var transspeed= 500;

var currentpos= 0;
var currentthumbpos= 0;
var moveamount= 144;
var maxthumbvisible = 4;

function moveThumbsNext()
{
    if(currentpos < thumbnailnum - maxthumbvisible)
    {
        currentpos += 1;
        
        manageButtonStatus();    
        
        move = (currentthumbpos - moveamount);
        
        var movethumbs = new Fx.Styles(
            'thumbnails',
            {duration: transspeed, transition: Fx.Transitions.quadOut});
        movethumbs.start({ left: [currentthumbpos, move]});
        
        currentthumbpos -= moveamount;     
    }
}

function moveThumbsPrev()
{
    if(currentpos > 0)
    {
        currentpos -= 1;
        
        manageButtonStatus();
        
        move = (currentthumbpos + moveamount);
        
        var movethumbs = new Fx.Styles(
            'thumbnails',
            {duration: transspeed, transition: Fx.Transitions.quadOut});
        movethumbs.start({ left: [currentthumbpos, move]});
        
        currentthumbpos += moveamount;  
    }    
}

function manageButtonStatus()
{
    var prev = $('previousThumbnails');
    var next = $('nextThumbnails');
    
    if(currentpos <= 0)
    {
        swapImage(
            prev,
            '/images/common/previousThumbDisabled.png');
    }
    else
    {
        swapImage(
            prev,
            '/images/common/previousThumbEnabled.png');
    }
    
    if(maxthumbvisible + currentpos >= thumbnailnum)
    {
        swapImage(
            next,
            '/images/common/nextThumbDisabled.png');
    }
    else
    {
        swapImage(
            next,
            '/images/common/nextThumbEnabled.png');    
    }
}

/**
 * Swaps an img, does additional work for IE and png fixed images.
 */
function swapImage(
    img,
    newImage)
{
    if(img.nodeName == 'IMG')
    {
        img.src= newImage;   
    }
    else if(img.nodeName == 'SPAN')
    {
        var filter = img.style.filter;
        var src_start = filter.indexOf( "(src='" );
        src_start += 6;
        src_end = filter.indexOf( "'," );
        left = filter.substring( 0, src_start );
        right = filter.substring( src_end );
        img.style.filter = left + newImage + right;
    }
}

function viewImage(image)
{
    var largeImage = $('mainImage');
    largeImage.src = image;
}