jQuery(function($) {
  var SERVICES = {
    'twitpic.com': function(path) {
      var code = path.match(/\/([a-zA-Z0-9]+)/)[1];

      return "http://twitpic.com/show/thumb/" + code;
    }
  };

  var expression = $.keys(SERVICES).join('|');
  var imageLinks = $("a[href*='" + expression + "']");

  function findService(hostname) {
    $.each($.keys(SERVICES), function(i, service) {
      if (hostname.indexOf(service) > 0)
        return service;
    });
  }

  function showImage(link) {
    var service = findService(link.host);
    var thumbnailURL = SERVICES[service](link.pathname);

    var img = new Image();
    img.src = thumbnailURL;
    img.onload = function() {
      $(this.element).parents('div.tweet').find('.imagebin').append(img);
    }
  }

  $(document).onscroll(function() {
    $.each(imageLinks, function(link) {
      if ((window.scrollY + window.innerHeight + 100) >= $(link).offset().top)
        showImage(link);
    })
  });
});