaseJob {
     Optional<Attachment>        sticker         = getStickerAttachment(message.getMessage().getSticker());
     Optional<List<Contact>>     sharedContacts  = getContacts(message.getMessage().getSharedContacts());
     Optional<List<LinkPreview>> previews        = getLinkPreviews(message.getMessage().getPreviews(), message.getMessage().getBody().or(""));
+    Optional<List<Mention>>     mentions        = getMentions(message.getMessage().getMentions());
     boolean                     viewOnce        = message.getMessage().isViewOnce();
     List<Attachment>            syncAttachments = viewOnce ? Collections.singletonList(new TombstoneAttachment(MediaUtil.VIEW_ONCE, false))
                                                            : PointerAttachment.forPointers(message.getMessage().getAttachments());
@@ -1125,6 +1132,7 @@ public final class PushProcessMessageJob extends BaseJob {
                                                                  ThreadDatabase.DistributionTypes.DEFAULT, quote.orNull(),
                                                                  sharedContacts.or(Collections.emptyList()),
                                                                  previews.or(Collections.emptyList()),
+                                                                 mentions.or(Collections.emptyList()),
                                                                  Collections.emptyList(), Collections.emptyList());
 
     mediaMessage = new OutgoingSecureMediaMessage(mediaMessage);
@@ -1290,7 +1298,18 @@ public final class PushProcessMessageJob extends BaseJob {
     long              messageId;
 
     if (isGroup) {
-      OutgoingMediaMessage outgoingMediaMessage = new OutgoingMediaMessage(recipient, new SlideDeck(), body, message.getTimestamp(), -1, expiresInMillis, false, ThreadDatabase.DistributionTypes.DEFAULT, null, Collections.emptyList(), Collections.emptyList());
+      OutgoingMediaMessage outgoingMediaMessage = new OutgoingMediaMessage(recipient,
+                                                                           new SlideDeck(),
+                                                                           body,
+                                                                           message.getTimestamp(),
+                                                                           -1,
+                                                                           expiresInMillis,
+                                                                           false,
+                                                                           ThreadDatabase.DistributionTypes.DEFAULT,
+                                                                           null,
+                                                                           Collections.emptyList(),
+                                                                           Collections.emptyList(),
+                                                                           Collections.emptyList());
       outgoingMediaMessage = new OutgoingSecureMediaMessage(outgoingMediaMessage);
 
       messageId = DatabaseFactory.getMmsDatabase(context).insertMessageOutbox(outgoingMediaMessage, threadId, false, GroupReceiptDatabase.STATUS_UNKNOWN, null);
@@ -1577,10 +1596,13 @@ public final class PushProcessMessageJob extends BaseJob {
       Log.i(TAG, "Found matching message record...");
 
       List<Attachment> attachments = new LinkedList<>();
+      List<Mention>    mentions    = new LinkedList<>();
 
       if (message.isMms()) {
         MmsMessageRecord mmsMessage = (MmsMessageRecord) message;
 
+        mentions.addAll(DatabaseFactory.getMentionDatabase(context).getMentionsForMessage(mmsMessage.getId()));
+
         if (mmsMessage.isViewOnce()) {
           attachments.add(new TombstoneAttachment(MediaUtil.VIEW_ONCE, true));
         } else {
@@ -1595,7 +1617,7 @@ public final class PushProcessMessageJob extends BaseJob {
         }
       }
 
-      return Optional.of(new QuoteModel(quote.get().getId(), author, message.getBody(), false, attachments));
+      return Optional.of(new QuoteModel(quote.get().getId(), author, message.getBody(), false, attachments, mentions));
     } else if (message != null) {
       Log.w(TAG, "Found the target for the quote, but it's flagged as remotely deleted.");
     }
@@ -1606,7 +1628,8 @@ public final class PushProcessMessageJob extends BaseJob {
                                       author,
                                       quote.get().getText(),
                                       true,
-                                      PointerAttachment.forPointers(quote.get().getAttachments())));
+                                      PointerAttachment.forPointers(quote.get().getAttachments()),
+                                      getMentions(quote.get().getMentions())));
   }
 
   private Optional<Attachment> getStickerAttachment(Optional<SignalServiceDataMessage.Sticker> sticker) {
@@ -1685,6 +1708,26 @@ public final class PushProcessMessageJob extends BaseJob {
     return Optional.of(linkPreviews);
   }
 
+  private Optional<List<Mention>> getMentions(Optional<List<SignalServiceDataMessage.Mention>> signalServiceMentions) {
+    if (!signalServiceMentions.isPresent()) return Optional.absent();
+
+    return Optional.of(getMentions(signalServiceMentions.get()));
+  }
+
+  private @NonNull List<Mention> getMentions(@Nullable List<SignalServiceDataMessage.Mention> signalServiceMentions) {
+    if (signalServiceMentions == null || signalServiceMentions.isEmpty()) {
+      return Collections.emptyList();
+    }
+
+    List<Mention> mentions = new ArrayList<>(signalServiceMentions.size());
+
+    for (SignalServiceDataMessage.Mention mention : signalServiceMentions) {
+      mentions.add(new Mention(Recipient.externalPush(context, mention.getUuid(), null, false).getId(), mention.getStart(), mention.getLength()));
+    }
+
+    return mentions;
+  }
+
   private Optional<InsertResult> insertPlaceholder(@NonNull String sender, int senderDevice, long timestamp) {
     return insertPlaceholder(sender, senderDevice, timestamp, Optional.absent());
   }

app/src/main/java/org/thoughtcrime/securesms/jobs/PushSendJob.java

@@ -20,6 +20,7 @@ import org.thoughtcrime.securesms.contactshare.Contact;
 import org.thoughtcrime.securesms.contactshare.ContactModelMapper;
 import org.thoughtcrime.securesms.crypto.ProfileKeyUtil;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.events.PartProgressEvent;
 import org.thoughtcrime.securesms.jobmanager.Job;
@@ -239,6 +240,7 @@ public abstract class PushSendJob extends SendJob {
     long                                                  quoteId             = message.getOutgoingQuote().getId();
     String                                                quoteBody           = message.getOutgoingQuote().getText();
     RecipientId                                           quoteAuthor         = message.getOutgoingQuote().getAuthor();
+    List<SignalServiceDataMessage.Mention>                quoteMentions       = getMentionsFor(message.getOutgoingQuote().getMentions());
     List<SignalServiceDataMessage.Quote.QuotedAttachment> quoteAttachments    = new LinkedList<>();
     List<Attachment>                                      filteredAttachments = Stream.of(message.getOutgoingQuote().getAttachments())
                                                                                       .filterNot(a -> MediaUtil.isViewOnceType(a.getContentType()))
@@ -284,7 +286,7 @@ public abstract class PushSendJob extends SendJob {
 
     Recipient            quoteAuthorRecipient = Recipient.resolved(quoteAuthor);
     SignalServiceAddress quoteAddress         = RecipientUtil.toSignalServiceAddress(context, quoteAuthorRecipient);
-    return Optional.of(new SignalServiceDataMessage.Quote(quoteId, quoteAddress, quoteBody, quoteAttachments));
+    return Optional.of(new SignalServiceDataMessage.Quote(quoteId, quoteAddress, quoteBody, quoteAttachments, quoteMentions));
   }
 
   protected Optional<SignalServiceDataMessage.Sticker> getStickerFor(OutgoingMediaMessage message) {
@@ -334,6 +336,12 @@ public abstract class PushSendJob extends SendJob {
     }).toList();
   }
 
+  List<SignalServiceDataMessage.Mention> getMentionsFor(@NonNull List<Mention> mentions) {
+    return Stream.of(mentions)
+                 .map(m -> new SignalServiceDataMessage.Mention(Recipient.resolved(m.getRecipientId()).requireUuid(), m.getStart(), m.getLength()))
+                 .toList();
+  }
+
   protected void rotateSenderCertificateIfNecessary() throws IOException {
     try {
       byte[] certificateBytes = TextSecurePreferences.getUnidentifiedAccessCertificate(context);

app/src/main/java/org/thoughtcrime/securesms/jobs/WakeGroupV2Job.java

@@ -98,7 +98,7 @@ public final class WakeGroupV2Job extends BaseJob {
       GroupDatabase.V2GroupProperties v2GroupProperties       = group.get().requireV2GroupProperties();
       DecryptedGroupV2Context         decryptedGroupV2Context = GroupProtoUtil.createDecryptedGroupV2Context(v2GroupProperties.getGroupMasterKey(), v2GroupProperties.getDecryptedGroup(), null, null);
       MmsDatabase                     mmsDatabase             = DatabaseFactory.getMmsDatabase(context);
-      OutgoingGroupUpdateMessage      outgoingMessage         = new OutgoingGroupUpdateMessage(groupRecipient, decryptedGroupV2Context, null, System.currentTimeMillis(), 0, false, null, Collections.emptyList(), Collections.emptyList());
+      OutgoingGroupUpdateMessage      outgoingMessage         = new OutgoingGroupUpdateMessage(groupRecipient, decryptedGroupV2Context, null, System.currentTimeMillis(), 0, false, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
 
       long messageId = mmsDatabase.insertMessageOutbox(outgoingMessage, threadId, false, null);
 

app/src/main/java/org/thoughtcrime/securesms/keyvalue/NotificationSettings.java

@@ -0,0 +1,20 @@
+package org.thoughtcrime.securesms.keyvalue;
+
+import androidx.annotation.NonNull;
+
+public class NotificationSettings extends SignalStoreValues {
+
+  public static final String MENTIONS_NOTIFY_ME = "notifications.mentions.notify_me";
+
+  NotificationSettings(@NonNull KeyValueStore store) {
+    super(store);
+  }
+
+  @Override
+  void onFirstEverAppLaunch() {
+  }
+
+  public boolean isMentionNotifiesMeEnabled() {
+    return getBoolean(MENTIONS_NOTIFY_ME, true);
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/keyvalue/SignalStore.java

@@ -1,7 +1,6 @@
 package org.thoughtcrime.securesms.keyvalue;
 
 import androidx.annotation.NonNull;
-import androidx.lifecycle.OnLifecycleEvent;
 import androidx.preference.PreferenceDataStore;
 
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
@@ -25,6 +24,7 @@ public final class SignalStore {
   private final MiscellaneousValues  misc;
   private final InternalValues       internalValues;
   private final EmojiValues          emojiValues;
+  private final NotificationSettings notificationSettings;
 
   private SignalStore() {
     this.store                = ApplicationDependencies.getKeyValueStore();
@@ -38,6 +38,7 @@ public final class SignalStore {
     this.misc                 = new MiscellaneousValues(store);
     this.internalValues       = new InternalValues(store);
     this.emojiValues          = new EmojiValues(store);
+    this.notificationSettings = new NotificationSettings(store);
   }
 
   public static void onFirstEverAppLaunch() {
@@ -50,6 +51,7 @@ public final class SignalStore {
     tooltips().onFirstEverAppLaunch();
     misc().onFirstEverAppLaunch();
     internalValues().onFirstEverAppLaunch();
+    notificationSettings().onFirstEverAppLaunch();
   }
 
   public static @NonNull KbsValues kbsValues() {
@@ -92,6 +94,10 @@ public final class SignalStore {
     return INSTANCE.emojiValues;
   }
 
+  public static @NonNull NotificationSettings notificationSettings() {
+    return INSTANCE.notificationSettings;
+  }
+
   public static @NonNull GroupsV2AuthorizationSignalStoreCache groupsV2AuthorizationCache() {
     return new GroupsV2AuthorizationSignalStoreCache(getStore());
   }

app/src/main/java/org/thoughtcrime/securesms/longmessage/LongMessage.java

@@ -1,28 +1,33 @@
 package org.thoughtcrime.securesms.longmessage;
 
+import android.content.Context;
 import android.text.TextUtils;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.thoughtcrime.securesms.conversation.ConversationMessage;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 
 /**
- * A wrapper around a {@link MessageRecord} and its extra text attachment expanded into a string
+ * A wrapper around a {@link ConversationMessage} and its extra text attachment expanded into a string
  * held in memory.
  */
 class LongMessage {
 
