jQuery.extend({

	createUploadIframe : function(id, uri){
		//create frame
		var frameId = 'jUploadFrame' + id;
		var io;
		if(window.ActiveXObject){
			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{
			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){
					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{
						$(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{
			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;
    }
});