/**
 * --------------------------------------------------------------------
 * jQuery-Plugin "preloadCssImages"
 * by Scott Jehl, scott@filamentgroup.com
 * http://www.filamentgroup.com
 * reference article: http://www.filamentgroup.com/lab/update_automatically_preload_images_from_css_with_jquery/
 * demo page: http://www.filamentgroup.com/examples/preloadImages/index_v4.php
 * 
 * Copyright (c) 2008 Filament Group, Inc
 * Dual licensed under the MIT (filamentgroup.com/examples/mit-license.txt) and GPL (filamentgroup.com/examples/gpl-license.txt) licenses.
 *
 * Version: 4.0, 07.24.2008
 * Changelog:
 * 	02.20.2008 initial Version 1.0
 *    06.04.2008 Version 2.0 : removed need for any passed arguments. Images load from any and all directories.
 *    06.21.2008 Version 3.0 : Added options for loading status. Fixed IE abs image path bug (thanks Sam Pohlenz).
 *    07.24.2008 Version 4.0 : Added support for @imported CSS (credit: http://marcarea.com/). Fixed support in Opera as well.
 * --------------------------------------------------------------------
 */
jQuery.preloadCssImages = function(settings){
	var settings = jQuery.extend({
		statusTextEl: null,
		statusBarEl: null
	}, settings);
	
	var allImgs = [];//new array for all the image urls  
	var k = 0; //iterator for adding images
	var sheets = document.styleSheets;//array of stylesheets
	
	for(var i = 0; i<sheets.length; i++){//loop through each stylesheet
		var cssPile = '';//create large string of all css rules in sheet
		var csshref = (sheets[i].href) ? sheets[i].href : 'window.location.href';
		var baseURLarr = csshref.split('/');//split href at / to make array
		baseURLarr.pop();//remove file path from baseURL array
		var baseURL = baseURLarr.join('/');//create base url for the images in this sheet (css file's dir)
		if(baseURL!="") baseURL+='/'; //tack on a / if needed
		if(sheets[i].cssRules){//w3 
			var thisSheetRules = sheets[i].cssRules; //w3 
			for(var j = 0; j<thisSheetRules.length; j++){ 
				if ( sheets[i].cssRules[j].constructor == 'CSSImportRule' ) { //added support for @imported css - credit: http://marcarea.com/
					var importSheetRules = sheets[i].cssRules[j].styleSheet.cssRules; 
					for ( var x=0; x<importSheetRules.length; x++ ) { 
						cssPile+= importSheetRules[x].cssText; 
					} 
				} 
				else { 
					cssPile+= thisSheetRules[j].cssText; 
				} 
			} 
		} 
		else { 
			if ( sheets[i].imports.length > 0 ) { 
				for (var m=0; m<sheets[i].imports.length; m++) { 
					cssPile+= sheets[i].imports[m].cssText;
				} 
			} 
			else { 
				cssPile+= sheets[i].cssText; 
			} 
		}
		//parse cssPile for image urls and load them into the DOM
		var imgUrls = cssPile.match(/[^\(]+\.(gif|jpg|jpeg|png)/g);//reg ex to get a string of between a "(" and a ".filename"
		var loaded = 0; //number of images loaded

		if(imgUrls != null && imgUrls.length>0 && imgUrls != ''){//loop array\
			var arr = jQuery.makeArray(imgUrls);//create array from regex obj	 
			jQuery(arr).each(function(){
				allImgs[k] = new Image(); //new img obj
				allImgs[k].src = (this.charAt(0) == '/' || this.indexOf('http://')>-1) ? this : baseURL + this;	//set src either absolute or rel to css dir
				
				if(allImgs[k].src.lastIndexOf('http://')>0){allImgs[k].src = allImgs[k].src.split('%22')[1];} //fixed opera's source doubling
				
				$(allImgs[k]).load(function(){
					loaded++;
					//send updates to status elements if applicable
					if(settings.statusTextEl) {
						$(settings.statusTextEl).html('<span class="numLoaded">'+loaded+'</span> of <span class="numTotal">'+allImgs.length+'</span> loaded (<span class="percentLoaded">'+(loaded/allImgs.length*100).toFixed(0)+'%</span>) <span class="currentImg">Now Loading: <span>'+allImgs[loaded-1].src.split('/')[allImgs[loaded-1].src.split('/').length-1]+'</span></span>');
					}
					if(settings.statusBarEl) {
						var barWidth = $(settings.statusBarEl).width();
						$(settings.statusBarEl).css('background-position', -(barWidth-(barWidth*loaded/allImgs.length).toFixed(0))+'px 50%');
					}
				});
				k++;
			});
		}
	}//loop
	return allImgs;
}