/**
 * EvEmitter v1.0.2
 * Lil' event emitter
 * MIT License
 */

/* jshint unused: true, undef: true, strict: true */

( function( global, factory ) {
  // universal module definition
  /* jshint strict: false */ /* globals define, module */
  if ( typeof define == 'function' && define.amd ) {
    // AMD - RequireJS
    define( factory );
  } else if ( typeof module == 'object' && module.exports ) {
    // CommonJS - Browserify, Webpack
    module.exports = factory();
  } else {
    // Browser globals
    global.EvEmitter = factory();
  }

}( this, function() {

"use strict";

function EvEmitter() {}

var proto = EvEmitter.prototype;

proto.on = function( eventName, listener ) {
  if ( !eventName || !listener ) {
    return;
  }
  // set events hash
  var events = this._events = this._events || {};
  // set listeners array
  var listeners = events[ eventName ] = events[ eventName ] || [];
  // only add once
  if ( listeners.indexOf( listener ) == -1 ) {
    listeners.push( listener );
  }

  return this;
};

proto.once = function( eventName, listener ) {
  if ( !eventName || !listener ) {
    return;
  }
  // add event
  this.on( eventName, listener );
  // set once flag
  // set onceEvents hash
  var onceEvents = this._onceEvents = this._onceEvents || {};
  // set onceListeners object
  var onceListeners = onceEvents[ eventName ] = onceEvents[ eventName ] || {};
  // set flag
  onceListeners[ listener ] = true;

  return this;
};

proto.off = function( eventName, listener ) {
  var listeners = this._events && this._events[ eventName ];
  if ( !listeners || !listeners.length ) {
    return;
  }
  var index = listeners.indexOf( listener );
  if ( index != -1 ) {
    listeners.splice( index, 1 );
  }

  return this;
};

proto.emitEvent = function( eventName, args ) {
  var listeners = this._events && this._events[ eventName ];
  if ( !listeners || !listeners.length ) {
    return;
  }
  var i = 0;
  var listener = listeners[i];
  args = args || [];
  // once stuff
  var onceListeners = this._onceEvents && this._onceEvents[ eventName ];

  while ( listener ) {
    var isOnce = onceListeners && onceListeners[ listener ];
    if ( isOnce ) {
      // remove listener
      // remove before trigger to prevent recursion
      this.off( eventName, listener );
      // unset once flag
      delete onceListeners[ listener ];
    }
    // trigger listener
    listener.apply( this, args );
    // get next listener
    i += isOnce ? 0 : 1;
    listener = listeners[i];
  }

  return this;
};

return EvEmitter;

}));