var galleryIndex=1;

function ajaxManager(){
	var args = ajaxManager.arguments;
	
	switch (args[0])
		{
		 case "load_page":
		     if (document.getElementById)
         {
			    var x = (window.ActiveXObject) ? new ActiveXObject("Microsoft.XMLHTTP") : new XMLHttpRequest();
		     }
		     if (x)
		     {
          x.onreadystatechange = function()
          {
           if (x.readyState == 4 && x.status == 200)
           {
			      el = document.getElementById(args[1]);
            el.innerHTML = x.responseText;
            des = document.getElementById('desc');
            des.innerHTML="Description #" + galleryIndex;
           }
          }
          var imgurl="GL_" + args[2] + galleryIndex +".html";
		      dest_div = document.getElementById(args[1]);
          dest_div.innerHTML="Loading...";
          x.open("GET", imgurl, true);
          x.send(null);
          ajaxManager('preload', args[2]);
         }
         break;
		 case "start_up":
         galleryIndex="1";
         ajaxManager('load_page', 'slideimg', 'TUR');
         break;
     case "back":
         (galleryIndex == 1) ? galleryIndex=19 : galleryIndex--;
         ajaxManager('load_page', 'slideimg', 'TUR');
         break;
     case "fwd":
         (galleryIndex == 19) ? galleryIndex=1 : galleryIndex++;
         ajaxManager('load_page', 'slideimg', 'TUR');
         break;
     case "preload":
         var prev= (galleryIndex==1) ? 19 : (galleryIndex-1);
         var next= (galleryIndex==19) ? 1 : (galleryIndex+1);
         prevImg = new Image();
         prevImg.src="slides/GL_" + args[1] + prev + ".gif";
         nextImg = new Image();
         nextImg.src="slides/GL_" + args[1] + next + ".gif";
         break;
   }
}