var xmlHttp

function CreateXmlHttpObject()
{
  var xmlHttp=null;
  try
  {
    // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
  }
  catch (e)
  {
    // Internet Explorer, pochwa se ot nai-wisokata wersiq na XMLHTTP bibliotekata
    //Ako zaredish po-wisoka biblioteka imash shans da ti dade korektno saobshtenie pri wazniknala
    //greshka, a ako zaredish po-niska biblioteka poluchawash nqkakwo hamawo saobshtenie.
    //Za primer - sas zaredena biblioteka Msxml2.XMLHTTP.4.0  (IE 6.0.2900.2180) dawa choweshko saobshte-
    //nie: "system does not support the specified encoding", a ako w sorsa ostawq samo da se zarevda
    //Msxml2.XMLHTTP dawa nqkakwo hamawo saobshtenie za greshka: "System error 1072896658"
    //Msxml2.XMLHTTP.5.0 predpolagam che e za IE7 (za towa pri men na IE6 se zarevda max Msxml2.XMLHTTP.4.0)
    try
    {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP.5.0");
      //alert("Zaredena XMLHTTP.5.0 biblioteka");
    }
    catch (e)
    {

      try
      {
        xmlHttp=new ActiveXObject("Msxml2.XMLHTTP.4.0");
        //alert("Zaredena XMLHTTP.4.0 biblioteka");
      }
      catch (e)
      {

        try
        {
          xmlHttp=new ActiveXObject("Msxml2.XMLHTTP.3.0");
          //alert("Zaredena XMLHTTP.3.0 biblioteka");
        }
        catch (e)
        {

          try
          {
            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
            //alert("Zaredena Msxml2.XMLHTTP biblioteka");
          }
          catch (e)
          {
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
            //alert("Zaredena Microsoft.XMLHTTP biblioteka");
          }

        }

      }

    }

  }
  return xmlHttp;
}


function stateChanged()
{
  if (xmlHttp.readyState==4)
  {
    //alert('Uspeh1');
    if (xmlHttp.status == 200)
    {
      //alert('Uspeh2');
      //document.getElementById("username_check").innerHTML=xmlHttp.responseText;


       //var xmlDoc=xmlHttp.responseXML.documentElement;
       var xmlDoc=xmlHttp.responseXML;
       //document.getElementById("username_check").innerHTML=xmlDoc.getElementsByTagName("root")[0].childNodes[0].nodeValue;

       var user_exist=xmlDoc.getElementsByTagName("root")[0].childNodes[0].nodeValue;
       if (user_exist==0)
       {
         document.getElementById("username_check").innerHTML='<font color="green">Е-мейла е свободен за регистрация.</font>';
       }
       else
       {
         document.getElementById("username_check").innerHTML='<font color="red">Е-мейла е зает ! Вече съществува потребител, регистрирал се през този е-мейл !</font>';
       };


      /*
       document.ajax.dyn.value="Received:" + req.responseText;

       //Zapiswa rezultata w Div-a
       document.getElementById("zone").innerHTML = "Received:" + req.responseText;

       //To get data from XML
       var doc = req.responseXML;   // Assign the XML file to a var
       var element = doc.getElementsByTagName('root').item(0);   // Read the first element
       document.ajax.dyn.value= element.firstChild.data;    // Assign the content to the form
      */

      /*
       //To get data from XML
       var doc = xmlHttp.responseXML;   // Assign the XML file to a var
       var element = doc.getElementsByTagName('root').item(0);   // Read the first element
       document.getElementById("username_check").innerHTML= element.firstChild.data;    // Assign the content to the form
      */
    }
    else
    {
      //alert('Greshka');
      //document.ajax.dyn.value="Error: returned status code " + req.status + " " + req.statusText;
      document.getElementById("username_check").innerHTML="Грешка: върнат код на грешката " + xmlHttp.status + " " + xmlHttp.statusText;
    }
  }
}


function CheckUsernameReg(str,ur)
{
  if (str.length==0)
  {
    document.getElementById("username_check").innerHTML="";
    return;
  }

  xmlHttp=CreateXmlHttpObject();

  if (xmlHttp==null)
  {
    //alert ("Вашият браузър е не поддържа AJAX! По всяка вероятност разполагате със стара версия на браузъра си !");
    //alert ("Your browser does not support AJAX !");
    return;
  }

  //za on-line registratsiqta
  if (ur=="")
  {
    var url="users_new_registration_check_user.php";
    url=url+"?user="+str;
    url=url+"&sid="+Math.random(); //zaradi keshiraniqta - da se predotwratqt
  }
  else  //za registratsiqta po poshtata
  {
    var url="post_new_registration_check_user.php";
    url=url+"?user="+str;
    url=url+"&u="+ur;  //towa e samo za registratsiqta po poshtata - towa e uroka. Za drugata reg. e samo izlishen parametar
    url=url+"&sid="+Math.random(); //zaradi keshiraniqta - da se predotwratqt
  };

  xmlHttp.onreadystatechange=stateChanged;


  //url='err1.xml'; //wremenno
  xmlHttp.open("GET",url,true);
  xmlHttp.send(null);

  /*
  xmlHttp.open("POST", "gethint.php", true);
  xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
  xmlHttp.send(str);
  */

}