//     Backbone may be freely distributed under the MIT license.

//     For all details and documentation:

//     http://backbonejs.org

(function(factory) {

  // Establish the root object, `window` (`self`) in the browser, or `global` on the server.

  // We use `self` instead of `window` for `WebWorker` support.

  var root = typeof self == 'object' && self.self === self && self ||

            typeof global == 'object' && global.global === global && global;

  // Set up Backbone appropriately for the environment. Start with AMD.

  if (typeof define === 'function' && define.amd) {

    define(['underscore', 'jquery', 'exports'], function(_, $, exports) {

      // Export global even in AMD case in case this script is loaded with

      // others that may still expect a global Backbone.

      root.Backbone = factory(root, exports, _, $);

    });

  // Next for Node.js or CommonJS. jQuery may not be needed as a module.

  } else if (typeof exports !== 'undefined') {

    var _ = require('underscore'), $;

    try { $ = require('jquery'); } catch (e) {}

    factory(root, exports, _, $);

  // Finally, as a browser global.

  } else {

    root.Backbone = factory(root, {}, root._, root.jQuery || root.Zepto || root.ender || root.$);

  }

})(function(root, Backbone, _, $) {

  // Initial Setup

  // -------------

  // Save the previous value of the `Backbone` variable, so that it can be

  // restored later on, if `noConflict` is used.

  var previousBackbone = root.Backbone;

  // Create a local reference to a common array method we'll want to use later.

  var slice = Array.prototype.slice;

  // Current version of the library. Keep in sync with `package.json`.

  // For Backbone's purposes, jQuery, Zepto, Ender, or My Library (kidding) owns

  // the `$` variable.

  Backbone.$ = $;

  // Runs Backbone.js in *noConflict* mode, returning the `Backbone` variable

  // to its previous owner. Returns a reference to this Backbone object.

  Backbone.noConflict = function() {

    root.Backbone = previousBackbone;

    return this;

  };

  // Turn on `emulateHTTP` to support legacy HTTP servers. Setting this option

  // will fake `"PATCH"`, `"PUT"` and `"DELETE"` requests via the `_method` parameter and

  // set a `X-Http-Method-Override` header.

  Backbone.emulateHTTP = false;

  // Turn on `emulateJSON` to support legacy servers that can't deal with direct

  // `application/json` requests ... this will encode the body as

  // `application/x-www-form-urlencoded` instead and will send the model in a

  // form param named `model`.

  Backbone.emulateJSON = false;

  // Backbone.Events

  // ---------------

  // A module that can be mixed in to *any object* in order to provide it with

  // a custom event channel. You may bind a callback to an event with `on` or

  // remove with `off`; `trigger`-ing an event fires all callbacks in

  // succession.

  //

  //     var object = {};

  //     _.extend(object, Backbone.Events);

  //     object.on('expand', function(){ alert('expanded'); });

  //     object.trigger('expand');

  //

  var Events = Backbone.Events = {};

  // Regular expression used to split event strings.

  var eventSplitter = /\s+/;

  // A private global variable to share between listeners and listenees.

  var _listening;

  // Iterates over the standard `event, callback` (as well as the fancy multiple

  // space-separated events `"change blur", callback` and jQuery-style event

  // maps `{event: callback}`).

  var eventsApi = function(iteratee, events, name, callback, opts) {

    var i = 0, names;

    if (name && typeof name === 'object') {

      // Handle event maps.

      if (callback !== void 0 && 'context' in opts && opts.context === void 0) opts.context = callback;

      for (names = _.keys(name); i < names.length ; i++) {

        events = eventsApi(iteratee, events, names[i], name[names[i]], opts);

      }

    } else if (name && eventSplitter.test(name)) {

      // Handle space-separated event names by delegating them individually.

      for (names = name.split(eventSplitter); i < names.length; i++) {

        events = iteratee(events, names[i], callback, opts);

      }

    } else {

      // Finally, standard events.

      events = iteratee(events, name, callback, opts);

    }

    return events;

  };

  // Bind an event to a `callback` function. Passing `"all"` will bind

  // the callback to all events fired.

  Events.on = function(name, callback, context) {

    this._events = eventsApi(onApi, this._events || {}, name, callback, {

      context: context,

      ctx: this,

      listening: _listening

    });

    if (_listening) {

      var listeners = this._listeners || (this._listeners = {});

      listeners[_listening.id] = _listening;

      // Allow the listening to use a counter, instead of tracking

      // callbacks for library interop

      _listening.interop = false;

    }

    return this;

  };

  // Inversion-of-control versions of `on`. Tell *this* object to listen to

  // an event in another object... keeping track of what it's listening to

  // for easier unbinding later.

  Events.listenTo = function(obj, name, callback) {

    if (!obj) return this;

    var id = obj._listenId || (obj._listenId = _.uniqueId('l'));

    var listeningTo = this._listeningTo || (this._listeningTo = {});

    var listening = _listening = listeningTo[id];

    // This object is not listening to any other events on `obj` yet.

