var ThemeSwitcher = Class.extend({
	
	ePRELOAD_COMPLETE : 'ePRELOAD_COMPLETE',
	
	// ***
	_domElement : null,
	
	_targetClassName : null,
	_currentTheme : null,
	_nextThemeStack : null,
	_themes : null,
	_imagePath : null,
	_imageType : null,
	_switchMs : null,
	_switchRunning : null,
	_autoSwitchDelayMs : null,
	_autoSwitchDelayTimer : null,
	
	init : function(config, autoStart){
		if( 
			jQuery.isPlainObject(config)
			&& (typeof config.imagePath == 'string')
			&& (jQuery.isArray(config.themes) && (config.themes.length > 0))
			/*(typeof config == 'object')
			&& (typeof config.imagePath == 'string')
			&& (config.themes.length > 0)*/
		){
			this._domElement = (typeof config.domElement == 'string') ? jQuery(config.domElement) : jQuery('body:first');
			this._targetClassName = (typeof config.targetClassName == 'string') ? config.targetClassName : 'theme';
			this._themes = config.themes;
			this._imagePath = config.imagePath;
			this._imageType = (typeof config.imageType == 'string') ? config.imageType : 'png';
			this._switchMs = (typeof config.switchMs == 'number') ? config.switchMs : 250;
			this._switchRunning = false;
			this._autoSwitchDelayMs = (typeof config.autoSwitchDelayMs == 'number') ? config.autoSwitchDelayMs : 0;
			
			autoStart = ((autoStart === undefined) || (autoStart === true)) ? true : false;
			if( autoStart ){
				this.start();
			}
		} else {
			throw 'cannot initialize ThemeSwitcher, missing params or wrong param type(s)';
		}
	},
	// ***
	
	
	
	// xxx
	destroy : function(){
		this._switchRunning = true;
		this.stopAutoSwitching();
	},
	// xxx
	
	
	
	//--|FUNCTIONALITY----------
	
	start : function(){
		this.switchTo(this._themes[0], 0);
		this.startAutoSwitching();
	},
	
	
	
	switchToNext : function(){
		this.switchTo();
	},
	
	
	
	switchTo : function(themeName, ms){
		if( (themeName === undefined) || ((jQuery.inArray('' + themeName, this._themes) != -1) && (themeName != this._currentTheme)) ){
			if( !this._switchRunning ){
				this._switchRunning = true;
			
				var that = this;
				
				if( themeName === undefined ){
					if( this._currentTheme == null ){
						themeName = this._themes[0];
					} else {
						themeName = this._themes[(jQuery.inArray(this._currentTheme, this._themes) + 1) % this._themes.length];
					}
				}
				
				if( ms === undefined ){
					ms = this._switchMs;
				}
				
				this._currentTheme = '' + themeName;
				
				var oldElements = this._domElement.find('.' + this._targetClassName);
				var newElements = null;
				var elementsToLoad = oldElements.length;
				var loadedElements = 0;
				
				oldElements.each(function(){
					var themeFileInfo = that.parseThemeFileInfo(jQuery(this).attr('class'), that._targetClassName);
					
					if( themeFileInfo.themeName !== null ){
						var themeFileExtension = (themeFileInfo.themeFileExtension !== null) ? themeFileInfo.themeFileExtension : that._imageType;
					
						var newImageUrl = that._imagePath + that._currentTheme + '/' + themeFileInfo.themeName + '.' + themeFileExtension;
						var hasSrc = (jQuery(this).attr('src') !== undefined);
						var hasBackgroundImage = (jQuery(this).css('background-image') != 'none');
						
						var newElement = jQuery(this).clone();
						newElement.hide();
						jQuery(this).after(newElement);
						
						if( newElements == null ){
							newElements = newElement;
						} else {
							newElements = newElements.add(newElement);
						}
						
						if( hasSrc || hasBackgroundImage ){
							var loader = new Image();
							loader.onload = function(){
								if( hasSrc ){
									
