var enablepersist="off" //Enable saving state of content structure using session cookies? (on/off)
var memoryduration="7" //persistence in # of days

var contractsymbol='http://www.cuhk.edu.hk/crs/0607/image/minus.gif' //Path to image to represent contract state.
var expandsymbol='http://www.cuhk.edu.hk/crs/0607/image/plus.gif' //Path to image to represent expand state.

/////No need to edit beyond here //////////////////////////
var ccollect=new Array();

function getElementbyClass(rootobj, classname){
var temparray=new Array()
var inc=0
var rootlength=rootobj.length
for (i=0; i<rootlength; i++){
if (rootobj[i].className==classname)
temparray[inc++]=rootobj[i]
}
return temparray
}

function sweeptoggle(ec){
var inc=0
while (ccollect[inc]){
ccollect[inc].style.display=(ec=="contract")? "none" : ""
inc++
}
revivestatus()
}


function expandcontent(curobj, cid){
if (ccollect.length>0){
document.getElementById(cid).style.display=(document.getElementById(cid).style.display!="none")? "none" : ""
curobj.src=(document.getElementById(cid).style.display=="none")? expandsymbol : contractsymbol
}
}

function revivecontent(){
selectedItem=getselectedItem()
selectedComponents=selectedItem.split("|")
for (i=0; i<selectedComponents.length-1; i++)
document.getElementById(selectedComponents[i]).style.display="none"
}

function revivestatus(){
var inc=0
while (statecollect[inc]){
if (ccollect[inc].style.display=="none")
statecollect[inc].src=expandsymbol
else
statecollect[inc].src=contractsymbol
inc++
}
}

function get_cookie(Name) { 
var search = Name + "="
var returnvalue = "";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search)
if (offset != -1) { 
offset += search.length
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
returnvalue=unescape(document.cookie.substring(offset, end))
}
}
return returnvalue;
}

function getselectedItem(){
if (get_cookie(window.location.pathname) != ""){
selectedItem=get_cookie(window.location.pathname)
return selectedItem
}
else
return ""
}

function saveswitchstate(){
var inc=0, selectedItem=""
while (ccollect[inc]){
if (ccollect[inc].style.display=="none")
selectedItem+=ccollect[inc].id+"|"
inc++
}
if (get_cookie(window.location.pathname)!=selectedItem){ //only update cookie if current states differ from cookie's
var expireDate = new Date()
expireDate.setDate(expireDate.getDate()+parseInt(memoryduration))
document.cookie = window.location.pathname+"="+selectedItem+";path=/;expires=" + expireDate.toGMTString()
}
}

function do_onload(){
uniqueidn=window.location.pathname+"firsttimeload"
var alltags=document.all? document.all : document.getElementsByTagName("*")
ccollect=getElementbyClass(alltags, "switchcontent")
statecollect=getElementbyClass(alltags, "showstate")
if (enablepersist=="on" && get_cookie(window.location.pathname)!="" && ccollect.length>0)
revivecontent()
if (ccollect.length>0 && statecollect.length>0)
revivestatus()
sweeptoggle("contract")
}

if (window.addEventListener)
window.addEventListener("load", do_onload, false)
else if (window.attachEvent)
window.attachEvent("onload", do_onload)
else if (document.getElementById)
window.onload=do_onload

if (enablepersist=="on" && document.getElementById)
window.onunload=saveswitchstate


function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_changeProp(objName,x,theProp,theValue) { //v6.0
  var obj = MM_findObj(objName);
  if (obj && (theProp.indexOf("style.")==-1 || obj.style)){
    if (theValue == true || theValue == false)
      eval("obj."+theProp+"="+theValue);
    else eval("obj."+theProp+"='"+theValue+"'");
  }
}

function changebg(tabobj) {
	var tobj = MM_findObj(tabobj);
//	alert(tobj.style.background);
	MM_changeProp(tabobj, '', 'style.background', '#E3C8C8','table');
}

function Rchangebg(tabobj) {
	var tobj = MM_findObj(tabobj);
//	alert(tobj.style.background);
	MM_changeProp(tabobj, '', 'style.background', '#FFFFFF','table');
}

function changetbg(tdobj) {
//	var dobj = MM_findObj(tdobj);
//	alert(tobj.style.background);
	MM_changeProp(tdobj, '', 'background', 'http://www.cuhk.edu.hk/crs/0607/0708/image/J01158442.GIF','td');
}

function Rchangetbg(tdobj) {
//	var dobj = MM_findObj(tdobj);
//	alert(tobj.style.background);
	MM_changeProp(tdobj, '', 'background', 'http://www.cuhk.edu.hk/crs/0607/0708/image/blank22.GIF','td');
}