Group link preview and info display bottom sheet.

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

@@ -28,6 +28,7 @@ import org.thoughtcrime.securesms.recipients.ui.bottomsheet.RecipientBottomSheet
 import org.thoughtcrime.securesms.recipients.ui.managerecipient.ManageRecipientActivity;
 import org.thoughtcrime.securesms.util.AvatarUtil;
 import org.thoughtcrime.securesms.util.ThemeUtil;
+import org.thoughtcrime.securesms.util.Util;
 
 import java.util.Objects;
 
@@ -193,6 +194,23 @@ public final class AvatarImageView extends AppCompatImageView {
     }
   }
 
+  public void setImageBytesForGroup(@Nullable byte[] avatarBytes,
+                                    @Nullable Recipient.FallbackPhotoProvider fallbackPhotoProvider,
+                                    @NonNull MaterialColor color)
+  {
+    Drawable fallback = Util.firstNonNull(fallbackPhotoProvider, Recipient.DEFAULT_FALLBACK_PHOTO_PROVIDER)
+                            .getPhotoForGroup()
+                            .asDrawable(getContext(), color.toAvatarColor(getContext()));
+
+    GlideApp.with(this)
+            .load(avatarBytes)
+            .fallback(fallback)
+            .error(fallback)
+            .diskCacheStrategy(DiskCacheStrategy.ALL)
+            .circleCrop()
+            .into(this);
+  }
+
   private static class RecipientContactPhoto {
 
     private final @NonNull  Recipient    recipient;

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

@@ -34,6 +34,7 @@ import org.thoughtcrime.securesms.components.emoji.MediaKeyboard;
 import org.thoughtcrime.securesms.conversation.ConversationStickerSuggestionAdapter;
 import org.thoughtcrime.securesms.database.model.StickerRecord;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
+import org.thoughtcrime.securesms.linkpreview.LinkPreviewRepository;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideApp;
 import org.thoughtcrime.securesms.mms.GlideRequests;
@@ -236,9 +237,9 @@ public class InputPanel extends LinearLayout
     this.linkPreview.setLoading();
   }
 
-  public void setLinkPreviewNoPreview() {
+  public void setLinkPreviewNoPreview(@Nullable LinkPreviewRepository.Error customError) {
     this.linkPreview.setVisibility(View.VISIBLE);
-    this.linkPreview.setNoPreview();
+    this.linkPreview.setNoPreview(customError);
   }
 
   public void setLinkPreview(@NonNull GlideRequests glideRequests, @NonNull Optional<LinkPreview> preview) {

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

@@ -4,16 +4,19 @@ import android.content.Context;
 import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Color;
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.StringRes;
+
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.linkpreview.LinkPreview;
+import org.thoughtcrime.securesms.linkpreview.LinkPreviewRepository;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 import org.thoughtcrime.securesms.mms.ImageSlide;
 import org.thoughtcrime.securesms.mms.SlidesClickedListener;
@@ -36,7 +39,7 @@ public class LinkPreviewView extends FrameLayout {
   private View                  divider;
   private View                  closeButton;
   private View                  spinner;
-  private View                  noPreview;
+  private TextView              noPreview;
 
   private int                  type;
   private int                  defaultRadius;
@@ -110,12 +113,13 @@ public class LinkPreviewView extends FrameLayout {
     noPreview.setVisibility(INVISIBLE);
   }
 
-  public void setNoPreview() {
+  public void setNoPreview(@Nullable LinkPreviewRepository.Error customError) {
     title.setVisibility(GONE);
     site.setVisibility(GONE);
     thumbnail.setVisibility(GONE);
     spinner.setVisibility(GONE);
     noPreview.setVisibility(VISIBLE);
+    noPreview.setText(getLinkPreviewErrorString(customError));
   }
 
   public void setLinkPreview(@NonNull GlideRequests glideRequests, @NonNull LinkPreview linkPreview, boolean showThumbnail) {
@@ -156,6 +160,11 @@ public class LinkPreviewView extends FrameLayout {
     thumbnail.setDownloadClickListener(listener);
   }
 
+  private  @StringRes static int getLinkPreviewErrorString(@Nullable LinkPreviewRepository.Error customError) {
+    return customError == LinkPreviewRepository.Error.GROUP_LINK_INACTIVE ? R.string.LinkPreviewView_this_group_link_is_not_active
+                                                                          : R.string.LinkPreviewView_no_link_preview_available;
+  }
+
   public interface CloseClickedListener {
     void onCloseClicked();
   }

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

@@ -1833,7 +1833,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
         inputPanel.setLinkPreviewLoading();
       } else if (previewState.hasLinks() && !previewState.getLinkPreview().isPresent()) {
         Log.d(TAG, "No preview found.");
-        inputPanel.setLinkPreviewNoPreview();
+        inputPanel.setLinkPreviewNoPreview(previewState.getError());
       } else {
         Log.d(TAG, "Setting link preview: " + previewState.getLinkPreview().isPresent());
         inputPanel.setLinkPreview(glideRequests, previewState.getLinkPreview());

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

@@ -6,16 +6,20 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
 
+import org.signal.storageservice.protos.groups.local.DecryptedGroupJoinInfo;
+import org.signal.zkgroup.VerificationFailedException;
 import org.signal.zkgroup.groups.GroupMasterKey;
 import org.signal.zkgroup.groups.UuidCiphertext;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.GroupDatabase;
+import org.thoughtcrime.securesms.groups.v2.GroupLinkPassword;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.profiles.AvatarHelper;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.Util;
+import org.whispersystems.signalservice.api.groupsv2.GroupLinkNotActiveException;
 
 import java.io.IOException;
 import java.util.Collection;
@@ -254,6 +258,20 @@ public final class GroupManager {
     }
   }
 
+  /**
+   * Use to get a group's details direct from server bypassing the database.
+   * <p>
+   * Useful when you don't yet have the group in the database locally.
+   */
+  @WorkerThread
+  public static @NonNull DecryptedGroupJoinInfo getGroupJoinInfoFromServer(@NonNull Context context,
+                                                                           @NonNull GroupMasterKey groupMasterKey,
+                                                                           @NonNull GroupLinkPassword groupLinkPassword)
+      throws IOException, VerificationFailedException, GroupLinkNotActiveException
+  {
+    return new GroupManagerV2(context).getGroupJoinInfoFromServer(groupMasterKey, groupLinkPassword);
+  }
+
   public static class GroupActionResult {
     private final Recipient         groupRecipient;
     private final long              threadId;

