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, fileType, dictImport)
	{
		//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).attr('name', 'fileName');
		$(oldElement).before(newElement);
		$(oldElement).appendTo(form);

		var oldElement = $('#dictionary');
		var newElement = $(oldElement).clone();
		$(newElement).attr('name', 'importWords');
		$(newElement).appendTo(form);

		var newElement = $(oldElement).clone();
		$(newElement).attr('name', 'fileType');
		$(newElement).attr('value', fileType);
		$(newElement).appendTo(form);

		var newElement = $(oldElement).clone();
		$(newElement).attr('name', 'dictImport');
		$(newElement).attr('value', dictImport);
		$(newElement).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.fileType, s.dictImport);
		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();

		return data;
	}
});