// JavaScript Document
/*
url-loading object and a request queue built on top of it
*/

/* namespacing object */
var net=new Object();

net.READY_STATE_UNINITIALIZED=0;
net.READY_STATE_LOADING=1;
net.READY_STATE_LOADED=2;
net.READY_STATE_INTERACTIVE=3;
net.READY_STATE_COMPLETE=4;


/*--- content loader object for cross-browser requests ---*/
net.ContentLoader=function(url,onload,onerror,method,params,contentType){
  this.req=null;
  net.currentLoader=this;
  this.onload=onload;
  this.onerror=(onerror) ? onerror : this.defaultError;
  this.loadXMLDoc(url,method,params,contentType);
}

net.ContentLoader.prototype.loadXMLDoc=function(url,method,params,contentType){
  if (!method){
    method="GET";
  }
  if (!contentType && method=="POST"){
    contentType='application/x-www-form-urlencoded';
  }
  if (window.XMLHttpRequest){
    this.req=new XMLHttpRequest();
  } else if (window.ActiveXObject){
    this.req=new ActiveXObject("Microsoft.XMLHTTP");
  }
  if (this.req){
    try{
      var loader=this;
      this.req.onreadystatechange=function(){
        net.ContentLoader.onReadyState.call(loader);
      }
      this.req.open(method,url,true);
      if (contentType){
        this.req.setRequestHeader('Content-Type', contentType);
      }
      this.req.send(params);
    }catch (err){
      this.onerror.call(this);
    }
  }
}


net.ContentLoader.onReadyState=function(){
  var req=this.req;
  var ready=req.readyState;
  if (ready==net.READY_STATE_COMPLETE){
     var httpStatus=req.status;
    //if (status==200 || httpStatus==0){
    if(httpStatus==200 || httpStatus==0){
      this.onload.call(this);
    }else{
      this.onerror.call(this);
    }
  }
}

net.ContentLoader.prototype.defaultError=function(){
  alert("error fetching data!"
    +"\n\nreadyState:"+this.req.readyState
    +"\nstatus: "+this.req.status
    +"\nheaders: "+this.req.getAllResponseHeaders());
}




/*--- queue system for efficient transfer of many small commands in a single request ---*/
net.cmdQueues=new Array();


net.CommandQueue=function(id,url,onUpdate,freq){
  this.id=id;
  net.cmdQueues[id]=this;
  this.url=url;
  this.queued=new Array();
  this.sent=new Array();
  this.onUpdate=onUpdate;
  if (freq){
    this.repeat(freq);
  }
  this.lastUpdateTime=0;
}

net.CommandQueue.STATUS_QUEUED=-1;
net.CommandQueue.STATE_UNINITIALIZED=net.READY_STATE_UNINITIALIZED;
net.CommandQueue.STATE_LOADING=net.READY_STATE_LOADING;
net.CommandQueue.STATE_LOADED=net.READY_STATE_LOADED;
net.CommandQueue.STATE_INTERACTIVE=net.READY_STATE_INTERACTIVE;
net.CommandQueue.STATE_COMPLETE=net.READY_STATE_COMPLETE;
net.CommandQueue.STATE_PROCESSED=5;

net.CommandQueue.PRIORITY_NORMAL=0;
net.CommandQueue.PRIORITY_IMMEDIATE=1;


net.CommandQueue.prototype.addCommand=function(command){
  if (this.isCommand(command)){
    this.queue.append(command,true);
    if (command.priority==net.CommandQueue.PRIORITY_IMMEDIATE){
      this.fireRequest();
    }
  }
}

net.CommandQueue.prototype.fireRequest=function(){
  if (!this.onUpdate && this.queued.length==0){
    return;
  }
  var data="lastUpdate="+this.lastUpdateTime+"&data=";
  for(var i=0;i<this.queued.length;i++){
    var cmd=this.queued[i];
    if (this.isCommand(cmd)){
      data+=cmd.toRequestString();
      this.sent[cmd.id]=cmd;
    }
  }
  this.queued=new Array();
  this.loader=new net.ContentLoader(
    this.url,
    net.CommandQueue.onload,
    net.CommandQueue.onerror,
    "POST",data
  );
}

net.CommandQueue.prototype.isCommand=function(obj){
  return (
    obj.implementsProp("id")
    && obj.implementsProp("priority")
    && obj.implementsFunc("toRequestString")
    && obj.implementsFunc("parseResponse")
  );
}

