unreads: In @-mentions count, exclude messages in muted DM conversations

As we do in the actual message list.

Author: chrisbobbe

lib/model/message_list.dart

@@ -691,6 +691,9 @@ class MessageListView with ChangeNotifier, _MessageSequence {
         return true;
 
       case MentionsNarrow():
+        // If changing this, consider whether [Unreads.countInMentionsNarrow]
+        // should be changed correspondingly, so the message-list view matches
+        // the unread-count badge.
       case StarredMessagesNarrow():
       case KeywordSearchNarrow():
         if (message.conversation case DmConversation(:final allRecipientIds)) {

lib/model/unreads.dart

@@ -220,7 +220,30 @@ class Unreads extends PerAccountStoreBase with ChangeNotifier {
 
   int countInDmNarrow(DmNarrow narrow) => dms[narrow]?.length ?? 0;
 
-  int countInMentionsNarrow() => mentions.length;
+  /// The unread count for the mentions narrow.
+  ///
+  /// This excludes DM messages in conversations that are considered muted,
+  /// by [UserStore.shouldMuteDmConversation].
+  // If changing which messages to exclude, consider whether the @-mentions
+  // view should change its "is-message-visible" code correspondingly,
+  // so the unread-count badge matches what you see in that view.
+  // TODO: deduplicate "is-message-visible" code
+  //   between [Unreads] and [MessageListView]?
+  // TODO(#370): maintain this count incrementally, rather than recomputing from scratch
+  int countInMentionsNarrow() {
+    int c = 0;
+    for (final messageId in mentions) {
+      final narrow = locatorMap[messageId];
+      if (narrow == null) continue;
+      switch (narrow) {
+        case DmNarrow():
+          if (channelStore.shouldMuteDmConversation(narrow)) continue;
+        case TopicNarrow():
+      }
+      c++;
+    }
+    return c;
+  }
 
   // TODO: Implement unreads handling.
   int countInStarredMessagesNarrow() => 0;

test/model/unreads_test.dart

@@ -254,12 +254,17 @@ void main() {
       final stream = eg.stream();
       prepare();
       await store.addStream(stream);
+      await store.setUserTopic(stream, 'a', UserTopicVisibilityPolicy.muted);
+      await store.setMutedUsers([eg.thirdUser.userId]);
       fillWithMessages([
         eg.streamMessage(stream: stream, flags: []),
         eg.streamMessage(stream: stream, flags: [MessageFlag.mentioned]),
+        eg.streamMessage(stream: stream, topic: 'a', flags: [MessageFlag.mentioned]),
         eg.streamMessage(stream: stream, flags: [MessageFlag.wildcardMentioned]),
+        eg.dmMessage(from: eg.otherUser, to: [eg.selfUser], flags: [MessageFlag.mentioned]),
+        eg.dmMessage(from: eg.thirdUser, to: [eg.selfUser], flags: [MessageFlag.mentioned]),
       ]);
-      check(model.countInMentionsNarrow()).equals(2);
+      check(model.countInMentionsNarrow()).equals(4);
     });
 
     test('countInStarredMessagesNarrow', () async {