AnimationService = {
	INTERVAL : 30,																// Default delay between steps
	STEP : 150,																	// Default pixels to move each step
	animations : new Object(),													// Used to reference a given animation by id
	addAnimation : function(id, obj) {
		obj.id = id;
		this.animations[id] = obj;
		return obj;
	},
	startById : function(id) {
		if (this.animations[id]) {
			this.animations[id].start();
		}
	},
	stopById : function(id) {
		if (this.animations[id]) {
			this.animations[id].stop();
		}
	},
	runScene : function(scene, cb) {											// Runs an array of Animations and executes a callback when finished.
		var completed = new Array();
		if (scene.length) {
			for (var n = 0; n < scene.length; n++) {
				scene[n].sceneIndex = n;
				completed[n] = false;
				scene[n].complete = function() {
					completed[this.sceneIndex] = true;
					this.sceneIndex = 0;
					allDone = true;
					for (var j = 0; j < completed.length; j++) {
						if (!completed[j]) {
							allDone = false;
						}
					}
					if (allDone) {
						cb();
					}
				}
				scene[n].start();
			}
		} else {
			cb();
		}
	}
}

fadeAnimation = function(element) {
	this.element = element;
	this.interval = AnimationService.INTERVAL;
	this.step = AnimationService.STEP;
	this.running = false;
	this.intervalId = null;
	this.startTime = null;
	this.sceneIndex = 0;
	this.id = null;

	this.toOpacity = 0;
	
	this.startOpacity = getOpacity(this.element);
	
	this.start = function() {
		//debug("start: " + this.element.id);
		if (this.intervalId == null) {
			this.beforeStart();
			this.running = true;
			
			if (this.toOpacity < 0) {
				this.toOpacity = 0;
			}
			
			this.startOpacity = getOpacity(this.element);
			
			var dist = this.toOpacity > this.startOpacity ? 1 : -1;
			
			//debug("Start: " + this.startOpacity + " To: " + this.toOpacity + " dist: " + dist);
			var self = this;
			this.intervalId = setInterval(function() {
					var currentOpacity = getOpacity(self.element)
					var dif = currentOpacity + self.step * dist;
					
					// debug("Current: " + currentOpacity + " dif: " + dif);
					if ((dist > 0 && dif <= self.toOpacity) || (dist < 0 && dif >= self.toOpacity)) {
						setOpacity(self.element, dif);
					} else {
						setOpacity(self.element, self.toOpacity);
					}
					
					if (currentOpacity == self.toOpacity) {
						//debug("Complete: " + self.element.id);
						self.stop();
						self.complete();
					}
				},
				this.interval
			);
		
		} else {
			throw new Error("fadeAnimation already started for " + this.element.id);
		}
	}
	this.stop = function() {
		if (this.intervalId != null) {
			clearInterval(this.intervalId);
			this.intervalId = null;
		}
		this.running = false;
	}
	this.complete = function() {}
	this.beforeStart = function() {
		this.startTime = new Date().getTime();
	}
}


getOpacity = function(element) {
	if (element.currentStyle) {
		if (element.currentStyle.filter) {
			if (value = (element.currentStyle.filter || '').match(/alpha\(opacity=(.*)\)/))
			if (value[1]) return parseFloat(value[1]);
		} else {
			return 100;
		}
	} else if (element.style.opacity) {
		return element.style.opacity * 100;
	} else if (element.style.MozOpacity) {
		return element.style.MozOpacity * 100;
	} else {
		var css = document.defaultView.getComputedStyle(element, null);
		return css ? css["opacity"] * 100 : null;
	}
}

setOpacity = function(element, value) {
	function stripAlpha(filter){
		return filter.replace(/alpha\([^\)]*\)/gi,'');
	}
	
	var filter = null;
	if (element.currentStyle) {
		var currentStyle = element.currentStyle;
		filter = (currentStyle.filter) ? currentStyle.filter : "";
	}
	var style = element.style;

	if (value == 100 || value === '') {
		if (filter != null) {
			(filter = stripAlpha(filter)) ? style.filter = filter : style.removeAttribute('filter');
		}
		element.style.opacity = 1;
		element.style.MozOpacity = 1;
		return element;
	} else if (value < 0.00001) value = 0;
	
	if (filter != null) {
		style.filter = stripAlpha(filter) + 'alpha(opacity=' + value + ')';
	}
	element.style.opacity = value / 100;
	element.style.MozOpacity = value / 100;

	return element;
}