-  private final MessageRecord messageRecord;
+  private final ConversationMessage conversationMessage;
-  private final String        fullBody;
+  private final String              fullBody;
 
-  LongMessage(MessageRecord messageRecord, String fullBody) {
+  LongMessage(@NonNull ConversationMessage conversationMessage, @NonNull String fullBody) {
-    this.messageRecord = messageRecord;
+    this.conversationMessage = conversationMessage;
-    this.fullBody      = fullBody;
+    this.fullBody            = fullBody;
   }
 
-  MessageRecord getMessageRecord() {
+  @NonNull MessageRecord getMessageRecord() {
-    return messageRecord;
+    return conversationMessage.getMessageRecord();
   }
 
-  String getFullBody() {
+  @NonNull CharSequence getFullBody(@NonNull Context context) {
-    return !TextUtils.isEmpty(fullBody) ? fullBody : messageRecord.getBody();
+    return !TextUtils.isEmpty(fullBody) ? fullBody : conversationMessage.getDisplayBody(context);
   }
 }

app/src/main/java/org/thoughtcrime/securesms/longmessage/LongMessageActivity.java

@@ -147,7 +147,7 @@ public class LongMessageActivity extends PassphraseRequiredActivity {
       TextView               text   = bubble.findViewById(R.id.longmessage_text);
       ConversationItemFooter footer = bubble.findViewById(R.id.longmessage_footer);
 
-      String          trimmedBody = getTrimmedBody(message.get().getFullBody());
+      CharSequence    trimmedBody = getTrimmedBody(message.get().getFullBody(this));
       SpannableString styledBody  = linkifyMessageBody(new SpannableString(trimmedBody));
 
       bubble.setVisibility(View.VISIBLE);
@@ -158,9 +158,9 @@ public class LongMessageActivity extends PassphraseRequiredActivity {
     });
   }
 
-  private String getTrimmedBody(@NonNull String text) {
+  private CharSequence getTrimmedBody(@NonNull CharSequence text) {
     return text.length() <= MAX_DISPLAY_LENGTH ? text
-                                               : text.substring(0, MAX_DISPLAY_LENGTH);
+                                               : text.subSequence(0, MAX_DISPLAY_LENGTH);
   }
 
   private SpannableString linkifyMessageBody(SpannableString messageBody) {

app/src/main/java/org/thoughtcrime/securesms/longmessage/LongMessageRepository.java

@@ -6,6 +6,8 @@ import android.net.Uri;
 import androidx.annotation.NonNull;
 import androidx.annotation.WorkerThread;
 
+import org.thoughtcrime.securesms.conversation.ConversationMessage;
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.MmsDatabase;
 import org.thoughtcrime.securesms.database.SmsDatabase;
@@ -38,7 +40,7 @@ class LongMessageRepository {
       if (isMms) {
         callback.onComplete(getMmsLongMessage(context, mmsDatabase, messageId));
       } else {
-        callback.onComplete(getSmsLongMessage(smsDatabase, messageId));
+        callback.onComplete(getSmsLongMessage(context, smsDatabase, messageId));
       }
     });
   }
@@ -51,9 +53,9 @@ class LongMessageRepository {
       TextSlide textSlide = record.get().getSlideDeck().getTextSlide();
 
       if (textSlide != null && textSlide.getUri() != null) {
-        return Optional.of(new LongMessage(record.get(), readFullBody(context, textSlide.getUri())));
+        return Optional.of(new LongMessage(ConversationMessageFactory.createWithUnresolvedData(context, record.get()), readFullBody(context, textSlide.getUri())));
       } else {
-        return Optional.of(new LongMessage(record.get(), ""));
+        return Optional.of(new LongMessage(ConversationMessageFactory.createWithUnresolvedData(context, record.get()), ""));
       }
     } else {
       return Optional.absent();
@@ -61,11 +63,11 @@ class LongMessageRepository {
   }
 
   @WorkerThread
-  private Optional<LongMessage> getSmsLongMessage(@NonNull SmsDatabase smsDatabase, long messageId) {
+  private Optional<LongMessage> getSmsLongMessage(@NonNull Context context, @NonNull SmsDatabase smsDatabase, long messageId) {
     Optional<MessageRecord> record = getSmsMessage(smsDatabase, messageId);
 
     if (record.isPresent()) {
-      return Optional.of(new LongMessage(record.get(), ""));
+      return Optional.of(new LongMessage(ConversationMessageFactory.createWithUnresolvedData(context, record.get()), ""));
     } else {
       return Optional.absent();
     }

app/src/main/java/org/thoughtcrime/securesms/mediasend/MediaSendActivity.java

@@ -30,6 +30,9 @@ import androidx.lifecycle.ViewModelProviders;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
+import com.annimon.stream.Collectors;
+import com.annimon.stream.Stream;
+
 import org.thoughtcrime.securesms.PassphraseRequiredActivity;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.TransportOption;
@@ -42,7 +45,9 @@ import org.thoughtcrime.securesms.components.emoji.EmojiEditText;
 import org.thoughtcrime.securesms.components.emoji.EmojiKeyboardProvider;
 import org.thoughtcrime.securesms.components.emoji.EmojiToggle;
 import org.thoughtcrime.securesms.components.emoji.MediaKeyboard;
+import org.thoughtcrime.securesms.components.mention.MentionAnnotation;
 import org.thoughtcrime.securesms.contactshare.SimpleTextWatcher;
+import org.thoughtcrime.securesms.conversation.ui.mentions.MentionsPickerViewModel;
 import org.thoughtcrime.securesms.imageeditor.model.EditorModel;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mediapreview.MediaRailAdapter;
@@ -55,6 +60,7 @@ import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.scribbles.ImageEditorFragment;
 import org.thoughtcrime.securesms.util.CharacterCalculator.CharacterState;
+import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.Function3;
 import org.thoughtcrime.securesms.util.IOFunction;
 import org.thoughtcrime.securesms.util.MediaUtil;
@@ -76,6 +82,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Encompasses the entire flow of sending media, starting from the selection process to the actual
@@ -130,6 +137,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
   private EmojiEditText       captionText;
   private EmojiToggle         emojiToggle;
   private Stub<MediaKeyboard> emojiDrawer;
+  private Stub<View>          mentionSuggestions;
   private TextView            charactersLeft;
   private RecyclerView        mediaRail;
   private MediaRailAdapter    mediaRailAdapter;
@@ -142,7 +150,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
   /**
    * Get an intent to launch the media send flow starting with the picker.
    */
-  public static Intent buildGalleryIntent(@NonNull Context context, @NonNull Recipient recipient, @Nullable String body, @NonNull TransportOption transport) {
+  public static Intent buildGalleryIntent(@NonNull Context context, @NonNull Recipient recipient, @Nullable CharSequence body, @NonNull TransportOption transport) {
     Intent intent = new Intent(context, MediaSendActivity.class);
     intent.putExtra(KEY_RECIPIENT, recipient.getId());
     intent.putExtra(KEY_TRANSPORT, transport);
@@ -174,7 +182,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
   public static Intent buildEditorIntent(@NonNull Context context,
                                          @NonNull List<Media> media,
                                          @NonNull Recipient recipient,
-                                         @NonNull String body,
+                                         @NonNull CharSequence body,
                                          @NonNull TransportOption transport)
   {
     Intent intent = buildGalleryIntent(context, recipient, body, transport);
@@ -207,6 +215,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
     charactersLeft      = findViewById(R.id.mediasend_characters_left);
     mediaRail           = findViewById(R.id.mediasend_media_rail);
     emojiDrawer         = new Stub<>(findViewById(R.id.mediasend_emoji_drawer_stub));
+    mentionSuggestions  = new Stub<>(findViewById(R.id.mediasend_mention_suggestions_stub));
 
     RecipientId recipientId = getIntent().getParcelableExtra(KEY_RECIPIENT);
     if (recipientId != null) {
@@ -222,7 +231,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
 
     viewModel.setTransport(transport);
     viewModel.setRecipient(recipient != null ? recipient.get() : null);
-    viewModel.onBodyChanged(getIntent().getStringExtra(KEY_BODY));
+    viewModel.onBodyChanged(getIntent().getCharSequenceExtra(KEY_BODY));
 
     List<Media> media    = getIntent().getParcelableArrayListExtra(KEY_MEDIA);
     boolean     isCamera = getIntent().getBooleanExtra(KEY_IS_CAMERA, false);
@@ -309,6 +318,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
     }
 
     initViewModel();
+    if (FeatureFlags.mentions()) initializeMentionsViewModel();
 
     revealButton.setOnClickListener(v -> viewModel.onRevealButtonToggled());
     continueButton.setOnClickListener(v -> navigateToContactSelect());
@@ -525,7 +535,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
     MediaSendFragment fragment = getMediaSendFragment();
 
     if (fragment != null) {
-      viewModel.onSendClicked(buildModelsToTransform(fragment), recipients).observe(this, result -> {
+      viewModel.onSendClicked(buildModelsToTransform(fragment), recipients, composeText.getMentions()).observe(this, result -> {
         finish();
       });
     } else {
@@ -546,7 +556,7 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
 
     sendButton.setEnabled(false);
 
-    viewModel.onSendClicked(buildModelsToTransform(fragment), Collections.emptyList()).observe(this, this::setActivityResultAndFinish);
+    viewModel.onSendClicked(buildModelsToTransform(fragment), Collections.emptyList(), composeText.getMentions()).observe(this, this::setActivityResultAndFinish);
   }
 
   private static Map<Media, MediaTransform> buildModelsToTransform(@NonNull MediaSendFragment fragment) {
@@ -751,6 +761,46 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
     });
   }
 
+  private void initializeMentionsViewModel() {
+    if (recipient == null) {
+      return;
+    }
+
+    MentionsPickerViewModel mentionsViewModel = ViewModelProviders.of(this, new MentionsPickerViewModel.Factory()).get(MentionsPickerViewModel.class);
+
+    recipient.observe(this, mentionsViewModel::onRecipientChange);
+    composeText.setMentionQueryChangedListener(query -> {
+      if (recipient.get().isPushV2Group()) {
+        if (!mentionSuggestions.resolved()) {
+          mentionSuggestions.get();
+        }
+        mentionsViewModel.onQueryChange(query);
+      }
+    });
+
+    composeText.setMentionValidator(annotations -> {
+      if (!recipient.get().isPushV2Group()) {
+        return annotations;
+      }
+
+      Set<String> validRecipientIds = Stream.of(recipient.get().getParticipants())
+                                            .map(r -> MentionAnnotation.idToMentionAnnotationValue(r.getId()))
+                                            .collect(Collectors.toSet());
+
+      return Stream.of(annotations)
+                   .filter(a -> !validRecipientIds.contains(a.getValue()))
+                   .toList();
+    });
+
+    mentionsViewModel.getSelectedRecipient().observe(this, recipient -> {
+      String replacementDisplayName = recipient.getDisplayName(this);
+      if (replacementDisplayName.equals(recipient.getDisplayUsername())) {
+        replacementDisplayName = recipient.getUsername().or(replacementDisplayName);
+      }
+      composeText.replaceTextWithMention(replacementDisplayName, recipient.getId());
+    });
+  }
+
   private void presentRecipient(@Nullable Recipient recipient) {
     if (recipient == null) {
       composeText.setHint(R.string.MediaSendActivity_message);
@@ -836,9 +886,9 @@ public class MediaSendActivity extends PassphraseRequiredActivity implements Med
 
 
   private void presentCharactersRemaining() {
-    String          messageBody     = composeText.getTextTrimmed();
+    String          messageBody     = composeText.getTextTrimmed().toString();
     TransportOption transportOption = sendButton.getSelectedTransport();
-    CharacterState characterState  = transportOption.calculateCharacters(messageBody);
+    CharacterState  characterState  = transportOption.calculateCharacters(messageBody);
 
     if (characterState.charactersRemaining <= 15 || characterState.messagesSpent > 1) {
       charactersLeft.setText(String.format(Locale.getDefault(),

app/src/main/java/org/thoughtcrime/securesms/mediasend/MediaSendActivityResult.java

