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

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, '.$2' + pseudo);
	var className = (/\.([a-z0-9_-]*on(hover|active))/i).exec(newSelect)[1];
	var affected = select.replace(/:(hover|active).*$/, '');
	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;
}