import { EventEmitter } from 'events'

const LOG_CHANNELS = [ 'emergency', 'critical', 'error', 'warning', 'notice', 'info', 'debug' ];


/**
 * Ayetier EventSystem module
 *
 * @class EventSystem
 * @extends EventEmitter
 */
export class EventSystem extends EventEmitter {

  /**
   * @class EventSystem
   * @constructor
   * @param {{maxListeners?: number}} [options]
   */
  constructor (options = { maxListeners: 50 }) {
    super();

    // Set Max Listeners (@default - 50)
    let maxListeners = (options.maxListeners) ? options.maxListeners : 50;
    this.setMaxListeners(maxListeners);

    // default error listener to handle error exceptions
    this.on('error', (...args) => {
      let listeners = this.listeners('error');
      if ( listeners.length < 2 ) console.error('NodeEventSystem Error: ', ...args);
    });
  }

  /**
   * Links an Emitter objects log events to the primary event system
   *
   * @methodOf EventSystem
   * @param {EventEmitter} emitter
   */
  public syncLogChannels (emitter) {
    try {
      LOG_CHANNELS.forEach(level => emitter.on(level, (...args) => this.emit(level, ...args)));
    } catch (e) {
      this.emit('error', `Error linking log events to emitter`, e);
    }
  }

  /**
   * Links an Emitter objects log events to the primary event system
   *
   * @alias EventSystem.syncLogChannels
   * @methodOf EventSystem
   * @param {EventEmitter} emitter
   */
  public syncLogEvents (emitter) {
    this.syncLogChannels(emitter);
  }

}