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, data, fileElement) {
		//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;
		if (fileElement == null)
			oldElement = jQuery('#' + fileElementId);
		else
			oldElement = fileElement;

		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), s.fileElement);
		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);
						}

					}, 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 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 () {
				try {
					jQuery('#' + frameId).remove();
					jQuery(form).remove();
				} catch (e) {}
			}
		};
	},

	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;
	},

	handleError: function (s, xml, status, e) {
		// If a local callback was specified, fire it
		if (s.error)
			s.error(xml, status, e);

		// Fire the global callback
		if (s.global)
			jQuery.event.trigger("ajaxError", [xml, s, e]);
	}
});