									newElement.attr('src', newImageUrl);
									
									if ( jQuery.browser.msie ) {
										/*newElement.get(0).style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled='true',sizingMethod='image',src='"+ newElement.attr('src') +"')";*/
										/*newElement.css("Filter", "progid: DXImageTransform.Microsoft.AlphaImageLoader(enabled='true', sizingMethod='image', src='"+ newElement.attr('src') +"')");*/
									}
								}
								if( hasBackgroundImage ){
									newElement.css('background-image', 'url(' + newImageUrl + ')');
								}
								
								loadedElements++;
								
								if( loadedElements == elementsToLoad){
									oldElements.fadeOut(ms);
									
									var completedNewElements = 0;
									newElements.fadeIn(ms, function(){
										completedNewElements++;
										
										if( completedNewElements == newElements.length ){
											oldElements.remove();
											
											that._switchRunning = false;
											
											if( that._nextThemeStack != null ){
												var nextThemeName = that._nextThemeStack;
												that._nextThemeStack = null;
												that.switchTo(nextThemeName, ms);
											}
										}
									});
								}
							};
							loader.onerror = function(){
								throw 'cannot execute switch, an img-url is incorrect: ' + this.src;
							};
							loader.src = newImageUrl;
						} else {
							elementsToLoad--;
						}
					} else {
						elementsToLoad--;
					}
				});
			} else {
				this._nextThemeStack = themeName;
			}
		}
	},
	
	
	
	startAutoSwitching : function(){
		if( this._autoSwitchDelayMs > 0 ){
			this._autoSwitchDelayTimer = window.setInterval(jQuery.proxy(this.switchToNext, this), this._autoSwitchDelayMs);
		}
	},
	
	
	
	stopAutoSwitching : function(){
		if( this._autoSwitchDelayTimer != null ){
			window.clearInterval(this._autoSwitchDelayTimer);
			this._autoSwitchDelayTimer = null;
		}
	},
	
	
	
	preload : function(){
		var that = this;
		var elements = this._domElement.find('.' + this._targetClassName);
		var loadedElements = 0;
		
		for( var i = 0; i < this._themes.length; i++ ){
			elements.each(function(){
				var themeFileInfo = that.parseThemeFileInfo(jQuery(this).attr('class'), that._targetClassName);
				
				if( themeFileInfo.themeName !== null ){
					var loadHandler = function(){
						loadedElements++;
						if( loadedElements == elements.length ){
							jQuery(that).trigger(that.ePRELOAD_COMPLETE);
						}
					};
					
					var themeFileExtension = (themeFileInfo.themeFileExtension !== null) ? themeFileInfo.themeFileExtension : that._imageType;
					var newImageUrl = that._imagePath + that._themes[i] + '/' + themeFileInfo.themeName + '.' + themeFileExtension;
					var loader = new Image();
					loader.onload = function(){
						loadHandler();
					};
					loader.onerror = function(){
						loadHandler();
						throw 'cannot properly preload ThemeSwitcher, an img-url is incorrect: ' + this.src;
					};
					loader.src = newImageUrl;
				}
			});
		}
	},
	
	
	
	parseThemeFileInfo : function(classString, targetClassName){
		var nameClassRex = new RegExp('\\b' + targetClassName + 'name-([a-z\-_]+)\\b', 'gi');
		var nameClassInfo = nameClassRex.exec(classString);
		
		var extClassRex = new RegExp('\\b' + targetClassName + 'extension-([a-z\-_]+)\\b', 'gi');
		var extClassInfo = extClassRex.exec(classString);
		
		return {
			themeName : ( (nameClassInfo !== null) && (nameClassInfo.length >= 2) ) ? nameClassInfo[1] : null ,
			themeFileExtension : ( (extClassInfo !== null) && (extClassInfo.length >= 2) ) ? extClassInfo[1] : null
		};
	}
	
});