var ImageTeaser = Class.extend({
	
	// ***
	URL_REGEXP : /(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/,
	
	_domElement : null,
	
	_changeMs : 0,
	_changeTimer : null,
	_streams :	{currentIndex : 0, pools : []},
	
	init : function(config){
		if(
			$.isPlainObject(config)
			&& (typeof config.id === 'string')
			&& (typeof config.changeMs === 'number')
			&& $.isArray(config.streams)
		){
			this._domElement = $('#' + config.id);
		
			this._changeMs = config.changeMs;
			
			for( var i = 0; i < config.streams.length; i++ ){
				if( $.isArray(config.streams[i]) ){
					this._streams.pools[i] = {currentIndex : 0, urls : []};
				
					for( var j = 0; j < config.streams[i].length; j++ ){
						if( this.URL_REGEXP.test(config.streams[i][j]) ){
							this._streams.pools[i].urls[j] = config.streams[i][j];
						} else {
							throw 'one of the streams contains a non-url';
						}
					}
				} else {
					throw 'one of the given streams is not an array';
				}
			}
			
			this._changeTimer = window.setInterval($.proxy(this.change, this), this._changeMs);
		} else {
			throw 'cannot initialize imageteaser, missing params or wrong param type(s)';
		}
	},
	// ***
	
	
	
	// xxx
	destroy : function(){
		window.clearInterval(this._changeTimer);
		this.changeMs = 0;
		this._streams = {};
	},
	// xxx
	
	
	
	//--|FUNCTIONALITY----------
	
	change : function(){
		var that = this;
	
		var nextStreamIndex = this.getRandomIndex(this._streams.pools.length);
		while( nextStreamIndex == this._streams.currentIndex ){
			nextStreamIndex = this.getRandomIndex(this._streams.pools.length);
		}
		
		var nextImageIndex = this.getRandomIndex(this._streams.pools[nextStreamIndex].urls.length);
		while( nextImageIndex == this._streams.pools[nextStreamIndex].currentIndex ){
			nextImageIndex = this.getRandomIndex(this._streams.pools[nextStreamIndex].urls.length);
		}
		
		var nextEntry = this._domElement.find('li').eq(nextStreamIndex);
		
		var nextImage = new Image();
		nextImage.onload = function(){ that.switchImages(nextEntry, nextImage); };
		nextImage.src = this._streams.pools[nextStreamIndex].urls[nextImageIndex];
		
		this._streams.currentIndex = nextStreamIndex;
		this._streams.pools[nextStreamIndex].currentIndex = nextImageIndex;
	},
	
	
	
	getRandomIndex : function(firstNot){
		return Math.floor(Math.random() * firstNot);
	},
	
	
	
	switchImages : function(targetEntry, targetImage){
		oldImg = targetEntry.children('a:first');
		newImg = oldImg.clone().hide();
		newImg.css('background-image', 'url(' + targetImage.src + ')');
		targetEntry.append(newImg);
		
		execute = function(){
			oldImg.remove();
		};
	
		oldImg.fadeOut('1500');
		newImg.fadeIn('1500', execute);
	}
	
});