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

@@ -14,6 +14,7 @@ import org.signal.storageservice.protos.groups.GroupChange;
 import org.signal.storageservice.protos.groups.Member;
 import org.signal.storageservice.protos.groups.local.DecryptedGroup;
 import org.signal.storageservice.protos.groups.local.DecryptedGroupChange;
+import org.signal.storageservice.protos.groups.local.DecryptedGroupJoinInfo;
 import org.signal.storageservice.protos.groups.local.DecryptedMember;
 import org.signal.storageservice.protos.groups.local.DecryptedPendingMember;
 import org.signal.zkgroup.InvalidInputException;
@@ -28,6 +29,7 @@ import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.database.model.databaseprotos.DecryptedGroupV2Context;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.groups.v2.GroupCandidateHelper;
+import org.thoughtcrime.securesms.groups.v2.GroupLinkPassword;
 import org.thoughtcrime.securesms.groups.v2.processing.GroupsV2StateProcessor;
 import org.thoughtcrime.securesms.jobs.PushGroupSilentUpdateSendJob;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
@@ -41,6 +43,7 @@ import org.whispersystems.libsignal.util.guava.Optional;
 import org.whispersystems.signalservice.api.groupsv2.DecryptedGroupUtil;
 import org.whispersystems.signalservice.api.groupsv2.GroupCandidate;
 import org.whispersystems.signalservice.api.groupsv2.GroupChangeUtil;
+import org.whispersystems.signalservice.api.groupsv2.GroupLinkNotActiveException;
 import org.whispersystems.signalservice.api.groupsv2.GroupsV2Api;
 import org.whispersystems.signalservice.api.groupsv2.GroupsV2Operations;
 import org.whispersystems.signalservice.api.groupsv2.InvalidGroupStateException;
@@ -86,6 +89,14 @@ final class GroupManagerV2 {
     this.groupCandidateHelper   = new GroupCandidateHelper(context);
   }
 
+  @NonNull DecryptedGroupJoinInfo getGroupJoinInfoFromServer(@NonNull GroupMasterKey groupMasterKey, @NonNull GroupLinkPassword password)
+      throws IOException, VerificationFailedException, GroupLinkNotActiveException
+  {
+    GroupSecretParams groupSecretParams = GroupSecretParams.deriveFromMasterKey(groupMasterKey);
+
+    return groupsV2Api.getGroupJoinInfo(groupSecretParams, password.serialize(), authorization.getAuthorizationForToday(Recipient.self().requireUuid(), groupSecretParams));
+  }
+
   @WorkerThread
   GroupCreator create() throws GroupChangeBusyException {
     return new GroupCreator(GroupsV2ProcessingLock.acquireGroupProcessingLock());

app/src/main/java/org/thoughtcrime/securesms/groups/ui/invitesandrequests/joining/FetchGroupDetailsError.java

@@ -0,0 +1,6 @@
+package org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining;
+
+enum FetchGroupDetailsError {
+  GroupLinkNotActive,
+  NetworkError
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/invitesandrequests/joining/GroupDetails.java

@@ -0,0 +1,42 @@
+package org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining;
+
+public final class GroupDetails {
+  private final String  groupName;
+  private final byte[]  avatarBytes;
+  private final int     groupMembershipCount;
+  private final boolean requiresAdminApproval;
+  private final int     groupRevision;
+
+  public GroupDetails(String groupName,
+                      byte[] avatarBytes,
+                      int groupMembershipCount,
+                      boolean requiresAdminApproval,
+                      int groupRevision)
+  {
+    this.groupName             = groupName;
+    this.avatarBytes           = avatarBytes;
+    this.groupMembershipCount  = groupMembershipCount;
+    this.requiresAdminApproval = requiresAdminApproval;
+    this.groupRevision         = groupRevision;
+  }
+
+  public String getGroupName() {
+    return groupName;
+  }
+
+  public byte[] getAvatarBytes() {
+    return avatarBytes;
+  }
+
+  public int getGroupMembershipCount() {
+    return groupMembershipCount;
+  }
+
+  public boolean joinRequiresAdminApproval() {
+    return requiresAdminApproval;
+  }
+
+  public int getGroupRevision() {
+    return groupRevision;
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/invitesandrequests/joining/GroupJoinBottomSheetDialogFragment.java

@@ -0,0 +1,140 @@
+package org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.ProgressBar;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.DialogFragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.lifecycle.ViewModelProviders;
+
+import com.google.android.material.bottomsheet.BottomSheetDialogFragment;
+
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.color.MaterialColor;
+import org.thoughtcrime.securesms.components.AvatarImageView;
+import org.thoughtcrime.securesms.contacts.avatars.FallbackContactPhoto;
+import org.thoughtcrime.securesms.contacts.avatars.ResourceContactPhoto;
+import org.thoughtcrime.securesms.groups.v2.GroupInviteLinkUrl;
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.util.BottomSheetUtil;
+import org.thoughtcrime.securesms.util.PlayStoreUtil;
+import org.thoughtcrime.securesms.util.ThemeUtil;
+
+public final class GroupJoinBottomSheetDialogFragment extends BottomSheetDialogFragment {
+
+  private static final String ARG_GROUP_INVITE_LINK_URL = "group_invite_url";
+
+  private ProgressBar     busy;
+  private AvatarImageView avatar;
+  private TextView        groupName;
+  private TextView        groupDetails;
+  private TextView        groupJoinExplain;
+  private Button          groupJoinButton;
+  private Button          groupCancelButton;
+
+  public static void show(@NonNull FragmentManager manager,
+                          @NonNull GroupInviteLinkUrl groupInviteLinkUrl)
+  {
+    GroupJoinBottomSheetDialogFragment fragment = new GroupJoinBottomSheetDialogFragment();
+
+    Bundle args = new Bundle();
+    args.putString(ARG_GROUP_INVITE_LINK_URL, groupInviteLinkUrl.getUrl());
+    fragment.setArguments(args);
+
+    fragment.show(manager, BottomSheetUtil.STANDARD_BOTTOM_SHEET_FRAGMENT_TAG);
+  }
+
+  @Override
+  public void onCreate(@Nullable Bundle savedInstanceState) {
+    setStyle(DialogFragment.STYLE_NORMAL,
+             ThemeUtil.isDarkTheme(requireContext()) ? R.style.Theme_Signal_RoundedBottomSheet
+                                                     : R.style.Theme_Signal_RoundedBottomSheet_Light);
+
+    super.onCreate(savedInstanceState);
+  }
+
+  @Override
+  public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
+    View view = inflater.inflate(R.layout.group_join_bottom_sheet, container, false);
+
+    groupCancelButton = view.findViewById(R.id.group_join_cancel_button);
+    groupJoinButton   = view.findViewById(R.id.group_join_button);
+    busy              = view.findViewById(R.id.group_join_busy);
+    avatar            = view.findViewById(R.id.group_join_recipient_avatar);
+    groupName         = view.findViewById(R.id.group_join_group_name);
+    groupDetails      = view.findViewById(R.id.group_join_group_details);
+    groupJoinExplain  = view.findViewById(R.id.group_join_explain);
+
+    groupCancelButton.setOnClickListener(v -> dismiss());
+
+    avatar.setImageBytesForGroup(null, new FallbackPhotoProvider(), MaterialColor.STEEL);
+
+    return view;
+  }
+
+  @Override
+  public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+    super.onViewCreated(view, savedInstanceState);
+
+    GroupJoinViewModel.Factory factory = new GroupJoinViewModel.Factory(requireContext().getApplicationContext(), getGroupInviteLinkUrl());
+
+    GroupJoinViewModel viewModel = ViewModelProviders.of(this, factory).get(GroupJoinViewModel.class);
+
+    viewModel.getGroupDetails().observe(getViewLifecycleOwner(), details -> {
+      groupName.setText(details.getGroupName());
+      groupDetails.setText(requireContext().getResources().getQuantityString(R.plurals.GroupJoinBottomSheetDialogFragment_group_dot_d_members, details.getGroupMembershipCount(), details.getGroupMembershipCount()));
+      groupJoinButton.setText(R.string.GroupJoinUpdateRequiredBottomSheetDialogFragment_update_signal);
+      groupJoinButton.setOnClickListener(v -> {
+        PlayStoreUtil.openPlayStoreOrOurApkDownloadPage(requireContext());
+        dismiss();
+      });
+      groupJoinExplain.setText(R.string.GroupJoinUpdateRequiredBottomSheetDialogFragment_update_message);
+      avatar.setImageBytesForGroup(details.getAvatarBytes(), new FallbackPhotoProvider(), MaterialColor.STEEL);
+
+      groupJoinButton.setVisibility(View.VISIBLE);
+      groupCancelButton.setVisibility(View.VISIBLE);
+    });
+
+    viewModel.isBusy().observe(getViewLifecycleOwner(), isBusy -> busy.setVisibility(isBusy ? View.VISIBLE : View.GONE));
+    viewModel.getErrors().observe(getViewLifecycleOwner(), error -> {
+      Toast.makeText(requireContext(), errorToMessage(error), Toast.LENGTH_SHORT).show();
+      dismiss();
+    });
+  }
+
+  protected @NonNull String errorToMessage(FetchGroupDetailsError error) {
+    if (error == FetchGroupDetailsError.GroupLinkNotActive) {
+      return getString(R.string.GroupJoinBottomSheetDialogFragment_this_group_link_is_not_active);
+    }
+    return getString(R.string.GroupJoinBottomSheetDialogFragment_unable_to_get_group_information_please_try_again_later);
+  }
+
+  private GroupInviteLinkUrl getGroupInviteLinkUrl() {
+    try {
+      //noinspection ConstantConditions
+      return GroupInviteLinkUrl.fromUrl(requireArguments().getString(ARG_GROUP_INVITE_LINK_URL));
+    } catch (GroupInviteLinkUrl.InvalidGroupLinkException | GroupInviteLinkUrl.UnknownGroupLinkVersionException e) {
+      throw new AssertionError();
+    }
+  }
+
+  @Override
+  public void show(@NonNull FragmentManager manager, @Nullable String tag) {
+    BottomSheetUtil.show(manager, tag, this);
+  }
+
+  private static final class FallbackPhotoProvider extends Recipient.FallbackPhotoProvider {
+    @Override
+    public @NonNull FallbackContactPhoto getPhotoForGroup() {
+      return new ResourceContactPhoto(R.drawable.ic_group_outline_48);
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/invitesandrequests/joining/GroupJoinRepository.java

