/**
 * domready.js
 * 
 * Cross browser mozilla's 'onDOMContentLoaded' implementation.
 * Executes a function when the dom tree is loaded without waiting for images.
 * 
 * Based on +Element.Events.domready+ from Mootools open source project, 
 * this tiny javascript library adds the emulated 'DOMContentLoaded' functionality.
 * 
 * Features:
 *	 - No dependency on external libraries
 *	 - Compatible with Prototype.js 
 * 
 * Tested browsers (Windows):
 *	 - IE 7 (XP standalone)
 *	 - IE 6 SP2
 *	 - Firefox 2.0.0.4
 *	 - Opera 9.21
 * 
 * Tested browsers (Mac OS X):
 *	 - Safari 2.0.4
 *	 - Firefox 2.0.0.4
 *	 - Mac Opera 9.21
 *	 - Mac IE 5.2.3
 *
 * Copyright (c) 2007 Takanori Ishikawa.
 * License: MIT-style license.
 * 
 * MooTools Copyright:
 * copyright (c) 2007 Valerio Proietti, <http://mad4milk.net>
 *
 *
 * See Also:
 *
 *	 mootools 
 *	 http://mootools.net/
 *	 
 *	 The window.onload Problem - Solved!
 *	 http://dean.edwards.name/weblog/2005/09/busted/
 *	 
 *	 [PATCH] Faster onload for Event.onload
 *	 http://dev.rubyonrails.org/ticket/5414
 *	 Changeset 6596: Support for "DOMContentLoaded" event handling (prototype.js event branch)
 *	 http://dev.rubyonrails.org/changeset/6596
 *
 */

if (typeof Event == 'undefined') Event = new Object();

/*
 * Registers function +fn+ will be executed when the dom 
 * tree is loaded without waiting for images. 
 * 
 * Example:
 *
 *	Event.domReady.add(function() {
 *		...
 *	});
 *
 */
Event.domReady = {
	add: function(fn) {
		
		//-----------------------------------------------------------
		// Already loaded?
		//-----------------------------------------------------------
		if (Event.domReady.loaded) return fn();
		
		//-----------------------------------------------------------
		// Observers
		//-----------------------------------------------------------
		var observers = Event.domReady.observers;
		if (!observers) observers = Event.domReady.observers = [];
		// Array#push is not supported by Mac IE 5
		observers[observers.length] = fn;
		
		//-----------------------------------------------------------
		// domReady function
		//-----------------------------------------------------------
		if (Event.domReady.callback) return;
		Event.domReady.callback = function() {
			if (Event.domReady.loaded) return;
			
			Event.domReady.loaded = true;
			if (Event.domReady.timer) {
				clearInterval(Event.domReady.timer);
				Event.domReady.timer = null;
			}
			
			var observers = Event.domReady.observers;
			for (var i = 0, length = observers.length; i < length; i++) {
				var fn = observers[i];
				observers[i] = null;
				fn(); // make 'this' as window
			}
			Event.domReady.callback = Event.domReady.observers = null;
		};
		
		//-----------------------------------------------------------
		// Emulates 'onDOMContentLoaded'
		//-----------------------------------------------------------
		var ie = !!(window.attachEvent && !window.opera);
		var webkit = navigator.userAgent.indexOf('AppleWebKit/') > -1;
		
		if (document.readyState && webkit) {
			
			// Apple WebKit (Safari, OmniWeb, ...)
			Event.domReady.timer = setInterval(function() {
				var state = document.readyState;
				if (state == 'loaded' || state == 'complete') {
					Event.domReady.callback();
				}
			}, 50);
			
		} else if (document.readyState && ie) {
			
			// Windows IE 
			var src = (window.location.protocol == 'https:') ? '://0' : 'javascript:void(0)';
			document.write(
				'<script type="text/javascript" defer="defer" src="' + src + '" ' + 
				'onreadystatechange="if (this.readyState == \'complete\') Event.domReady.callback();"' + 
				'><\/script>');
			
		} else {
			
			if (window.addEventListener) {
				// for Mozilla browsers, Opera 9
				document.addEventListener("DOMContentLoaded", Event.domReady.callback, false);
				// Fail safe 
				window.addEventListener("load", Event.domReady.callback, false);
			} else if (window.attachEvent) {
				window.attachEvent('onload', Event.domReady.callback);
			} else {
				// Legacy browsers (e.g. Mac IE 5)
				var fn = window.onload;
				window.onload = function() {
					Event.domReady.callback();
					if (fn) fn();
				}
			}
			
		}
		
	}
}