/**
 * Совместимость с IE6.
 */
if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(elt /*, from*/) {
    var len = this.length;
    var from = Number(arguments[1]) || 0;
    from = (from < 0) ? Math.ceil(from) : Math.floor(from);
    if (from < 0) from += len;

    for (; from < len; from++) {
      if (from in this && this[from] === elt) return from;
    }
    return -1;
  };
}

jQuery(document).ready(function()
{
  var bannersList = [], bannersParent = [];

  /**
   * Функция ротации баннеров.
   * Меняет разом все баннеры во всех блоках.
   */
  function rotateBanner() {
    var banList = [], previous = 0, nextbx = 0;

    for(var px in bannersParent)
    {
      banList = bannersList[px];
      if (1 == banList.length) continue;

      for(var bx in banList)
      {
        if ('function' != typeof(banList[bx].css)) continue;
        if ('block' == banList[bx].css('display')) { previous = bx; }        
        //banList[bx].css('display', 'none');
      }

      banList[previous].animate(
        { opacity: "0.1" },
        {
          easing: 'swing',
          duration: 400,
          complete: function(){
            for(var bx in banList)
            {
              if ('function' != typeof(banList[bx].css)) continue;
              banList[bx].css('display', 'none');
            }

            if (2 < banList.length)
            {
              do {
                nextbx = Math.floor(Math.random() * banList.length);
              }
              while (previous == nextbx);
            }
            else {
              for(bx in banList)
              {
                if (bx != previous)
                { 
                  nextbx = bx;
                  break;
                }
              }
            }

            banList[nextbx].css('display', 'block');
          }
        }
      );

      banList[previous].animate({ opacity: "1" }, 1);
    }

    delete banList, previous, nextbx;
  }

  /**
   * Формируем списки баннеров
   * относительно их родительских блоков.
   */
  jQuery('.ban_rotator').each(function(ix, val) {
    var parent = jQuery(this).parent();
    var parent_uq = parent.get(0).tagName + parent.attr('class') + parent.attr('id');
    var kp = bannersParent.indexOf(parent_uq);

    if (-1 == kp)
    {
      kp = bannersParent.length;
      bannersParent.push(parent_uq);
      bannersList[kp] = [];
    }

    bannersList[kp].push(jQuery(this));
  });

  if (0 < bannersList.length)
  {
    setInterval(rotateBanner, 4000);
  }
});