@@ -7,6 +7,7 @@ import androidx.annotation.NonNull;
 
 import org.thoughtcrime.securesms.TransportOption;
 import org.thoughtcrime.securesms.conversation.ConversationActivity;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.sms.MessageSender.PreUploadResult;
 import org.thoughtcrime.securesms.util.ParcelUtil;
 import org.whispersystems.libsignal.util.guava.Preconditions;
@@ -24,36 +25,41 @@ public class MediaSendActivityResult implements Parcelable {
   private final String                      body;
   private final TransportOption             transport;
   private final boolean                     viewOnce;
+  private final Collection<Mention>         mentions;
 
   static @NonNull MediaSendActivityResult forPreUpload(@NonNull Collection<PreUploadResult> uploadResults,
                                                        @NonNull String body,
                                                        @NonNull TransportOption transport,
-                                                       boolean viewOnce)
+                                                       boolean viewOnce,
+                                                       @NonNull List<Mention> mentions)
   {
     Preconditions.checkArgument(uploadResults.size() > 0, "Must supply uploadResults!");
-    return new MediaSendActivityResult(uploadResults, Collections.emptyList(), body, transport, viewOnce);
+    return new MediaSendActivityResult(uploadResults, Collections.emptyList(), body, transport, viewOnce, mentions);
   }
 
   static @NonNull MediaSendActivityResult forTraditionalSend(@NonNull List<Media> nonUploadedMedia,
                                                              @NonNull String body,
                                                              @NonNull TransportOption transport,
-                                                             boolean viewOnce)
+                                                             boolean viewOnce,
+                                                             @NonNull List<Mention> mentions)
   {
     Preconditions.checkArgument(nonUploadedMedia.size() > 0, "Must supply media!");
-    return new MediaSendActivityResult(Collections.emptyList(), nonUploadedMedia, body, transport, viewOnce);
+    return new MediaSendActivityResult(Collections.emptyList(), nonUploadedMedia, body, transport, viewOnce, mentions);
   }
 
   private MediaSendActivityResult(@NonNull Collection<PreUploadResult> uploadResults,
                                   @NonNull List<Media> nonUploadedMedia,
                                   @NonNull String body,
                                   @NonNull TransportOption transport,
-                                  boolean viewOnce)
+                                  boolean viewOnce,
+                                  @NonNull List<Mention> mentions)
   {
     this.uploadResults    = uploadResults;
     this.nonUploadedMedia = nonUploadedMedia;
     this.body             = body;
     this.transport        = transport;
     this.viewOnce         = viewOnce;
+    this.mentions         = mentions;
   }
 
   private MediaSendActivityResult(Parcel in) {
@@ -62,6 +68,7 @@ public class MediaSendActivityResult implements Parcelable {
     this.body             = in.readString();
     this.transport        = in.readParcelable(TransportOption.class.getClassLoader());
     this.viewOnce         = ParcelUtil.readBoolean(in);
+    this.mentions         = ParcelUtil.readParcelableCollection(in, Mention.class);
   }
 
   public boolean isPushPreUpload() {
@@ -88,6 +95,10 @@ public class MediaSendActivityResult implements Parcelable {
     return viewOnce;
   }
 
+  public @NonNull Collection<Mention> getMentions() {
+    return mentions;
+  }
+
   public static final Creator<MediaSendActivityResult> CREATOR = new Creator<MediaSendActivityResult>() {
     @Override
     public MediaSendActivityResult createFromParcel(Parcel in) {
@@ -112,5 +123,6 @@ public class MediaSendActivityResult implements Parcelable {
     dest.writeString(body);
     dest.writeParcelable(transport, 0);
     ParcelUtil.writeBoolean(dest, viewOnce);
+    ParcelUtil.writeParcelableCollection(dest, mentions);
   }
 }

app/src/main/java/org/thoughtcrime/securesms/mediasend/MediaSendViewModel.java

@@ -17,6 +17,7 @@ import com.annimon.stream.Stream;
 
 import org.thoughtcrime.securesms.TransportOption;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.MediaConstraints;
 import org.thoughtcrime.securesms.mms.OutgoingMediaMessage;
@@ -453,7 +454,7 @@ class MediaSendViewModel extends ViewModel {
     savedDrawState.putAll(state);
   }
 
-  @NonNull LiveData<MediaSendActivityResult> onSendClicked(Map<Media, MediaTransform> modelsToTransform, @NonNull List<Recipient> recipients) {
+  @NonNull LiveData<MediaSendActivityResult> onSendClicked(Map<Media, MediaTransform> modelsToTransform, @NonNull List<Recipient> recipients, @NonNull List<Mention> mentions) {
     if (isSms && recipients.size() > 0) {
       throw new IllegalStateException("Provided recipients to send to, but this is SMS!");
     }
@@ -476,7 +477,7 @@ class MediaSendViewModel extends ViewModel {
 
       if (isSms || MessageSender.isLocalSelfSend(application, recipient, isSms)) {
         Log.i(TAG, "SMS or local self-send. Skipping pre-upload.");
-        result.postValue(MediaSendActivityResult.forTraditionalSend(updatedMedia, trimmedBody, transport, isViewOnce()));
+        result.postValue(MediaSendActivityResult.forTraditionalSend(updatedMedia, trimmedBody, transport, isViewOnce(), mentions));
         return;
       }
 
@@ -493,12 +494,12 @@ class MediaSendViewModel extends ViewModel {
       uploadRepository.updateDisplayOrder(updatedMedia);
       uploadRepository.getPreUploadResults(uploadResults -> {
         if (recipients.size() > 0) {
-          sendMessages(recipients, splitBody, uploadResults);
+          sendMessages(recipients, splitBody, uploadResults, mentions);
           uploadRepository.deleteAbandonedAttachments();
         }
 
         Util.cancelRunnableOnMain(dialogRunnable);
-        result.postValue(MediaSendActivityResult.forPreUpload(uploadResults, splitBody, transport, isViewOnce()));
+        result.postValue(MediaSendActivityResult.forPreUpload(uploadResults, splitBody, transport, isViewOnce(), mentions));
       });
     });
 
@@ -632,7 +633,7 @@ class MediaSendViewModel extends ViewModel {
   }
 
   @WorkerThread
-  private void sendMessages(@NonNull List<Recipient> recipients, @NonNull String body, @NonNull Collection<PreUploadResult> preUploadResults) {
+  private void sendMessages(@NonNull List<Recipient> recipients, @NonNull String body, @NonNull Collection<PreUploadResult> preUploadResults, @NonNull List<Mention> mentions) {
     List<OutgoingSecureMediaMessage> messages = new ArrayList<>(recipients.size());
 
     for (Recipient recipient : recipients) {
@@ -647,6 +648,7 @@ class MediaSendViewModel extends ViewModel {
                                                                 null,
                                                                 Collections.emptyList(),
                                                                 Collections.emptyList(),
+                                                                mentions,
                                                                 Collections.emptyList(),
                                                                 Collections.emptyList());
 

app/src/main/java/org/thoughtcrime/securesms/messagedetails/MessageDetails.java

@@ -4,6 +4,7 @@ import androidx.annotation.NonNull;
 
 import com.annimon.stream.ComparatorCompat;
 
+import org.thoughtcrime.securesms.conversation.ConversationMessage;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 
@@ -17,7 +18,7 @@ final class MessageDetails {
   private static final Comparator<RecipientDeliveryStatus> ALPHABETICAL         = (r1, r2) -> r1.getRecipient().getDisplayName(ApplicationDependencies.getApplication()).compareToIgnoreCase(r2.getRecipient().getDisplayName(ApplicationDependencies.getApplication()));
   private static final Comparator<RecipientDeliveryStatus> RECIPIENT_COMPARATOR = ComparatorCompat.chain(HAS_DISPLAY_NAME).thenComparing(ALPHABETICAL);
 
-  private final MessageRecord messageRecord;
+  private final ConversationMessage conversationMessage;
 
   private final Collection<RecipientDeliveryStatus> pending;
   private final Collection<RecipientDeliveryStatus> sent;
@@ -25,8 +26,8 @@ final class MessageDetails {
   private final Collection<RecipientDeliveryStatus> read;
   private final Collection<RecipientDeliveryStatus> notSent;
 
-  MessageDetails(MessageRecord messageRecord, List<RecipientDeliveryStatus> recipients) {
+  MessageDetails(@NonNull ConversationMessage conversationMessage, @NonNull List<RecipientDeliveryStatus> recipients) {
-    this.messageRecord = messageRecord;
+    this.conversationMessage = conversationMessage;
 
     pending   = new TreeSet<>(RECIPIENT_COMPARATOR);
     sent      = new TreeSet<>(RECIPIENT_COMPARATOR);
@@ -34,7 +35,7 @@ final class MessageDetails {
     read      = new TreeSet<>(RECIPIENT_COMPARATOR);
     notSent   = new TreeSet<>(RECIPIENT_COMPARATOR);
 
-    if (messageRecord.isOutgoing()) {
+    if (conversationMessage.getMessageRecord().isOutgoing()) {
       for (RecipientDeliveryStatus status : recipients) {
         switch (status.getDeliveryStatus()) {
           case UNKNOWN:
@@ -59,8 +60,8 @@ final class MessageDetails {
     }
   }
 
-  @NonNull MessageRecord getMessageRecord() {
+  @NonNull ConversationMessage getConversationMessage() {
-    return messageRecord;
+    return conversationMessage;
   }
 
   @NonNull Collection<RecipientDeliveryStatus> getPending() {

app/src/main/java/org/thoughtcrime/securesms/messagedetails/MessageDetailsActivity.java

@@ -124,7 +124,7 @@ public final class MessageDetailsActivity extends PassphraseRequiredActivity {
     assert getSupportActionBar() != null;
     getSupportActionBar().setBackgroundDrawable(new ColorDrawable(color.toActionBarColor(this)));
 
-    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+    if (Build.VERSION.SDK_INT >= 21) {
       getWindow().setStatusBarColor(color.toStatusBarColor(this));
     }
   }
@@ -132,9 +132,9 @@ public final class MessageDetailsActivity extends PassphraseRequiredActivity {
   private List<MessageDetailsViewState<?>> convertToRows(MessageDetails details) {
     List<MessageDetailsViewState<?>> list = new ArrayList<>();
 
-    list.add(new MessageDetailsViewState<>(details.getMessageRecord(), MessageDetailsViewState.MESSAGE_HEADER));
+    list.add(new MessageDetailsViewState<>(details.getConversationMessage(), MessageDetailsViewState.MESSAGE_HEADER));
 
-    if (details.getMessageRecord().isOutgoing()) {
+    if (details.getConversationMessage().getMessageRecord().isOutgoing()) {
       addRecipients(list, RecipientHeader.NOT_SENT, details.getNotSent());
       addRecipients(list, RecipientHeader.READ, details.getRead());
       addRecipients(list, RecipientHeader.DELIVERED, details.getDelivered());

app/src/main/java/org/thoughtcrime/securesms/messagedetails/MessageDetailsAdapter.java

@@ -10,6 +10,7 @@ import androidx.recyclerview.widget.ListAdapter;
 import androidx.recyclerview.widget.RecyclerView;
 
 import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.conversation.ConversationMessage;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 
@@ -45,7 +46,7 @@ final class MessageDetailsAdapter extends ListAdapter<MessageDetailsAdapter.Mess
   @Override
   public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
     if (holder instanceof MessageHeaderViewHolder) {
-      ((MessageHeaderViewHolder) holder).bind((MessageRecord) getItem(position).data, running);
+      ((MessageHeaderViewHolder) holder).bind((ConversationMessage) getItem(position).data, running);
     } else if (holder instanceof RecipientHeaderViewHolder) {
       ((RecipientHeaderViewHolder) holder).bind((RecipientHeader) getItem(position).data);
     } else if (holder instanceof RecipientViewHolder) {
@@ -60,7 +61,7 @@ final class MessageDetailsAdapter extends ListAdapter<MessageDetailsAdapter.Mess
     if (payloads.isEmpty()) {
       super.onBindViewHolder(holder, position, payloads);
     } else if (holder instanceof MessageHeaderViewHolder) {
-      ((MessageHeaderViewHolder) holder).partialBind((MessageRecord) getItem(position).data, running);
+      ((MessageHeaderViewHolder) holder).partialBind((ConversationMessage) getItem(position).data, running);
     }
   }
 

app/src/main/java/org/thoughtcrime/securesms/messagedetails/MessageDetailsRepository.java

