// JavaScript Document


/* CLOSED_IMAGE - the image to be displayed when the sublists are closed
* OPEN_IMAGE   - the image to be displayed when the sublists are opened
*/
CLOSED_IMAGE = 'images/plus.png';
OPEN_IMAGE = 'images/minus.png';

/* makeCollapsible - makes a list have collapsible sublists
* 
* listElement - the element representing the list to make collapsible
*/
function makeCollapsible(listElement) {

    // removed list item bullets and the space they occupy
    listElement.style.listStyle = 'none';
    listElement.style.marginLeft = '0';
    listElement.style.paddingLeft = '0';

    // loop over all child elements of the list
    var child = listElement.firstChild;
    while (child != null) {

        // only process li elements (and not text elements)
        if (child.nodeType == 1) {

            // build a list of child ol and ul elements and hide them
            var list = new Array();
            var grandchild = child.firstChild;
            while (grandchild != null) {
                if (grandchild.tagName == 'OL' || grandchild.tagName == 'UL') {
                    grandchild.style.display = 'none';
                    list.push(grandchild);
                }
                grandchild = grandchild.nextSibling;
            }

            // add toggle buttons
            var node = document.createElement('img');
            node.setAttribute('src', CLOSED_IMAGE);
            node.setAttribute('class', 'collapsibleClosed');
            node.onclick = createToggleFunction(node, list);
            child.insertBefore(node, child.firstChild);

        }

        child = child.nextSibling;
    }

}

/* createToggleFunction - returns a function that toggles the sublist display
* 
* toggleElement  - the element representing the toggle gadget
* sublistElement - an array of elements representing the sublists that should
*                  be opened or closed when the toggle gadget is clicked
*/
function createToggleFunction(toggleElement, sublistElements) {

    return function () {

        // toggle status of toggle gadget
        if (toggleElement.getAttribute('class') == 'collapsibleClosed') {
            toggleElement.setAttribute('class', 'collapsibleOpen');
            toggleElement.setAttribute('src', OPEN_IMAGE);
        } else {
            toggleElement.setAttribute('class', 'collapsibleClosed');
            toggleElement.setAttribute('src', CLOSED_IMAGE);
        }

        // toggle display of sublists
        for (var i = 0; i < sublistElements.length; i++) {
            sublistElements[i].style.display =
          (sublistElements[i].style.display == 'block') ? 'none' : 'block';
        }

    }

}

function getCurrentYear() {
    var date = new Date();
    var year = date.getYear();
    if (year < 1000) {
        year += 1900;
    }
    return year;
}