!function(window){
  var targetWindow = (window.inDapIF) ? window.parent : window;

  function buildPlaceHolder() {
    var placeHolder = document.createElement("div");

    if(window.inDapIF)
      appendToBody(placeHolder);
    else
      insertBeforeScriptTag(placeHolder);

    return placeHolder;
  }

  function appendToBody(placeHolder) {
    document.getElementsByTagName("body")[0].appendChild(placeHolder);
  }

  function insertBeforeScriptTag(placeHolder) {
    var script = document.getElementById("biowebben");
    if(script == null) return;
    var scriptParent = script.parentNode;
    scriptParent.insertBefore(placeHolder, script);
  }

  function buildIframe() {
    var newIframe = document.createElement("iframe");
    newIframe.setAttribute("data-src","http://biowebb-data.s3.amazonaws.com/pages/12/city/56/date/today/index.html");
    newIframe.setAttribute("frameborder","0");
    newIframe.setAttribute("scrolling","no");
    newIframe.setAttribute("width", "980");
    newIframe.setAttribute("height", "1000");
    placeHolder.appendChild(newIframe);
    return newIframe;
  }

  function getParentIframe() {
    var iframes = targetWindow.document.getElementsByTagName("iframe");
    for (var i=0, length = iframes.length; i < length; ++i) {
      var frame = iframes[i];
      if (frame.contentWindow == window) {
        return frame;
      }
    }
  }

  function insertImpressionLink() {
    var image = new Image();
    image.setAttribute("width", 1);
    image.setAttribute("height", 1);
    image.setAttribute("alt", "");
    image.setAttribute("src", "//de17a.com/a/57409.counter?tags=3376.1x1,3357.262x75,3932.122x146,3330.122x146,4087.122x146,3737.122x146,4089.262x344,4099.262x344,3734.262x344,3868.262x344");
    placeHolder.appendChild(image);
  }

  function addEventListener(evt, fn){
    targetWindow.addEventListener
      ? targetWindow.addEventListener(evt, fn, false)
      : (targetWindow.attachEvent)
      ? targetWindow.attachEvent('on' + evt, fn)
      : targetWindow['on' + evt] = fn;
  };

  function loadIframe (el) {
    var dataSrc = el.getAttribute("data-src");
    if(dataSrc != el.src)
      el.src = dataSrc;
  }

  function isElementInViewport(el, offsetTop) {
    offsetTop = parseInt(offsetTop,10)||0;
    var rect = el.getBoundingClientRect();
    return (rect.top >= 0 && rect.left >= 0 && rect.top+offsetTop <= (targetWindow.innerHeight || targetWindow.document.documentElement.clientHeight))
  }

  var placeHolder = buildPlaceHolder();
  insertImpressionLink();
  iframe = buildIframe();
  targetIframe = (window.inDapIF) ? getParentIframe() : iframe;
  var offsetTop = "-300px";
  var processScroll = function(){
    if (isElementInViewport(targetIframe, offsetTop)) {
      loadIframe(iframe);
    }
  };
  processScroll();
  addEventListener('scroll',processScroll);
}(this);