var lightbox = function(trigger, target, close) {
	
	this.modal = false;
	
	this.documentSize = function() {
		var windowSize = this.windowSize();
		var scrollHeight = (document.compatMode != 'CSS1Compat') ? document.body.scrollHeight : document.documentElement.scrollHeight;
		var scrollWidth = (document.compatMode != 'CSS1Compat') ? document.body.scrollWidth : document.documentElement.scrollWidth;
		return {width: Math.max(scrollWidth, windowSize.width), height: Math.max(scrollHeight,windowSize.height)};
	};
	
	this.windowCenter = function() {
		var viewport = this.windowSize();
		return {left: Math.round(viewport.width / 2), top: Math.round(viewport.height / 2)};
	};
	
	this.windowOffset = function() {
		if(typeof(window.pageYOffset)=='number') 
		{
			return {left: window.pageXOffset, top: window.pageYOffset};
		}
		return {left: document.documentElement.scrollLeft, top: document.documentElement.scrollTop};
	};
	
	this.windowSize = function() {
		// the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
		if (typeof window.innerWidth != 'undefined')
		{
			return {width: window.innerWidth, height: window.innerHeight};
		}
		 
		// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
		if (typeof document.documentElement != 'undefined' && 
			typeof document.documentElement.clientWidth != 'undefined' && 
			document.documentElement.clientWidth !== 0)
		{
			return {width: document.documentElement.clientWidth, height: document.documentElement.clientHeight};
		}
		 
		 // older versions of IE
		return {width: document.getElementsByTagName('body')[0].clientWidth, height: document.getElementsByTagName('body')[0].clientHeight};
	};
	
	this.trueCoordinates = function(el) {
		var position 	= this.truePosition(el), 
			size 		= this.trueSize(el);
		
		return [{left: position.left, top: position.top}, 
				{top:position.top+size.height, left:position.left+size.width}];
	};
	
	this.truePosition = function(el) {
		var size 		= this.trueSize(el),
			windowSize	= $.windowSize();
			curleft 	= 0, 
			curtop 		= 0;
		
		do {
			curleft += el.offsetLeft;
			curtop += el.offsetTop;
		} while (el = el.offsetParent);
		
		return {
			left: curleft, top: curtop,
			right: windowSize.width-(curleft+size.width),
			bottom: windowSize.height-(curtop+size.height)};
	};
	
	this.trueSize = function(el) {
		var display = el.style.display, originalWidth, originalHeight;
		if (display != 'none' && display !== null) // Safari bug
		{
			originalHeight = el.style.offsetHeight;
			originalWidth = el.style.offsetWidth;
			if(originalWidth && originalHeight)
			{
				return {width: originalWidth, height: originalHeight};
			}
			
			return {width: el.clientWidth, height: el.clientHeight};
		}
		
		// All *Width *Height properties give 0 on elements with display none,
		// so enable the element temporarily
		var originalVisibility = el.style.visibility;
		var originalPosition = el.style.position;
		var originalDisplay = el.style.display;
		
		el.style.visibility = 'visible';
		el.style.position = 'absolute';
		el.style.display = 'block';
		
		originalHeight = el.clientHeight;
		originalWidth = el.clientWidth;
		
		this.css('visibility', originalVisibility);
		this.css('position', originalPosition);
		this.css('display', originalDisplay);
		
		return  {width: originalWidth, height: originalHeight};
	};
	
	this.center = function(el) {
		var windowCenter = this.windowCenter(),
			windowOffset = this.windowOffset(),
			size = this.trueSize(el);
		el.style.position = 'absolute';
		el.style.margin = 0;
		el.style.top = (windowCenter.top + windowOffset.top - (size.height / 2))+'px';
		el.style.left = (windowCenter.left + windowOffset.left - (size.width / 2))+'px';

		return this;
	};
	
	this.opacity = function(el, value) {
		el.style.opacity =  value/10;
		el.style.filter ='alpha(opacity=' + value*10 + ')';
		
		return this;
	};
	
	this.buildModal = function() {
		var modal = document.createElement('div');
		this.opacity(modal, 4);
		modal.style.position = 'absolute';
		modal.style.top = 0;
		modal.style.left = 0;
		modal.style.background = 'black';
		return modal;
	};
	
	this.open = function() {
		var first = !this.modal;
		if(first)
		{
			this.modal = this.buildModal();
			document.body.appendChild(this.modal);
			document.body.appendChild(target);
		}
		
		var pageSize = this.documentSize();
		this.modal.style.width = pageSize.width+'px';
		this.modal.style.height = pageSize.height+'px';
		
		target.style.display = 'block';
		this.modal.style.display = 'block';
		this.center(target);
		
		if(first)
		{
			this.close();
			this.open();
		}
	};
	
	this.close = function() {
		target.style.display = 'none';
		this.modal.style.display = 'none';
	};
	
	var _this = this;
	
	//contruct
	Element.observe(trigger, 'click', function(e) {
		Event.stop(e);
		_this.open();
	});
	
	Element.observe(close, 'click', function(e) {
		Event.stop(e);
		_this.close();
	});
	
	Element.observe(window, 'resize', function(e) {
		var pageSize = _this.documentSize();
		if(_this.modal)
		{
			_this.modal.style.width = pageSize.width+'px';
			_this.modal.style.height = pageSize.height+'px';
		}
	});
}