var ROTATION_TIME = 6;
var shoppingLinks = [
  {
    'url':    'https://www.petacatalog.org/prodinfo.asp?number=PC193',
    'imgUrl': '/buttons/120-toiletries.jpg',
    'text':   'PETA Recycled Billboard Toiletry Set'
  },
  {
    'url':    'https://www.petacatalog.org/prodinfo.asp?number=PC188',
    'imgUrl': 'buttons/120-lip_balm_set.jpg',
    'text':   'PETA Lip Balms'
  },
  {
    'url':    'https://www.petacatalog.org/prodinfo.asp?number=PC181',
    'imgUrl': 'buttons/120-wallyRazor.jpg',
    'text':   '\'Wally\' Cruelty-Free Razor'
  },
  {}
];
var preloadedImages = [];
var adIndex = 0;
function generateShoppingLink()
{
//  var adIndex = Math.floor(Math.random() * shoppingLinks.length - 1);
  var adHtml = '<a href="'+ shoppingLinks[adIndex].url +'" target="_blank">'+
               '<img src="'+ preloadedImages[adIndex].src +'" border="0" style="border: 1px #ccc solid;" /></a>'+
               '<br /><a href="'+ shoppingLinks[adIndex].url +'" target="_blank">'+
               shoppingLinks[adIndex].text +'</a>';
  document.getElementById('shoppingLinkBlock').innerHTML = adHtml;
}
function rotateShoppingLink()
{
  if (adIndex > shoppingLinks.length - 2)
    adIndex = 0;
  generateShoppingLink();
  adIndex++;
  setTimeout("rotateShoppingLink()", (ROTATION_TIME * 1000));
}
function initShoppingLink()
{
  for (var i = 0; i < shoppingLinks.length; i++)
  {
    if (shoppingLinks[i].imgUrl)
    {
      var img = new Image();
      img.src = shoppingLinks[i].imgUrl;
      preloadedImages[i] = img;
    }
  }
  rotateShoppingLink();
}