/***
 * Filename:
 * 	vertnav.js
 * 
 * Purpose:
 * 	Facilitate a vertical navigation menu with collapsable submenus.
 *  This code will automatically detect which menu items have submenus 
 *  and handle them accordingly.
 * 
 * Notes:
 *  DON'T bother using this file to:
 *  	-change look/feel of menu: this is done from CSS script (ie: vertnav.css).
 *  	-add/remove/edit menu items: this is done within the HTML
 *   
 *  .
 *  
 * 
 */

/*
 * 
 * CSS settings:
 *  Normally never has to be touched, unless class names are changed 
 *  in the CSS or id is changed of the div wrapping the navigation <li> 
 *  tags(list items) in the HTML. 
 *  TO CHANGE LOOK/FEEL: simly edit the corresponding CSS class entries (not here)!!
 *  
 *  The navconfig_ settings should match with existing class entries in a linked stylesheet or CSS script
 * 
 * 
 */
var vertnavcfg_subshow_class = "subshow"; /* class used when toggled visible */
var vertnavcfg_subhide_class = "subhide"; /* class used when toggled hidden */
var vertnavcfg_hashiddensub_class = "hashiddensub"; /* class used when parent has a hidden submenu */
var vertnavcfg_hasvisiblesub_class = "hasvisiblesub"; /* class used when parent has a visible submenu */
var vertnavcfg_navlistdiv_id = "vertnavlist"; /* div wrapping the navigation <li> tags (list items) */

/*
 * 
 * register event handler to initialize the navigation system on page load
 * 
 */
window.onload=vertnav_init;


/*
 * 
 * state handling variables
 * 
 */
var vertnavst_subclick = false;

/**
 * Function:
 *  toggleNav
 *  
 * Purpose:
 *  for use on click event to
 *  appropriately change the classes according to above configuration
 *  typically to expand the menu to reveal a submenu
 * 
 */
function vertnav_toggle(what){
	/*
	 * get submenu within the expected <li> calling this function (aka var what)
	 */
	var subnav = what.getElementsByTagName("ul");
	for(i=0;i<subnav.length;i++) { /*--loop thru 'submenu', typically should only be 1 iteration--*/
		if (vertnavst_subclick) { /* if a submenu item is being clicked */
			vertnavst_subclick = false;
			return false;
		}
		if (subnav[i].className == vertnavcfg_subshow_class) 
		{ /* if visible, make hidden */
			subnav[i].className = vertnavcfg_subhide_class;
			subnav[i].parentNode.className = vertnavcfg_hashiddensub_class;
		} 
		else 
		{ /* if hidden, make visible */
			subnav[i].className = vertnavcfg_subshow_class;
			subnav[i].parentNode.className = vertnavcfg_hasvisiblesub_class;
		}
	} /*--end 'submenu' loop--*/
} /*--vertnav_toggle()--*/

/**
 * Function:
 *  initNav
 *  
 * Purpose:
 *  for use on page load (or similar) to 
 *  appropriately change the classes according to above configuration
 * 
 */
function vertnav_init() {
	/*
	 * hide all the nested ULs ('submenus') the #leftnavlist div
	 */
	var subnav = document.getElementById(vertnavcfg_navlistdiv_id).getElementsByTagName("ul");
	for (i = 0; i < subnav.length ; i++) { /*--loop thru all the 'submenus'--*/
		subnav[i].className = vertnavcfg_subhide_class; /* change class to the one indicated as 'hidden' */
		subnav[i].parentNode.className = vertnavcfg_hashiddensub_class; /* change class to one indicating the parent li has a 'hidden' submenu */
		subnav[i].parentNode.onclick = function(){vertnav_toggle(this);} /* register toggleNav() as the onclick event handler for the parent li */
		var subnavli = subnav[i].parentNode.getElementsByTagName("li"); /* get submenu entries */
		for(j=0;j<subnavli.length;j++) { /* loop thru submenu entries */
			subnavli[j].onclick = function() {vertnavst_subclick = true;} /* register state handling */
		}
	} /*--end 'submenus' loop--*/
} /*--vertnav_init()--*/