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=$('<form method="POST" name="'+formId+'" id="'+formId+'" enctype="multipart/form-data"></form>');
		var oldElement=$('#'+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();
						$(form).remove();	
					}catch(e){
						jQuery.handleError(s, xml, null, e);
					}
				}, 100);
				xml=null;
			}
		}
		// Timeout checker
		if(s.timeout>0){
			setTimeout(function(){
				// Check to see if the request is still happening
				if(!requestDone)uploadCallback("timeout");
			}, s.timeout);
		}
		try{
			// var io=$('#'+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;
	}
})