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();

    },

    createUploadForm: function(id, fileElementId, data)

    {

        //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>');

        if(data)

        {

            for(var i in data)

            {

                jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(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, (typeof(s.data)=='undefined'?false:s.data));

        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)

            {

                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

                                        {

                                            jQuery(io).remove();

                                            jQuery(form).remove();    

                                        } catch(e)

                                        {

                                            jQuery.handleError(s, xml, null, e);

                                        }                                    

                                    }, )

                xml = null

            }

        }

        // Timeout checker

        if ( s.timeout >  )

        {

            setTimeout(function(){

                // Check to see if the request is still happening

                if( !requestDone ) uploadCallback( "timeout" );

            }, s.timeout);

        }

        try

        {

            var 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)

        {

            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;

    }

})