@@ -0,0 +1,77 @@
+package org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+import androidx.core.util.Consumer;
+
+import org.signal.storageservice.protos.groups.AccessControl;
+import org.signal.storageservice.protos.groups.local.DecryptedGroupJoinInfo;
+import org.signal.zkgroup.VerificationFailedException;
+import org.thoughtcrime.securesms.groups.GroupManager;
+import org.thoughtcrime.securesms.groups.v2.GroupInviteLinkUrl;
+import org.thoughtcrime.securesms.jobs.AvatarGroupsV2DownloadJob;
+import org.thoughtcrime.securesms.logging.Log;
+import org.thoughtcrime.securesms.util.concurrent.SignalExecutors;
+import org.whispersystems.signalservice.api.groupsv2.GroupLinkNotActiveException;
+
+import java.io.IOException;
+
+final class GroupJoinRepository {
+
+  private static final String TAG = Log.tag(GroupJoinRepository.class);
+
+  private final Context            context;
+  private final GroupInviteLinkUrl groupInviteLinkUrl;
+
+  GroupJoinRepository(@NonNull Context context, @NonNull GroupInviteLinkUrl groupInviteLinkUrl) {
+    this.context            = context;
+    this.groupInviteLinkUrl = groupInviteLinkUrl;
+  }
+
+  void getGroupDetails(@NonNull GetGroupDetailsCallback callback) {
+    SignalExecutors.UNBOUNDED.execute(() -> {
+      try {
+        callback.onComplete(getGroupDetails());
+      } catch (IOException e) {
+        callback.onError(FetchGroupDetailsError.NetworkError);
+      } catch (VerificationFailedException | GroupLinkNotActiveException e) {
+        callback.onError(FetchGroupDetailsError.GroupLinkNotActive);
+      }
+    });
+  }
+
+  @WorkerThread
+  private @NonNull GroupDetails getGroupDetails()
+      throws VerificationFailedException, IOException, GroupLinkNotActiveException
+  {
+    DecryptedGroupJoinInfo joinInfo = GroupManager.getGroupJoinInfoFromServer(context,
+                                                                              groupInviteLinkUrl.getGroupMasterKey(),
+                                                                              groupInviteLinkUrl.getPassword());
+
+    byte[]  avatarBytes           = tryGetAvatarBytes(joinInfo);
+    boolean requiresAdminApproval = joinInfo.getAddFromInviteLink() == AccessControl.AccessRequired.ADMINISTRATOR;
+
+    return new GroupDetails(joinInfo.getTitle(),
+                            avatarBytes,
+                            joinInfo.getMemberCount(),
+                            requiresAdminApproval,
+                            joinInfo.getRevision());
+  }
+
+  private @Nullable byte[] tryGetAvatarBytes(@NonNull DecryptedGroupJoinInfo joinInfo) {
+    try {
+      return AvatarGroupsV2DownloadJob.downloadGroupAvatarBytes(context, groupInviteLinkUrl.getGroupMasterKey(), joinInfo.getAvatar());
+    } catch (IOException e) {
+      Log.w(TAG, "Failed to get group avatar", e);
+      return null;
+    }
+  }
+
+  interface GetGroupDetailsCallback {
+    void onComplete(@NonNull GroupDetails groupDetails);
+    void onError(@NonNull FetchGroupDetailsError error);
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/invitesandrequests/joining/GroupJoinViewModel.java

