lastMessageStream method

Stream<Message?> lastMessageStream(String roomId)

Returns a stream of the last message in a room, checking if it's deleted

Implementation

Stream<mm.Message?> lastMessageStream(String roomId) {
  return getFirebaseFirestore
      .collection('${FireChatConst.roomsCollectionName}/$roomId/messages')
      .orderBy('createdAt', descending: true)
      .limit(1)
      .snapshots()
      .asyncMap(
    (snapshot) async {
      if (snapshot.docs.isEmpty) return null;

      final doc = snapshot.docs.first;
      final data = doc.data();

      // Skip if message is deleted
      // if (data['isDeleted'] == true) return null;

      // Get room to resolve author info
      final roomDoc = await getFirebaseFirestore
          .collection(FireChatConst.roomsCollectionName)
          .doc(roomId)
          .get();

      if (!roomDoc.exists) return null;

      final room = await processRoomDocument(
        roomDoc,
        firebaseUser!,
        getFirebaseFirestore,
        FireChatConst.usersCollectionName,
      );

      final author = room.users.firstWhere(
        (u) => u.id == data['authorId'],
        orElse: () => mm.User(id: data['authorId'] as String),
      );

      data['author'] = author.toJson();
      data['createdAt'] = data['createdAt']?.millisecondsSinceEpoch;
      data['id'] = doc.id;
      data['updatedAt'] = data['updatedAt']?.millisecondsSinceEpoch;
      data['isDeleted'] = data['isDeleted'];

      // Check if the message has been seen by all users
      final seenBy = data['seenBy'] as Map<String, dynamic>? ?? {};

      final allUsersHaveSeen =
          room.users.every((user) => seenBy.containsKey(user.id));

      return mm.Message.fromJson(data).copyWith(
        metadata: {
          ...data['metadata'] ?? {},
          'seen': allUsersHaveSeen,
        },
      );
    },
  );
}