/*
 * @Author       : Linloir
 * @Date         : 2022-03-05 21:50:33
 * @LastEditTime : 2022-03-07 10:26:04
 * @Description  : Event bus class
 */

typedef EventCallBack = void Function(dynamic args);

final EventBus mainBus = EventBus();

class EventBus {
  EventBus._internal();
  static final EventBus _bus = EventBus._internal();
  factory EventBus() => _bus;

  final _eventMap = <String, List<EventCallBack>>{};

  void onBus({required String event, required EventCallBack onEvent}) {
    _eventMap[event] ??= <EventCallBack>[];
    _eventMap[event]!.add(onEvent);
  }

  void offBus({required String event, EventCallBack? callBack}) {
    if(callBack == null) {
      _eventMap.remove(event);
    }
    else{
      _eventMap[event]?.remove(callBack);
    }
  }

  void emit({required String event, dynamic args}) {
    // _eventMap[event]?.forEach((func) {
    //   func(args);
    // });
    if(_eventMap[event] != null) {
      for(int i = _eventMap[event]!.length - 1; i >= 0; i--) {
        _eventMap[event]![i](args);
      }
    }
  }
}