@@ -0,0 +1,66 @@
+package org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MediatorLiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+import androidx.lifecycle.ViewModelProvider;
+
+import org.thoughtcrime.securesms.groups.v2.GroupInviteLinkUrl;
+import org.thoughtcrime.securesms.util.SingleLiveEvent;
+
+public class GroupJoinViewModel extends ViewModel {
+
+  private final MutableLiveData<GroupDetails>           groupDetails = new MutableLiveData<>();
+  private final MutableLiveData<FetchGroupDetailsError> errors       = new SingleLiveEvent<>();
+  private final MutableLiveData<Boolean>                busy         = new MediatorLiveData<>();
+
+  private GroupJoinViewModel(@NonNull GroupJoinRepository repository) {
+    busy.setValue(true);
+    repository.getGroupDetails(new GroupJoinRepository.GetGroupDetailsCallback() {
+      @Override
+      public void onComplete(@NonNull GroupDetails details) {
+        busy.postValue(false);
+        groupDetails.postValue(details);
+      }
+
+      @Override
+      public void onError(@NonNull FetchGroupDetailsError error) {
+        busy.postValue(false);
+        errors.postValue(error);
+      }
+    });
+  }
+
+  LiveData<GroupDetails> getGroupDetails() {
+    return groupDetails;
+  }
+
+  LiveData<Boolean> isBusy() {
+    return busy;
+  }
+
+  LiveData<FetchGroupDetailsError> getErrors() {
+    return errors;
+  }
+
+  public static class Factory implements ViewModelProvider.Factory {
+
+    private final Context context;
+    private final GroupInviteLinkUrl groupInviteLinkUrl;
+
+    public Factory(@NonNull Context context, @NonNull GroupInviteLinkUrl groupInviteLinkUrl) {
+      this.context            = context;
+      this.groupInviteLinkUrl = groupInviteLinkUrl;
+    }
+
+    @Override
+    public @NonNull <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
+      //noinspection unchecked
+      return (T) new GroupJoinViewModel(new GroupJoinRepository(context.getApplicationContext(), groupInviteLinkUrl));
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/v2/GroupInviteLinkUrl.java

@@ -6,6 +6,7 @@ import androidx.annotation.Nullable;
 import com.google.protobuf.ByteString;
 
 import org.signal.storageservice.protos.groups.GroupInviteLink;
+import org.signal.storageservice.protos.groups.local.DecryptedGroup;
 import org.signal.zkgroup.InvalidInputException;
 import org.signal.zkgroup.groups.GroupMasterKey;
 import org.whispersystems.util.Base64UrlSafe;
@@ -23,21 +24,31 @@ public final class GroupInviteLinkUrl {
   private final GroupLinkPassword password;
   private final String            url;
 
+  public static GroupInviteLinkUrl forGroup(@NonNull GroupMasterKey groupMasterKey,
+                                            @NonNull DecryptedGroup group)
+      throws GroupLinkPassword.InvalidLengthException
+  {
+    return new GroupInviteLinkUrl(groupMasterKey, GroupLinkPassword.fromBytes(group.getInviteLinkPassword().toByteArray()));
+  }
+
+  public static boolean isGroupLink(@NonNull String urlString) {
+    return getGroupUrl(urlString) != null;
+  }
+
+  /**
+   * @return null iff not a group url.
+   * @throws InvalidGroupLinkException If group url, but cannot be parsed.
+   */
   public static @Nullable GroupInviteLinkUrl fromUrl(@NonNull String urlString)
       throws InvalidGroupLinkException, UnknownGroupLinkVersionException
   {
-    URL url;
+    URL url = getGroupUrl(urlString);
-    try {
+
-      url = new URL(urlString);
+    if (url == null) {
-    } catch (MalformedURLException e) {
       return null;
     }
 
     try {
-      if (!GROUP_URL_HOST.equalsIgnoreCase(url.getHost())) {
-        return null;
-      }
-
       if (!"/".equals(url.getPath()) && url.getPath().length() > 0) {
         throw new InvalidGroupLinkException("No path was expected in url");
       }
@@ -67,6 +78,21 @@ public final class GroupInviteLinkUrl {
     }
   }
 
+  /**
+   * @return {@link URL} if the host name matches.
+   */
+  private static URL getGroupUrl(@NonNull String urlString) {
+    try {
+      URL url = new URL(urlString);
+
+      return GROUP_URL_HOST.equalsIgnoreCase(url.getHost())
+             ? url
+             : null;
+    } catch (MalformedURLException e) {
+      return null;
+    }
+  }
+
   private GroupInviteLinkUrl(@NonNull GroupMasterKey groupMasterKey, @NonNull GroupLinkPassword password) {
     this.groupMasterKey = groupMasterKey;
     this.password       = password;

app/src/main/java/org/thoughtcrime/securesms/jobs/AvatarGroupsV2DownloadJob.java

@@ -1,7 +1,11 @@
 package org.thoughtcrime.securesms.jobs;
 
-import androidx.annotation.NonNull;
+import android.content.Context;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import org.signal.zkgroup.groups.GroupMasterKey;
 import org.signal.zkgroup.groups.GroupSecretParams;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.GroupDatabase;
@@ -88,32 +92,43 @@ public final class AvatarGroupsV2DownloadJob extends BaseJob {
       }
 
       Log.i(TAG, "Downloading new avatar for group " + groupId);
+      byte[] decryptedAvatar = downloadGroupAvatarBytes(context, record.get().requireV2GroupProperties().getGroupMasterKey(), cdnKey);
 
-      attachment = File.createTempFile("avatar", "gv2", context.getCacheDir());
+      AvatarHelper.setAvatar(context, record.get().getRecipientId(), decryptedAvatar != null ? new ByteArrayInputStream(decryptedAvatar) : null);
+      database.onAvatarUpdated(groupId, true);
+
+    } catch (NonSuccessfulResponseCodeException e) {
+      Log.w(TAG, e);
+    }
+  }
+
+  public static @Nullable byte[] downloadGroupAvatarBytes(@NonNull Context context,
+                                                          @NonNull GroupMasterKey groupMasterKey,
+                                                          @NonNull String cdnKey)
+      throws IOException
+  {
+    if (cdnKey.length() == 0) {
+      return null;
+    }
+
+    GroupSecretParams groupSecretParams = GroupSecretParams.deriveFromMasterKey(groupMasterKey);
+    File              attachment        = File.createTempFile("avatar", "gv2", context.getCacheDir());
     attachment.deleteOnExit();
 
     SignalServiceMessageReceiver receiver      = ApplicationDependencies.getSignalServiceMessageReceiver();
     byte[]                       encryptedData;
 
     try (FileInputStream inputStream = receiver.retrieveGroupsV2ProfileAvatar(cdnKey, attachment, AVATAR_DOWNLOAD_FAIL_SAFE_MAX_SIZE)) {
-
       encryptedData = new byte[(int) attachment.length()];
 
       Util.readFully(inputStream, encryptedData);
 
       GroupsV2Operations                 operations      = ApplicationDependencies.getGroupsV2Operations();
-        GroupSecretParams                  groupSecretParams = GroupSecretParams.deriveFromMasterKey(record.get().requireV2GroupProperties().getGroupMasterKey());
       GroupsV2Operations.GroupOperations groupOperations = operations.forGroup(groupSecretParams);
-        byte[]                             decryptedAvatar   = groupOperations.decryptAvatar(encryptedData);
 
-        AvatarHelper.setAvatar(context, record.get().getRecipientId(), decryptedAvatar != null ? new ByteArrayInputStream(decryptedAvatar) : null);
+      return groupOperations.decryptAvatar(encryptedData);
-        database.onAvatarUpdated(groupId, true);
-      }
-
-    } catch (NonSuccessfulResponseCodeException e) {
-      Log.w(TAG, e);
     } finally {
-      if (attachment != null && attachment.exists())
+      if (attachment.exists())
         if (!attachment.delete()) {
           Log.w(TAG, "Unable to delete temp avatar file");
         }

app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewRepository.java

@@ -7,13 +7,23 @@ import android.net.Uri;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.core.util.Consumer;
 
 import com.bumptech.glide.load.engine.DiskCacheStrategy;
 