@@ -8,11 +8,14 @@ import androidx.annotation.WorkerThread;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import org.thoughtcrime.securesms.conversation.ConversationMessage;
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.database.GroupReceiptDatabase;
 import org.thoughtcrime.securesms.database.documents.IdentityKeyMismatch;
 import org.thoughtcrime.securesms.database.documents.NetworkFailure;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.recipients.Recipient;
@@ -86,7 +89,7 @@ final class MessageDetailsRepository {
       }
     }
 
-    return new MessageDetails(messageRecord, recipients);
+    return new MessageDetails(ConversationMessageFactory.createWithUnresolvedData(context, messageRecord), recipients);
   }
 
   private @Nullable NetworkFailure getNetworkFailure(MessageRecord messageRecord, Recipient recipient) {

app/src/main/java/org/thoughtcrime/securesms/messagedetails/MessageHeaderViewHolder.java

@@ -13,6 +13,7 @@ import androidx.recyclerview.widget.RecyclerView;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.conversation.ConversationItem;
 import org.thoughtcrime.securesms.conversation.ConversationMessage;
+import org.thoughtcrime.securesms.conversation.ConversationMessage.ConversationMessageFactory;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 import org.thoughtcrime.securesms.sms.MessageSender;
@@ -63,25 +64,30 @@ final class MessageHeaderViewHolder extends RecyclerView.ViewHolder {
     receivedStub    = itemView.findViewById(R.id.message_details_header_message_view_received_multimedia);
   }
 
-  void bind(MessageRecord messageRecord, boolean running) {
+  void bind(ConversationMessage conversationMessage, boolean running) {
-    bindMessageView(messageRecord);
+    MessageRecord messageRecord = conversationMessage.getMessageRecord();
+    bindMessageView(conversationMessage);
     bindErrorState(messageRecord);
     bindSentReceivedDates(messageRecord);
     bindExpirationTime(messageRecord, running);
     bindTransport(messageRecord);
   }
 
-  void partialBind(MessageRecord messageRecord, boolean running) {
+  void partialBind(ConversationMessage conversationMessage, boolean running) {
-    bindExpirationTime(messageRecord, running);
+    bindExpirationTime(conversationMessage.getMessageRecord(), running);
   }
 
-  private void bindMessageView(MessageRecord messageRecord) {
+  private void bindMessageView(ConversationMessage conversationMessage) {
     if (conversationItem == null) {
-      if      (messageRecord.isGroupAction()) conversationItem = (ConversationItem) updateStub.inflate();
+      if (conversationMessage.getMessageRecord().isGroupAction()) {
-      else if (messageRecord.isOutgoing())    conversationItem = (ConversationItem) sentStub.inflate();
+        conversationItem = (ConversationItem) updateStub.inflate();
-      else                                    conversationItem = (ConversationItem) receivedStub.inflate();
+      } else if (conversationMessage.getMessageRecord().isOutgoing()) {
+        conversationItem = (ConversationItem) sentStub.inflate();
+      } else {
+        conversationItem = (ConversationItem) receivedStub.inflate();
+      }
     }
-    conversationItem.bind(new ConversationMessage(messageRecord), Optional.absent(), Optional.absent(), glideRequests, Locale.getDefault(), new HashSet<>(), messageRecord.getRecipient(), null, false);
+    conversationItem.bind(conversationMessage, Optional.absent(), Optional.absent(), glideRequests, Locale.getDefault(), new HashSet<>(), conversationMessage.getMessageRecord().getRecipient(), null, false);
   }
 
   private void bindErrorState(MessageRecord messageRecord) {

app/src/main/java/org/thoughtcrime/securesms/mms/AttachmentManager.java

@@ -377,7 +377,7 @@ public class AttachmentManager {
                .execute();
   }
 
-  public static void selectGallery(Activity activity, int requestCode, @NonNull Recipient recipient, @NonNull String body, @NonNull TransportOption transport) {
+  public static void selectGallery(Activity activity, int requestCode, @NonNull Recipient recipient, @NonNull CharSequence body, @NonNull TransportOption transport) {
     Permissions.with(activity)
                .request(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                .ifNecessary()

app/src/main/java/org/thoughtcrime/securesms/mms/IncomingMediaMessage.java

@@ -5,6 +5,7 @@ import androidx.annotation.NonNull;
 import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.attachments.PointerAttachment;
 import org.thoughtcrime.securesms.contactshare.Contact;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
 import org.thoughtcrime.securesms.recipients.RecipientId;
@@ -35,6 +36,7 @@ public class IncomingMediaMessage {
   private final List<Attachment>  attachments    = new LinkedList<>();
   private final List<Contact>     sharedContacts = new LinkedList<>();
   private final List<LinkPreview> linkPreviews   = new LinkedList<>();
+  private final List<Mention>     mentions       = new LinkedList<>();
 
   public IncomingMediaMessage(@NonNull RecipientId from,
                               Optional<GroupId> groupId,
@@ -78,6 +80,7 @@ public class IncomingMediaMessage {
                               Optional<QuoteModel> quote,
                               Optional<List<Contact>> sharedContacts,
                               Optional<List<LinkPreview>> linkPreviews,
+                              Optional<List<Mention>> mentions,
                               Optional<Attachment> sticker)
   {
     this.push             = true;
@@ -98,6 +101,7 @@ public class IncomingMediaMessage {
     this.attachments.addAll(PointerAttachment.forPointers(attachments));
     this.sharedContacts.addAll(sharedContacts.or(Collections.emptyList()));
     this.linkPreviews.addAll(linkPreviews.or(Collections.emptyList()));
+    this.mentions.addAll(mentions.or(Collections.emptyList()));
 
     if (sticker.isPresent()) {
       this.attachments.add(sticker.get());
@@ -164,6 +168,10 @@ public class IncomingMediaMessage {
     return linkPreviews;
   }
 
+  public @NonNull List<Mention> getMentions() {
+    return mentions;
+  }
+
   public boolean isUnidentified() {
     return unidentified;
   }

app/src/main/java/org/thoughtcrime/securesms/mms/OutgoingExpirationUpdateMessage.java

@@ -12,7 +12,7 @@ public class OutgoingExpirationUpdateMessage extends OutgoingSecureMediaMessage
   public OutgoingExpirationUpdateMessage(Recipient recipient, long sentTimeMillis, long expiresIn) {
     super(recipient, "", new LinkedList<Attachment>(), sentTimeMillis,
           ThreadDatabase.DistributionTypes.CONVERSATION, expiresIn, false, null, Collections.emptyList(),
-          Collections.emptyList());
+          Collections.emptyList(), Collections.emptyList());
   }
 
   @Override

app/src/main/java/org/thoughtcrime/securesms/mms/OutgoingGroupUpdateMessage.java

@@ -6,6 +6,7 @@ import androidx.annotation.Nullable;
 import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.contactshare.Contact;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.database.model.databaseprotos.DecryptedGroupV2Context;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
 import org.thoughtcrime.securesms.recipients.Recipient;
@@ -26,10 +27,11 @@ public final class OutgoingGroupUpdateMessage extends OutgoingSecureMediaMessage
                                     boolean viewOnce,
                                     @Nullable QuoteModel quote,
                                     @NonNull List<Contact> contacts,
-                                    @NonNull List<LinkPreview> previews)
+                                    @NonNull List<LinkPreview> previews,
+                                    @NonNull List<Mention> mentions)
   {
     super(recipient, groupContext.getEncodedGroupContext(), avatar, sentTimeMillis,
-          ThreadDatabase.DistributionTypes.CONVERSATION, expiresIn, viewOnce, quote, contacts, previews);
+          ThreadDatabase.DistributionTypes.CONVERSATION, expiresIn, viewOnce, quote, contacts, previews, mentions);
 
     this.messageGroupContext = groupContext;
   }
@@ -42,9 +44,10 @@ public final class OutgoingGroupUpdateMessage extends OutgoingSecureMediaMessage
                                     boolean viewOnce,
                                     @Nullable QuoteModel quote,
                                     @NonNull List<Contact> contacts,
-                                    @NonNull List<LinkPreview> previews)
+                                    @NonNull List<LinkPreview> previews,
+                                    @NonNull List<Mention> mentions)
   {
-    this(recipient, new MessageGroupContext(group), getAttachments(avatar), sentTimeMillis, expireIn, viewOnce, quote, contacts, previews);
+    this(recipient, new MessageGroupContext(group), getAttachments(avatar), sentTimeMillis, expireIn, viewOnce, quote, contacts, previews, mentions);
   }
 
   public OutgoingGroupUpdateMessage(@NonNull Recipient recipient,
@@ -55,9 +58,10 @@ public final class OutgoingGroupUpdateMessage extends OutgoingSecureMediaMessage
                                     boolean viewOnce,
                                     @Nullable QuoteModel quote,
                                     @NonNull List<Contact> contacts,
-                                    @NonNull List<LinkPreview> previews)
+                                    @NonNull List<LinkPreview> previews,
+                                    @NonNull List<Mention> mentions)
   {
-    this(recipient, new MessageGroupContext(group), getAttachments(avatar), sentTimeMillis, expireIn, viewOnce, quote, contacts, previews);
+    this(recipient, new MessageGroupContext(group), getAttachments(avatar), sentTimeMillis, expireIn, viewOnce, quote, contacts, previews, mentions);
   }
 
   @Override

app/src/main/java/org/thoughtcrime/securesms/mms/OutgoingMediaMessage.java

@@ -8,6 +8,7 @@ import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.contactshare.Contact;
 import org.thoughtcrime.securesms.database.documents.IdentityKeyMismatch;
 import org.thoughtcrime.securesms.database.documents.NetworkFailure;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
 import org.thoughtcrime.securesms.recipients.Recipient;
 
@@ -30,6 +31,7 @@ public class OutgoingMediaMessage {
   private   final List<IdentityKeyMismatch> identityKeyMismatches = new LinkedList<>();
   private   final List<Contact>             contacts              = new LinkedList<>();
   private   final List<LinkPreview>         linkPreviews          = new LinkedList<>();
+  private   final List<Mention>             mentions              = new LinkedList<>();
 
   public OutgoingMediaMessage(Recipient recipient, String message,
                               List<Attachment> attachments, long sentTimeMillis,
@@ -38,6 +40,7 @@ public class OutgoingMediaMessage {
                               @Nullable QuoteModel outgoingQuote,
                               @NonNull List<Contact> contacts,
                               @NonNull List<LinkPreview> linkPreviews,
+                              @NonNull List<Mention> mentions,
                               @NonNull List<NetworkFailure> networkFailures,
                               @NonNull List<IdentityKeyMismatch> identityKeyMismatches)
   {
@@ -53,6 +56,7 @@ public class OutgoingMediaMessage {
 
     this.contacts.addAll(contacts);
     this.linkPreviews.addAll(linkPreviews);
+    this.mentions.addAll(mentions);
     this.networkFailures.addAll(networkFailures);
     this.identityKeyMismatches.addAll(identityKeyMismatches);
   }
@@ -62,14 +66,15 @@ public class OutgoingMediaMessage {
                               boolean viewOnce, int distributionType,
                               @Nullable QuoteModel outgoingQuote,
                               @NonNull List<Contact> contacts,
-                              @NonNull List<LinkPreview> linkPreviews)
+                              @NonNull List<LinkPreview> linkPreviews,
+                              @NonNull List<Mention> mentions)
   {
     this(recipient,
          buildMessage(slideDeck, message),
          slideDeck.asAttachments(),
          sentTimeMillis, subscriptionId,
          expiresIn, viewOnce, distributionType, outgoingQuote,
-         contacts, linkPreviews, new LinkedList<>(), new LinkedList<>());
+         contacts, linkPreviews, mentions, new LinkedList<>(), new LinkedList<>());
   }
 
   public OutgoingMediaMessage(OutgoingMediaMessage that) {
@@ -87,6 +92,7 @@ public class OutgoingMediaMessage {
     this.networkFailures.addAll(that.networkFailures);
     this.contacts.addAll(that.contacts);
     this.linkPreviews.addAll(that.linkPreviews);
+    this.mentions.addAll(that.mentions);
   }
 
   public Recipient getRecipient() {
@@ -145,6 +151,10 @@ public class OutgoingMediaMessage {
     return linkPreviews;
   }
 
