observeConnectionState method

@override Future<Stream<BleConnectionState>> observeConnectionState({ required String deviceAddress, })

Observes connection state changes for a device without initiating a connection.

Unlike connect, this method does not initiate a connection attempt. It only sets up monitoring for connection state changes for a device that has been previously discovered or connected. This is useful for:

• Monitoring devices that may reconnect automatically
• Observing connection changes initiated by other apps or the system
• Tracking connection state without actively managing the connection

The device must have been discovered through scanning or previously connected before this method can monitor its state.

Returns a Stream of BleConnectionState that emits whenever the connection state changes for the specified device.

Implementation

@override
Future<Stream<BleConnectionState>> observeConnectionState({
  required String deviceAddress,
}) async {
  // For the fake implementation, create or reuse a stream controller
  // but don't initiate a connection
  final StreamController<BleConnectionState> controller =
      _connectionControllers.putIfAbsent(
    deviceAddress,
    StreamController<BleConnectionState>.broadcast,
  );

  // Emit the current state after a microtask delay to allow listeners to be set up
  // This simulates the async nature of the platform channel
  final BleConnectionState currentState =
      _connectionStates[deviceAddress] ?? BleConnectionState.disconnected;

  Future<void>.delayed(const Duration(milliseconds: 1), () {
    if (!controller.isClosed) {
      controller.add(currentState);
    }
  });

  return controller.stream;
}