//****************************************************************
//----------------------------------------------------------------
// Fading Slide Show
// ver 1.0
// Author: Samuele Carassai
//----------------------------------------------------------------
//
// API (user):
//
//****************************************************************

JSCSlideShow = function (target) {
    // Private
    var _parent = this;
    
    var _intervalId = null;
    var _transitionTime = 25;
    var _waitingTime = 4000;
    var _images = new Array();
    var _running = true;
    var _current = 0;
    var _inTransaction = false;

    // Next function is <so_xfade> revisited
    var _xfade = function () {	    
        _inTransaction = true;
		_stopInterval();
		
        var nIndex = (_images[_current + 1]) ? _current + 1 : 0;
        cOpacity = _images[_current].xOpacity;
        nOpacity = _images[nIndex].xOpacity;

        cOpacity -= .05;
        nOpacity += .05;

        _images[nIndex].style.display = 'block';
        _images[_current].xOpacity = cOpacity;
        _images[nIndex].xOpacity = nOpacity;

        _setOpacity(_images[_current]);
        _setOpacity(_images[nIndex]);

        if(cOpacity <= 0) {
	        _images[_current].style.display = 'none';
	        _current = nIndex;
	        
            if (_parent.onChange != null) _parent.onChange();            
            _inTransaction = false;
	        _startInterval();
        } else
            window.setTimeout(_xfade, _transitionTime);
            
    };

    var _setOpacity = function (obj) {
	    if(obj.xOpacity > .99) {
		    obj.xOpacity = .99;
		    return;
	    }

	    obj.style.opacity = obj.xOpacity;
	    obj.style.MozOpacity = obj.xOpacity;
	    obj.style.filter = 'alpha(opacity=' + (obj.xOpacity * 100) + ')';
    };
    
    var _create = function (target) {
        if (!document.getElementById) return ;
		if (typeof(target) == "string") target = document.getElementById(target);
		if (target == null) return ;
		
	    _images = target.getElementsByTagName('img');
	    for (var index = 0; index < _images.length; index ++) {
	        target.style.position = "relative";
	        
	        _images[index].style.display = "none";
	        _images[index].style.position = "absolute";
	        _images[index].style.top = 0;
	        _images[index].style.left = 0;
	        _images[index].xOpacity = 0;
	    };
	    
	    if (_images.length > 0) {
	        _images[0].style.display = 'block';
	        _images[0].xOpacity = .99;
            
	        _startInterval();
	    };
    };
    
    var _stopInterval = function () {
        if (_intervalId != null) {
            window.clearInterval(_intervalId);
            _intervalId = null;
        };
    };
    
    var _startInterval = function () {
        if (_running) 
            _intervalId = window.setInterval(_xfade, _waitingTime);
    };
    
    // Publiche
    this.stop = function () {
        _running = false;
        _stopInterval();
    };
    
    this.start = function () {
        _running = true;
        _startInterval();
    };
    
    this.showImage = function (imageIndex) {
        if (imageIndex >= 0 && imageIndex < _images.length && _inTransaction == false) {
            for (var index = 0; index < _images.length; index ++) {
	            _images[index].style.display = "none";
	            _images[index].style.position = "absolute";
	            _images[index].xOpacity = 0;
            };

	        _current = imageIndex;
	        _images[_current].style.display = 'block';
	        _images[_current].xOpacity = .99;
	        _setOpacity(_images[_current]);
	    };
    };
    
    this.getCurrentImageIndex = function () {
        return _current;
    };
    
    // Costruttore
    _create(target);
};