/***
 * 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()--*/