/* ***** BEGIN LICENSE BLOCK *****
 * Distributed under the BSD license:
 *
 * Copyright (c) 2010, Ajax.org B.V.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Ajax.org B.V. nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL AJAX.ORG B.V. BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ***** END LICENSE BLOCK ***** */

define(function (require, exports, module) {
    "use strict";

    var EventEmitter = {};
    var stopPropagation = function () {
        this.propagationStopped = true;
    };
    var preventDefault = function () {
        this.defaultPrevented = true;
    };

    EventEmitter._emit =
        EventEmitter._dispatchEvent = function (eventName, e) {
            this._eventRegistry || (this._eventRegistry = {});
            this._defaultHandlers || (this._defaultHandlers = {});

            var listeners = this._eventRegistry[eventName] || [];
            var defaultHandler = this._defaultHandlers[eventName];
            if (!listeners.length && !defaultHandler)
                return;

            if (typeof e != "object" || !e)
                e = {};

            if (!e.type)
                e.type = eventName;
            if (!e.stopPropagation)
                e.stopPropagation = stopPropagation;
            if (!e.preventDefault)
                e.preventDefault = preventDefault;

            listeners = listeners.slice();
            for (var i = 0; i < listeners.length; i++) {
                listeners[i](e, this);
                if (e.propagationStopped)
                    break;
            }

            if (defaultHandler && !e.defaultPrevented)
                return defaultHandler(e, this);
        };


    EventEmitter._signal = function (eventName, e) {
        var listeners = (this._eventRegistry || {})[eventName];
        if (!listeners)
            return;
        listeners = listeners.slice();
        for (var i = 0; i < listeners.length; i++)
            listeners[i](e, this);
    };

    EventEmitter.once = function (eventName, callback) {
        var _self = this;
        callback && this.addEventListener(eventName, function newCallback() {
            _self.removeEventListener(eventName, newCallback);
            callback.apply(null, arguments);
        });
    };


    EventEmitter.setDefaultHandler = function (eventName, callback) {
        var handlers = this._defaultHandlers
        if (!handlers)
            handlers = this._defaultHandlers = {_disabled_: {}};

        if (handlers[eventName]) {
            var old = handlers[eventName];
            var disabled = handlers._disabled_[eventName];
            if (!disabled)
                handlers._disabled_[eventName] = disabled = [];
            disabled.push(old);
            var i = disabled.indexOf(callback);
            if (i != -1)
                disabled.splice(i, 1);
        }
        handlers[eventName] = callback;
    };
    EventEmitter.removeDefaultHandler = function (eventName, callback) {
        var handlers = this._defaultHandlers
        if (!handlers)
            return;
        var disabled = handlers._disabled_[eventName];

        if (handlers[eventName] == callback) {
            var old = handlers[eventName];
            if (disabled)
                this.setDefaultHandler(eventName, disabled.pop());
        } else if (disabled) {
            var i = disabled.indexOf(callback);
            if (i != -1)
                disabled.splice(i, 1);
        }
    };

    EventEmitter.on =
        EventEmitter.addEventListener = function (eventName, callback, capturing) {
            this._eventRegistry = this._eventRegistry || {};

            var listeners = this._eventRegistry[eventName];
            if (!listeners)
                listeners = this._eventRegistry[eventName] = [];

            if (listeners.indexOf(callback) == -1)
                listeners[capturing ? "unshift" : "push"](callback);
            return callback;
        };

    EventEmitter.off =
        EventEmitter.removeListener =
            EventEmitter.removeEventListener = function (eventName, callback) {
                this._eventRegistry = this._eventRegistry || {};

                var listeners = this._eventRegistry[eventName];
                if (!listeners)
                    return;

                var index = listeners.indexOf(callback);
                if (index !== -1)
                    listeners.splice(index, 1);
            };

    EventEmitter.removeAllListeners = function (eventName) {
        if (this._eventRegistry) this._eventRegistry[eventName] = [];
    };

    exports.EventEmitter = EventEmitter;

});
