/**
 * 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);
	}
};

/**
 * 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 = "images/small-up-enabled.gif";
	} else {
		upImage.src = "images/small-up-disabled.gif";
	}

}



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

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

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

};

var changePage = function(e, args) {
	var carousel = args[0];
	var pageNum = args[1];

	carousel.scrollTo(pageNum);
};

var load = function(carousel, start, last) {
	for(var i=start;i<=last;i++) {
		carousel.addItem(i, fmtItem(newsArticleList[i-1]));
	}
}

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

/**
 * 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(newsItem) {

  	var innerHTML = 
  		'<a href="' + 
  		newsItem.url + 
  		'">' + 
  		newsItem.title + 
  		'</a>';
  
	return innerHTML;
	
}