fix: Do not update lastEvent with state events

lib/src/client.dart

@@ -2435,8 +2435,7 @@ class Client extends MatrixApi {
 
         // If last event is null or not a valid room preview event anyway,
         // just use this:
-        if (room.lastEvent == null ||
-            !roomPreviewLastEvents.contains(room.lastEvent?.type)) {
+        if (room.lastEvent == null) {
           room.lastEvent = event;
           break;
         }

lib/src/room.dart

@@ -98,7 +98,7 @@ class Room {
       summary: RoomSummary.fromJson(Map<String, dynamic>.from(json['summary'])),
     );
     if (json['last_event'] != null) {
-      room._lastEvent = Event.fromJson(json['last_event'], room);
+      room.lastEvent = Event.fromJson(json['last_event'], room);
     }
     return room;
   }
@@ -365,33 +365,7 @@ class Room {
   /// Wheither this is a direct chat or not
   bool get isDirectChat => directChatMatrixID != null;
 
-  Event? _lastEvent;
-
-  set lastEvent(Event? event) {
-    _lastEvent = event;
-  }
-
-  Event? get lastEvent {
-    if (_lastEvent != null) return _lastEvent;
-
-    // Just pick the newest state event as an indicator for when the last
-    // activity was in this room. This is better than nothing:
-    var lastTime = DateTime.fromMillisecondsSinceEpoch(0);
-    Event? lastEvent;
-
-    states.forEach((final String key, final entry) {
-      final state = entry[''];
-      if (state == null) return;
-      if (state is! Event) return;
-      if (state.originServerTs.millisecondsSinceEpoch >
-          lastTime.millisecondsSinceEpoch) {
-        lastTime = state.originServerTs;
-        lastEvent = state;
-      }
-    });
-
-    return lastEvent;
-  }
+  Event? lastEvent;
 
   /// Returns a list of all current typing users.
   List<User> get typingUsers {
@@ -416,9 +390,8 @@ class Room {
     required this.client,
     Map<String, BasicRoomEvent>? roomAccountData,
     RoomSummary? summary,
-    Event? lastEvent,
+    this.lastEvent,
   })  : roomAccountData = roomAccountData ?? <String, BasicRoomEvent>{},
-        _lastEvent = lastEvent,
         summary = summary ??
             RoomSummary.fromJson({
               'm.joined_member_count': 0,

test/encryption/key_manager_test.dart

@@ -323,26 +323,31 @@ void main() {
           .timeout(const Duration(seconds: 5));
       client.rooms.add(room);
       // we build up an encrypted message so that we can test if it successfully decrypted afterwards
-      room.setState(
-        Event(
-          senderId: '@test:example.com',
-          type: 'm.room.encrypted',
-          room: room,
-          eventId: '12345',
-          originServerTs: DateTime.now(),
-          content: {
-            'algorithm': AlgorithmTypes.megolmV1AesSha2,
-            'ciphertext': session.encrypt(json.encode({
-              'type': 'm.room.message',
-              'content': {'msgtype': 'm.text', 'body': 'foxies'},
-            })),
-            'device_id': client.deviceID,
-            'sender_key': client.identityKey,
-            'session_id': sessionId,
-          },
-          stateKey: '',
-        ),
-      );
+      await client.handleSync(SyncUpdate(
+          nextBatch: '',
+          rooms: RoomsUpdate(join: {
+            room.id: JoinedRoomUpdate(
+                timeline: TimelineUpdate(events: [
+              Event(
+                senderId: '@test:example.com',
+                type: 'm.room.encrypted',
+                room: room,
+                eventId: '12345',
+                originServerTs: DateTime.now(),
+                content: {
+                  'algorithm': AlgorithmTypes.megolmV1AesSha2,
+                  'ciphertext': session.encrypt(json.encode({
+                    'type': 'm.room.message',
+                    'content': {'msgtype': 'm.text', 'body': 'foxies'},
+                  })),
+                  'device_id': client.deviceID,
+                  'sender_key': client.identityKey,
+                  'session_id': sessionId,
+                },
+                stateKey: '',
+              )
+            ]))
+          })));
       expect(room.lastEvent?.type, 'm.room.encrypted');
       // set a payload...
       var sessionPayload = <String, dynamic>{