/**
 * Image src URLs
 **/


/**
 * Since carousel.addItem uses an HTML string to create the interface
 * for each carousel item, this method formats the HTML for an LI.
 **/
var fmtItem = function(imgUrl, url, title) {

 	var innerHTML = 
  		'<img src="' + 
  		imgUrl +
		'" width="' +
		75 +
		'" height="' +
		75+
		'"/>';
	return innerHTML;

};

/**
 * Custom inital load handler. Called when the carousel loads the initial
 * set of data items. Specified to the carousel as the configuration
 * parameter: loadInitHandler
 **/
var loadInitialItems = function(type, args) {

	var start = args[0];
	var last = args[1]; 
	load(this, start, last);	
};

/**
 * Custom load next handler. Called when the carousel loads the next
 * set of data items. Specified to the carousel as the configuration
 * parameter: loadNextHandler
 **/
var loadNextItems = function(type, args) {	

	var start = args[0];
	var last = args[1]; 
	var alreadyCached = args[2];
	
	if(!alreadyCached) {
		load(this, start, last);
	}
};

/**
 * Custom load previous handler. Called when the carousel loads the previous
 * set of data items. Specified to the carousel as the configuration
 * parameter: loadPrevHandler
 **/
var loadPrevItems = function(type, args) {
	var start = args[0];
	var last = args[1]; 
	var alreadyCached = args[2];
	
	if(!alreadyCached) {
		load(this, start, last);
	}
};  

var load = function(carousel, start, last) {
	for(var i=start;i<=last;i++) {
		var randomIndex = getRandom(8, lastRan);
		lastRan = randomIndex;
		carousel.addItem(i, fmtItem(imageList[randomIndex], "#", "Number " + i));
	}
};

var getRandom = function(max, last) {
	var randomIndex;
	do {
		randomIndex = Math.floor(Math.random()*max);
	} while(randomIndex == last);
	
	return randomIndex;
};

/**
 * Custom button state handler for enabling/disabling button state. 
 * Called when the carousel has determined that the previous button
 * state should be changed.
 * Specified to the carousel as the configuration
 * parameter: prevButtonStateHandler
 **/
var handlePrevButtonState = function(type, args) {

	var enabling = args[0];
	var upImage = args[1];

	if(enabling) {
		upImage.src = "test/images/up-enabled.gif";
	} else {
		upImage.src = "test/images/up-disabled.gif";
	}
	
};
var handleNextButtonState = function(type, args) {

	var enabling = args[0];
	var downImage = args[1];

	if(enabling) {
		downImage.src = "test/images/down-enabled.gif";
	} else {
		downImage.src = "test/images/down-disabled.gif";
	}
	
};

var carousel; // for ease of debugging; globals generally not a good idea
var pageLoad = function() 
{
	carousel = new YAHOO.extension.Carousel("dhtml-carousel", 
		{
			numVisible:        4,
			animationSpeed:    0.25,
			scrollInc:         4,
			orientation:       "vertical",
			navMargin:         0,
			firstVisible:      5,
			revealAmount:      4,
			size:              12,
			loadInitHandler:   loadInitialItems,
			prevElement:     "up-arrow",
			nextElement:     "down-arrow",
			loadNextHandler:   loadNextItems,
			loadPrevHandler:   loadPrevItems,
			prevButtonStateHandler:   handlePrevButtonState,
			nextButtonStateHandler:   handleNextButtonState
		}
	);
};

YAHOO.util.Event.addListener(window, 'load', pageLoad);