define(function(require) {

  // Based on https://github.com/diy/intercom.js/blob/master/lib/events.js
  // Copyright 2012 DIY Co Apache License, Version 2.0
  // http://www.apache.org/licenses/LICENSE-2.0

  function removeItem(item, array) {
    for (var i = array.length - 1; i >= 0; i--) {
      if (array[i] === item) {
        array.splice(i, 1);
      }
    }
    return array;
  }

  var EventEmitter = function() {};

  EventEmitter.createInterface = function(space) {
    var methods = {};

    methods.on = function(name, fn) {
      if (typeof this[space] === 'undefined') {
        this[space] = {};
      }
      if (!this[space].hasOwnProperty(name)) {
        this[space][name] = [];
      }
      this[space][name].push(fn);
    };

    methods.off = function(name, fn) {
      if (typeof this[space] === 'undefined') return;
      if (this[space].hasOwnProperty(name)) {
        removeItem(fn, this[space][name]);
      }
    };

    methods.trigger = function(name) {
      if (typeof this[space] !== 'undefined' && this[space].hasOwnProperty(name)) {
        var args = Array.prototype.slice.call(arguments, 1);
        for (var i = 0; i < this[space][name].length; i++) {
          this[space][name][i].apply(this[space][name][i], args);
        }
      }
    };

    methods.removeAllListeners = function(name) {
      if (typeof this[space] === 'undefined') return;
      var self = this;
      self[space][name].forEach(function(fn) {
        self.off(name, fn);
      });
    };

    return methods;
  };

  var pvt = EventEmitter.createInterface('_handlers');
  EventEmitter.prototype._on = pvt.on;
  EventEmitter.prototype._off = pvt.off;
  EventEmitter.prototype._trigger = pvt.trigger;

  var pub = EventEmitter.createInterface('handlers');
  EventEmitter.prototype.on = function() {
    pub.on.apply(this, arguments);
    Array.prototype.unshift.call(arguments, 'on');
    this._trigger.apply(this, arguments);
  };
  EventEmitter.prototype.off = pub.off;
  EventEmitter.prototype.trigger = pub.trigger;
  EventEmitter.prototype.removeAllListeners = pub.removeAllListeners;

  return EventEmitter;
});