/*!
 * Casper is a navigation utility for PhantomJS.
 *
 * Documentation: http://casperjs.org/
 * Repository:    http://github.com/n1k0/casperjs
 *
 * Copyright (c) 2011-2012 Nicolas Perriault
 *
 * Part of source code is Copyright Joyent, Inc. and other Node contributors.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 */

/*global CasperError*/

var isArray = Array.isArray;

function EventEmitter() {
  this._filters = {};
}
exports.EventEmitter = EventEmitter;

// By default EventEmitters will print a warning if more than
// 10 listeners are added to it. This is a useful default which
// helps finding memory leaks.
//
// Obviously not all Emitters should be limited to 10. This function allows
// that to be increased. Set to zero for unlimited.
var defaultMaxListeners = 10;
EventEmitter.prototype.setMaxListeners = function(n) {
  if (!this._events) this._events = {};
  this._maxListeners = n;
};


EventEmitter.prototype.emit = function emit() {
  var type = arguments[0];
  // If there is no 'error' event listener then throw.
  if (type === 'error') {
    if (!this._events || !this._events.error ||
        (isArray(this._events.error) && !this._events.error.length))
    {
      if (arguments[1] instanceof Error) {
        throw arguments[1]; // Unhandled 'error' event
      } else {
        throw new CasperError("Uncaught, unspecified 'error' event.");
      }
    }
  }

  if (!this._events) return false;
  var handler = this._events[type];
  if (!handler) return false;

  if (typeof handler === 'function') {
    try {
      switch (arguments.length) {
        // fast cases
        case 1:
          handler.call(this);
          break;
        case 2:
          handler.call(this, arguments[1]);
          break;
        case 3:
          handler.call(this, arguments[1], arguments[2]);
          break;
        // slower
        default:
          var l = arguments.length;
          var args = new Array(l - 1);
          for (var i = 1; i < l; i++) args[i - 1] = arguments[i];
          handler.apply(this, args);
      }
    } catch (err) {
      this.emit('event.error', err);
    }
    return true;

  } else if (isArray(handler)) {
    var l = arguments.length;
    var args = new Array(l - 1);
    for (var i = 1; i < l; i++) args[i - 1] = arguments[i];

    var listeners = handler.slice();
    for (var i = 0, l = listeners.length; i < l; i++) {
      listeners[i].apply(this, args);
    }
    return true;

  } else {
    return false;
  }
};

// EventEmitter is defined in src/node_events.cc
// EventEmitter.prototype.emit() is also defined there.
EventEmitter.prototype.addListener = function addListener(type, listener) {
  if ('function' !== typeof listener) {
    throw new CasperError('addListener only takes instances of Function');
  }

  if (!this._events) this._events = {};

  // To avoid recursion in the case that type == "newListeners"! Before
  // adding it to the listeners, first emit "newListeners".
  this.emit('newListener', type, listener);

  if (!this._events[type]) {
    // Optimize the case of one listener. Don't need the extra array object.
    this._events[type] = listener;
  } else if (isArray(this._events[type])) {

    // If we've already got an array, just append.
    this._events[type]['fail' === type ? 'unshift' : 'push'](listener);

    // Check for listener leak
    if (!this._events[type].warned) {
      var m;
      if (this._maxListeners !== undefined) {
        m = this._maxListeners;
      } else {
        m = defaultMaxListeners;
      }

      if (m && m > 0 && this._events[type].length > m) {
        this._events[type].warned = true;
        console.error('(node) warning: possible EventEmitter memory ' +
                      'leak detected. %d listeners added. ' +
                      'Use emitter.setMaxListeners() to increase limit.',
                      this._events[type].length);
        console.trace();
      }
    }
  } else {
    // Adding the second element, need to change to array.
    this._events[type] = 'fail' === type ? [listener, this._events[type]] : [this._events[type], listener];
  }

  return this;
};

EventEmitter.prototype.prependListener = function prependListener(type, listener) {
  if ('function' !== typeof listener) {
    throw new CasperError('addListener only takes instances of Function');
  }

  if (!this._events) this._events = {};

