HORIZON PROJECT

'use strict';

var has = Object.prototype.hasOwnProperty;

/**

 * An auto incrementing id which we can use to create "unique" Ultron instances

 * so we can track the event emitters that are added through the Ultron

 * interface.

 *

 * @type {Number}

 * @private

 */

var id = 0;

/**

 * Ultron is high-intelligence robot. It gathers intelligence so it can start improving

 * upon his rudimentary design. It will learn from your EventEmitting patterns

 * and exterminate them.

 *

 * @constructor

 * @param {EventEmitter} ee EventEmitter instance we need to wrap.

 * @api public

 */

function Ultron(ee) {

  if (!(this instanceof Ultron)) return new Ultron(ee);

  this.id = id++;

  this.ee = ee;

}

/**

 * Register a new EventListener for the given event.

 *

 * @param {String} event Name of the event.

 * @param {Functon} fn Callback function.

 * @param {Mixed} context The context of the function.

 * @returns {Ultron}

 * @api public

 */

Ultron.prototype.on = function on(event, fn, context) {

  fn.__ultron = this.id;

  this.ee.on(event, fn, context);

  return this;

};

/**

 * Add an EventListener that's only called once.

 *

 * @param {String} event Name of the event.

 * @param {Function} fn Callback function.

 * @param {Mixed} context The context of the function.

 * @returns {Ultron}

 * @api public

 */

Ultron.prototype.once = function once(event, fn, context) {

  fn.__ultron = this.id;

  this.ee.once(event, fn, context);

  return this;

};

/**

 * Remove the listeners we assigned for the given event.

 *

 * @returns {Ultron}

 * @api public

 */

Ultron.prototype.remove = function remove() {

  var args = arguments

    , ee = this.ee

    , event;

  //

  // When no event names are provided we assume that we need to clear all the

  // events that were assigned through us.

  //

  if (args.length === 1 && 'string' === typeof args[0]) {

    args = args[0].split(/[, ]+/);

  } else if (!args.length) {

    if (ee.eventNames) {

      args = ee.eventNames();

    } else if (ee._events) {

      args = [];

      for (event in ee._events) {

        if (has.call(ee._events, event)) args.push(event);

      }

      if (Object.getOwnPropertySymbols) {

        args = args.concat(Object.getOwnPropertySymbols(ee._events));

      }

    }

  }

  for (var i = 0; i < args.length; i++) {

    var listeners = ee.listeners(args[i]);

    for (var j = 0; j < listeners.length; j++) {

      event = listeners[j];

      //

      // Once listeners have a `listener` property that stores the real listener

      // in the EventEmitter that ships with Node.js.

      //

      if (event.listener) {

        if (event.listener.__ultron !== this.id) continue;

      } else if (event.__ultron !== this.id) {

        continue;

      }

      ee.removeListener(args[i], event);

    }

  }

  return this;

};

/**

 * Destroy the Ultron instance, remove all listeners and release all references.

 *

 * @returns {Boolean}

 * @api public

 */

Ultron.prototype.destroy = function destroy() {

  if (!this.ee) return false;

  this.remove();

  this.ee = null;

  return true;

};

//

// Expose the module.

//

module.exports = Ultron;