fix: Older state events overwrite newer ones on fetching history

lib/src/client.dart

@@ -2665,8 +2665,27 @@ class Client extends MatrixApi {
       if (syncRoomUpdate is JoinedRoomUpdate) {
         final state = syncRoomUpdate.state;
 
+        // If we are receiving states when fetching history we need to check if
+        // we are not overwriting a newer state.
+        if (direction == Direction.b) {
+          await room.postLoad();
+          state?.removeWhere((state) {
+            final existingState =
+                room.getState(state.type, state.stateKey ?? '');
+            if (existingState == null) return false;
+            if (existingState is User) {
+              return existingState.originServerTs
+                      ?.isAfter(state.originServerTs) ??
+                  true;
+            }
+            if (existingState is MatrixEvent) {
+              return existingState.originServerTs.isAfter(state.originServerTs);
+            }
+            return true;
+          });
+        }
+
         if (state != null && state.isNotEmpty) {
-          // TODO: This method seems to be comperatively slow for some updates
           await _handleRoomEvents(
             room,
             state,

lib/src/event.dart

@@ -256,6 +256,7 @@ class Event extends MatrixEvent {
         typeKey: type,
         senderId: senderId,
         room: room,
+        originServerTs: originServerTs,
       );
 
   String get messageType => type == EventTypes.Sticker

lib/src/user.dart

@@ -22,12 +22,14 @@ import 'package:matrix/matrix.dart';
 class User extends StrippedStateEvent {
   final Room room;
   final Map<String, Object?>? prevContent;
+  final DateTime? originServerTs;
 
   factory User(
     String id, {
     String? membership,
     String? displayName,
     String? avatarUrl,
+    DateTime? originServerTs,
     required Room room,
   }) {
     return User.fromState(
@@ -40,6 +42,7 @@ class User extends StrippedStateEvent {
       },
       typeKey: EventTypes.RoomMember,
       room: room,
+      originServerTs: originServerTs,
     );
   }
 
@@ -49,6 +52,7 @@ class User extends StrippedStateEvent {
     required String typeKey,
     required super.senderId,
     required this.room,
+    this.originServerTs,
     this.prevContent,
   }) : super(
           type: typeKey,
@@ -254,5 +258,6 @@ extension FromStrippedStateEventExtension on StrippedStateEvent {
         typeKey: type,
         senderId: senderId,
         room: room,
+        originServerTs: null,
       );
 }

test/client_test.dart

@@ -695,6 +695,35 @@ void main() {
       );
       expect(room.lastEvent!.content['body'], '* floooof');
 
+      // Older state event should not overwrite current state events
+      room.partial = false;
+      await matrix.handleSync(
+        SyncUpdate(
+          nextBatch: '',
+          rooms: RoomsUpdate(
+            join: {
+              room.id: JoinedRoomUpdate(
+                state: [
+                  MatrixEvent(
+                    type: EventTypes.RoomMember,
+                    content: {'displayname': 'Alice Catgirl'},
+                    senderId: '@alice:example.com',
+                    eventId: 'oldEventId',
+                    stateKey: '@alice:example.com',
+                    originServerTs:
+                        DateTime.now().subtract(const Duration(days: 365 * 30)),
+                  ),
+                ],
+              ),
+            },
+          ),
+        ),
+        direction: Direction.b,
+      );
+      room.partial = true;
+      expect(room.getParticipants().first.id, '@alice:example.com');
+      expect(room.getParticipants().first.displayName, 'Alice Margatroid');
+
       // accepts a consecutive edit
       await matrix.handleSync(
         SyncUpdate.fromJson({