  // To avoid recursion in the case that type == "newListeners"! Before
  // adding it to the listeners, first emit "newListeners".
  this.emit('newListener', type, listener);

  if (!this._events[type]) {
    // Optimize the case of one listener. Don't need the extra array object.
    this._events[type] = listener;
  } else if (isArray(this._events[type])) {

    // If we've already got an array, just append.
    this._events[type].unshift(listener);

    // Check for listener leak
    if (!this._events[type].warned) {
      var m;
      if (this._maxListeners !== undefined) {
        m = this._maxListeners;
      } else {
        m = defaultMaxListeners;
      }

      if (m && m > 0 && this._events[type].length > m) {
        this._events[type].warned = true;
        console.error('(node) warning: possible EventEmitter memory ' +
                      'leak detected. %d listeners added. ' +
                      'Use emitter.setMaxListeners() to increase limit.',
                      this._events[type].length);
        console.trace();
      }
    }
  } else {
    // Adding the second element, need to change to array.
    this._events[type] = [listener, this._events[type]];
  }

  return this;
};

EventEmitter.prototype.on = EventEmitter.prototype.addListener;

EventEmitter.prototype.once = function once(type, listener) {
  if ('function' !== typeof listener) {
    throw new CasperError('.once only takes instances of Function');
  }

  var self = this;
  function g() {
    self.removeListener(type, g);
    listener.apply(this, arguments);
  }

  g.listener = listener;
  self.on(type, g);

  return this;
};

EventEmitter.prototype.removeListener = function removeListener(type, listener) {
  if ('function' !== typeof listener) {
    throw new CasperError('removeListener only takes instances of Function');
  }

  // does not use listeners(), so no side effect of creating _events[type]
  if (!this._events || !this._events[type]) return this;

  var list = this._events[type];

  if (isArray(list)) {
    var position = -1;
    for (var i = 0, length = list.length; i < length; i++) {
      if (list[i] === listener ||
          (list[i].listener && list[i].listener === listener))
      {
        position = i;
        break;
      }
    }

    if (position < 0) return this;
    list.splice(position, 1);
    if (list.length === 0)
      delete this._events[type];
  } else if (list === listener ||
             (list.listener && list.listener === listener))
  {
    delete this._events[type];
  }

  return this;
};

EventEmitter.prototype.removeAllListeners = function removeAllListeners(type) {
  if (arguments.length === 0) {
    this._events = {};
    return this;
  }

  // does not use listeners(), so no side effect of creating _events[type]
  if (type && this._events && this._events[type]) this._events[type] = null;
  return this;
};

EventEmitter.prototype.listeners = function listeners(type) {
  if (!this._events) this._events = {};
  if (!this._events[type]) this._events[type] = [];
  if (!isArray(this._events[type])) {
    this._events[type] = [this._events[type]];
  }
  return this._events[type];
};

// Added for CasperJS: filters a value attached to an event
EventEmitter.prototype.filter = function filter() {
  var type = arguments[0];
  if (!this._filters) {
    this._filters = {};
    return;
  }

  var _filter = this._filters[type];
  if (typeof _filter !== 'function') {
    return;
  }
  return _filter.apply(this, Array.prototype.splice.call(arguments, 1));
};

EventEmitter.prototype.removeAllFilters = function removeAllFilters(type) {
  if (arguments.length === 0) {
    this._filters = {};
    return this;
  }
  if (type && this._filters && this._filters[type]) {
    this._filters[type] = null;
  }
  return this;
};

EventEmitter.prototype.setFilter = function setFilter(type, filterFn) {
  if (!this._filters) {
    this._filters = {};
  }
  if ('function' !== typeof filterFn) {
    throw new CasperError('setFilter only takes instances of Function');
  }
  if (!this._filters[type]) {
    this._filters[type] = filterFn;
    return true;
  }
  // TODO: process multiple filters? in which order? disallow?
  return false;
};