/**

 * 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_v2.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: 5.0, 10.31.2008

 * 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. 

 *    10.31.2008 Version: 5.0 : Many feature and performance enhancements from trixta

 * --------------------------------------------------------------------

 */



;jQuery.preloadCssImages = function(settings){

	settings = jQuery.extend({

		statusTextEl: null,

		statusBarEl: null,

		errorDelay: 999, // handles 404-Errors in IE

		simultaneousCacheLoading: 2

	}, settings);

	var allImgs = [],

		loaded = 0,

		imgUrls = [],

		thisSheetRules,	

		errorTimer;

	

	function onImgComplete(){

		clearTimeout(errorTimer);

		if (imgUrls && imgUrls.length && imgUrls[loaded]) {

			loaded++;

			if (settings.statusTextEl) {

				var nowloading = (imgUrls[loaded]) ? 

					'Now Loading: <span>' + imgUrls[loaded].split('/')[imgUrls[loaded].split('/').length - 1] : 

					'Loading complete'; // wrong status-text bug fixed

				jQuery(settings.statusTextEl).html('<span class="numLoaded">' + loaded + '</span> of <span class="numTotal">' + imgUrls.length + '</span> loaded (<span class="percentLoaded">' + (loaded / imgUrls.length * 100).toFixed(0) + '%</span>) <span class="currentImg">' + nowloading + '</span></span>');

			}

			if (settings.statusBarEl) {

				var barWidth = jQuery(settings.statusBarEl).width();

				jQuery(settings.statusBarEl).css('background-position', -(barWidth - (barWidth * loaded / imgUrls.length).toFixed(0)) + 'px 50%');

			}

			loadImgs();

		}

	}

	

	function loadImgs(){

		//only load 1 image at the same time / most browsers can only handle 2 http requests, 1 should remain for user-interaction (Ajax, other images, normal page requests...)

		// otherwise set simultaneousCacheLoading to a higher number for simultaneous downloads

		if(imgUrls && imgUrls.length && imgUrls[loaded]){

			var img = new Image(); //new img obj

			img.src = imgUrls[loaded];	//set src either absolute or rel to css dir

			if(!img.complete){

				jQuery(img).bind('error load onreadystatechange', onImgComplete);

			} else {

				onImgComplete();

			}

			errorTimer = setTimeout(onImgComplete, settings.errorDelay); // handles 404-Errors in IE

		}

	}

	

	function parseCSS(sheets, urls) {

		var w3cImport = false,

			imported = [],

			importedSrc = [],

			baseURL;

		var sheetIndex = sheets.length;

		while(sheetIndex--){//loop through each stylesheet

			

			var cssPile = '';//create large string of all css rules in sheet

			

			if(urls && urls[sheetIndex]){

				baseURL = urls[sheetIndex];

			} else {

				var csshref = (sheets[sheetIndex].href) ? sheets[sheetIndex].href : 'window.location.href';

				var baseURLarr = csshref.split('/');//split href at / to make array

				baseURLarr.pop();//remove file path from baseURL array

				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[sheetIndex].cssRules || sheets[sheetIndex].rules){

				thisSheetRules = (sheets[sheetIndex].cssRules) ? //->>> http://www.quirksmode.org/dom/w3c_css.html

					sheets[sheetIndex].cssRules : //w3

					sheets[sheetIndex].rules; //ie 

				var ruleIndex = thisSheetRules.length;

				while(ruleIndex--){

					if(thisSheetRules[ruleIndex].style && thisSheetRules[ruleIndex].style.cssText){

						var text = thisSheetRules[ruleIndex].style.cssText;

						if(text.toLowerCase().indexOf('url') != -1){ // only add rules to the string if you can assume, to find an image, speed improvement

							cssPile += text; // thisSheetRules[ruleIndex].style.cssText instead of thisSheetRules[ruleIndex].cssText is a huge speed improvement

						}

					} else if(thisSheetRules[ruleIndex].styleSheet) {

						imported.push(thisSheetRules[ruleIndex].styleSheet);

						w3cImport = true;

					}

					

				}

			}

			//parse cssPile for image urls

			var tmpImage = cssPile.match(/[^\("]+\.(gif|jpg|jpeg|png)/g);//reg ex to get a string of between a "(" and a ".filename" / '"' for opera-bugfix

			if(tmpImage){

				var i = tmpImage.length;

				while(i--){ // handle baseUrl here for multiple stylesheets in different folders bug

					var imgSrc = (tmpImage[i].charAt(0) == '/' || tmpImage[i].match('://')) ? // protocol-bug fixed

						tmpImage[i] : 

						baseURL + tmpImage[i];

					

					if(jQuery.inArray(imgSrc, imgUrls) == -1){

						imgUrls.push(imgSrc);

					}

				}

			}

			

			if(!w3cImport && sheets[sheetIndex].imports && sheets[sheetIndex].imports.length) {

				for(var iImport = 0, importLen = sheets[sheetIndex].imports.length; iImport < importLen; iImport++){

					var iHref = sheets[sheetIndex].imports[iImport].href;

					iHref = iHref.split('/');

					iHref.pop();

					iHref = iHref.join('/');

					if (iHref) {

						iHref += '/'; //tack on a / if needed

					}

					var iSrc = (iHref.charAt(0) == '/' || iHref.match('://')) ? // protocol-bug fixed

						iHref : 

						baseURL + iHref;

					

					importedSrc.push(iSrc);

					imported.push(sheets[sheetIndex].imports[iImport]);

				}

				

				

			}

		}//loop

		if(imported.length){

			parseCSS(imported, importedSrc);

			return false;

		}

		var downloads = settings.simultaneousCacheLoading;

		while( downloads--){

			setTimeout(loadImgs, downloads);

		}

	}

	parseCSS(document.styleSheets);

	return imgUrls;

};