/**
 * Copyright (c) 2006-2015, JGraph Ltd
 * Copyright (c) 2006-2015, Gaudenz Alder
 */
/**
 * Class: mxXmlRequest
 * 
 * XML HTTP request wrapper. See also: <mxUtils.get>, <mxUtils.post> and
 * <mxUtils.load>. This class provides a cross-browser abstraction for Ajax
 * requests.
 * 
 * Encoding:
 * 
 * For encoding parameter values, the built-in encodeURIComponent JavaScript
 * method must be used. For automatic encoding of post data in <mxEditor> the
 * <mxEditor.escapePostData> switch can be set to true (default). The encoding
 * will be carried out using the conte type of the page. That is, the page
 * containting the editor should contain a meta tag in the header, eg.
 * <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 * 
 * Example:
 * 
 * (code)
 * var onload = function(req)
 * {
 *   mxUtils.alert(req.getDocumentElement());
 * }
 * 
 * var onerror = function(req)
 * {
 *   mxUtils.alert('Error');
 * }
 * new mxXmlRequest(url, 'key=value').send(onload, onerror);
 * (end)
 * 
 * Sends an asynchronous POST request to the specified URL.
 * 
 * Example:
 * 
 * (code)
 * var req = new mxXmlRequest(url, 'key=value', 'POST', false);
 * req.send();
 * mxUtils.alert(req.getDocumentElement());
 * (end)
 * 
 * Sends a synchronous POST request to the specified URL.
 * 
 * Example:
 * 
 * (code)
 * var encoder = new mxCodec();
 * var result = encoder.encode(graph.getModel());
 * var xml = encodeURIComponent(mxUtils.getXml(result));
 * new mxXmlRequest(url, 'xml='+xml).send();
 * (end)
 * 
 * Sends an encoded graph model to the specified URL using xml as the
 * parameter name. The parameter can then be retrieved in C# as follows:
 * 
 * (code)
 * string xml = HttpUtility.UrlDecode(context.Request.Params["xml"]);
 * (end)
 * 
 * Or in Java as follows:
 * 
 * (code)
 * String xml = URLDecoder.decode(request.getParameter("xml"), "UTF-8").replace("\n", "&#xa;");
 * (end)
 *
 * Note that the linefeeds should only be replaced if the XML is
 * processed in Java, for example when creating an image.
 * 
 * Constructor: mxXmlRequest
 * 
 * Constructs an XML HTTP request.
 * 
 * Parameters:
 * 
 * url - Target URL of the request.
 * params - Form encoded parameters to send with a POST request.
 * method - String that specifies the request method. Possible values are
 * POST and GET. Default is POST.
 * async - Boolean specifying if an asynchronous request should be used.
 * Default is true.
 * username - String specifying the username to be used for the request.
 * password - String specifying the password to be used for the request.
 */
function mxXmlRequest(url, params, method, async, username, password)
{
	this.url = url;
	this.params = params;
	this.method = method || 'POST';
	this.async = (async != null) ? async : true;
	this.username = username;
	this.password = password;
};

/**
 * Variable: url
 * 
 * Holds the target URL of the request.
 */
mxXmlRequest.prototype.url = null;

/**
 * Variable: params
 * 
 * Holds the form encoded data for the POST request.
 */
mxXmlRequest.prototype.params = null;

/**
 * Variable: method
 * 
 * Specifies the request method. Possible values are POST and GET. Default
 * is POST.
 */
mxXmlRequest.prototype.method = null;

/**
 * Variable: async
 * 
 * Boolean indicating if the request is asynchronous.
 */
mxXmlRequest.prototype.async = null;

/**
 * Variable: binary
 * 
 * Boolean indicating if the request is binary. This option is ignored in IE.
 * In all other browsers the requested mime type is set to
 * text/plain; charset=x-user-defined. Default is false.
 */
mxXmlRequest.prototype.binary = false;

/**
 * Variable: withCredentials
 * 
 * Specifies if withCredentials should be used in HTML5-compliant browsers. Default is
 * false.
 */
mxXmlRequest.prototype.withCredentials = false;

/**
 * Variable: username
 * 
 * Specifies the username to be used for authentication.
 */
mxXmlRequest.prototype.username = null;

/**
 * Variable: password
 * 
 * Specifies the password to be used for authentication.
 */
mxXmlRequest.prototype.password = null;

/**
 * Variable: request
 * 
 * Holds the inner, browser-specific request object.
 */
mxXmlRequest.prototype.request = null;

/**
 * Variable: decodeSimulateValues
 * 
 * Specifies if request values should be decoded as URIs before setting the
 * textarea value in <simulate>. Defaults to false for backwards compatibility,
 * to avoid another decode on the server this should be set to true.
 */
mxXmlRequest.prototype.decodeSimulateValues = false;

/**
 * Function: isBinary
 * 
 * Returns <binary>.
 */
mxXmlRequest.prototype.isBinary = function()
{
	return this.binary;
};

/**
 * Function: setBinary
 * 
 * Sets <binary>.
 */
mxXmlRequest.prototype.setBinary = function(value)
{
	this.binary = value;
};

/**
 * Function: getText
 * 
 * Returns the response as a string.
 */
mxXmlRequest.prototype.getText = function()
{
	return this.request.responseText;
};

/**
 * Function: isReady
 * 
 * Returns true if the response is ready.
 */
mxXmlRequest.prototype.isReady = function()
{
	return this.request.readyState == 4;
};

/**
 * Function: getDocumentElement
 * 
 * Returns the document element of the response XML document.
 */
mxXmlRequest.prototype.getDocumentElement = function()
{
	var doc = this.getXml();
	
	if (doc != null)
	{
		return doc.documentElement;
	}
	
	return null;
};

