$(document).ready(function() {
  var z = 0;
  var inAnimation = false;
  
  $('#pictures img').each(function() {
    z++;
    $(this).css('z-index', z);
  });

  function swapFirstLast(isFirst) {
    if(inAnimation) return false;
    else inAnimation = true;
    
    var processZindex, direction, newZindex, inDeCrease;
    
    if(isFirst) { processZindex = z; direction = '-'; newZindex = 1; inDeCrease = 1; }
    else { processZindex = 1; direction = ''; newZindex = z; inDeCrease = -1; }
    
    $('#pictures img').each(function() {
      if($(this).css('z-index') == processZindex) {
        $(this).animate({ 'top' : direction + $(this).height() + 'px' }, 'slow', function() {
          $(this).css('z-index', newZindex)
            .animate({ 'top' : '0' }, 'slow', function() {
              inAnimation = false;
            });
        });
      } else {
        $(this).animate({ 'top' : '0' }, 'slow', function() {
          $(this).css('z-index', parseInt($(this).css('z-index')) + inDeCrease);
        });
      }
    });
    
    return false;
  }
  
  $('#next a').click(function() {
    return swapFirstLast(true);
  });
  
  $('#prev a').click(function() {
    return swapFirstLast(false);
  });

	setInterval(function() {
		swapFirstLast(true);
	}, 8000);
});