var Mask = (function()
{
	var settings = {
		overlayBgColor:	'#000',
		overlayOpacity:		0.4
	}

	function show_mask()
	{ // turn on or off the soft dark mask
		var softDarkMask = $('#mask');

		if(arguments[0])
		{
			var arrPageSizes = _getPageSize();
			softDarkMask.css({
				backgroundColor:	settings.overlayBgColor,
				opacity:			settings.overlayOpacity,
				width:				arrPageSizes[0],
				height:				arrPageSizes[1],
				zIndex:				arguments[0]
			}).fadeIn();
		}
		else {
			softDarkMask.hide();
		}
	};

	function _getPageSize()
	{
		var xScroll, yScroll;
		if (window.innerHeight && window.scrollMaxY) {
			xScroll = window.innerWidth + window.scrollMaxX;
			yScroll = window.innerHeight + window.scrollMaxY;
		}
		else if (document.body.scrollHeight > document.body.offsetHeight) // all but Explorer Mac
		{
			xScroll = document.body.scrollWidth;
			yScroll = document.body.scrollHeight;
		}
		else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
			xScroll = document.body.offsetWidth;
			yScroll = document.body.offsetHeight;
		}

		var windowWidth, windowHeight;
		if (self.innerHeight) {	// all except Explorer
			if(document.documentElement.clientWidth){
				windowWidth = document.documentElement.clientWidth;
			} else {
				windowWidth = self.innerWidth;
			}
			windowHeight = self.innerHeight;
		}
		else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
			windowWidth = document.documentElement.clientWidth;
			windowHeight = document.documentElement.clientHeight;
		}
		else if (document.body) { // other Explorers
			windowWidth = document.body.clientWidth;
			windowHeight = document.body.clientHeight;
		}
		// for small pages with total height less then height of the viewport
		if(yScroll < windowHeight){
			pageHeight = windowHeight;
		}else {
			pageHeight = yScroll;
		}
		// for small pages with total width less then width of the viewport
		if(xScroll < windowWidth){
			pageWidth = xScroll;
		}
		else {
			pageWidth = windowWidth;
		}
		arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight);
		return arrayPageSize;
	}

	/**
	* getPageScroll() by quirksmode.com
	*
	* @return Array Return an array with x,y page scroll values.
	*/
	function _getPageScroll()
	{
		var xScroll, yScroll;
		if (self.pageYOffset) {
			yScroll = self.pageYOffset;
			xScroll = self.pageXOffset;
		} else if (document.documentElement && document.documentElement.scrollTop) {	 // Explorer 6 Strict
			yScroll = document.documentElement.scrollTop;
			xScroll = document.documentElement.scrollLeft;
		} else if (document.body) {// all other Explorers
			yScroll = document.body.scrollTop;
			xScroll = document.body.scrollLeft;
		}
		arrayPageScroll = new Array(xScroll,yScroll);
		return arrayPageScroll;
	}

	return {
		show_mask: show_mask
	};
})();