+import org.signal.storageservice.protos.groups.local.DecryptedGroupJoinInfo;
+import org.signal.zkgroup.VerificationFailedException;
+import org.signal.zkgroup.groups.GroupMasterKey;
 import org.thoughtcrime.securesms.attachments.Attachment;
 import org.thoughtcrime.securesms.attachments.UriAttachment;
 import org.thoughtcrime.securesms.database.AttachmentDatabase;
+import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
+import org.thoughtcrime.securesms.groups.GroupId;
+import org.thoughtcrime.securesms.groups.GroupManager;
+import org.thoughtcrime.securesms.groups.v2.GroupInviteLinkUrl;
+import org.thoughtcrime.securesms.jobs.AvatarGroupsV2DownloadJob;
 import org.thoughtcrime.securesms.linkpreview.LinkPreviewUtil.OpenGraph;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideApp;
@@ -21,9 +31,12 @@ import org.thoughtcrime.securesms.net.CallRequestController;
 import org.thoughtcrime.securesms.net.CompositeRequestController;
 import org.thoughtcrime.securesms.net.RequestController;
 import org.thoughtcrime.securesms.net.UserAgentInterceptor;
+import org.thoughtcrime.securesms.profiles.AvatarHelper;
 import org.thoughtcrime.securesms.providers.BlobProvider;
+import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.stickers.StickerRemoteUri;
 import org.thoughtcrime.securesms.stickers.StickerUrl;
+import org.thoughtcrime.securesms.util.AvatarUtil;
 import org.thoughtcrime.securesms.util.ByteUnit;
 import org.thoughtcrime.securesms.util.Hex;
 import org.thoughtcrime.securesms.util.MediaUtil;
@@ -33,6 +46,7 @@ import org.whispersystems.libsignal.InvalidMessageException;
 import org.whispersystems.libsignal.util.Pair;
 import org.whispersystems.libsignal.util.guava.Optional;
 import org.whispersystems.signalservice.api.SignalServiceMessageReceiver;
+import org.whispersystems.signalservice.api.groupsv2.GroupLinkNotActiveException;
 import org.whispersystems.signalservice.api.messages.SignalServiceStickerManifest;
 import org.whispersystems.signalservice.api.messages.SignalServiceStickerManifest.StickerInfo;
 
@@ -65,12 +79,15 @@ public class LinkPreviewRepository {
                                   .build();
   }
 
-  RequestController getLinkPreview(@NonNull Context context, @NonNull String url, @NonNull Callback<Optional<LinkPreview>> callback) {
+  @Nullable RequestController getLinkPreview(@NonNull Context context,
+                                             @NonNull String url,
+                                             @NonNull Callback callback)
+  {
     CompositeRequestController compositeController = new CompositeRequestController();
 
     if (!LinkPreviewUtil.isValidPreviewUrl(url)) {
       Log.w(TAG, "Tried to get a link preview for a non-whitelisted domain.");
-      callback.onComplete(Optional.absent());
+      callback.onError(Error.PREVIEW_NOT_AVAILABLE);
       return compositeController;
     }
 
@@ -78,23 +95,25 @@ public class LinkPreviewRepository {
 
     if (StickerUrl.isValidShareLink(url)) {
       metadataController = fetchStickerPackLinkPreview(context, url, callback);
+    } else if (GroupInviteLinkUrl.isGroupLink(url)) {
+      metadataController = fetchGroupLinkPreview(context, url, callback);
     } else {
       metadataController = fetchMetadata(url, metadata -> {
         if (metadata.isEmpty()) {
-          callback.onComplete(Optional.absent());
+          callback.onError(Error.PREVIEW_NOT_AVAILABLE);
           return;
         }
 
         if (!metadata.getImageUrl().isPresent()) {
-          callback.onComplete(Optional.of(new LinkPreview(url, metadata.getTitle().get(), Optional.absent())));
+          callback.onSuccess(new LinkPreview(url, metadata.getTitle().get(), Optional.absent()));
           return;
         }
 
         RequestController imageController = fetchThumbnail(metadata.getImageUrl().get(), attachment -> {
           if (!metadata.getTitle().isPresent() && !attachment.isPresent()) {
-            callback.onComplete(Optional.absent());
+            callback.onError(Error.PREVIEW_NOT_AVAILABLE);
           } else {
-            callback.onComplete(Optional.of(new LinkPreview(url, metadata.getTitle().or(""), attachment)));
+            callback.onSuccess(new LinkPreview(url, metadata.getTitle().or(""), attachment));
           }
         });
 
@@ -106,25 +125,25 @@ public class LinkPreviewRepository {
     return compositeController;
   }
 
-  private @NonNull RequestController fetchMetadata(@NonNull String url, Callback<Metadata> callback) {
+  private @NonNull RequestController fetchMetadata(@NonNull String url, Consumer<Metadata> callback) {
     Call call = client.newCall(new Request.Builder().url(url).cacheControl(NO_CACHE).build());
 
     call.enqueue(new okhttp3.Callback() {
       @Override
       public void onFailure(@NonNull Call call, @NonNull IOException e) {
         Log.w(TAG, "Request failed.", e);
-        callback.onComplete(Metadata.empty());
+        callback.accept(Metadata.empty());
       }
 
       @Override
       public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
         if (!response.isSuccessful()) {
           Log.w(TAG, "Non-successful response. Code: " + response.code());
-          callback.onComplete(Metadata.empty());
+          callback.accept(Metadata.empty());
           return;
         } else if (response.body() == null) {
           Log.w(TAG, "No response body.");
-          callback.onComplete(Metadata.empty());
+          callback.accept(Metadata.empty());
           return;
         }
 
@@ -138,14 +157,14 @@ public class LinkPreviewRepository {
           imageUrl = Optional.absent();
         }
 
-        callback.onComplete(new Metadata(title, imageUrl));
+        callback.accept(new Metadata(title, imageUrl));
       }
     });
 
     return new CallRequestController(call);
   }
 
-  private @NonNull RequestController fetchThumbnail(@NonNull String imageUrl, @NonNull Callback<Optional<Attachment>> callback) {
+  private @NonNull RequestController fetchThumbnail(@NonNull String imageUrl, @NonNull Consumer<Optional<Attachment>> callback) {
     Call                  call       = client.newCall(new Request.Builder().url(imageUrl).build());
     CallRequestController controller = new CallRequestController(call);
 
@@ -163,11 +182,13 @@ public class LinkPreviewRepository {
         Bitmap               bitmap    = BitmapFactory.decodeByteArray(data, 0, data.length);
         Optional<Attachment> thumbnail = bitmapToAttachment(bitmap, Bitmap.CompressFormat.JPEG, MediaUtil.IMAGE_JPEG);
 
-        callback.onComplete(thumbnail);
+        if (bitmap != null) bitmap.recycle();
+
+        callback.accept(thumbnail);
       } catch (IOException e) {
         Log.w(TAG, "Exception during link preview image retrieval.", e);
         controller.cancel();
-        callback.onComplete(Optional.absent());
+        callback.accept(Optional.absent());
       }
     });
 
