var xmlhttp = null;

var checkLoginTimeout = null;

function checkLoginAvailability( login ) {

	clearTimeout( checkLoginTimeout );
	setTimeout( "checkLoginAvailabilityRaw( '" + login + "' )", 1000 );
	
}

function checkLoginAvailabilityRaw( login ) {

	login = login.replace( /^\s+/g, "" );// strip leading
	login = login.replace( /\s+$/g, "" );// strip trailing

	if( login.length < 1 ) {
		displayLoginAvailability( -1 );
		return;
	}
	
	var sURL = "ajax_check_login_availability.php";
	var sQueryString = 'u=' + login;

	if (window.XMLHttpRequest) {// code for Mozilla, Safari, etc
		xmlhttp=new XMLHttpRequest();
		xmlhttp.onreadystatechange=handleCheckLoginAvailability;
		xmlhttp.open("POST",sURL,true);
		xmlhttp.setRequestHeader('content-type', 'application/x-www-form-urlencoded');
		xmlhttp.send(sQueryString);
	} else if (window.ActiveXObject) {//IE
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
		if (xmlhttp) {
			xmlhttp.onreadystatechange=handleCheckLoginAvailability;
			xmlhttp.open("POST",sURL,true);
			xmlhttp.setRequestHeader('content-type', 'application/x-www-form-urlencoded');
			xmlhttp.send(sQueryString);
		}
	}
}

function handleCheckLoginAvailability () {
	if( !xmlhttp ) { return }
	if (xmlhttp.readyState==4) {
		if (xmlhttp.status==200) {
			var oXML;
			oXML = xmlhttp.responseXML;

			var oRedirect = oXML.getElementsByTagName("redirect").item(0);
			if (oRedirect) {
				self.location = oRedirect.getAttribute("url");
			} else {
				var oError = oXML.getElementsByTagName("e").item(0);
				if (oError) {
					alert (oError.getAttribute("m"));
				} else {
               var available = oXML.getElementsByTagName("loginAvailability").item(0);
			   if( available ) {
				   displayLoginAvailability( parseInt( available.getAttribute( 'available' ) ) );
 			   } else {
				   displayLoginAvailability( -2 );
			   }

				}
			}
			xmlhttp = null;
		}
	}
}

function displayLoginAvailability( state ) {
	message = null;
	if ( state == 0 ) { message = '<span style="color: red;">This username is unavailable!</span>'; } 
	if ( state == -1 ) { message = '<span style="color: red;">This username is too short!</span>'; }
	if ( state == -2 ) { message = 'An error has occured. Please continue filling the form.'; }
	$( 'loginAvailabilityMessage' ).innerHTML = message;
	if( message ) {
		DrElement.show( $( 'loginAvailabilityMessage' ) );
	} else {
		DrElement.hide( $( 'loginAvailabilityMessage' ) );
	}
}

function clearLoginAvailabilityMessage() {
	$( 'loginAvailabilityMessage' ).innerHTML = '';
	DrElement.hide( $( 'loginAvailabilityMessage' ) );
}