var xmlHttp;
var imagesArray;
var firstClick = false;
var CONST_SECOND_LAST_SLASH_POSITION = 44;
var currentImageName;
var currentImageSrc;

function GetGalleryPics(selectedGallery)
{
    xmlHttp = GetXmlHttpObject();

    if (xmlHttp == null) 
    {
        alert("Your browser does not support AJAX!");
        return;
    }
    else 
    {
        var url = "../ImageFiles.asp";
        url = url + "?q=" + selectedGallery;
        xmlHttp.onreadystatechange = stateChanged;
        xmlHttp.open("GET", url, true);
        xmlHttp.send(null);
    }

}

function stateChanged() 
{ 
	if (xmlHttp.readyState == 4)
	{ 
		//document.getElementById("AgentDiv").innerHTML=xmlHttp3.responseText;
	    //alert(xmlHttp.responseText.length);
	    //imagesArray = xmlHttp.responseText;
	   cleanImageArray(xmlHttp.responseText);
	}
}

function cleanImageArray(strImageArray) 
{
    var cleanStringArray = strImageArray.substring(0, strImageArray.length - 1)
    imagesArray = cleanStringArray.split(",");
    
    //change the images on display to be the first image in the gallery
    firstClick = true;

    if (firstClick) 
    {
        rotateImages();
    }
}

function rotateImages() 
{
    var lastSlashPosition;
    currentImageSrc = document.getElementById("Gallery").src;
    var imageName;

    for (i = 0; i < currentImageSrc.length; i++) 
    {
        //find the index of the 5th /
        if (currentImageSrc.charAt(i) == "/" && i > CONST_SECOND_LAST_SLASH_POSITION) 
        {
            currentImageName = currentImageSrc.substring(i + 1, currentImageSrc.length)
            lastSlashPosition = i+1;
        }
     
    }
  //  alert(imagesArray);
   // alert(currentImageName);
    for (j = 0; j < imagesArray.length; j++) 
    {
       // alert(imagesArray[j]);
        
        if (imagesArray[j] == currentImageName) 
        {

            if ((j + 1) < imagesArray.length) 
            {
                //alert(currentImageSrc);
                //alert(currentImageSrc.substring(0, lastSlashPosition)+""+ imagesArray[j + 1]);
                document.getElementById("Gallery").src = currentImageSrc.substring(0, lastSlashPosition) +""+ imagesArray[j + 1];
                vCenterImages();
            }
            else if ((j + 1) == imagesArray.length) 
            {
               // alert(imagesArray[0]);
                //document.getElementById("Gallery").src = currentImageSrc.substring(0, lastSlashPosition) + imagesArray[0];
                document.getElementById("Gallery").src = currentImageSrc.substring(0, lastSlashPosition) + "" + imagesArray[0];
                vCenterImages();
            }
        }
        
    }
}





function GetXmlHttpObject()
{
	var xmlHttp = null;
	try
	{
		// Firefox, Opera 8.0+, Safari
		 xmlHttp = new XMLHttpRequest();
	}
	catch (e)
	{
	// Internet Explorer
	try
	{
		xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch (e)
	{
		xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
	}
  }
return xmlHttp;
}

function vCenterImages() 
{
    var img = document.getElementById("Gallery");
    var ImageHeight = img.height;
    var ImageWidth = img.width;
    var DivHeight = 800;

    var MarginTop = Math.round((DivHeight - ImageHeight) / 2) + "px";
    var MarginBottom = Math.round((DivHeight - ImageHeight) / 2) + "px";

    document.getElementById("Gallery").style.marginTop = MarginTop;
    document.getElementById("Gallery").style.marginBottom = MarginBottom;
    document.getElementById("Gallery").style.marginLeft = "auto";
    document.getElementById("Gallery").style.marginRight = "auto";
    //document.getElementById("Gallery").style.border = "1px solid green";
}