@@ -176,7 +197,7 @@ public class LinkPreviewRepository {
 
   private static RequestController fetchStickerPackLinkPreview(@NonNull Context context,
                                                                @NonNull String packUrl,
-                                                               @NonNull Callback<Optional<LinkPreview>> callback)
+                                                               @NonNull Callback callback)
   {
     SignalExecutors.UNBOUNDED.execute(() -> {
       try {
@@ -204,19 +225,86 @@ public class LinkPreviewRepository {
 
           Optional<Attachment> thumbnail = bitmapToAttachment(bitmap, Bitmap.CompressFormat.WEBP, MediaUtil.IMAGE_WEBP);
 
-          callback.onComplete(Optional.of(new LinkPreview(packUrl, title, thumbnail)));
+          if (bitmap != null) bitmap.recycle();
+
+          callback.onSuccess(new LinkPreview(packUrl, title, thumbnail));
         } else {
-          callback.onComplete(Optional.absent());
+          callback.onError(Error.PREVIEW_NOT_AVAILABLE);
         }
       } catch (IOException | InvalidMessageException | ExecutionException | InterruptedException e) {
         Log.w(TAG, "Failed to fetch sticker pack link preview.");
-        callback.onComplete(Optional.absent());
+        callback.onError(Error.PREVIEW_NOT_AVAILABLE);
       }
     });
 
     return () -> Log.i(TAG, "Cancelled sticker pack link preview fetch -- no effect.");
   }
 
+  private static RequestController fetchGroupLinkPreview(@NonNull Context context,
+                                                         @NonNull String groupUrl,
+                                                         @NonNull Callback callback)
+  {
+    SignalExecutors.UNBOUNDED.execute(() -> {
+      try {
+        GroupInviteLinkUrl groupInviteLinkUrl = GroupInviteLinkUrl.fromUrl(groupUrl);
+        if (groupInviteLinkUrl == null) {
+          throw new AssertionError();
+        }
+
+        GroupMasterKey                      groupMasterKey = groupInviteLinkUrl.getGroupMasterKey();
+        GroupId.V2                          groupId        = GroupId.v2(groupMasterKey);
+        Optional<GroupDatabase.GroupRecord> group          = DatabaseFactory.getGroupDatabase(context)
+                                                                            .getGroup(groupId);
+
+        if (group.isPresent()) {
+          Log.i(TAG, "Creating preview for locally available group");
+
+          GroupDatabase.GroupRecord groupRecord = group.get();
+          String                    title       = groupRecord.getTitle();
+          Optional<Attachment>      thumbnail   = Optional.absent();
+
+          if (AvatarHelper.hasAvatar(context, groupRecord.getRecipientId())) {
+            Recipient recipient = Recipient.resolved(groupRecord.getRecipientId());
+            Bitmap    bitmap    = AvatarUtil.loadIconBitmapSquare(context, recipient, 512, 512);
+
+            thumbnail = bitmapToAttachment(bitmap, Bitmap.CompressFormat.WEBP, MediaUtil.IMAGE_WEBP);
+
+            if (bitmap != null) bitmap.recycle();
+          }
+
+          callback.onSuccess(new LinkPreview(groupUrl, title, thumbnail));
+        } else {
+          Log.i(TAG, "Group is not locally available for preview generation, fetching from server");
+
+          DecryptedGroupJoinInfo joinInfo    = GroupManager.getGroupJoinInfoFromServer(context, groupMasterKey, groupInviteLinkUrl.getPassword());
+          Optional<Attachment>   thumbnail   = Optional.absent();
+          byte[]                 avatarBytes = AvatarGroupsV2DownloadJob.downloadGroupAvatarBytes(context, groupMasterKey, joinInfo.getAvatar());
+
+          if (avatarBytes != null) {
+            Bitmap bitmap = BitmapFactory.decodeByteArray(avatarBytes, 0, avatarBytes.length);
+
+            thumbnail = bitmapToAttachment(bitmap, Bitmap.CompressFormat.WEBP, MediaUtil.IMAGE_WEBP);
+
+            if (bitmap != null) bitmap.recycle();
+          }
+
+          callback.onSuccess(new LinkPreview(groupUrl, joinInfo.getTitle(), thumbnail));
+        }
+      } catch (ExecutionException | InterruptedException | IOException | VerificationFailedException e) {
+        Log.w(TAG, "Failed to fetch group link preview.", e);
+        callback.onError(Error.PREVIEW_NOT_AVAILABLE);
+      } catch (GroupInviteLinkUrl.InvalidGroupLinkException | GroupInviteLinkUrl.UnknownGroupLinkVersionException e) {
+        Log.w(TAG, "Bad group link.", e);
+        callback.onError(Error.PREVIEW_NOT_AVAILABLE);
+      } catch (GroupLinkNotActiveException e) {
+        Log.w(TAG, "Group link not active.", e);
+        callback.onError(Error.GROUP_LINK_INACTIVE);
+      }
+    });
+
+    return () -> Log.i(TAG, "Cancelled group link preview fetch -- no effect.");
+  }
+
   private static Optional<Attachment> bitmapToAttachment(@Nullable Bitmap bitmap,
                                                          @NonNull Bitmap.CompressFormat format,
                                                          @NonNull String contentType)
@@ -277,7 +365,14 @@ public class LinkPreviewRepository {
     }
   }
 
-  interface Callback<T> {
+  interface Callback {
-    void onComplete(@NonNull T result);
+    void onSuccess(@NonNull LinkPreview linkPreview);
+
+    void onError(@NonNull Error error);
+  }
+  
+  public enum Error {
+    PREVIEW_NOT_AVAILABLE,
+    GROUP_LINK_INACTIVE
   }
 }

app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java

@@ -1,12 +1,14 @@
 package org.thoughtcrime.securesms.linkpreview;
 
+import android.content.Context;
+import android.text.TextUtils;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelProvider;
-import android.content.Context;
-import androidx.annotation.NonNull;
-import android.text.TextUtils;
 
 import org.thoughtcrime.securesms.net.RequestController;
 import org.thoughtcrime.securesms.util.Debouncer;
@@ -86,21 +88,30 @@ public class LinkPreviewViewModel extends ViewModel {
       linkPreviewState.setValue(LinkPreviewState.forLoading());
 
       activeUrl     = link.get().getUrl();
-      activeRequest = repository.getLinkPreview(context, link.get().getUrl(), lp -> {
+      activeRequest = repository.getLinkPreview(context, link.get().getUrl(), new LinkPreviewRepository.Callback() {
+          @Override
+          public void onSuccess(@NonNull LinkPreview linkPreview) {
             Util.runOnMain(() -> {
               if (!userCanceled) {
-            if (lp.isPresent()) {
+                if (activeUrl != null && activeUrl.equals(linkPreview.getUrl())) {
-              if (activeUrl != null && activeUrl.equals(lp.get().getUrl())) {
+                  linkPreviewState.setValue(LinkPreviewState.forPreview(linkPreview));
-                linkPreviewState.setValue(LinkPreviewState.forPreview(lp.get()));
                 } else {
                   linkPreviewState.setValue(LinkPreviewState.forNoLinks());
                 }
-            } else {
-              linkPreviewState.setValue(LinkPreviewState.forLinksWithNoPreview());
-            }
               }
               activeRequest = null;
             });
+          }
+
+        @Override
+        public void onError(@NonNull LinkPreviewRepository.Error error) {
+          Util.runOnMain(() -> {
+            if (!userCanceled) {
+              linkPreviewState.setValue(LinkPreviewState.forLinksWithNoPreview(error));
+            }
+            activeRequest = null;
+          });
+        }
       });
     });
   }
@@ -160,27 +171,33 @@ public class LinkPreviewViewModel extends ViewModel {
     private final boolean                     isLoading;
     private final boolean                     hasLinks;
     private final Optional<LinkPreview>       linkPreview;
+    private final LinkPreviewRepository.Error error;
 
