jQuery.extend({
  createUploadIframe: function(id, uri) {
    //create frame
    var frameId = 'jUploadFrame' + id;
    if (window.ActiveXObject) {
      var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
      if (typeof uri== 'boolean') {
        io.src = 'javascript:false';
      } else if (typeof uri== 'string') {
        io.src = uri;
      }
    } else {
      var io = document.createElement('iframe');
      io.id = frameId;
      io.name = frameId;
    }
    io.style.position = 'absolute';
    io.style.top = '-1000px';
    io.style.left = '-1000px';
    document.body.appendChild(io);
    return io
  },

  createUploadForm: function(id, fileElementId) {
    //create form
    var formId = 'jUploadForm' + id;
    var fileId = 'jUploadFile' + id;
    var form = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
    var oldElement = $('#' + fileElementId);
    var newElement = $(oldElement).clone();
    $(oldElement).attr('id', fileId);
    $(oldElement).before(newElement);
    $(oldElement).appendTo(form);
    //set attributes
    $(form).css('position', 'absolute');
    $(form).css('top', '-1200px');
    $(form).css('left', '-1200px');
    $(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) {alert('gg');
          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;
        }*/
        
          xml.responseText = '"OK"';
          xml.responseXML  = '"OK"';
      } catch(e) {
        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) {
          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 {
              $(io).remove();
              $(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 {
      // var io = $('#' + frameId);
      var form = $('#' + formId);
      $(form).attr('action', s.url);
      $(form).attr('method', 'POST');
      $(form).attr('target', frameId);
      if (form.encoding) {
        form.encoding = 'multipart/form-data';
      } else {
        form.enctype = 'multipart/form-data';
      }
      $(form).submit();

    } catch(e) {
      jQuery.handleError(s, xml, null, e);
    }
    if (window.attachEvent) {
      document.getElementById(frameId).attachEvent('onload', uploadCallback);
    } else {
      document.getElementById(frameId).addEventListener('load', uploadCallback, false);
    }
    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();
    }
    //alert($('param', data).each(function(){alert($(this).attr('value'));}));
    return data;
  }
})