Add sync message handling and stop formatting behavior.

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

@@ -298,6 +298,8 @@ public class ComposeText extends EmojiEditText {
     addTextChangedListener(mentionValidatorWatcher);
 
     if (FeatureFlags.textFormatting()) {
+      addTextChangedListener(new ComposeTextStyleWatcher());
+
       setCustomSelectionActionModeCallback(new ActionMode.Callback() {
         @Override
         public boolean onCreateActionMode(ActionMode mode, Menu menu) {
@@ -350,7 +352,7 @@ public class ComposeText extends EmojiEditText {
           }
 
           if (style != null) {
-            replacement.setSpan(style, 0, charSequence.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+            replacement.setSpan(style, 0, charSequence.length(), MessageStyler.SPAN_FLAGS);
           }
 
           clearComposingText();

app/src/main/java/org/thoughtcrime/securesms/components/ComposeTextStyleWatcher.kt

@@ -0,0 +1,80 @@
+package org.thoughtcrime.securesms.components
+
+import android.text.Annotation
+import android.text.Editable
+import android.text.Spannable
+import android.text.Spanned
+import android.text.TextUtils
+import android.text.TextWatcher
+import android.text.style.CharacterStyle
+import org.signal.core.util.StringUtil
+import org.thoughtcrime.securesms.conversation.MessageStyler
+
+/**
+ * Formatting should only grow when appending until a white space character is entered/pasted.
+ *
+ * This watcher observes changes to the text and will shrink supported style ranges as necessary
+ * to provide the desired behavior.
+ */
+class ComposeTextStyleWatcher : TextWatcher {
+  private val markerAnnotation = Annotation("text-formatting", "marker")
+  private var textSnapshotPriorToChange: CharSequence? = null
+
+  override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {
+    if (s is Spannable) {
+      s.removeSpan(markerAnnotation)
+    }
+
+    textSnapshotPriorToChange = s.subSequence(start, start + count)
+  }
+
+  override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+    if (s is Spannable) {
+      s.removeSpan(markerAnnotation)
+
+      if (count > 0) {
+        s.setSpan(markerAnnotation, start, start + count, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
+      }
+    }
+  }
+
+  override fun afterTextChanged(s: Editable) {
+    val editStart = s.getSpanStart(markerAnnotation)
+    val editEnd = s.getSpanEnd(markerAnnotation)
+
+    s.removeSpan(markerAnnotation)
+
+    if (editStart < 0 || editEnd < 0 || editStart >= editEnd || (editStart == 0 && editEnd == s.length)) {
+      return
+    }
+
+    val change = s.subSequence(editStart, editEnd)
+    if (change.isEmpty() || textSnapshotPriorToChange == null || (editEnd - editStart == 1 && !StringUtil.isVisuallyEmpty(change[0])) || TextUtils.equals(textSnapshotPriorToChange, change)) {
+      textSnapshotPriorToChange = null
+      return
+    }
+    textSnapshotPriorToChange = null
+
+    var newEnd = editStart
+    for (i in change.indices) {
+      if (StringUtil.isVisuallyEmpty(change[i])) {
+        newEnd = editStart + i
+        break
+      }
+    }
+
+    s.getSpans(editStart, editEnd, CharacterStyle::class.java)
+      .filter { MessageStyler.isSupportedCharacterStyle(it) }
+      .forEach { style ->
+        val styleStart = s.getSpanStart(style)
+        val styleEnd = s.getSpanEnd(style)
+
+        if (styleEnd == editEnd && styleStart < styleEnd) {
+          s.removeSpan(style)
+          s.setSpan(style, styleStart, newEnd, MessageStyler.SPAN_FLAGS)
+        } else {
+          s.removeSpan(style)
+        }
+      }
+  }
+}