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, ms)
	{
		//create form
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;		
		var msh = '';
		if( ms!==undefined && ms!==null && ms>0 && ms<20 )
			msh = '<input type="hidden" name="MAX_FILE_SIZE" value="'+(ms*1024*1024)+'" />';
		var form = $('<form action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data">'+msh+'</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, s.maxsize );
		
		// Extra params goes to get
		if( s.addparams!==undefined && s.addparams!==null  && s.addparams!== '' )
		{
			var frs = ( s.url.indexOf('?') >= 0 ) ? '&' : '?';
			for(var ah in s.addparams)
			{
				s.url += frs + ah + '=' + escape( s.addparams[ah] );
				frs = '&';
			}
		}		
		
		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 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;
		
		try
		{
			// 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();
		}
		
		catch(e)
		{
			data.error = e.name + ':' + e.message;
			data.msg   = '';			
		}
		
		return data;
	}
});