net.CommandQueue.onload=function(){
  var xmlDoc=this.req.responseXML;
  var elDocRoot=xmlDoc.getElementsByTagName("responses")[0];
  var lastUpdate=elDocRoot.attributes.getNamedItem("updateTime");
  if (parseInt(lastUpdate)>this.lastUpdateTime){
    this.lastUpdateTime=lastUpdate;
  }
  if (elDocRoot){
    for(i=0;i<elDocRoot.childNodes.length;i++){
      elChild=elDocRoot.childNodes[i];
      if (elChild.nodeType==1){
        if (elChild.tagName=="command"){
          var attrs=elChild.attributes;
          var id=attrs.getNamedItem("id").value;
          var command=net.commandQueue.sent[id];
          if (command){
            command.parseResponse(elChild);
          }
        }else if (elChild.tagName=="update"){
          if (this.implementsFunc("onUpdate")){
            this.onUpdate.call(this,elChild);
          }
        }
      }
    }
  }
}

net.CommandQueue.onerror=function(){
  alert("problem sending the data to the server");
}

net.CommandQueue.prototype.repeat=function(freq){
  this.unrepeat();
  if (freq>0){
    this.freq=freq;
    var cmd="net.cmdQueues["+this.id+"].fireRequest()";
    this.repeater=setInterval(cmd,freq*1000);
  }
}
net.CommandQueue.prototype.unrepeat=function(){
  if (this.repeater){
    clearInterval(this.repeater);
  }
  this.repeater=null;
}

//Useful functions
function el(i) {
  return document.getElementById(i);
}

// Function that clears the element 
function expire(id) {
 el(id).innerHTML = "";
 el(id).style.backgroundColor = '#ffffff';
 el(id).style.border = '';
}
//Function to notify the user of a response from the readystate. It updates the passed element with the results
function notify(id, results) {
	el(id).innerHTML = results;
	el(id).style.backgroundColor = '#FFFF99';
	el(id).style.border = '1px solid #D0E0F9';
}
function displayresults(id, results) {
	el(id).style.display = '';
	el(id).innerHTML = results;	
}
//Show an element
function showdiv(id) {
el(id).style.display = '';
}
//Hide an element
function hidediv(id) {
el(id).style.display = 'none';
}
//Function to add a requested course
function addCourse() {
var oldCourses = el('RequestedCourses').value;
var newCourse = el('Courses').value;
var result = 0;
if (oldCourses == ""){
 	result = newCourse;}
else
	{result = oldCourses + ", " + newCourse;}
el('RequestedCourses').value = result;
}
function edit(div1, div2, div3, div4) {
	el(div1).style.display = 'none';
	el(div2).style.display = '';
	el(div3).style.display = 'none';
	el(div4).style.display = 'none';
}
function finishedit(div1, div2, div3, div4) {
	el(div1).style.display = '';
	el(div2).style.display = 'none';
	el(div3).style.display = '';
	el(div4).style.display = '';
	checkdetails();
}
function hideshow(id, id2) {
	el(id).style.display = 'none';
	el(id2).style.display = '';
}
function browse() {
var ID = el('CourseTypeID').value;
var previous = el('content').innerHTML;
pushStack(previous);
if ((ID == null) || (ID == "")) return;
var url = "http://www.cosensa.co.uk/Includes/BrowseBarServer.php";
var str = "CourseTypeID=" + escape(ID);
var loader = new net.ContentLoader(url, showresponse, null, 'POST', str );
}

function showresponse() {
	// Complete status
	var results = this.req.responseText;
	if (results != "") {
	displayresults('content', results)
  }
}
// Onload Observer
window.onloadListeners = new Array();
window.addOnloadListener = function(listener) {
	window.onloadListeners[window.onloadListeners.length] = listener;
}
// OnLoad listeners
// Onload
window.onload = function()
{
	for (var i = 0; i < window.onloadListeners.length; i++)
	{
		var func = window.onloadListeners[i];
		func.call();
	}
}
//Undo functions
var stack = new Array(); 

function pushStack(newVal) { 
   stack.unshift(newVal); 
} 
function popStack() {
   var popVal = stack.shift(); 
   if (popVal == undefined) 
   history.go(-1); 
   else 
   return popVal; 
} 
function showStack(theSelect){ 
   theSelect.options.length = 0; 
   for (var i = 0; i < stack.length; i++){ 
      var theOption = new Option(stack[i]); 
      theSelect.options[theSelect.options.length] = theOption; 
   } 
}