+  public @NonNull List<Mention> getMentions() {
+    return mentions;
+  }
+
   public @NonNull List<NetworkFailure> getNetworkFailures() {
     return networkFailures;
   }

app/src/main/java/org/thoughtcrime/securesms/mms/OutgoingSecureMediaMessage.java

@@ -5,6 +5,7 @@ import androidx.annotation.Nullable;
 
 import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.contactshare.Contact;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
 import org.thoughtcrime.securesms.recipients.Recipient;
 
@@ -21,9 +22,10 @@ public class OutgoingSecureMediaMessage extends OutgoingMediaMessage {
                                     boolean viewOnce,
                                     @Nullable QuoteModel quote,
                                     @NonNull List<Contact> contacts,
-                                    @NonNull List<LinkPreview> previews)
+                                    @NonNull List<LinkPreview> previews,
+                                    @NonNull List<Mention> mentions)
   {
-    super(recipient, body, attachments, sentTimeMillis, -1, expiresIn, viewOnce, distributionType, quote, contacts, previews, Collections.emptyList(), Collections.emptyList());
+    super(recipient, body, attachments, sentTimeMillis, -1, expiresIn, viewOnce, distributionType, quote, contacts, previews, mentions, Collections.emptyList(), Collections.emptyList());
   }
 
   public OutgoingSecureMediaMessage(OutgoingMediaMessage base) {

app/src/main/java/org/thoughtcrime/securesms/mms/QuoteModel.java

@@ -5,8 +5,10 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import org.thoughtcrime.securesms.attachments.Attachment;
+import org.thoughtcrime.securesms.database.model.Mention;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 
+import java.util.Collections;
 import java.util.List;
 
 public class QuoteModel {
@@ -16,13 +18,15 @@ public class QuoteModel {
   private final String           text;
   private final boolean          missing;
   private final List<Attachment> attachments;
+  private final List<Mention>    mentions;
 
-  public QuoteModel(long id, @NonNull RecipientId author, String text, boolean missing, @Nullable List<Attachment> attachments) {
+  public QuoteModel(long id, @NonNull RecipientId author, String text, boolean missing, @Nullable List<Attachment> attachments, @Nullable List<Mention> mentions) {
     this.id          = id;
     this.author      = author;
     this.text        = text;
     this.missing     = missing;
     this.attachments = attachments;
+    this.mentions    = mentions != null ? mentions : Collections.emptyList();
   }
 
   public long getId() {
@@ -44,4 +48,8 @@ public class QuoteModel {
   public List<Attachment> getAttachments() {
     return attachments;
   }
+
+  public @NonNull List<Mention> getMentions() {
+    return mentions;
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/notifications/AndroidAutoReplyReceiver.java

@@ -75,7 +75,20 @@ public class AndroidAutoReplyReceiver extends BroadcastReceiver {
 
           if (recipient.resolve().isGroup()) {
             Log.w(TAG, "GroupRecipient, Sending media message");
-            OutgoingMediaMessage reply = new OutgoingMediaMessage(recipient, responseText.toString(), new LinkedList<>(), System.currentTimeMillis(), subscriptionId, expiresIn, false, 0, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
+            OutgoingMediaMessage reply = new OutgoingMediaMessage(recipient,
+                                                                  responseText.toString(),
+                                                                  new LinkedList<>(),
+                                                                  System.currentTimeMillis(),
+                                                                  subscriptionId,
+                                                                  expiresIn,
+                                                                  false,
+                                                                  0,
+                                                                  null,
+                                                                  Collections.emptyList(),
+                                                                  Collections.emptyList(),
+                                                                  Collections.emptyList(),
+                                                                  Collections.emptyList(),
+                                                                  Collections.emptyList());
             replyThreadId = MessageSender.send(context, reply, threadId, false, null);
           } else {
             Log.w(TAG, "Sending regular message ");

app/src/main/java/org/thoughtcrime/securesms/notifications/DefaultMessageNotifier.java

@@ -43,15 +43,18 @@ import org.thoughtcrime.securesms.contactshare.Contact;
 import org.thoughtcrime.securesms.contactshare.ContactUtil;
 import org.thoughtcrime.securesms.conversation.ConversationActivity;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.MentionUtil;
 import org.thoughtcrime.securesms.database.MessagingDatabase.MarkedMessageInfo;
 import org.thoughtcrime.securesms.database.MmsSmsColumns;
 import org.thoughtcrime.securesms.database.MmsSmsDatabase;
+import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.ThreadBodyUtil;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.database.model.MmsMessageRecord;
 import org.thoughtcrime.securesms.database.model.ReactionRecord;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.messages.IncomingMessageObserver;
 import org.thoughtcrime.securesms.mms.Slide;
@@ -59,6 +62,7 @@ import org.thoughtcrime.securesms.mms.SlideDeck;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientUtil;
 import org.thoughtcrime.securesms.service.KeyCachingService;
+import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.MediaUtil;
 import org.thoughtcrime.securesms.util.MessageRecordUtil;
 import org.thoughtcrime.securesms.util.ServiceUtil;
@@ -243,18 +247,14 @@ public class DefaultMessageNotifier implements MessageNotifier {
   {
     boolean isVisible = visibleThread == threadId;
 
-    ThreadDatabase threads    = DatabaseFactory.getThreadDatabase(context);
+    ThreadDatabase threads = DatabaseFactory.getThreadDatabase(context);
-    Recipient      recipients = DatabaseFactory.getThreadDatabase(context)
-                                               .getRecipientForThreadId(threadId);
 
     if (isVisible) {
       List<MarkedMessageInfo> messageIds = threads.setRead(threadId, false);
       MarkReadReceiver.process(context, messageIds);
     }
 
-    if (!TextSecurePreferences.isNotificationsEnabled(context) ||
+    if (!TextSecurePreferences.isNotificationsEnabled(context)) {
-        (recipients != null && recipients.isMuted()))
-    {
       return;
     }
 
@@ -499,7 +499,7 @@ public class DefaultMessageNotifier implements MessageNotifier {
       Recipient    recipient             = record.getIndividualRecipient().resolve();
       Recipient    conversationRecipient = record.getRecipient().resolve();
       long         threadId              = record.getThreadId();
-      CharSequence body                  = record.getDisplayBody(context);
+      CharSequence body                  = MentionUtil.updateBodyWithDisplayNames(context, record);
       Recipient    threadRecipients      = null;
       SlideDeck    slideDeck             = null;
       long         timestamp             = record.getTimestamp();
@@ -527,7 +527,17 @@ public class DefaultMessageNotifier implements MessageNotifier {
           slideDeck = ((MmsMessageRecord) record).getSlideDeck();
         }
 
-        if (threadRecipients == null || !threadRecipients.isMuted()) {
+        boolean includeMessage = true;
+        if (threadRecipients != null && threadRecipients.isMuted()) {
+          RecipientDatabase.MentionSetting mentionSetting = threadRecipients.getMentionSetting();
+
+          boolean overrideMuted = (mentionSetting == RecipientDatabase.MentionSetting.GLOBAL && SignalStore.notificationSettings().isMentionNotifiesMeEnabled()) ||
+                                  mentionSetting == RecipientDatabase.MentionSetting.ALWAYS_NOTIFY;
+
+          includeMessage = FeatureFlags.mentions() && overrideMuted && record.hasSelfMention();
+        }
+
+        if (threadRecipients == null || includeMessage) {
           notificationState.addNotification(new NotificationItem(id, mms, recipient, conversationRecipient, threadRecipients, threadId, body, timestamp, receivedTimestamp, slideDeck, false));
         }
       }

app/src/main/java/org/thoughtcrime/securesms/notifications/RemoteReplyReceiver.java

@@ -77,7 +77,20 @@ public class RemoteReplyReceiver extends BroadcastReceiver {
 
           switch (replyMethod) {
             case GroupMessage: {
-              OutgoingMediaMessage reply = new OutgoingMediaMessage(recipient, responseText.toString(), new LinkedList<>(), System.currentTimeMillis(), subscriptionId, expiresIn, false, 0, null, Collections.emptyList(), Collections.emptyList(), Collections.emptyList(), Collections.emptyList());
+              OutgoingMediaMessage reply = new OutgoingMediaMessage(recipient,
+                                                                    responseText.toString(),
+                                                                    new LinkedList<>(),
+                                                                    System.currentTimeMillis(),
+                                                                    subscriptionId,
+                                                                    expiresIn,
+                                                                    false,
+                                                                    0,
+                                                                    null,
+                                                                    Collections.emptyList(),
+                                                                    Collections.emptyList(),
+                                                                    Collections.emptyList(),
+                                                                    Collections.emptyList(),
+                                                                    Collections.emptyList());
               threadId = MessageSender.send(context, reply, -1, false, null);
               break;
             }

app/src/main/java/org/thoughtcrime/securesms/preferences/NotificationsPreferenceFragment.java

@@ -12,13 +12,18 @@ import android.provider.Settings;
 import androidx.annotation.Nullable;
 import androidx.preference.ListPreference;
 import androidx.preference.Preference;
+import androidx.preference.PreferenceDataStore;
+
 import android.text.TextUtils;
 
 import org.thoughtcrime.securesms.ApplicationPreferencesActivity;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.components.SwitchPreferenceCompat;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
+import org.thoughtcrime.securesms.keyvalue.NotificationSettings;
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.notifications.NotificationChannels;
+import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
 
 import static android.app.Activity.RESULT_OK;
@@ -115,11 +120,18 @@ public class NotificationsPreferenceFragment extends ListSummaryPreferenceFragme
     initializeCallRingtoneSummary(findPreference(TextSecurePreferences.CALL_RINGTONE_PREF));
     initializeMessageVibrateSummary((SwitchPreferenceCompat)findPreference(TextSecurePreferences.VIBRATE_PREF));
     initializeCallVibrateSummary((SwitchPreferenceCompat)findPreference(TextSecurePreferences.CALL_VIBRATE_PREF));
+
+    if (FeatureFlags.mentions()) {
+      initializeMentionsNotifyMeSummary((SwitchPreferenceCompat)findPreference(NotificationSettings.MENTIONS_NOTIFY_ME));
+    }
   }
 
   @Override
   public void onCreatePreferences(@Nullable Bundle savedInstanceState, String rootKey) {
     addPreferencesFromResource(R.xml.preferences_notifications);
+    if (FeatureFlags.mentions()) {
+      addPreferencesFromResource(R.xml.preferences_notifications_mentions);
+    }
   }
 
   @Override
@@ -197,6 +209,11 @@ public class NotificationsPreferenceFragment extends ListSummaryPreferenceFragme
     pref.setChecked(TextSecurePreferences.isCallNotificationVibrateEnabled(getContext()));
   }
 
