var currentThumb = 0;
var maxPage = 0;

function getMaxPage()
{
	var maxPageUrl = './scripts/get_max_page.php';
	
	var maxPageAjax = new Ajax.Request(
			maxPageUrl,
			{
				method: 'get',
				onComplete: setMaxPage
			}
		)
}

function setMaxPage(responseData)
{
	maxPage = responseData.responseText;
	checkMaxPage();
}

function checkMaxPage()
{
	var leftArrow = $("left_arrow");
	var rightArrow = $("right_arrow");
	
	rightArrow.src = './images/right_arrow.jpg';
	leftArrow.src = './images/left_arrow.jpg';
	
	if (currentThumb == 0)
	{
		leftArrow.src = './images/left_arrow_gray.jpg';
	}
	if (currentThumb == maxPage)
	{
		rightArrow.src = './images/right_arrow_gray.jpg';
	}
}

function load_pics(offset)
{
	var picsUrl = './scripts/get_thumbs.php';
	var picsPars = 'thumb=' + offset;
	
	var picsAjax = new Ajax.Updater(
			'portfolio_div',
			picsUrl,
			{
				method: 'get',
				parameters: picsPars
			}
		);
}

function forward() {
	if (currentThumb < maxPage)
	{
		currentThumb++;
		load_pics(currentThumb);
	}
	checkMaxPage();
}

function back() {
	if (currentThumb > 0)
	{
		currentThumb--;
		load_pics(currentThumb);
	}
	checkMaxPage();
}

function pageLoadEvents()
{
	getMaxPage();
	load_pics(currentThumb);
}

/* The following is a helper function published by Simon Willison */
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  }
  else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(pageLoadEvents);