fix: incorrect Event status update in constructor

lib/src/event.dart

@@ -126,7 +126,17 @@ class Event extends MatrixEvent {
           originServerTs.millisecondsSinceEpoch;
 
       final room = this.room;
-      if (age > room.client.sendTimelineEventTimeout.inMilliseconds) {
+
+      if (
+          // We don't want to mark the event as failed if it's the lastEvent in the room
+          // since that would be a race condition (with the same event from timeline)
+          // The `room.lastEvent` is null at the time this constructor is called for it,
+          // there's no other way to check this.
+          room.lastEvent?.eventId != null &&
+              // If the event is in the sending queue, then we don't mess with it.
+              !room.sendingQueueEventsByTxId.contains(transactionId) &&
+              // Else, if the event is older than the timeout, then we mark it as failed.
+              age > room.client.sendTimelineEventTimeout.inMilliseconds) {
         // Update this event in database and open timelines
         final json = toJson();
         json['unsigned'] ??= <String, dynamic>{};

lib/src/room.dart

@@ -72,7 +72,12 @@ class Room {
   /// Key-Value store for private account data only visible for this user.
   Map<String, BasicEvent> roomAccountData = {};
 
-  final _sendingQueue = <Completer>[];
+  /// Queue of sending events
+  /// NOTE: This shouldn't be modified directly, use [sendEvent] instead. This is only used for testing.
+  final sendingQueue = <Completer>[];
+
+  /// List of transaction IDs of events that are currently queued to be sent
+  final sendingQueueEventsByTxId = <String>[];
 
   Timer? _clearTypingIndicatorTimer;
 
@@ -1106,11 +1111,14 @@ class Room {
         },
       ),
     );
+    // we need to add the transaction ID to the set of events that are currently queued to be sent
+    // even before the fake sync is called, so that the event constructor can check if the event is in the sending state
+    sendingQueueEventsByTxId.add(messageID);
     await _handleFakeSync(syncUpdate);
     final completer = Completer();
-    _sendingQueue.add(completer);
-    while (_sendingQueue.first != completer) {
-      await _sendingQueue.first.future;
+    sendingQueue.add(completer);
+    while (sendingQueue.first != completer) {
+      await sendingQueue.first.future;
     }
 
     final timeoutDate = DateTime.now().add(client.sendTimelineEventTimeout);
@@ -1142,7 +1150,8 @@ class Room {
               .unsigned![messageSendingStatusKey] = EventStatus.error.intValue;
           await _handleFakeSync(syncUpdate);
           completer.complete();
-          _sendingQueue.remove(completer);
+          sendingQueue.remove(completer);
+          sendingQueueEventsByTxId.remove(messageID);
           if (e is EventTooLarge ||
               (e is MatrixException && e.error == MatrixError.M_FORBIDDEN)) {
             rethrow;
@@ -1160,8 +1169,8 @@ class Room {
     syncUpdate.rooms!.join!.values.first.timeline!.events!.first.eventId = res;
     await _handleFakeSync(syncUpdate);
     completer.complete();
-    _sendingQueue.remove(completer);
-
+    sendingQueue.remove(completer);
+    sendingQueueEventsByTxId.remove(messageID);
     return res;
   }
 

test/event_timeout_test.dart

@@ -0,0 +1,117 @@
+import 'dart:async';
+import 'dart:io';
+
+import 'package:path/path.dart';
+import 'package:test/test.dart';
+
+import 'package:matrix/matrix.dart';
+import 'fake_client.dart';
+
+void main() {
+  group('Event timeout tests', () {
+    late Client client;
+    late Room room;
+
+    setUp(() async {
+      client = await getClient(
+        sendTimelineEventTimeout: const Duration(seconds: 5),
+        databasePath: join(Directory.current.path, 'test.sqlite'),
+      );
+      room = Room(
+        id: '!1234:example.com',
+        client: client,
+        roomAccountData: {},
+      );
+      client.rooms.add(room);
+    });
+
+    tearDown(() async {
+      await client.logout();
+      await client.dispose(closeDatabase: true);
+    });
+
+    test('Event constructor correctly checks timeout from originServerTs',
+        () async {
+      final completer = Completer();
+      room.sendingQueue.add(completer); // to block the events from being sent
+
+      String? eventId;
+      // we don't await this because the actual sending will only be done after
+      // `sendingQueue` is unblocked.
+      // but the fake sync will be called with this event in sending state right away
+      unawaited(
+        room.sendTextEvent('test', txid: '1234').then((value) {
+          eventId = value;
+        }),
+      );
+
+      // do the timeout
+      final timeout =
+          Duration(seconds: client.sendTimelineEventTimeout.inSeconds + 2);
+      await Future.delayed(timeout);
+
+      // this will trigger the check in the Event constructor to see if the
+      // event is in error state (and call fake sync with updated error status)
+      await client.oneShotSync();
+      Timeline timeline = await room.getTimeline();
+      expect(timeline.events.length, 1);
+      expect(timeline.events.first.status, EventStatus.sending);
+
+      // fake sync would have been triggered by now (if there was one), which shouldn't happen
+      await client.oneShotSync();
+      timeline = await room.getTimeline();
+      expect(timeline.events.length, 1);
+      expect(timeline.events.first.status, EventStatus.sending);
+
+      // now we unblock the sending queue and this will make `sendTextEvent`
+      // actually send the event and the fake sync that's used to update the
+      // event status to sent
+      completer.complete();
+      room.sendingQueue.remove(completer);
+      await FakeMatrixApi.firstWhere(
+        (a) => a.startsWith(
+          '/client/v3/rooms/!1234%3Aexample.com/send/m.room.message/1234',
+        ),
+      );
+      await Future.delayed(const Duration(seconds: 1));
+      expect(eventId, isNotNull);
+
+      // now the event should be in sent state after the fake sync is called
+      await client.oneShotSync();
+      timeline = await room.getTimeline();
+      expect(timeline.events.length, 1);
+      expect(timeline.events.first.status, EventStatus.sent);
+
+      // simulate the event being synced from server
+      await client.handleSync(
+        SyncUpdate(
+          nextBatch: '1',
+          rooms: RoomsUpdate(
+            join: {
+              room.id: JoinedRoomUpdate(
+                timeline: TimelineUpdate(
+                  events: [
+                    Event(
+                      eventId: eventId!,
+                      content: {'msgtype': 'm.text', 'body': 'test'},
+                      type: 'm.room.message',
+                      senderId: '@test:example.com',
+                      originServerTs: DateTime.now(),
+                      room: room,
+                      unsigned: {
+                        'transaction_id': '1234',
+                      },
+                    ),
+                  ],
+                ),
+              ),
+            },
+          ),
+        ),
+      );
+      timeline = await room.getTimeline();
+      expect(timeline.events.length, 1);
+      expect(timeline.events.first.status, EventStatus.synced);
+    });
+  });
+}