/**
* history 1.2 - Plugin for jQuery
*
*
* IE8 is supporting onhashchange event
* http://msdn.microsoft.com/en-us/library/cc288209(VS.85).aspx
* 
* Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
* and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
*
* Depends:
*   jquery.js
*
*  Copyright (c) 2008 Oleg Slobodskoi (ajaxsoft.de)
*/

; (function($, window, top) {

	var instance;

	$.history = function(method, param) {
		if (typeof method == 'function') {
			param = method;
			method = 'bind';
		}
		// bind and unbind methods need a callback function
		else if (/bind|unbind/.test(method) && !$.isFunction(param)) return;

		if (!instance) {
			instance = new hist;
			instance.init();
		};

		method != 'init' && instance[method](param);
	};

	function hist() {
		var self = this,
        IE67 = $.browser.msie && parseInt($.browser.version) < 8,
        IE8 = $.browser.msie && parseInt($.browser.version) >= 8,
        $iframe,
        $wnd = $(window),
        stop = false;

		self.value = top.location.hash.substr(1);

		this.init = function() {
			if (IE8) {
				$wnd.bind('hashchange', IE8Handler);
			} else if (IE67) {
				initIframe();
			} else
				(function() {
					if (stop) return;
					top.location.hash.substr(1) !== self.value && changed(top.location.hash);
					setTimeout(arguments.callee, 50);
				})();
		};

		this.destroy = function() {
			// stop timeout
			stop = true;
			// remove iframe for IE6-7
			$iframe && $iframe.remove();
			// unbind all events
			$wnd.unbind('hashchanged');
			// remove the reference to the instance
			instance = null;
			// unbind event for IE8
			IE8 && $wnd.unbind('hashchange', IE8Handler);
		};

		this.bind = function(callback) {
			$wnd.bind('hashchanged', callback);
		};

		this.unbind = function(callback) {
			$wnd.unbind('hashchanged', callback);
		};

		this.add = function(value) {
			top.location.hash = value;
		};

		this.forward = function() {
			history.go(1);
		};

		this.back = function() {
			history.go(-1);
		};

		/**
		* Only for IE6-7
		* Check if iframe hash the same as document
		*/
		function initIframe() {
			$iframe = $iframe || $('<iframe style="display: none;" class="x-history-iframe"/>').appendTo(document.body);
			// if document is not ready, access to the contentWindow of the iframe is not immediately available
			try { $iframe[0].contentWindow; } catch (e) {
				setTimeout(arguments.callee, 50);
				return;
			};

			var iHash = iDoc().location.hash,
            hash = top.location.hash,
            iHashNew, hashNew;

			(function() {
				if (stop) return;
				iHashNew = iDoc().location.hash;
				hashNew = top.location.hash;

				// changed using navigation buttons
				if (iHashNew !== iHash) {
					iHash = iHashNew;
					hash = iHash;
					top.location.hash = changed(iHash);
					// changed using link or add method
				} else if (hashNew !== hash) {
					hash = hashNew;
					updateIFrame(hash);
				};
				setTimeout(arguments.callee, 50);
			})();


			// get the document of the iframe
			function iDoc() {
				return $iframe[0].contentWindow.document;
			};

			// save value to the iframe
			function updateIFrame(value) {
				iDoc().open();
				iDoc().close();
				iDoc().location.hash = value;
			};
		};

		/**
		* hash was changed - do something
		* @param {String} value - '#value'
		*/
		function changed(value) {
			self.value = value.substr(1);
			// call all callbacks
			$wnd.trigger('hashchanged',[self]);
			return self.value;
		};

		function IE8Handler(e) {
			changed(top.location.hash);
		};


	};

})(jQuery, window, top);