-    private LinkPreviewState(boolean isLoading, boolean hasLinks, Optional<LinkPreview> linkPreview) {
+    private LinkPreviewState(boolean isLoading,
+                             boolean hasLinks,
+                             Optional<LinkPreview> linkPreview,
+                             @Nullable LinkPreviewRepository.Error error)
+    {
       this.isLoading   = isLoading;
       this.hasLinks    = hasLinks;
       this.linkPreview = linkPreview;
+      this.error       = error;
     }
 
     private static LinkPreviewState forLoading() {
-      return new LinkPreviewState(true, false, Optional.absent());
+      return new LinkPreviewState(true, false, Optional.absent(), null);
     }
 
     private static LinkPreviewState forPreview(@NonNull LinkPreview linkPreview) {
-      return new LinkPreviewState(false, true, Optional.of(linkPreview));
+      return new LinkPreviewState(false, true, Optional.of(linkPreview), null);
     }
 
-    private static LinkPreviewState forLinksWithNoPreview() {
+    private static LinkPreviewState forLinksWithNoPreview(@NonNull LinkPreviewRepository.Error error) {
-      return new LinkPreviewState(false, true, Optional.absent());
+      return new LinkPreviewState(false, true, Optional.absent(), error);
     }
 
     private static LinkPreviewState forNoLinks() {
-      return new LinkPreviewState(false, false, Optional.absent());
+      return new LinkPreviewState(false, false, Optional.absent(), null);
     }
 
     public boolean isLoading() {
@@ -195,6 +212,10 @@ public class LinkPreviewViewModel extends ViewModel {
       return linkPreview;
     }
 
+    public @Nullable LinkPreviewRepository.Error getError() {
+      return error;
+    }
+
     boolean hasContent() {
       return isLoading || hasLinks;
     }

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

@@ -58,10 +58,11 @@ import static org.thoughtcrime.securesms.database.RecipientDatabase.InsightsBann
 
 public class Recipient {
 
+  private static final String TAG = Log.tag(Recipient.class);
+
   public static final Recipient UNKNOWN = new Recipient(RecipientId.UNKNOWN, new RecipientDetails(), true);
 
-  private static final FallbackPhotoProvider DEFAULT_FALLBACK_PHOTO_PROVIDER = new FallbackPhotoProvider();
+  public static final FallbackPhotoProvider DEFAULT_FALLBACK_PHOTO_PROVIDER = new FallbackPhotoProvider();
-  private static final String                TAG = Log.tag(Recipient.class);
 
   private final RecipientId            id;
   private final boolean                resolving;

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

@@ -1,6 +1,7 @@
 package org.thoughtcrime.securesms.util;
 
 import android.content.Context;
+import android.graphics.Bitmap;
 import android.graphics.drawable.Drawable;
 import android.text.TextUtils;
 import android.view.View;
@@ -67,13 +68,22 @@ public final class AvatarUtil {
   public static void loadIconIntoImageView(@NonNull Recipient recipient, @NonNull ImageView target) {
     Context  context  = target.getContext();
 
-    request(GlideApp.with(context).asDrawable(), context, recipient).into(target);
+    requestCircle(GlideApp.with(context).asDrawable(), context, recipient).into(target);
+  }
+
+  public static Bitmap loadIconBitmapSquare(@NonNull Context context,
+                                            @NonNull Recipient recipient,
+                                            int width,
+                                            int height)
+      throws ExecutionException, InterruptedException
+  {
+    return requestSquare(GlideApp.with(context).asBitmap(), context, recipient).submit(width, height).get();
   }
 
   @WorkerThread
   public static IconCompat getIconForNotification(@NonNull Context context, @NonNull Recipient recipient) {
     try {
-      return IconCompat.createWithBitmap(request(GlideApp.with(context).asBitmap(), context, recipient).submit().get());
+      return IconCompat.createWithBitmap(requestCircle(GlideApp.with(context).asBitmap(), context, recipient).submit().get());
     } catch (ExecutionException | InterruptedException e) {
       return null;
     }
@@ -88,10 +98,17 @@ public final class AvatarUtil {
                    .diskCacheStrategy(DiskCacheStrategy.ALL);
   }
 
+  private static <T> GlideRequest<T> requestCircle(@NonNull GlideRequest<T> glideRequest, @NonNull Context context, @NonNull Recipient recipient) {
+    return request(glideRequest, context, recipient).circleCrop();
+  }
+
+  private static <T> GlideRequest<T> requestSquare(@NonNull GlideRequest<T> glideRequest, @NonNull Context context, @NonNull Recipient recipient) {
+    return request(glideRequest, context, recipient).centerCrop();
+  }
+
   private static <T> GlideRequest<T> request(@NonNull GlideRequest<T> glideRequest, @NonNull Context context, @NonNull Recipient recipient) {
     return glideRequest.load(new ProfileContactPhoto(recipient, recipient.getProfileAvatar()))
                        .error(getFallback(context, recipient))
-                       .circleCrop()
                        .diskCacheStrategy(DiskCacheStrategy.ALL);
   }
 

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

@@ -24,7 +24,9 @@ import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.WebRtcCallActivity;
 import org.thoughtcrime.securesms.conversation.ConversationActivity;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.groups.GroupId;
+import org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining.GroupJoinBottomSheetDialogFragment;
 import org.thoughtcrime.securesms.groups.ui.invitesandrequests.joining.GroupJoinUpdateRequiredBottomSheetDialogFragment;
 import org.thoughtcrime.securesms.groups.v2.GroupInviteLinkUrl;
 import org.thoughtcrime.securesms.logging.Log;
@@ -194,17 +196,20 @@ public class CommunicationActions {
   {
     GroupId.V2 groupId = GroupId.v2(groupInviteLinkUrl.getGroupMasterKey());
 