/**
 * Function: getXml
 * 
 * Returns the response as an XML document. Use <getDocumentElement> to get
 * the document element of the XML document.
 */
mxXmlRequest.prototype.getXml = function()
{
	var xml = this.request.responseXML;
	
	// Handles missing response headers in IE, the first condition handles
	// the case where responseXML is there, but using its nodes leads to
	// type errors in the mxCellCodec when putting the nodes into a new
	// document. This happens in IE9 standards mode and with XML user
	// objects only, as they are used directly as values in cells.
	if (document.documentMode >= 9 || xml == null || xml.documentElement == null)
	{
		xml = mxUtils.parseXml(this.request.responseText);
	}
	
	return xml;
};

/**
 * Function: getText
 * 
 * Returns the response as a string.
 */
mxXmlRequest.prototype.getText = function()
{
	return this.request.responseText;
};

/**
 * Function: getStatus
 * 
 * Returns the status as a number, eg. 404 for "Not found" or 200 for "OK".
 * Note: The NS_ERROR_NOT_AVAILABLE for invalid responses cannot be cought.
 */
mxXmlRequest.prototype.getStatus = function()
{
	return this.request.status;
};

/**
 * Function: create
 * 
 * Creates and returns the inner <request> object.
 */
mxXmlRequest.prototype.create = function()
{
	if (window.XMLHttpRequest)
	{
		return function()
		{
			var req = new XMLHttpRequest();
			
			// TODO: Check for overrideMimeType required here?
			if (this.isBinary() && req.overrideMimeType)
			{
				req.overrideMimeType('text/plain; charset=x-user-defined');
			}

			return req;
		};
	}
	else if (typeof(ActiveXObject) != 'undefined')
	{
		return function()
		{
			// TODO: Implement binary option
			return new ActiveXObject('Microsoft.XMLHTTP');
		};
	}
}();

/**
 * Function: send
 * 
 * Send the <request> to the target URL using the specified functions to
 * process the response asychronously.
 * 
 * Note: Due to technical limitations, onerror is currently ignored.
 * 
 * Parameters:
 * 
 * onload - Function to be invoked if a successful response was received.
 * onerror - Function to be called on any error.
 * timeout - Optional timeout in ms before calling ontimeout.
 * ontimeout - Optional function to execute on timeout.
 */
mxXmlRequest.prototype.send = function(onload, onerror, timeout, ontimeout)
{
	this.request = this.create();
	
	if (this.request != null)
	{
		if (onload != null)
		{
			this.request.onreadystatechange = mxUtils.bind(this, function()
			{
				if (this.isReady())
				{
					onload(this);
					this.request.onreadystatechaange = null;
				}
			});
		}

		this.request.open(this.method, this.url, this.async,
			this.username, this.password);
		this.setRequestHeaders(this.request, this.params);
		
		if (window.XMLHttpRequest && this.withCredentials)
		{
			this.request.withCredentials = 'true';
		}
		
		if (!mxClient.IS_QUIRKS && (document.documentMode == null || document.documentMode > 9) &&
			window.XMLHttpRequest && timeout != null && ontimeout != null)
		{
			this.request.timeout = timeout;
			this.request.ontimeout = ontimeout;
		}
				
		this.request.send(this.params);
	}
};

/**
 * Function: setRequestHeaders
 * 
 * Sets the headers for the given request and parameters. This sets the
 * content-type to application/x-www-form-urlencoded if any params exist.
 * 
 * Example:
 * 
 * (code)
 * request.setRequestHeaders = function(request, params)
 * {
 *   if (params != null)
 *   {
 *     request.setRequestHeader('Content-Type',
 *             'multipart/form-data');
 *     request.setRequestHeader('Content-Length',
 *             params.length);
 *   }
 * };
 * (end)
 * 
 * Use the code above before calling <send> if you require a
 * multipart/form-data request.   
 */
mxXmlRequest.prototype.setRequestHeaders = function(request, params)
{
	if (params != null)
	{
		request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	}
};

/**
 * Function: simulate
 * 
 * Creates and posts a request to the given target URL using a dynamically
 * created form inside the given document.
 * 
 * Parameters:
 * 
 * docs - Document that contains the form element.
 * target - Target to send the form result to.
 */
mxXmlRequest.prototype.simulate = function(doc, target)
{
	doc = doc || document;
	var old = null;

	if (doc == document)
	{
		old = window.onbeforeunload;		
		window.onbeforeunload = null;
	}
			
	var form = doc.createElement('form');
	form.setAttribute('method', this.method);
	form.setAttribute('action', this.url);

	if (target != null)
	{
		form.setAttribute('target', target);
	}

	form.style.display = 'none';
	form.style.visibility = 'hidden';
	
	var pars = (this.params.indexOf('&') > 0) ?
		this.params.split('&') :
		this.params.split();

	// Adds the parameters as textareas to the form
	for (var i=0; i<pars.length; i++)
	{
		var pos = pars[i].indexOf('=');
		
		if (pos > 0)
		{
			var name = pars[i].substring(0, pos);
			var value = pars[i].substring(pos+1);
			
			if (this.decodeSimulateValues)
			{
				value = decodeURIComponent(value);
			}
			
			var textarea = doc.createElement('textarea');
			textarea.setAttribute('wrap', 'off');
			textarea.setAttribute('name', name);
			mxUtils.write(textarea, value);
			form.appendChild(textarea);
		}
	}
	
	doc.body.appendChild(form);
	form.submit();
	
	if (form.parentNode != null)
	{
		form.parentNode.removeChild(form);
	}

	if (old != null)
	{		
		window.onbeforeunload = old;
	}
};