    // Setup the necessary references to track the listening callbacks.

    if (!listening) {

      this._listenId || (this._listenId = _.uniqueId('l'));

      listening = _listening = listeningTo[id] = new Listening(this, obj);

    }

    // Bind callbacks on obj.

    var error = tryCatchOn(obj, name, callback, this);

    _listening = void 0;

    if (error) throw error;

    // If the target obj is not Backbone.Events, track events manually.

    if (listening.interop) listening.on(name, callback);

    return this;

  };

  // The reducing API that adds a callback to the `events` object.

  var onApi = function(events, name, callback, options) {

    if (callback) {

      var handlers = events[name] || (events[name] = []);

      var context = options.context, ctx = options.ctx, listening = options.listening;

      if (listening) listening.count++;

      handlers.push({callback: callback, context: context, ctx: context || ctx, listening: listening});

    }

    return events;

  };

  // An try-catch guarded #on function, to prevent poisoning the global

  // `_listening` variable.

  var tryCatchOn = function(obj, name, callback, context) {

    try {

      obj.on(name, callback, context);

    } catch (e) {

      return e;

    }

  };

  // Remove one or many callbacks. If `context` is null, removes all

  // callbacks with that function. If `callback` is null, removes all

  // callbacks for the event. If `name` is null, removes all bound

  // callbacks for all events.

  Events.off = function(name, callback, context) {

    if (!this._events) return this;

    this._events = eventsApi(offApi, this._events, name, callback, {

      context: context,

      listeners: this._listeners

    });

    return this;

  };

  // Tell this object to stop listening to either specific events ... or

  // to every object it's currently listening to.

  Events.stopListening = function(obj, name, callback) {

    var listeningTo = this._listeningTo;

    if (!listeningTo) return this;

    var ids = obj ? [obj._listenId] : _.keys(listeningTo);

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

      var listening = listeningTo[ids[i]];

      // If listening doesn't exist, this object is not currently

      // listening to obj. Break out early.

      if (!listening) break;

      listening.obj.off(name, callback, this);

      if (listening.interop) listening.off(name, callback);

    }

    if (_.isEmpty(listeningTo)) this._listeningTo = void 0;

    return this;

  };

  // The reducing API that removes a callback from the `events` object.

  var offApi = function(events, name, callback, options) {

    if (!events) return;

    var context = options.context, listeners = options.listeners;

    var i = 0, names;

    // Delete all event listeners and "drop" events.

    if (!name && !context && !callback) {

      for (names = _.keys(listeners); i < names.length; i++) {

        listeners[names[i]].cleanup();

      }

      return;

    }

    names = name ? [name] : _.keys(events);

    for (; i < names.length; i++) {

      name = names[i];

      var handlers = events[name];

      // Bail out if there are no events stored.

      if (!handlers) break;

      // Find any remaining events.

      var remaining = [];

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

        var handler = handlers[j];

        if (

          callback && callback !== handler.callback &&

            callback !== handler.callback._callback ||

              context && context !== handler.context

        ) {

          remaining.push(handler);

        } else {

          var listening = handler.listening;

          if (listening) listening.off(name, callback);

        }

      }

      // Replace events if there are any remaining.  Otherwise, clean up.

      if (remaining.length) {

        events[name] = remaining;

      } else {

        delete events[name];

      }

    }

    return events;

  };

  // Bind an event to only be triggered a single time. After the first time

  // the callback is invoked, its listener will be removed. If multiple events

  // are passed in using the space-separated syntax, the handler will fire

  // once for each event, not once for a combination of all events.

  Events.once = function(name, callback, context) {

    // Map the event into a `{event: once}` object.

    var events = eventsApi(onceMap, {}, name, callback, this.off.bind(this));

    if (typeof name === 'string' && context == null) callback = void 0;

    return this.on(events, callback, context);

  };

  // Inversion-of-control versions of `once`.

  Events.listenToOnce = function(obj, name, callback) {

    // Map the event into a `{event: once}` object.

    var events = eventsApi(onceMap, {}, name, callback, this.stopListening.bind(this, obj));

    return this.listenTo(obj, events);

  };

  // Reduces the event callbacks into a map of `{event: onceWrapper}`.

  // `offer` unbinds the `onceWrapper` after it has been called.

  var onceMap = function(map, name, callback, offer) {

    if (callback) {

      var once = map[name] = _.once(function() {

        offer(name, once);

        callback.apply(this, arguments);

      });

      once._callback = callback;

    }

    return map;

  };

  // Trigger one or many events, firing all bound callbacks. Callbacks are

  // passed the same arguments as `trigger` is, apart from the event name

  // (unless you're listening on `"all"`, which will cause your callback to

  // receive the true name of the event as the first argument).

  Events.trigger = function(name) {

    if (!this._events) return this;

    var length = Math.max(0, arguments.length - 1);

    var args = Array(length);

    for (var i = 0; i < length; i++) args[i] = arguments[i + 1];

    eventsApi(triggerApi, this._events, name, void 0, args);

    return this;

  };

  // Handles triggering the appropriate event callbacks.

  var triggerApi = function(objEvents, name, callback, args) {

    if (objEvents) {

      var events = objEvents[name];

      var allEvents = objEvents.all;

      if (events && allEvents) allEvents = allEvents.slice();

      if (events) triggerEvents(events, args);

      if (allEvents) triggerEvents(allEvents, [name].concat(args));

    }

    return objEvents;

  };

  // A difficult-to-believe, but optimized internal dispatch function for

  // triggering events. Tries to keep the usual cases speedy (most internal

  // Backbone events have 3 arguments).

  var triggerEvents = function(events, args) {

    var ev, i = -1, l = events.length, a1 = args[0], a2 = args[1], a3 = args[2];

    switch (args.length) {

      case 0: while (++i < l) (ev = events[i]).callback.call(ev.ctx); return;

      case 1: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1); return;

      case 2: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2); return;

      case 3: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2, a3); return;

      default: while (++i < l) (ev = events[i]).callback.apply(ev.ctx, args); return;