Implemented conversation search.

You can now search for messages within a specific conversation.

src/org/thoughtcrime/securesms/util/CloseableLiveData.java

@@ -0,0 +1,35 @@
+package org.thoughtcrime.securesms.util;
+
+import android.arch.lifecycle.MutableLiveData;
+
+import java.io.Closeable;
+
+/**
+ * Implementation of {@link android.arch.lifecycle.LiveData} that will handle closing the contained
+ * {@link Closeable} when the value changes.
+ */
+public class CloseableLiveData<E extends Closeable> extends MutableLiveData<E> {
+
+  @Override
+  public void setValue(E value) {
+    setValue(value, true);
+  }
+
+  public void setValue(E value, boolean closePrevious) {
+    E previous = getValue();
+
+    if (previous != null && closePrevious) {
+      Util.close(previous);
+    }
+
+    super.setValue(value);
+  }
+
+  public void close() {
+    E value = getValue();
+
+    if (value != null) {
+      Util.close(value);
+    }
+  }
+}

src/org/thoughtcrime/securesms/util/SearchUtil.java

@@ -0,0 +1,96 @@
+package org.thoughtcrime.securesms.util;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.text.Spannable;
+import android.text.SpannableString;
+import android.text.Spanned;
+import android.text.TextUtils;
+import android.text.style.CharacterStyle;
+
+import com.annimon.stream.Stream;
+
+import org.whispersystems.libsignal.util.Pair;
+
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+
+public class SearchUtil {
+
+  public static Spannable getHighlightedSpan(@NonNull Locale locale,
+                                             @NonNull StyleFactory styleFactory,
+                                             @Nullable String text,
+                                             @Nullable String highlight)
+  {
+    if (TextUtils.isEmpty(text)) {
+      return new SpannableString("");
+    }
+
+    text = text.replaceAll("\n", " ");
+
+    return getHighlightedSpan(locale, styleFactory, new SpannableString(text), highlight);
+  }
+
+  public static Spannable getHighlightedSpan(@NonNull Locale locale,
+                                             @NonNull StyleFactory styleFactory,
+                                             @Nullable Spannable text,
+                                             @Nullable String highlight)
+  {
+    if (TextUtils.isEmpty(text)) {
+      return new SpannableString("");
+    }
+
+
+    if (TextUtils.isEmpty(highlight)) {
+      return text;
+    }
+
+    List<Pair<Integer, Integer>> ranges  = getHighlightRanges(locale, text.toString(), highlight);
+    SpannableString              spanned = new SpannableString(text);
+
+    for (Pair<Integer, Integer> range : ranges) {
+      spanned.setSpan(styleFactory.create(), range.first(), range.second(), Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
+    }
+
+    return spanned;
+  }
+
+  static List<Pair<Integer, Integer>> getHighlightRanges(@NonNull Locale locale,
+                                                         @NonNull String text,
+                                                         @NonNull String highlight)
+  {
+    String       normalizedText      = text.toLowerCase(locale);
+    String       normalizedHighlight = highlight.toLowerCase(locale);
+    List<String> highlightTokens     = Stream.of(normalizedHighlight.split("\\s")).filter(s -> s.trim().length() > 0).toList();
+    List<String> textTokens          = Stream.of(normalizedText.split("\\s")).filter(s -> s.trim().length() > 0).toList();
+
+    List<Pair<Integer, Integer>> ranges = new LinkedList<>();
+
+    int textListIndex = 0;
+    int textCharIndex = 0;
+
+    for (String highlightToken : highlightTokens) {
+      for (int i = textListIndex; i < textTokens.size(); i++) {
+        if (textTokens.get(i).startsWith(highlightToken)) {
+          textListIndex = i + 1;
+          ranges.add(new Pair<>(textCharIndex, textCharIndex + highlightToken.length()));
+          textCharIndex += textTokens.get(i).length() + 1;
+          break;
+        }
+        textCharIndex += textTokens.get(i).length() + 1;
+      }
+    }
+
+    if (ranges.size() != highlightTokens.size()) {
+      return Collections.emptyList();
+    }
+
+    return ranges;
+  }
+
+  public interface StyleFactory {
+    CharacterStyle create();
+  }
+}