+  private void initializeMentionsNotifyMeSummary(SwitchPreferenceCompat pref) {
+    pref.setPreferenceDataStore(SignalStore.getPreferenceDataStore());
+    pref.setChecked(SignalStore.notificationSettings().isMentionNotifiesMeEnabled());
+  }
+
   public static CharSequence getSummary(Context context) {
     final int onCapsResId   = R.string.ApplicationPreferencesActivity_On;
     final int offCapsResId  = R.string.ApplicationPreferencesActivity_Off;

app/src/main/java/org/thoughtcrime/securesms/recipients/Recipient.java

@@ -26,6 +26,7 @@ import org.thoughtcrime.securesms.contacts.avatars.TransparentContactPhoto;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.IdentityDatabase.VerifiedStatus;
 import org.thoughtcrime.securesms.database.RecipientDatabase;
+import org.thoughtcrime.securesms.database.RecipientDatabase.MentionSetting;
 import org.thoughtcrime.securesms.database.RecipientDatabase.RegisteredState;
 import org.thoughtcrime.securesms.database.RecipientDatabase.UnidentifiedAccessMode;
 import org.thoughtcrime.securesms.database.RecipientDatabase.VibrateState;
@@ -102,6 +103,7 @@ public class Recipient {
   private final byte[]                 storageId;
   private final byte[]                 identityKey;
   private final VerifiedStatus         identityStatus;
+  private final MentionSetting         mentionSetting;
 
 
   /**
@@ -316,6 +318,7 @@ public class Recipient {
     this.storageId              = null;
     this.identityKey            = null;
     this.identityStatus         = VerifiedStatus.DEFAULT;
+    this.mentionSetting         = MentionSetting.GLOBAL;
   }
 
   public Recipient(@NonNull RecipientId id, @NonNull RecipientDetails details, boolean resolved) {
@@ -359,6 +362,7 @@ public class Recipient {
     this.storageId              = details.storageId;
     this.identityKey            = details.identityKey;
     this.identityStatus         = details.identityStatus;
+    this.mentionSetting         = details.mentionSetting;
   }
 
   public @NonNull RecipientId getId() {
@@ -809,6 +813,10 @@ public class Recipient {
     }
   }
 
+  public @NonNull MentionSetting getMentionSetting() {
+    return mentionSetting;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;

app/src/main/java/org/thoughtcrime/securesms/recipients/RecipientDetails.java

@@ -9,7 +9,9 @@ import androidx.annotation.Nullable;
 
 import org.thoughtcrime.securesms.color.MaterialColor;
 import org.thoughtcrime.securesms.database.IdentityDatabase.VerifiedStatus;
+import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.RecipientDatabase.InsightsBannerTier;
+import org.thoughtcrime.securesms.database.RecipientDatabase.MentionSetting;
 import org.thoughtcrime.securesms.database.RecipientDatabase.RecipientSettings;
 import org.thoughtcrime.securesms.database.RecipientDatabase.RegisteredState;
 import org.thoughtcrime.securesms.database.RecipientDatabase.UnidentifiedAccessMode;
@@ -66,6 +68,7 @@ public class RecipientDetails {
   final byte[] storageId;
   final byte[]                 identityKey;
   final VerifiedStatus         identityStatus;
+  final MentionSetting         mentionSetting;
 
   public RecipientDetails(@Nullable String name,
                           @NonNull Optional<Long> groupAvatarId,
@@ -112,6 +115,7 @@ public class RecipientDetails {
     this.storageId                       = settings.getStorageId();
     this.identityKey                     = settings.getIdentityKey();
     this.identityStatus                  = settings.getIdentityStatus();
+    this.mentionSetting                  = settings.getMentionSetting();
 
     if (name == null) this.name = settings.getSystemDisplayName();
     else              this.name = name;
@@ -160,6 +164,7 @@ public class RecipientDetails {
     this.storageId              = null;
     this.identityKey            = null;
     this.identityStatus         = VerifiedStatus.DEFAULT;
+    this.mentionSetting         = MentionSetting.GLOBAL;
   }
 
   public static @NonNull RecipientDetails forIndividual(@NonNull Context context, @NonNull RecipientSettings settings) {

app/src/main/java/org/thoughtcrime/securesms/sharing/ShareActivity.java

@@ -296,7 +296,7 @@ public class ShareActivity extends PassphraseRequiredActivity
 
   private void openConversation(long threadId, @NonNull RecipientId recipientId, @Nullable ShareData shareData) {
     Intent           intent          = new Intent(this, ConversationActivity.class);
-    String           textExtra       = getIntent().getStringExtra(Intent.EXTRA_TEXT);
+    CharSequence     textExtra       = getIntent().getCharSequenceExtra(Intent.EXTRA_TEXT);
     ArrayList<Media> mediaExtra      = getIntent().getParcelableArrayListExtra(ConversationActivity.MEDIA_EXTRA);
     StickerLocator   stickerExtra    = getIntent().getParcelableExtra(ConversationActivity.STICKER_EXTRA);
     boolean          borderlessExtra = getIntent().getBooleanExtra(ConversationActivity.BORDERLESS_EXTRA, false);

app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java

@@ -180,4 +180,21 @@ public final class StringUtil {
               .appendCodePoint(Bidi.PDI)
               .toString();
   }
+
+  /**
+   * Trims a {@link CharSequence} of starting and trailing whitespace. Behavior matches
+   * {@link String#trim()} to preserve expectations around results.
+   */
+  public static CharSequence trimSequence(CharSequence text) {
+    int length     = text.length();
+    int startIndex = 0;
+
+    while ((startIndex < length) && (text.charAt(startIndex) <= ' ')) {
+      startIndex++;
+    }
+    while ((startIndex < length) && (text.charAt(length - 1) <= ' ')) {
+      length--;
+    }
+    return (startIndex > 0 || length < text.length()) ? text.subSequence(startIndex, length) : text;
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/util/Util.java

@@ -176,6 +176,10 @@ public class Util {
     return value != null ? value : "";
   }
 
+  public static @NonNull CharSequence emptyIfNull(@Nullable CharSequence value) {
+    return value != null ? value : "";
+  }
+
   public static <E> List<List<E>> chunk(@NonNull List<E> list, int chunkSize) {
     List<List<E>> chunks = new ArrayList<>(list.size() / chunkSize);
 

app/src/main/proto/Database.proto

@@ -55,3 +55,16 @@ message ProfileChangeDetails {
 
     StringChange profileNameChange = 1;
 }
+
+message BodyRangeList {
+    message BodyRange {
+        int32 start  = 1;
+        int32 length = 2;
+
+        oneof associatedValue {
+            string mentionUuid = 3;
+        }
+    }
+
+    repeated BodyRange ranges = 1;
+}

app/src/main/res/layout/group_manage_fragment.xml

@@ -290,6 +290,46 @@
 
                     </LinearLayout>
 
+                    <LinearLayout
+                        android:id="@+id/group_mentions_row"
+                        android:layout_width="match_parent"
+                        android:layout_height="@dimen/group_manage_fragment_row_height"
+                        android:background="?selectableItemBackground"
+                        android:clickable="true"
+                        android:focusable="true">
+
+                        <TextView
+                            android:id="@+id/group_mentions"
+                            android:layout_width="0dp"
+                            android:layout_height="match_parent"
+                            android:layout_weight="1"
+                            android:gravity="start|center_vertical"
+                            android:paddingStart="@dimen/group_manage_fragment_row_horizontal_padding"
+                            android:paddingEnd="@dimen/group_manage_fragment_row_horizontal_padding"
+                            android:text="@string/ManageGroupActivity_mentions"
+                            android:textAlignment="viewStart"
+                            android:textAppearance="@style/Signal.Text.Body"
+                            app:layout_constraintBottom_toBottomOf="parent"
+                            app:layout_constraintEnd_toStartOf="@id/group_mute_notifications_switch"
+                            app:layout_constraintStart_toStartOf="parent" />
+
+                        <TextView
+                            android:id="@+id/group_mentions_value"
+                            android:layout_width="wrap_content"
+                            android:layout_height="match_parent"
+                            android:gravity="center_vertical|end"
+                            android:paddingStart="@dimen/group_manage_fragment_row_horizontal_padding"
+                            android:paddingEnd="@dimen/group_manage_fragment_row_horizontal_padding"
+                            android:textAppearance="@style/Signal.Text.Body"
+                            android:textColor="@color/ultramarine_text_button"
+                            app:layout_constraintBottom_toBottomOf="parent"
+                            app:layout_constraintEnd_toEndOf="parent"
+                            app:layout_constraintStart_toEndOf="@id/group_custom_notifications"
+                            app:layout_constraintTop_toBottomOf="@id/group_mute_notifications_switch"
+                            tools:text="Default (Notify me)" />
+
+                    </LinearLayout>
+
                 </LinearLayout>
 
             </androidx.cardview.widget.CardView>

app/src/main/res/layout/group_mention_setting_dialog.xml

@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <TextView
+        style="@style/TextAppearance.AppCompat.Subhead"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:layout_marginBottom="4dp"
+        android:paddingLeft="?attr/dialogPreferredPadding"
+        android:paddingRight="?attr/dialogPreferredPadding"
+        android:text="@string/GroupMentionSettingDialog_receive_notifications_when_youre_mentioned_in_muted_chats" />
+
+    <CheckedTextView
+        android:id="@+id/group_mention_setting_default"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="?selectableItemBackground"
+        android:drawableStart="?android:attr/listChoiceIndicatorSingle"
+        android:drawablePadding="20dp"
+        android:gravity="center_vertical"
+        android:minHeight="?attr/listPreferredItemHeightSmall"
+        android:paddingStart="20dp"
+        android:paddingEnd="?attr/dialogPreferredPadding"
+        android:textAppearance="?android:attr/textAppearanceMedium"
+        android:textColor="?attr/textColorAlertDialogListItem"
+        tools:text="@string/GroupMentionSettingDialog_default_notify_me" />
+
+    <CheckedTextView
+        android:id="@+id/group_mention_setting_always_notify"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="?selectableItemBackground"
+        android:drawableStart="?android:attr/listChoiceIndicatorSingle"
+        android:drawablePadding="20dp"
+        android:gravity="center_vertical"
+        android:minHeight="?attr/listPreferredItemHeightSmall"
+        android:paddingStart="20dp"
+        android:paddingEnd="?attr/dialogPreferredPadding"
+        android:text="@string/GroupMentionSettingDialog_always_notify_me"
+        android:textAppearance="?android:attr/textAppearanceMedium"
+        android:textColor="?attr/textColorAlertDialogListItem" />
+
+    <CheckedTextView
+        android:id="@+id/group_mention_setting_dont_notify"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="?selectableItemBackground"
+        android:drawableStart="?android:attr/listChoiceIndicatorSingle"
+        android:drawablePadding="20dp"
+        android:gravity="center_vertical"
+        android:minHeight="?attr/listPreferredItemHeightSmall"
+        android:paddingStart="20dp"
+        android:paddingEnd="?attr/dialogPreferredPadding"
+        android:text="@string/GroupMentionSettingDialog_dont_notify_me"
+        android:textAppearance="?android:attr/textAppearanceMedium"
+        android:textColor="?attr/textColorAlertDialogListItem" />
+
+</LinearLayout>

app/src/main/res/layout/mediasend_activity.xml

@@ -27,6 +27,13 @@
             android:clickable="true"
             android:background="@color/transparent_black_40">
 
+            <ViewStub
+                android:id="@+id/mediasend_mention_suggestions_stub"
+                android:layout_width="match_parent"
+                android:layout_height="0dp"
+                android:layout_weight="1"
+                android:layout="@layout/conversation_mention_suggestions_stub"/>
+
             <org.thoughtcrime.securesms.components.emoji.EmojiEditText
                 android:id="@+id/mediasend_caption"
                 android:layout_width="match_parent"
@@ -117,7 +124,7 @@
                     android:layout_marginStart="12dp"
                     android:layout_gravity="bottom"
                     android:background="@drawable/circle_tintable"
-                    tools:backgroundTint="@color/core_blue">
+                    tools:backgroundTint="@color/core_ultramarine">
 
                     <org.thoughtcrime.securesms.components.SendButton
                         android:id="@+id/mediasend_send_button"

app/src/main/res/layout/mentions_picker_fragment.xml

@@ -16,7 +16,7 @@
         <View
             android:layout_width="match_parent"
             android:layout_height="1dp"
-            android:background="@color/core_grey_65"/>
+            android:background="?conversation_mention_divider_color"/>
 
