/**
 * @author alexander.farkas
 * 
 * Usage Example:
 * 
 * 

$('#photo-index a').each(function(){
	$.imgPreLoad.add($(this).attr('href'));
});

 */
(function($){
	$.imgPreLoad = (function(){
		var srcList 	= [], 
			ready 		= false, 
			started 	= false,
			loaded 		= false,
			errorDelay 	= 5000,
			errorTimer
		;
		
		function createImg(){
			return (window.Image) ? new Image() : document.createElement('img');
		}
			
		function loadImg(src, callback){
			var img = createImg(),
				fn = function(e){
					var that = this, args = arguments;
					clearTimeout(errorTimer);
					$(this).unbind('load error');
					src[1].apply(that, args);
					callback.apply(that, args);
				};
			
			img.src = src[0];
			
			if(!img.complete){
				clearTimeout(errorTimer);
				errorTimer = setTimeout(function(){
					fn.call(img, {type: 'timeouterror'});
				}, errorDelay);
				$(img)
					.bind('load error', fn);
			} else {
				fn.call(img, {type: 'cacheLoad'});
			}
		}
		
		function loadNextImg(){
			if(srcList.length && ready){
				started = true;
				var src = srcList.shift();
				loadImg(src, loadNextImg);
			} else {
				started = false;
			}
		}
		
		function pause(){
			started = false;
			ready = false;
		}
		
		function restart(){
			if(loaded) {
				ready = true;
				loadNextImg();
			}
		}
		
		function loadNow(src, callback){
			pause();
			callback = callback || function(){};
			loadImg([src, callback], restart);
		}
		
		return {
			add: function(src, 	fn, priority){
				fn = fn || function(){};
				src = [src, fn];
				if(priority){
					srcList.unshift(src);
				} else {
					srcList.push(src);
				}
				if(ready && !started){
					loadNextImg();
				}
			},
			loadNow: loadNow,
			ready: function(){
				loaded = true;
				ready = true;
				loadNextImg();
			}
		};
	})();
	if($.windowLoaded){
		$.imgPreLoad.ready();
	} else {
		$(window).bind('load', $.imgPreLoad.ready);
	}
})(jQuery);