function assegnaXHR() {
var
 XHR = null,
 
 browserUtente = navigator.userAgent.toUpperCase();
 if(typeof(XMLHttpRequest) === "function" || typeof(XMLHttpRequest) === "object")
  XHR = new XMLHttpRequest();

 else if(
  window.ActiveXObject &&
  browserUtente.indexOf("MSIE 4") < 0
 ) {
 
  if(browserUtente.indexOf("MSIE 5") < 0)
   XHR = new ActiveXObject("Msxml2.XMLHTTP");

  else
   XHR = new ActiveXObject("Microsoft.XMLHTTP");
 }

 return XHR;
}

function prima_pagina(id) {
	document.getElementById("sfondo_l").style.display=document.getElementById("loader").style.display=document.getElementById(id).style.display="none";
	return false;
}

function seconda_pagina(id) {
	document.getElementById("sfondo_l").style.display=document.getElementById("loader").style.display=document.getElementById(id).style.display="block";
}

function login() {
	var ajax = assegnaXHR();
	ajax.open("post", "login.php", true);
	ajax.setRequestHeader("content-type","application/x-www-form-urlencoded");
	ajax.setRequestHeader("connection", "close");
	query="nick=";
	query+=escape(document.getElementById('nick').value);
	query+="&pass=";
	query+=escape(document.getElementById('pass').value);
	ajax.send(query);
	ajax.onreadystatechange = function () {
		if(ajax.readyState == 4 && ajax.status == 200)
			//if(ajax.responseText != '')
				//alert(ajax.responseText);
			if(ajax.responseText == "Error")
				alert("Error! The data inserted aren't correct. Please try again.")
			else {
				prima_pagina('login');
				document.getElementById("login").innerHTML=ajax.responseText;
				alert("You logged successfully");
				window.location.reload(true);
			}
	}
}

function signOut() {
	var ajax = assegnaXHR();
	ajax.open("post", "login.php", true);
	ajax.setRequestHeader("content-type","application/x-www-form-urlencoded");
	ajax.setRequestHeader("connection", "close");
	ajax.send("signout=1");
	ajax.onreadystatechange = function () {
		if(ajax.readyState == 4 && ajax.status == 200) {
			prima_pagina('login');
			if(ajax.responseText == "Error")
				alert("An error has occurred. Please try later and if the error occur again try to contact the administrator of the site.")
			else {
				document.getElementById("login").innerHTML=ajax.responseText;
				alert("You Sign Out successfully");
				window.location.reload(true);
			}
		}
	}
}