Widget Event Bus
---

Widget event bus is a simple implementation of observer pattern. It has a stream controller to broadcast widget events which is coming from to network layer to the widgets that listen for them.
* Upcoming events have two fields:
1. Widget event id (known as widgetEventKey)
2. Data

* Listener widgets listen to these events by using their own id

You can see the implementation of it below:

@singleton
class NeoWidgetEventBus {
  final _eventBus = StreamController<NeoWidgetEvent>.broadcast();
  final Set<StreamSubscription<NeoWidgetEvent>> _subscriptions = {};

  StreamSubscription<NeoWidgetEvent> listen({
    required String eventId,
    required Function(NeoWidgetEvent) onEventReceived,
  }) {
    final subscription = _eventBus.stream.listen((event) {
      if (event.eventId == eventId) {
        onEventReceived(event);
      }
    });
    _subscriptions.add(subscription);
    return subscription;
  }

  StreamSubscription<NeoWidgetEvent> listenEvents({
    required List<String> eventIds,
    required Function(NeoWidgetEvent) onEventReceived,
  }) {
    final subscription = _eventBus.stream.listen((event) {
      if (eventIds.contains(event.eventId)) {
        onEventReceived(event);
      }
    });
    _subscriptions.add(subscription);
    return subscription;
  }

  void addEvent(NeoWidgetEvent event) {
    _eventBus.add(event);
  }

  void close() {
    for (final subscription in _subscriptions) {
      subscription.cancel();
    }
    _subscriptions.clear();
    _eventBus.close();
  }
}

class NeoWidgetEvent {
  final String eventId;
  final Object? data;

  NeoWidgetEvent({required this.eventId, this.data});
}