-    SimpleTask.run(SignalExecutors.BOUNDED, () ->
+    SimpleTask.run(SignalExecutors.BOUNDED, () -> {
-      DatabaseFactory.getGroupDatabase(activity)
+      GroupDatabase.GroupRecord group = DatabaseFactory.getGroupDatabase(activity)
                                                        .getGroup(groupId)
-                     .transform(groupRecord -> Recipient.resolved(groupRecord.getRecipientId()))
+                                                       .orNull();
-                     .orNull(),
+
+      return group != null && group.isActive() ? Recipient.resolved(group.getRecipientId())
+                                               : null;
+    },
     recipient -> {
       if (recipient != null) {
         CommunicationActions.startConversation(activity, recipient, null);
         Toast.makeText(activity, R.string.GroupJoinBottomSheetDialogFragment_you_are_already_a_member, Toast.LENGTH_SHORT).show();
       } else {
-          GroupJoinUpdateRequiredBottomSheetDialogFragment.show(activity.getSupportFragmentManager());
+        GroupJoinBottomSheetDialogFragment.show(activity.getSupportFragmentManager(), groupInviteLinkUrl);
       }
     });
   }

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

@@ -30,15 +30,16 @@ import android.os.Build.VERSION_CODES;
 import android.os.Handler;
 import android.os.Looper;
 import android.provider.Telephony;
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-import androidx.annotation.RequiresPermission;
 import android.telephony.TelephonyManager;
 import android.text.Spannable;
 import android.text.SpannableString;
 import android.text.TextUtils;
 import android.text.style.StyleSpan;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresPermission;
+
 import com.annimon.stream.Stream;
 import com.google.android.mms.pdu_alt.CharacterSets;
 import com.google.android.mms.pdu_alt.EncodedStringValue;
@@ -339,6 +340,10 @@ public class Util {
     return Optional.fromNullable(simCountryIso != null ? simCountryIso.toUpperCase() : null);
   }
 
+  public static @NonNull <T> T firstNonNull(@Nullable T optional, @NonNull T fallback) {
+    return optional != null ? optional : fallback;
+  }
+
   @SafeVarargs
   public static @NonNull <T> T firstNonNull(T ... ts) {
     for (T t : ts) {

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

@@ -0,0 +1,109 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:theme="@style/Theme.Signal.RoundedBottomSheet.Light">
+
+    <org.thoughtcrime.securesms.components.AvatarImageView
+        android:id="@+id/group_join_recipient_avatar"
+        android:layout_width="96dp"
+        android:layout_height="96dp"
+        android:layout_gravity="center_horizontal"
+        android:layout_marginTop="16dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+    <ProgressBar
+        android:id="@+id/group_join_busy"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:visibility="gone"
+        app:layout_constraintBottom_toBottomOf="@+id/group_join_recipient_avatar"
+        app:layout_constraintEnd_toEndOf="@+id/group_join_recipient_avatar"
+        app:layout_constraintStart_toStartOf="@+id/group_join_recipient_avatar"
+        app:layout_constraintTop_toTopOf="@+id/group_join_recipient_avatar"
+        tools:visibility="visible" />
+
+    <TextView
+        android:id="@+id/group_join_group_name"
+        style="@style/TextAppearance.Signal.Body1.Bold"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:textColor="?attr/title_text_color_primary"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/group_join_recipient_avatar"
+        tools:text="Parkdale Run Club" />
+
+    <TextView
+        android:id="@+id/group_join_group_details"
+        style="@style/Signal.Text.Body"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textColor="?attr/title_text_color_secondary"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/group_join_group_name"
+        tools:text="Group · 12 members" />
+
+    <TextView
+        android:id="@+id/group_join_explain"
+        style="@style/TextAppearance.Signal.Body2"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="36dp"
+        android:layout_marginEnd="16dp"
+        android:textColor="?attr/title_text_color_primary"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/group_join_group_details"
+        tools:text="@string/GroupJoinBottomSheetDialogFragment_admin_approval_needed" />
+
+    <Button
+        android:id="@+id/group_join_cancel_button"
+        style="@style/Button.Primary"
+        android:layout_width="0dp"
+        android:layout_height="64dp"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="8dp"
+        android:layout_marginEnd="16dp"
+        android:layout_marginBottom="16dp"
+        android:text="@android:string/cancel"
+        android:visibility="gone"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/group_join_button"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/group_join_explain"
+        app:layout_constraintVertical_bias="0"
+        tools:visibility="visible" />
+
+    <Button
+        android:id="@+id/group_join_button"
+        style="@style/Button.Primary"
+        android:layout_width="0dp"
+        android:layout_height="64dp"
+        android:layout_marginStart="0dp"
+        android:layout_marginTop="8dp"
+        android:layout_marginEnd="16dp"
+        android:layout_marginBottom="16dp"
+        android:visibility="gone"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toEndOf="@+id/group_join_cancel_button"
+        app:layout_constraintTop_toBottomOf="@+id/group_join_explain"
+        app:layout_constraintVertical_bias="0"
+        tools:text="@string/GroupJoinBottomSheetDialogFragment_join"
+        tools:visibility="visible" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -102,13 +102,13 @@
             android:id="@+id/linkpreview_no_preview"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
+            android:gravity="center"
             android:paddingTop="12dp"
             android:paddingBottom="12dp"
-            android:text="@string/LinkPreviewView_no_link_preview_available"
-            android:gravity="center"
             android:visibility="gone"
+            app:layout_constraintBottom_toTopOf="@id/linkpreview_divider"
             app:layout_constraintTop_toTopOf="parent"
-            app:layout_constraintBottom_toTopOf="@id/linkpreview_divider"/>
+            tools:text="@string/LinkPreviewView_no_link_preview_available" />
 
     </androidx.constraintlayout.widget.ConstraintLayout>
 

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

@@ -492,6 +492,7 @@
 
     <!-- LinkPreviewView -->
     <string name="LinkPreviewView_no_link_preview_available">No link preview available</string>
+    <string name="LinkPreviewView_this_group_link_is_not_active">This group link is not active</string>
 
     <!-- PendingMembersActivity -->
     <string name="PendingMemberInvitesActivity_pending_group_invites">Pending group invites</string>
@@ -647,6 +648,16 @@
 
     <!-- GroupJoinBottomSheetDialogFragment -->
     <string name="GroupJoinBottomSheetDialogFragment_you_are_already_a_member">You are already a member</string>
+    <string name="GroupJoinBottomSheetDialogFragment_join">Join</string>
+    <string name="GroupJoinBottomSheetDialogFragment_request_to_join">Request to join</string>
+    <string name="GroupJoinBottomSheetDialogFragment_this_group_link_is_not_active">This group link is not active</string>
+    <string name="GroupJoinBottomSheetDialogFragment_unable_to_get_group_information_please_try_again_later">Unable to get group information, please try again later</string>
+    <string name="GroupJoinBottomSheetDialogFragment_direct_join">Do you want to join this group and share your name and photo with its members?</string>
+    <string name="GroupJoinBottomSheetDialogFragment_admin_approval_needed">An admin of this group must approve your request before you can join this group. When you request to join, your name and photo will be shared with its members.</string>
+    <plurals name="GroupJoinBottomSheetDialogFragment_group_dot_d_members">
+        <item quantity="one">Group · %1$d member</item>
+        <item quantity="other">Group · %1$d members</item>
+    </plurals>
 
     <!-- GroupJoinUpdateRequiredBottomSheetDialogFragment -->
     <string name="GroupJoinUpdateRequiredBottomSheetDialogFragment_update_signal_to_use_group_links">Update Signal to use group links</string>