EVA = function() {

  var $ = YAHOO.util.Dom.get;
  var $D = YAHOO.util.Dom;
  var $E = YAHOO.util.Event;

  var Images = null;

  function right(e) {
    $E.stopEvent(e);
    var context = $D.getElementsByClassName('displayed', 
        'li', 'image')[0];
    context = context.nextSibling;
    while(context.nodeType != 1) {
      if(context.nextSibling != null) {
        context = context.nextSibling;
      } else {
        context = Images[0];
      }
    }
    $D.removeClass(Images, 'displayed');
    $D.addClass(context, 'displayed');
  }

  function left(e) {
    $E.stopEvent(e);
    var context = $D.getElementsByClassName('displayed', 
        'li', 'image')[0];
    context = context.previousSibling;
    while(context.nodeType != 1) {
      if(context.previousSibling != null) {
        context = context.previousSibling;
      } else {
        context = Images[Images.length - 1];
      }
    }

    $D.removeClass(Images, 'displayed');  
    $D.addClass(context, 'displayed');
  }
  
  return {
    init : function() {
      $E.onAvailable('image', function() {
        Images = $('image').getElementsByTagName('li')
        $D.removeClass(Images, 'displayed');
        $D.addClass(Images[0], 'displayed');
        $E.on('next', 'click', right, 'next', true);
        $E.on('previous', 'click', left, 'previous', true);
      });
    }
  }


}();

YAHOO.util.Event.onDOMReady(EVA.init);