//
  // CSS Linked Photo Shuffler v1.1 by
  //   Carl Camera
  //   http://iamacamera.org
  //
  // SetOpacity Function and inpiration from Photo Fade by
  //   Richard Rutter
  //   http://clagnut.com
  //
  // XML-retrieval code and cache control patch by
  //   Matt Farmer
  //
  // License: Creative Commons Attribution 2.5  License
  //   http://creativecommons.org/licenses/by/2.5/
  //

  // Customize your photo shuffle settings
  //
  // * Surround the target <img /> with an anchor <a> and <div>.
  //   specify unique id= in all three
  // * The first and final photo displayed is in the html <img> tag
  // * The image array contains paths to photos you want in the rotation.
  //   If you want the first photo in the rotation, then it's best to
  //   put it as the final array image.  All photos must be same dimension
  // * The Href array contains the link you want associated with each image
  //   each image must have a corresponding link.
  // * The rotations variable specifies how many times to repeat array.
  //   images. zero is a valid rotation value.

  var gblPhotoShufflerDivId = "bannerdiv";
  var gblPhotoShufflerImgId = "bannerimg";
  var gblPhotoShufflerAnchorId = "photoanchor";
  var gblImg = new Array();
  var gblHref = new Array();
  var gblPauseSeconds = 7.25;
  var gblFadeSeconds = .85;
  var gblRotations = 50;

  // End Customization section

  var gblDeckSize = gblImg.length; //this will be wrong at first
  var gblOpacity = 100;
  var gblOnDeck = 0;
  var gblStartImg;
  var gblStartHref;
  var gblImageRotations = gblDeckSize * (gblRotations+1); //this will be wrong at first

  //window.onload = photoShufflerLaunch; // OVERRIDE default behavior.
  window.onload = photoShufflerXMLRetrieval;
  
  function photoShufflerXMLRetrieval() {
  	//We need to fetch the arrays from our XML file.
  	var url = 'http://www.ugabyx.org/images/rotation/rotation.xml';
  	
  	//grab the XML from the server and pass it to photoShufflerLaunch
  	//when you've got it. Thank you PROTOTYPE!
  	var myAjax = new Ajax.Request(
  		url,
  		{
  			method: 'get',
  			onComplete: photoShufflerLaunch
  		}
  	);
  }
  
  function photoShufflerLaunch(request)
  {
  	//Retrieve the url and href tags out of the
  	//response XML. There's no idiot proof code here
  	//so we'll need to test the generator throughly.
  	var root = request.responseXML;
  	var urlTags = root.getElementsByTagName('url');
  	var hrefTags = root.getElementsByTagName('href');
  	
  	//Populate gblImg and gblHref from the XML document
  	//that we pull down from the server.
  	for(var i = 0; i < urlTags.length; i++) {
  		gblImg[i] = urlTags[i].textContent;
  		gblHref[i] = hrefTags[i].textContent;
  	}
  	
  	//We've gotta redo any computations that depended
  	//on gblImg.length
  	gblDeckSize = gblImg.length;
  	gblImageRotations = gblDeckSize * (gblRotations+1);
  	
    //Preload all of the images to (hopefully) prevent the double-take
    //effect that was happening when the cache expired.
    preloadObject = new Image();
    for(i = 0; i < gblImg.length; i++)
    	preloadObject.src = gblImg[i];
  	
  	//The rest of this code is from the origial photoShufflerLaunch().
  	var theimg = document.getElementById(gblPhotoShufflerImgId);
        gblStartImg = theimg.src; // save away to show as final image
  	var theanchor = document.getElementById(gblPhotoShufflerAnchorId);
        gblStartHref = theanchor.href; // save away to show as final image

	document.getElementById(gblPhotoShufflerDivId).style.backgroundImage='url(' + gblImg[gblOnDeck] + ')';
	setTimeout("photoShufflerFade()",gblPauseSeconds*1000);
  }

  function photoShufflerFade()
  {
  	var theimg = document.getElementById(gblPhotoShufflerImgId);

  	// determine delta based on number of fade seconds
	// the slower the fade the more increments needed
        var fadeDelta = 100 / (30 * gblFadeSeconds);

	// fade top out to reveal bottom image
	if (gblOpacity < 2*fadeDelta )
	{
	  gblOpacity = 100;
	  // stop the rotation if we're done
	  //if (gblImageRotations < 1) return;
	  photoShufflerShuffle();
	  // pause before next fade
          setTimeout("photoShufflerFade()",gblPauseSeconds*1000);
	}
	else
	{
	  gblOpacity -= fadeDelta;
	  setOpacity(theimg,gblOpacity);
	  setTimeout("photoShufflerFade()",30);  // 1/30th of a second
	}
  }

  function photoShufflerShuffle()
  {
	var thediv = document.getElementById(gblPhotoShufflerDivId);
	var theimg = document.getElementById(gblPhotoShufflerImgId);
	var theanchor = document.getElementById(gblPhotoShufflerAnchorId);

	// copy div background-image to img.src
	theimg.src = gblImg[gblOnDeck];
	theanchor.href = gblHref[gblOnDeck];
	//window.status = gblHref[gblOnDeck]; // updates status bar (optional)
	// set img opacity to 100
	setOpacity(theimg,100);

        // shuffle the deck
	gblOnDeck = ++gblOnDeck % gblDeckSize;
	// decrement rotation counter
	if (--gblImageRotations < 1)
	{
	  // insert start/final image if we're done
	  gblImg[gblOnDeck] = gblStartImg;
	  gblHref[gblOnDeck] = gblStartHref;
	}

	// slide next image underneath
	thediv.style.backgroundImage='url(' + gblImg[gblOnDeck] + ')';
  }

function setOpacity(obj, opacity) {
  opacity = (opacity == 100)?99.999:opacity;

  // IE/Win
  obj.style.filter = "alpha(opacity:"+opacity+")";

  // Safari<1.2, Konqueror
  obj.style.KHTMLOpacity = opacity/100;

  // Older Mozilla and Firefox
  obj.style.MozOpacity = opacity/100;

  // Safari 1.2, newer Firefox and Mozilla, CSS3
  obj.style.opacity = opacity/100;
}