         <androidx.recyclerview.widget.RecyclerView
             android:id="@+id/mentions_picker_list"

app/src/main/res/layout/mentions_recipient_list_item.xml

@@ -3,11 +3,12 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:padding="12dp"
+    android:background="?selectableItemBackground"
-    android:minHeight="52dp"
-    android:orientation="horizontal"
     android:gravity="center_vertical"
-    android:background="?selectableItemBackground">
+    android:paddingStart="12dp"
+    android:paddingTop="10dp"
+    android:paddingEnd="8dp"
+    android:paddingBottom="10dp">
 
     <org.thoughtcrime.securesms.components.AvatarImageView
         android:id="@+id/mention_recipient_avatar"
@@ -17,12 +18,25 @@
 
     <TextView
         android:id="@+id/mention_recipient_name"
-        android:layout_width="0dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_weight="1"
         android:layout_marginStart="12dp"
+        android:layout_marginEnd="12dp"
+        android:ellipsize="end"
+        android:singleLine="true"
         android:textAlignment="viewStart"
         android:textAppearance="@style/Signal.Text.Preview"
         tools:text="@tools:sample/full_names" />
 
+    <TextView
+        android:id="@+id/mention_recipient_username"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:ellipsize="end"
+        android:singleLine="true"
+        android:textAlignment="viewStart"
+        android:textAppearance="@style/Signal.Text.Preview"
+        android:textColor="@color/core_grey_60"
+        tools:text="@tools:sample/last_names" />
+
 </LinearLayout>

app/src/main/res/layout/quote_view.xml

@@ -98,6 +98,7 @@
                     style="@style/Signal.Text.Body"
                     android:ellipsize="end"
                     android:maxLines="2"
+                    app:emoji_renderMentions="false"
                     tools:text="With great power comes great responsibility."
                     tools:visibility="visible" />
 

app/src/main/res/values/attrs.xml

@@ -90,6 +90,7 @@
     <attr name="conversation_title_color" format="reference" />
     <attr name="conversation_subtitle_color" format="reference" />
     <attr name="conversation_mention_background_color" format="reference" />
+    <attr name="conversation_mention_divider_color" format="reference" />
 
     <attr name="emoji_tab_strip_background" format="color" />
     <attr name="emoji_tab_indicator" format="color" />
@@ -404,6 +405,7 @@
         <attr name="scaleEmojis" format="boolean" />
         <attr name="emoji_maxLength" format="integer" />
         <attr name="emoji_forceCustom" format="boolean" />
+        <attr name="emoji_renderMentions" format="boolean" />
     </declare-styleable>
 
     <declare-styleable name="RingtonePreference">

app/src/main/res/values/dimens.xml

@@ -159,4 +159,6 @@
     <dimen name="group_manage_fragment_row_horizontal_padding">16dp</dimen>
 
     <dimen name="wave_form_bar_width">2dp</dimen>
+
+    <dimen name="mentions_picker_peek_height">216dp</dimen>
 </resources>

app/src/main/res/values/strings.xml

@@ -549,6 +549,7 @@
     <string name="ManageGroupActivity_leave_group">Leave group</string>
     <string name="ManageGroupActivity_mute_notifications">Mute notifications</string>
     <string name="ManageGroupActivity_custom_notifications">Custom notifications</string>
+    <string name="ManageGroupActivity_mentions">Mentions</string>
     <string name="ManageGroupActivity_until_s">Until %1$s</string>
     <string name="ManageGroupActivity_off">Off</string>
     <string name="ManageGroupActivity_on">On</string>
@@ -576,6 +577,13 @@
     <string name="ManageGroupActivity_legacy_group">Legacy Group</string>
     <string name="ManageGroupActivity_legacy_group_learn_more">This is a Legacy Group. To access features like group admins, create a New Group.</string>
 
+    <!-- GroupMentionSettingDialog -->
+    <string name="GroupMentionSettingDialog_notify_me_for_mentions">Notify me for Mentions</string>
+    <string name="GroupMentionSettingDialog_receive_notifications_when_youre_mentioned_in_muted_chats">Receive notifications when you’re mentioned in muted chats?</string>
+    <string name="GroupMentionSettingDialog_default_notify_me">Default (Notify me)</string>
+    <string name="GroupMentionSettingDialog_default_dont_notify_me">Default (Don\'t notify me)</string>
+    <string name="GroupMentionSettingDialog_always_notify_me">Always notify me</string>
+    <string name="GroupMentionSettingDialog_dont_notify_me">Don\'t notify me</string>
     
     <!-- ManageRecipientActivity -->
     <string name="ManageRecipientActivity_add_to_system_contacts">Add to system contacts</string>
@@ -1995,6 +2003,9 @@
     <string name="preferences_communication__sealed_sender_allow_from_anyone">Allow from anyone</string>
     <string name="preferences_communication__sealed_sender_allow_from_anyone_description">Enable sealed sender for incoming messages from non-contacts and people with whom you have not shared your profile.</string>
     <string name="preferences_communication__sealed_sender_learn_more">Learn more</string>
+    <string name="preferences_notifications__mentions">Mentions</string>
+    <string name="preferences_notifications__notify_me">Notify me</string>
+    <string name="preferences_notifications__receive_notifications_when_youre_mentioned_in_muted_chats">Receive notifications when you’re mentioned in muted chats</string>
 
     <!-- Internal only preferences -->
     <string name="preferences__internal_preferences" translatable="false">Internal Preferences</string>

app/src/main/res/values/themes.xml

@@ -263,6 +263,7 @@
         <item name="conversation_title_color">@color/white</item>
         <item name="conversation_subtitle_color">@color/transparent_white_90</item>
         <item name="conversation_mention_background_color">@color/core_grey_20</item>
+        <item name="conversation_mention_divider_color">@color/core_grey_05</item>
 
         <item name="safety_number_change_dialog_button_background">@color/core_grey_05</item>
         <item name="safety_number_change_dialog_button_text_color">@color/core_ultramarine</item>
@@ -622,6 +623,7 @@
         <item name="conversation_title_color">@color/transparent_white_90</item>
         <item name="conversation_subtitle_color">@color/transparent_white_80</item>
         <item name="conversation_mention_background_color">@color/core_grey_75</item>
+        <item name="conversation_mention_divider_color">@color/core_grey_25</item>
         <item name="conversation_scroll_to_bottom_background">@drawable/scroll_to_bottom_background_dark</item>
         <item name="conversation_scroll_to_bottom_foreground_color">@color/core_white</item>
 

app/src/main/res/xml/preferences_notifications_mentions.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <PreferenceCategory android:layout="@layout/preference_divider"/>
+
+    <PreferenceCategory android:title="@string/preferences_notifications__mentions">
+        <org.thoughtcrime.securesms.components.SwitchPreferenceCompat
+            android:key="notifications.mentions.notify_me"
+            android:title="@string/preferences_notifications__notify_me"
+            android:summary="@string/preferences_notifications__receive_notifications_when_youre_mentioned_in_muted_chats"
+            android:defaultValue="true" />
+    </PreferenceCategory>
+
+</PreferenceScreen>

app/src/test/java/org/thoughtcrime/securesms/database/MentionUtilTest_updateBodyAndMentionsWithPlaceholders.java

@@ -0,0 +1,121 @@
+package org.thoughtcrime.securesms.database;
+
+import android.app.Application;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.ParameterizedRobolectricTestRunner;
+import org.robolectric.ParameterizedRobolectricTestRunner.Parameters;
+import org.robolectric.annotation.Config;
+import org.thoughtcrime.securesms.database.model.Mention;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+
+import static org.junit.Assert.assertEquals;
+import static org.thoughtcrime.securesms.database.MentionUtil.MENTION_PLACEHOLDER;
+import static org.thoughtcrime.securesms.database.MentionUtil.MENTION_STARTER;
+
+@RunWith(ParameterizedRobolectricTestRunner.class)
+@Config(manifest = Config.NONE, application = Application.class)
+public class MentionUtilTest_updateBodyAndMentionsWithPlaceholders {
+
+  private final String        body;
+  private final List<Mention> mentions;
+  private final String        updatedBody;
+  private final List<Mention> updatedMentions;
+
+  @Parameters
+  public static Collection<Object[]> data() {
+    return Arrays.asList(new Object[][]{
+      /* Empty states */
+      { null, Collections.emptyList(), null, Collections.emptyList() },
+      builder().text("no mentions").build(),
+      builder().text("").build(),
+      builder().text("no mentions but @tester text").build(),
+
+      /* Singles */
+      builder().mention("test").text(" start").build(),
+      builder().text("middle ").mention("test").text(" middle").build(),
+      builder().text("end end ").mention("test").build(),
+      builder().mention("test").build(),
+
+      /* Doubles */
+      builder().mention("foo").text(" ").mention("barbaz").build(),
+      builder().text("start text ").mention("barbazbuzz").text(" ").mention("barbaz").build(),
+      builder().text("what what ").mention("foo").text(" ").mention("barbaz").text(" more text").build(),
+      builder().mention("barbazbuzz").text(" ").mention("foo").build(),
+
+      /* Triples */
+      builder().mention("test").text(" ").mention("test2").text(" ").mention("test3").build(),
+      builder().text("Starting ").mention("test").text(" ").mention("test2").text(" ").mention("test3").build(),
+      builder().mention("test").text(" ").mention("test2").text(" ").mention("test3").text(" ending").build(),
+      builder().mention("test").text(" ").mention("test2").text(" ").mention("test3").build(),
+      builder().mention("no").mention("spaces").mention("atall").build(),
+
+      /* Emojis and Spaces */
+      builder().mention("test").text(" start 🤘").build(),
+      builder().mention("test").text(" start 🤘🤘").build(),
+      builder().mention("test").text(" start 👍🏾").build(),
+      builder().text("middle 🤡 ").mention("foo").text(" 👍🏾 middle").build(),
+      builder().text("middle 🤡👍🏾 ").mention("test").text(" 👍🏾 middle").build(),
+      builder().text("end end 💀 💀 💀 ").mention("bar baz buzz").build(),
+      builder().text("end end 🖖🏼 🖖🏼 🖖🏼 ").mention("really long name").build(),
+      builder().text("middle 🤡👍🏾 👨🏼‍🤝‍👨🏽 ").mention("a").text(" 👍🏾 middle 👩‍👩‍👦‍👦").build(),
+      builder().text("start ").mention("emoji 🩳").build(),
+      builder().text("start ").mention("emoji 🩳").text(" middle ").mention("emoji 🩳").text(" end").build(),
+    });
+  }
+
+  public MentionUtilTest_updateBodyAndMentionsWithPlaceholders(String body, List<Mention> mentions, String updatedBody, List<Mention> updatedMentions) {
+    this.body            = body;
+    this.mentions        = mentions;
+    this.updatedBody     = updatedBody;
+    this.updatedMentions = updatedMentions;
+  }
+
+  @Test
+  public void updateBodyAndMentions() {
+    MentionUtil.UpdatedBodyAndMentions updated = MentionUtil.updateBodyAndMentionsWithPlaceholders(body, mentions);
+    assertEquals(updatedBody, updated.getBodyAsString());
+    assertEquals(updatedMentions, updated.getMentions());
+  }
+
+  private static Builder builder() {
+    return new Builder();
+  }
+
+  private static class Builder {
+    private StringBuilder bodyBuilder     = new StringBuilder();
+    private StringBuilder expectedBuilder = new StringBuilder();
+
+    private List<Mention> mentions         = new ArrayList<>();
+    private List<Mention> expectedMentions = new ArrayList<>();
+
+    Builder text(String text) {
+      bodyBuilder.append(text);
+      expectedBuilder.append(text);
+      return this;
+    }
+
+    Builder mention(String name) {
+      Mention input = new Mention(RecipientId.from(new Random().nextLong()), bodyBuilder.length(), name.length() + 1);
+      bodyBuilder.append(MENTION_STARTER).append(name);
+      mentions.add(input);
+
+      Mention output = new Mention(input.getRecipientId(), expectedBuilder.length(), MENTION_PLACEHOLDER.length());
+      expectedBuilder.append(MENTION_PLACEHOLDER);
+      expectedMentions.add(output);
+      return this;
+    }
+
+    Object[] build() {
+      return new Object[]{ bodyBuilder.toString(), mentions, expectedBuilder.toString(), expectedMentions };
+    }
+  }
+}

libsignal/service/src/main/java/org/whispersystems/signalservice/api/SignalServiceMessageSender.java

