var csshoverReg = /(^|\s)((([^a]([^ ]+)?)|(a([^#.][^ ]+)+)):(hover|active))|((a|input|textarea)([#.][^ ]+)?:unknown)/i,
currentSheet, doc = window.document, hoverEvents = [], activators = {
	onhover:{on:'onmouseover', off:'onmouseout'},
	onactive:{on:'onmousedown', off:'onmouseup'},
	onunknown:{on:'onfocus', off:'onblur'}
}

function parseStylesheets() {
	if(!/MSIE (5|6)/.test(navigator.userAgent)) return;
	window.attachEvent('onunload', unhookHoverEvents);
	var sheets = doc.styleSheets, l = sheets.length;
	for(var i=0; i<l; i++) 
		parseStylesheet(sheets[i]);
}
	function parseStylesheet(sheet) {
		if(sheet.imports) {
			try {
				var imports = sheet.imports, l = imports.length;
				for(var i=0; i<l; i++) parseStylesheet(sheet.imports[i]);
			} catch(securityException){}
		}

		try {
			var rules = (currentSheet = sheet).rules, l = rules.length;
			for(var j=0; j<l; j++) parseCSSRule(rules[j]);
		} catch(securityException){}
	}

	function parseCSSRule(rule) {
		var select = rule.selectorText, style = rule.style.cssText;
		if(!csshoverReg.test(select) || !style) return;
		
		var pseudo = select.replace(/[^:]+:([a-z-]+).*/i, 'on$1');
		var newSelect = select.replace(/(\.([a-z0-9_-]+):[a-z]+)|(:[a-z]+)/gi, '.$2' + pseudo);
		var className = (/\.([a-z0-9_-]*on(hover|active|unknown))/i).exec(newSelect)[1];
		var affected = select.replace(/:(hover|active|unknown).*$/, '');
		var elements = getElementsBySelect(affected);
		if(elements.length == 0) return;

		currentSheet.addRule(newSelect, style);
		for(var i=0; i<elements.length; i++)
			new HoverElement(elements[i], className, activators[pseudo]);
	}

function HoverElement(node, className, events) {
	if(!node.hovers) node.hovers = {};
	if(node.hovers[className]) return;
	node.hovers[className] = true;
	hookHoverEvent(node, events.on, function() { node.className += ' ' + className; });
	hookHoverEvent(node, events.off, function() { node.className = node.className.replace(new RegExp('\\s+'+className, 'g'),''); });
}
	function hookHoverEvent(node, type, handler) {
		node.attachEvent(type, handler);
		hoverEvents[hoverEvents.length] = { 
			node:node, type:type, handler:handler 
		};
	}

	function unhookHoverEvents() {
		for(var e,i=0; i<hoverEvents.length; i++) {
			e = hoverEvents[i]; 
			e.node.detachEvent(e.type, e.handler);
		}
	}

function getElementsBySelect(rule) {
	var parts, nodes = [doc];
	parts = rule.split(' ');
	for(var i=0; i<parts.length; i++) {
		nodes = getSelectedNodes(parts[i], nodes);
	}	return nodes;
}
	function getSelectedNodes(select, elements) {
		var result, node, nodes = [];
		var identify = (/\#([a-z0-9_-]+)/i).exec(select);
		if(identify) {
			var element = doc.getElementById(identify[1]);
			return element? [element]:nodes;
		}
		
		var classname = (/\.([a-z0-9_-]+)/i).exec(select);
		var tagName = select.replace(/(\.|\#|\:)[a-z0-9_-]+/i, '');
		var classReg = classname? new RegExp('\\b' + classname[1] + '\\b'):false;
		for(var i=0; i<elements.length; i++) {
			result = tagName? elements[i].all.tags(tagName):elements[i].all; 
			for(var j=0; j<result.length; j++) {
				node = result[j];
				if(classReg && !classReg.test(node.className)) continue;
				nodes[nodes.length] = node;
			}
		}	
		
		return nodes;
	}