/*
 * @创建者: oliverfan
 * @内容描述: 新建事件总线，提供事件订阅和发布功能
 */

type EventCallback = (...args) => any;
class EventBus {
  private listeners = new Map<string, EventCallback[]>();
  public on(eventName: string, callback: EventCallback) {
    if (!this.listeners.has(eventName)) {
      this.listeners.set(eventName, [callback]);
    } else {
      const callbacks = this.listeners.get(eventName);
      callbacks.push(callback);
      this.listeners.set(eventName, callbacks);
    }
  }

  public emit(eventName: string, ...args) {
    if (!this.listeners.has(eventName)) {
      // console.warn(`未注册过此方法【${eventName}】`);
      return;
    }
    this.listeners.get(eventName).forEach((callback) => {
      callback(...args);
    });
  }

  public off(eventName?: string, callback?: EventCallback) {
    if (!eventName) {
      this.listeners.clear();
      return;
    }

    if (!callback) {
      this.listeners.delete(eventName);
      return;
    }

    const callbacks = this.listeners.get(eventName);

    const newCallbacks = callbacks.filter(cb => cb !== callback);
    this.listeners.set(eventName, newCallbacks);
  }
}

export { EventCallback, EventBus };