@@ -578,11 +578,22 @@ public class SignalServiceMessageSender {
                                                                 .setText(message.getQuote().get().getText());
 
       if (message.getQuote().get().getAuthor().getUuid().isPresent()) {
-        quoteBuilder = quoteBuilder.setAuthorUuid(message.getQuote().get().getAuthor().getUuid().get().toString());
+        quoteBuilder.setAuthorUuid(message.getQuote().get().getAuthor().getUuid().get().toString());
       }
 
       if (message.getQuote().get().getAuthor().getNumber().isPresent()) {
-        quoteBuilder = quoteBuilder.setAuthorE164(message.getQuote().get().getAuthor().getNumber().get());
+        quoteBuilder.setAuthorE164(message.getQuote().get().getAuthor().getNumber().get());
+      }
+
+      if (!message.getQuote().get().getMentions().isEmpty()) {
+        for (SignalServiceDataMessage.Mention mention : message.getQuote().get().getMentions()) {
+          quoteBuilder.addBodyRanges(DataMessage.BodyRange.newBuilder()
+                                                          .setStart(mention.getStart())
+                                                          .setLength(mention.getLength())
+                                                          .setMentionUuid(mention.getUuid().toString()));
+        }
+        
+        builder.setRequiredProtocolVersion(Math.max(DataMessage.ProtocolVersion.MENTIONS_VALUE, builder.getRequiredProtocolVersion()));
       }
 
       for (SignalServiceDataMessage.Quote.QuotedAttachment attachment : message.getQuote().get().getAttachments()) {
@@ -626,6 +637,16 @@ public class SignalServiceMessageSender {
       }
     }
 
+    if (message.getMentions().isPresent()) {
+      for (SignalServiceDataMessage.Mention mention : message.getMentions().get()) {
+        builder.addBodyRanges(DataMessage.BodyRange.newBuilder()
+                                                   .setStart(mention.getStart())
+                                                   .setLength(mention.getLength())
+                                                   .setMentionUuid(mention.getUuid().toString()));
+      }
+      builder.setRequiredProtocolVersion(Math.max(DataMessage.ProtocolVersion.MENTIONS_VALUE, builder.getRequiredProtocolVersion()));
+    }
+
     if (message.getSticker().isPresent()) {
       DataMessage.Sticker.Builder stickerBuilder = DataMessage.Sticker.newBuilder();
 

libsignal/service/src/main/java/org/whispersystems/signalservice/api/messages/SignalServiceContent.java

@@ -347,6 +347,7 @@ public final class SignalServiceContent {
     SignalServiceDataMessage.Quote         quote            = createQuote(content);
     List<SharedContact>                    sharedContacts   = createSharedContacts(content);
     List<SignalServiceDataMessage.Preview> previews         = createPreviews(content);
+    List<SignalServiceDataMessage.Mention> mentions         = createMentions(content);
     SignalServiceDataMessage.Sticker       sticker          = createSticker(content);
     SignalServiceDataMessage.Reaction      reaction         = createReaction(content);
     SignalServiceDataMessage.RemoteDelete  remoteDelete     = createRemoteDelete(content);
@@ -381,6 +382,7 @@ public final class SignalServiceContent {
                                         quote,
                                         sharedContacts,
                                         previews,
+                                        mentions,
                                         sticker,
                                         content.getIsViewOnce(),
                                         reaction,
@@ -662,7 +664,8 @@ public final class SignalServiceContent {
       return new SignalServiceDataMessage.Quote(content.getQuote().getId(),
                                                 address,
                                                 content.getQuote().getText(),
-                                                attachments);
+                                                attachments,
+                                                createMentions(content));
     } else {
       Log.w(TAG, "Quote was missing an author! Returning null.");
       return null;
@@ -689,6 +692,35 @@ public final class SignalServiceContent {
     return results;
   }
 
+  private static List<SignalServiceDataMessage.Mention> createMentions(SignalServiceProtos.DataMessage content) throws ProtocolInvalidMessageException {
+    if (content.getBodyRangesCount() <= 0 || !content.hasBody()) return null;
+
+    List<SignalServiceDataMessage.Mention> mentions = new LinkedList<>();
+
+    for (SignalServiceProtos.DataMessage.BodyRange bodyRange : content.getBodyRangesList()) {
+      if (bodyRange.hasMentionUuid()) {
+        try {
+          validateBodyRange(content, bodyRange);
+          mentions.add(new SignalServiceDataMessage.Mention(UuidUtil.parseOrThrow(bodyRange.getMentionUuid()), bodyRange.getStart(), bodyRange.getLength()));
+        } catch (IllegalArgumentException e) {
+          throw new ProtocolInvalidMessageException(new InvalidMessageException(e), null, 0);
+        }
+      }
+    }
+
+    return mentions;
+  }
+
+  private static void validateBodyRange(SignalServiceProtos.DataMessage content, SignalServiceProtos.DataMessage.BodyRange bodyRange) throws ProtocolInvalidMessageException {
+    int incomingBodyLength = content.hasBody() ? content.getBody().length() : -1;
+    int start              = bodyRange.hasStart() ? bodyRange.getStart() : -1;
+    int length             = bodyRange.hasLength() ? bodyRange.getLength() : -1;
+
+    if (start < 0 || length < 0 || (start + length) > incomingBodyLength) {
+      throw new ProtocolInvalidMessageException(new InvalidMessageException("Incoming body range has out-of-bound range"), null, 0);
+    }
+  }
+
   private static SignalServiceDataMessage.Sticker createSticker(SignalServiceProtos.DataMessage content) throws ProtocolInvalidMessageException {
     if (!content.hasSticker()                ||
         !content.getSticker().hasPackId()    ||

libsignal/service/src/main/java/org/whispersystems/signalservice/api/messages/SignalServiceDataMessage.java

@@ -14,6 +14,7 @@ import org.whispersystems.signalservice.api.util.OptionalUtil;
 
 import java.util.LinkedList;
 import java.util.List;
+import java.util.UUID;
 
 /**
  * Represents a decrypted Signal Service data message.
@@ -32,6 +33,7 @@ public class SignalServiceDataMessage {
   private final Optional<Quote>                         quote;
   private final Optional<List<SharedContact>>           contacts;
   private final Optional<List<Preview>>                 previews;
+  private final Optional<List<Mention>>                 mentions;
   private final Optional<Sticker>                       sticker;
   private final boolean                                 viewOnce;
   private final Optional<Reaction>                      reaction;
@@ -54,7 +56,7 @@ public class SignalServiceDataMessage {
                            String body, boolean endSession, int expiresInSeconds,
                            boolean expirationUpdate, byte[] profileKey, boolean profileKeyUpdate,
                            Quote quote, List<SharedContact> sharedContacts, List<Preview> previews,
-                           Sticker sticker, boolean viewOnce, Reaction reaction, RemoteDelete remoteDelete)
+                           List<Mention> mentions, Sticker sticker, boolean viewOnce, Reaction reaction, RemoteDelete remoteDelete)
   {
     try {
       this.group = SignalServiceGroupContext.createOptional(group, groupV2);
@@ -92,6 +94,12 @@ public class SignalServiceDataMessage {
     } else {
       this.previews = Optional.absent();
     }
+
+    if (mentions != null && !mentions.isEmpty()) {
+      this.mentions = Optional.of(mentions);
+    } else {
+      this.mentions = Optional.absent();
+    }
   }
 
   public static Builder newBuilder() {
@@ -174,6 +182,10 @@ public class SignalServiceDataMessage {
     return previews;
   }
 
+  public Optional<List<Mention>> getMentions() {
+    return mentions;
+  }
+
   public Optional<Sticker> getSticker() {
     return sticker;
   }
@@ -195,6 +207,7 @@ public class SignalServiceDataMessage {
     private List<SignalServiceAttachment> attachments    = new LinkedList<>();
     private List<SharedContact>           sharedContacts = new LinkedList<>();
     private List<Preview>                 previews       = new LinkedList<>();
+    private List<Mention>                 mentions       = new LinkedList<>();
 
     private long                 timestamp;
     private SignalServiceGroup   group;
@@ -302,6 +315,11 @@ public class SignalServiceDataMessage {
       return this;
     }
 
+    public Builder withMentions(List<Mention> mentions) {
+      this.mentions.addAll(mentions);
+      return this;
+    }
+
     public Builder withSticker(Sticker sticker) {
       this.sticker = sticker;
       return this;
@@ -327,7 +345,7 @@ public class SignalServiceDataMessage {
       return new SignalServiceDataMessage(timestamp, group, groupV2, attachments, body, endSession,
                                           expiresInSeconds, expirationUpdate, profileKey,
                                           profileKeyUpdate, quote, sharedContacts, previews,
-                                          sticker, viewOnce, reaction, remoteDelete);
+                                          mentions, sticker, viewOnce, reaction, remoteDelete);
     }
   }
 
@@ -336,12 +354,14 @@ public class SignalServiceDataMessage {
     private final SignalServiceAddress   author;
     private final String                 text;
     private final List<QuotedAttachment> attachments;
+    private final List<Mention>          mentions;
 
-    public Quote(long id, SignalServiceAddress author, String text, List<QuotedAttachment> attachments) {
+    public Quote(long id, SignalServiceAddress author, String text, List<QuotedAttachment> attachments, List<Mention> mentions) {
       this.id          = id;
       this.author      = author;
       this.text        = text;
       this.attachments = attachments;
+      this.mentions    = mentions;
     }
 
     public long getId() {
@@ -360,6 +380,10 @@ public class SignalServiceDataMessage {
       return attachments;
     }
 
+    public List<Mention> getMentions() {
+      return mentions;
+    }
+
     public static class QuotedAttachment {
       private final String                  contentType;
       private final String                  fileName;
@@ -480,4 +504,28 @@ public class SignalServiceDataMessage {
       return targetSentTimestamp;
     }
   }
+
+  public static class Mention {
+    private final UUID uuid;
+    private final int  start;
+    private final int  length;
+
+    public Mention(UUID uuid, int start, int length) {
+      this.uuid   = uuid;
+      this.start  = start;
+      this.length = length;
+    }
+
+    public UUID getUuid() {
+      return uuid;
+    }
+
+    public int getStart() {
+      return start;
+    }
+
+    public int getLength() {
+      return length;
+    }
+  }
 }

libsignal/service/src/main/proto/SignalService.proto

@@ -111,6 +111,15 @@ message DataMessage {
     PROFILE_KEY_UPDATE      = 4;
   }
 
+  message BodyRange {
+    optional int32 start  = 1;
+    optional int32 length = 2;
+
+    oneof associatedValue {
+      string mentionUuid = 3;
+    }
+  }
+
   message Quote {
     message QuotedAttachment {
       optional string            contentType = 1;
@@ -123,6 +132,7 @@ message DataMessage {
     optional string           authorUuid  = 5;
     optional string           text        = 3;
     repeated QuotedAttachment attachments = 4;
+    repeated BodyRange        bodyRanges  = 6;
   }
 
   message Contact {
@@ -226,7 +236,8 @@ message DataMessage {
     VIEW_ONCE_VIDEO          = 3;
     REACTIONS                = 4;
     CDN_SELECTOR_ATTACHMENTS = 5;
-    CURRENT                  = 5;
+    MENTIONS                 = 6;
+    CURRENT                  = 6;
   }
 
   optional string             body                    = 1;
@@ -245,6 +256,7 @@ message DataMessage {
   optional bool               isViewOnce              = 14;
   optional Reaction           reaction                = 16;
   optional Delete             delete                  = 17;
+  repeated BodyRange          bodyRanges              = 18;
 }
 
 message NullMessage {