/**
 * add_reference.js
 *
 * Manages AJAX requests when adding referencess
 *
 * @author Paul Nicholls
 *
 */

var xmlhttp

function loadWriter(id, subject)
{
  document.getElementById("writer").innerHTML="<img src=\"/img/ajax-loader.gif\" alt=\"Loading\" />";
if (subject.length==0)
  {
    document.getElementById("writer").innerHTML="";
  return;
  }
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Your browser does not support XMLHTTP!");
  return;
  }
var url="https://secure.urmant.org/funcs/ajax.php";
url=url+"?m=writereference&q="+id+"&s="+subject;
url=url+"&sid="+Math.random();
xmlhttp.onreadystatechange=writerStateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}

function loadStudents(form)
{
document.getElementById("studentlist").innerHTML="<img src=\"/img/ajax-loader.gif\" alt=\"Loading\" />";
document.getElementById("writer").innerHTML="";
  document.getElementById("studentlist").innerHTML="";
if (form.length==0)
  {
  document.getElementById("studentlist").innerHTML="";
  return;
  }
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Your browser does not support XMLHTTP!");
  return;
  }
var url="https://secure.urmant.org/funcs/ajax.php";
url=url+"?m=studentlist&q="+form;
url=url+"&sid="+Math.random();
xmlhttp.onreadystatechange=studentStateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}

function studentStateChanged()
{
if (xmlhttp.readyState==4)
  {
  document.getElementById("studentlist").innerHTML=xmlhttp.responseText;
  document.getElementById("subjectlist").innerHTML="";
  }
}

function loadSubjects(student)
{
document.getElementById("subjectlist").innerHTML="<img src=\"/img/ajax-loader.gif\" alt=\"Loading\" />";
document.getElementById("writer").innerHTML="";
if (student.length==0)
  {
  document.getElementById("subjectlist").innerHTML="";
  return;
  }
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Your browser does not support XMLHTTP!");
  return;
  }
var url="https://secure.urmant.org/funcs/ajax.php";
url=url+"?m=subjectlist&q="+student;
url=url+"&sid="+Math.random();
xmlhttp.onreadystatechange=subjectStateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}

function subjectStateChanged()
{
if (xmlhttp.readyState==4)
  {
  document.getElementById("subjectlist").innerHTML=xmlhttp.responseText;
  }
}

function writerStateChanged()
{
if (xmlhttp.readyState==4)
  {
  document.getElementById("writer").innerHTML=xmlhttp.responseText;
  }
}


function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}