var imageviewerEngine = function() {
	/*
	author:Giuseppe
	date: 20/08/2007
	notes: This  function is to fade in and out the images and linkboxes. I'm using script.aculo for the animation and the prototype.js
	(the function $() is from prototype.js and returns an array of html elements passing an element_id or element itself.)		
	
	*/
	this.name = 'imageviewerEngine';
	this.currentIndex = 0;
	//initializing to new Array so later on the a.length function will not fail if either the images or linkboxes are not available
	this.images = new Array();
	this.linkboxes = new Array();
	this.pairs = new Array();
	this.interval = null;
	this.linkboxMaxHeight = 0;

	this.init = function(interval) {
		for (var i = 1; i < this.images.length; i++) {
			this.initElement(this.images[i]);
		}
		for (var i = 1; i < this.linkboxes.length; i++) {
			this.initElement(this.linkboxes[i]);
		}
		this.associateImagesToLinkboxes();
		this.interval = setInterval("imgEngine.fadeEngine()", interval);
	};

	this.fadeEngine = function() {

		var pairout = this.pairs[this.currentIndex];
		this.currentIndex = (this.currentIndex == undefined) ? 0 : (++(this.currentIndex) >= this.pairs.length) ? 0 : this.currentIndex;
		var pairin = this.pairs[this.currentIndex];

		if (pairout.image != pairin.image) {
			this.fadeOut(pairout.image);
		}
		if (pairout.linkbox != pairin.linkbox) {
			this.fadeOut(pairout.linkbox);
		}

		this.fadeIn(pairin.image);
		this.fadeIn(pairin.linkbox);
	};
	this.getLinkboxMaxHeight = function() {
		for (var i = 0; i < this.linkboxes.length; i++) {
			this.linkboxMaxHeight = Math.max(this.linkboxMaxHeight, this.linkboxes[i].offsetHeight);
		}
		return this.linkboxMaxHeight;
	}
	this.associateImagesToLinkboxes = function() {
		var maxindex = this.images.length > this.linkboxes.length ? this.images.length : this.linkboxes.length;

		for (var i = 0; i < maxindex; i++) {
			var o = new Object();
			o.image = (this.images[i]) ? this.images[i] : this.images.length > 0 ? this.images[this.images.length - 1] : null;
			o.linkbox = (this.linkboxes[i]) ? this.linkboxes[i] : this.linkboxes.length > 0 ? this.linkboxes[this.linkboxes.length - 1] : null;
			this.pairs.push(o);
		}
	};

	this.initElement = function(el) {
		try {
			if (el != null) {
				el.style.display = 'none';
				el.style.visibility = 'visible';
			}
		} catch (e) { }
	};

	this.fadeIn = function(el) {
		try {
			if (el != null)
				Effect.Appear(el, { duration: 2.0 });
		} catch (e) { }
	};

	this.fadeOut = function(el) {
		try {
			if (el != null)
				Effect.Fade(el);
		} catch (e) { }
	};
}