// Make a POST to the server 
// and pass on any data from browser
// via the XMLHTTPRequest

function talktoServer(){
	
	if (checkCookie())
	{
		cookie_status='set';
	}
	else
	{
		if (isCookieEnabled())
		{
			cookie_status='enabled';
		}
		else
		{
			cookie_status='disabled';
		}			
	}
	
	var req = newXMLHttpRequest();
	//register the callback handler function
  	var callbackHandler = getReadyStateHandler(req, updateMsgOnBrowser);
  	req.onreadystatechange = callbackHandler;
  	req.open("POST", "client_exchange.php?cookie_status=" + cookie_status, true);
  	req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
  	//get the value from the text input element and send it to server
  	var msg_value = ""//testmsg.value;
  	req.send("msg="+msg_value);
}

// This is the callback functions that gets called
// for the response from the server with the XML data

var lastPing = 0;
function updateMsgOnBrowser(testXML) {

	var test = testXML.getElementsByTagName("test")[0];
	var message = testXML.getElementsByTagName("message")[0];
	var ip = testXML.getElementsByTagName("ip")[0];

	var timestamp = test.getAttribute("timestamp");
	if (timestamp > lastPing) {
		lastPing = timestamp;

		var ip_value = ip.firstChild.nodeValue;
		var message_value = message.firstChild.nodeValue;
	//Here comes the server's answer
		var msg_display = document.getElementById("msg_display");
		msg_display.innerHTML =	message_value;
	}
}


//the following two functions are helper infrastructure to 
//create a XMLHTTPRequest and register a listner callback function

function newXMLHttpRequest() {
	var xmlreq = false;
	if (window.XMLHttpRequest) {
		xmlreq = new XMLHttpRequest();
	} else if (window.ActiveXObject) {
    		// Try ActiveX
		try { 
			xmlreq = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e1) { 
			// first method failed 
			try {
				xmlreq = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e2) {
				 // both methods failed 
			} 
		}
 	}
   	return xmlreq;
} 


//Getting status of handler. If status=200 - everthing if fine

function getReadyStateHandler(req, responseXmlHandler) {
	return function () {
	if (req.readyState == 4) {
		if (req.status == 200) {
        		responseXmlHandler(req.responseXML);
		} else {
			var hellomsg = document.getElementById("hellomsg");
			hellomsg.innerHTML = "ERROR: "+ req.status;
      		}
    	}
 	}
}

function setCookie(c_name,value,expiredays)
{
	var exdate=new Date()
	exdate.setDate(exdate.getDate()+expiredays)
	document.cookie=c_name+ "=" +escape(value)+
	((expiredays==null) ? "" : ";expires="+exdate.toGMTString())
}
	
function getCookie(c_name)
{
	if (document.cookie.length>0)
	  {
	  c_start=document.cookie.indexOf(c_name + "=")
	  if (c_start!=-1)
	    { 
	    c_start=c_start + c_name.length+1 
	    c_end=document.cookie.indexOf(";",c_start)
	    if (c_end==-1) c_end=document.cookie.length
	    return unescape(document.cookie.substring(c_start,c_end))
	    } 
	  }
	return ""
}


function checkCookie()
{
	counter_cookie=getCookie('counter_cookie')
	if (counter_cookie!=null && counter_cookie!="")
	{
	    return 1;
	}
	else 
    {
	  	setCookie('counter_cookie', 1, 1);
	  	return 0;
	}
}

function isCookieEnabled()
{
	setCookie('test_cookie', 1, 1);
	test_cookie=getCookie('test_cookie');
	if (test_cookie!=null && test_cookie!="")
	{
  		return 1;
	}
	else 
  	{
    	return 0;
  }
}