/* DEFINE GLOBALS
================================================== */

var currentSlide = new Number(-1);
var nextSlide = new Number(0);
var t_s; // slideshow timer
var galleryDuration = new Number(2600); // milliseconds
var transitionDuration = new Number(0.5); // seconds
var slideshowElements = new Array();
var galleryRandomStart = new Boolean(false);
var galleryRandomAdvance = new Boolean(false);

Event.observe(window,'load',function()
{

	// slideshow
	if(document.getElementById('header-slideshow'))
	{
		startGallery();
	}


});


/* SLIDESHOWS
================================================== */

function startGallery()
{
	document.getElementById('loading_message').style.display='none';
	slideshowElements = $$('p.slideshow_item'); // get all slideshow elements
	if (galleryRandomStart == true)
	{
		nextSlide = Math.floor(Math.random() * slideshowElements.length); // randomize position
	}
	advanceGallerySlide(); // begin gallery
}

function advanceGallerySlide()
{
	if (slideshowElements[currentSlide]) // not necessary for first slide on page load
	{
		new Effect.Fade(slideshowElements[currentSlide],{from: 1.0, to: 0, duration: (transitionDuration * 2)});
	}
	new Effect.Appear(slideshowElements[nextSlide],{from: 0, to: 1.0, duration: transitionDuration});
	currentSlide = nextSlide;
	if (galleryRandomAdvance == true)
	{
		nextSlide = Math.floor(Math.random() * slideshowElements.length); // randomize position
		while (nextSlide == currentSlide) // pick random slides until we get a unique one
		{
			nextSlide = Math.floor(Math.random() * slideshowElements.length); // randomize position
		}
	} else {
		nextSlide++;
	}
	if(nextSlide >= slideshowElements.length) 
	{
		nextSlide = 0;
	}
	t_s = setTimeout("advanceGallerySlide()", galleryDuration);
}