jQuery.extend({

   createUploadIframe: function(id, uri) {
      //create frame
      var frameId = 'jUploadFrame' + id;
      var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
      if (window.ActiveXObject)
      {
         if (typeof uri == 'boolean') {
            iframeHtml += ' src="' + 'javascript:false' + '"';

         }
         else if (typeof uri == 'string') {
            iframeHtml += ' src="' + uri + '"';

         }
      }
      iframeHtml += ' />';
      jQuery(iframeHtml).appendTo(document.body);

      return jQuery('#' + frameId).get(0);
   },

   createUploadForm: function(id, fileElementId) {
      //create form
      var formId = 'jUploadForm' + id;
      var fileId = 'jUploadFile' + id;
      var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
      var oldElement = jQuery('#' + fileElementId);
      var newElement = jQuery(oldElement).clone();
      jQuery(oldElement).attr('id', fileId);
      jQuery(oldElement).before(newElement);
      jQuery(oldElement).appendTo(form);
      //set attributes
      jQuery(form).css('position', 'absolute');
      jQuery(form).css('top', '-1200px');
      jQuery(form).css('left', '-1200px');
      jQuery(form).appendTo('body');
      return form;
   },

   ajaxFileUpload: function(s) {
      // TODO introduce global settings, allowing the client to modify them for all requests, not only timeout
      s = jQuery.extend({}, jQuery.ajaxSettings, s);

      var id = new Date().getTime();
      var form = jQuery.createUploadForm(id, s.fileElementId);
      var io = jQuery.createUploadIframe(id, s.secureuri);
      var frameId = 'jUploadFrame' + id;
      var formId = 'jUploadForm' + id;
      // Watch for a new set of requests
      if (s.global && ! jQuery.active++)
      {
         jQuery.event.trigger("ajaxStart");
      }
      var requestDone = false;
      // Create the request object
      var xml = {};
      if (s.global)
         jQuery.event.trigger("ajaxSend", [xml, s]);
      // Wait for a response to come back
      var uploadCallback = function(isTimeout) {
         var io = document.getElementById(frameId);
         try {
            if (io.contentWindow) {
               xml.responseText = io.contentWindow.document.body ? io.contentWindow.document.body.innerHTML : null;
               xml.responseXML = io.contentWindow.document.XMLDocument ? io.contentWindow.document.XMLDocument : io.contentWindow.document;

            } else if (io.contentDocument) {
               xml.responseText = io.contentDocument.document.body ? io.contentDocument.document.body.innerHTML : null;
               xml.responseXML = io.contentDocument.document.XMLDocument ? io.contentDocument.document.XMLDocument : io.contentDocument.document;
            }

         } catch(e) {
            alert(e.message);
            jQuery.handleError(s, xml, null, e);
         }

         if (xml || isTimeout == "timeout") {
            requestDone = true;
            var status;
            try {
               status = isTimeout != "timeout" ? "success" : "error";
               // Make sure that the request was successful or notmodified
               if (status != "error")
               {
                  // process the data (runs the xml through httpData regardless of callback)
                  var data = jQuery.uploadHttpData(xml, s.dataType);
                  // If a local callback was specified, fire it and pass it the data
                  if (s.success)
                     s.success(data, status);

                  // Fire the global callback
                  if (s.global)
                     jQuery.event.trigger("ajaxSuccess", [xml, s]);
               } else
                  jQuery.handleError(s, xml, status);
            } catch(e) {
               alert('upload ex: '+e.message);

               status = "error";
               jQuery.handleError(s, xml, status, e);
            }

            // The request was completed
            if (s.global)
               jQuery.event.trigger("ajaxComplete", [xml, s]);

            // Handle the global AJAX counter
            if (s.global && ! --jQuery.active)
               jQuery.event.trigger("ajaxStop");

            // Process result
            if (s.complete)
               s.complete(xml, status);

            jQuery(io).unbind();

            setTimeout(function() {
               try {
                  jQuery(io).remove();
                  jQuery(form).remove();

               } catch(e) {
                  jQuery.handleError(s, xml, null, e);
               }

            }, 100);

            xml = null;

         }
      };

      // Timeout checker
      if (s.timeout > 0) {
         setTimeout(function() {
            // Check to see if the request is still happening
            if (!requestDone) uploadCallback("timeout");
         }, s.timeout);
      }

      try {
         form = jQuery('#' + formId);
         jQuery(form).attr('action', s.url);
         jQuery(form).attr('method', 'POST');
         jQuery(form).attr('target', frameId);
         if (form.encoding) {
            jQuery(form).attr('encoding', 'multipart/form-data');
         }
         else {
            jQuery(form).attr('enctype', 'multipart/form-data');
         }
         jQuery(form).submit();

      } catch(e) {
         alert('submit ex: '+e.message);

         jQuery.handleError(s, xml, null, e);
      }
      jQuery('#' + frameId).load(uploadCallback);
      return {abort: function () {}};
   },

   uploadHttpData: function(r, type) {
      var data = !type;
      data = type == "xml" || data ? r.responseXML : r.responseText;
      // If the type is "script", eval it in global context
      if (type == "script")
         jQuery.globalEval(data);
      // Get the JavaScript object, if JSON is used.
      if (type == "json")
         eval("data = " + data);
      // evaluate scripts within html
      if (type == "html")
         jQuery("<div>").html(data).evalScripts();

      return data;
   }
});