import {Klass} from '../core/Klass';
import {EventEmitter} from 'events';
import {EventListenerMetadata} from './EventListenerMetadata';
import {DependencyRegistry} from '../di/DependencyRegistry';

export class EventListenerRegistry {

  private static _listeners: Map<Function, EventListenerMetadata[]> = new Map();

  public static registerListeners(klass: Klass) {

    const listeners = this._listeners.get(klass);

    if (typeof listeners !== 'undefined') {

      listeners.forEach(listener => {

        const emitter = DependencyRegistry.get(listener.emitterKlass);
        const subscriber = DependencyRegistry.get(listener.klass);

        emitter.on(listener.eventName, listener.handler.bind(subscriber));

      });

    }
  }

  public static registerEventListener(klass: Klass,
    method: string,
    eventName: string,
    emitterKlass: new (...args) => EventEmitter,
    handler: (...args) => any) {

    const listenerMetadata = new EventListenerMetadata();

    listenerMetadata.klass = klass;
    listenerMetadata.method = method;
    listenerMetadata.eventName = eventName;
    listenerMetadata.emitterKlass = emitterKlass;
    listenerMetadata.handler = handler;

    let listeners = this._listeners.get(klass);

    if (typeof listeners === 'undefined') {
      listeners = [listenerMetadata];
    } else {
      listeners.push(listenerMetadata);
    }

    this._listeners.set(klass, listeners);
  }
}