unreads [nfc]: Enhance performance in _removeAllInStreams

Author: Khader-1

lib/model/unreads.dart

@@ -353,7 +353,7 @@ class Unreads extends ChangeNotifier {
             } else {
               final messageIdsSet = Set.of(event.messages);
               mentions.removeAll(messageIdsSet);
-              _slowRemoveAllInStreams(messageIdsSet);
+              _removeAllInStreams(messageIdsSet);
               _slowRemoveAllInDms(messageIdsSet);
             }
           case UpdateMessageFlagsRemoveEvent():
@@ -456,29 +456,18 @@ class Unreads extends ChangeNotifier {
       messageIds.map((messageId) => MapEntry(messageId, messageInfo)));
   }
 
-  // TODO use efficient model lookups
-  void _slowRemoveAllInStreams(Set<int> idsToRemove) {
-    final newlyEmptyStreams = <int>[];
-    for (final MapEntry(key: streamId, value: topics) in streams.entries) {
-      final newlyEmptyTopics = <String>[];
-      for (final MapEntry(key: topic, value: messageIds) in topics.entries) {
-        messageIds.removeWhere((id) => idsToRemove.contains(id));
-        if (messageIds.isEmpty) {
-          newlyEmptyTopics.add(topic);
+  void _removeAllInStreams(Set<int> idsToRemove) {
+    for (var messageId in idsToRemove) {
+      final info = _reverseStreamsLookup.remove(messageId);
+      if (info != null && streams[info.streamId]?[info.topic] != null) {
+        streams[info.streamId]![info.topic]!.remove(messageId);
+        if (streams[info.streamId]![info.topic]!.isEmpty) {
+          streams[info.streamId]!.remove(info.topic);
+        }
+        if (streams[info.streamId]!.isEmpty) {
+          streams.remove(info.streamId);
         }
       }
-      for (final topic in newlyEmptyTopics) {
-        topics.remove(topic);
-      }
-      if (topics.isEmpty) {
-        newlyEmptyStreams.add(streamId);
-      }
-    }
-    for (final streamId in newlyEmptyStreams) {
-      streams.remove(streamId);
-    }
-    for (var messageId in idsToRemove) {
-      _reverseStreamsLookup.remove(messageId);
     }
   }