// JavaScript Document
/*

 * Expandable list implementation.

 * by David Lindquist <first name><at><last name><dot><net>

 * See:

 * http://www.gazingus.org/html/DOM-Scripted_Lists_Revisited.html

 * Modifies lists so that sublists can be hidden and shown by means of

 * a switch. The switch is a node inserted into the DOM tree as the

 * first child of the list item containing the sublist.

 */



// The script will only be applied to lists containing this class name,

// e.g.: <ul class="foo expandable">...</ul>.

var CLASS_NAME = "expandable";



// This value is the assumed initial display style for a sublist when it cannot

// be determined by other means. See below.

var DEFAULT_DISPLAY = "none";



// The namespace to use when using this script in an XML context.

var XMLNS = "http://www.w3.org/1999/xhtml";



// The beginning of the title text for the switch when the sublist is collapsed.

var CLOSED_PREFIX = "Expand list: ";



// The beginning of the title text for the switch when the sublist is expanded.

var OPENED_PREFIX = "Collapse list: ";



/******************************************************************************/



// Returns a copy of a string with leading and trailing whitespace removed.

String.prototype.trim = function() {

    return this.replace(/^\s+/, "").replace(/\s+$/, "");

}



// Walks the DOM tree starting at a given root element. Returns an

// array of nodes of the specified type and conforming to the criteria

// of the given filter function. The filter should return a boolean.

function getNodesByType(root, type, filter) {

    var node = root;

    var nodes = [];

    var next;



    while (node != null) {

        if (node.hasChildNodes())

            node = node.firstChild;

        else if (node != root && null != (next = node.nextSibling))

            node = next;

        else {

            next = null;

            for ( ; node != root; node = node.parentNode) {

                next = node.nextSibling;

                if (next != null) break;

            }

            node = next;

        }

        if (node != null && node.nodeType == type && filter(node))

            nodes.push(node);

    }

    return nodes;

}



// Simulates the innerText property of IE and other browsers.

// Mozilla/Firefox need this.

function getInnerText(node) {

    if (node == null || node.nodeType != 1)

        return;

    var text = "";

    var textnodes = getNodesByType(node, 3, function() { return true; });

    for (var i = 0; i < textnodes.length; i++)

        text += textnodes[i].data;

    return text;

}



function initExpandableLists() {

    if (!document.getElementsByTagName) return;



    // Top-level function to accommodate browsers that do not register

    // a click event when a link is activated by the keyboard.

    switchNode = function(id) {

        var node = document.getElementById(id);

        if (node && /^switch /.test(node.className)) node.onclick();

    }



    // Top-level function to be assigned as the event handler for the

    // switch. This could have been bound to the handler as a closure,

    // but closures are associated with memory leak problems in IE.

    actuate = function() {

        var sublist = this.parentNode.getElementsByTagName("ul")[0] ||

                      this.parentNode.getElementsByTagName("ol")[0];

        if (sublist.style.display == "block") {

            sublist.style.display = "none";

            this.firstChild.data = "+";

            this.className = "switch off";

            this.title = this.title.replace(OPENED_PREFIX, CLOSED_PREFIX);

        } else {

            sublist.style.display = "block";

            this.firstChild.data = "-";

            this.className = "switch on";

            this.title = this.title.replace(CLOSED_PREFIX, OPENED_PREFIX);

        }

        return false;

    }



    // Create switch node from which the others will be cloned.

    if (typeof document.createElementNS == "function")

        var template = document.createElementNS(XMLNS, "a");

    else

        var template = document.createElement("a");

    template.appendChild(document.createTextNode(" "));



    var list, i = 0, j = 0;

    var pattern = new RegExp("(^| )" + CLASS_NAME + "( |$)");



    while ((list = document.getElementsByTagName("ul")[i++]) ||

           (list = document.getElementsByTagName("ol")[j++]))

    {

        // Only lists with the given class name are processed.

        if (pattern.test(list.className) == false) continue;



        var item, k = 0;

        while ((item = list.getElementsByTagName("li")[k++])) {

            var sublist = item.getElementsByTagName("ul")[0] ||

                          item.getElementsByTagName("ol")[0];

            // No sublist under this list item. Skip it.

            if (sublist == null) continue;



            // Attempt to determine initial display style of the

            // sublist so the proper symbol is used.

            var symbol;

            switch (sublist.style.display) {

            case "none" : symbol = "+"; break;

            case "block": symbol = "-"; break;

            default:

                var display = DEFAULT_DISPLAY;

                if (sublist.currentStyle) {

                    display = sublist.currentStyle.display;

                } else if (document.defaultView &&

                           document.defaultView.getComputedStyle &&

                           document.defaultView.getComputedStyle(sublist, ""))

                {

                    var view = document.defaultView;

                    var computed = view.getComputedStyle(sublist, "");

                    display = computed.getPropertyValue("display");

                }

                symbol = (display == "none") ? "+" : "-";

                // Explicitly set the display style to make sure it is

                // set for the next read. If it is somehow the empty

                // string, use the default value from the (X)HTML DTD.

                sublist.style.display = display || "block";

                break;

            }



            // This bit attempts to extract some text from the first

            // child node of the list item to append to the title

            // attribute of the switch.

            var child = item.firstChild;

            var text = "";

            while (child) {

                if (child.nodeType == 3 && "" != child.data.trim()) {

                    text = child.data;

                    break;

                } else if (child.nodeType == 1 &&

                           !/^[ou]l$/i.test(child.tagName))

                {

                    text = child.innerText || getInnerText(child);

                    break;

                }

                child = child.nextSibling;

            }



            var actuator = template.cloneNode(true);

            // a reasonably unique ID

            var uid = "switch" + i + "-" + j + "-" + k;

            actuator.id = uid;

            actuator.href = "javascript:switchNode('" + uid + "')";

            actuator.className = "switch " + ((symbol == "+") ? "off" : "on");

            actuator.title = ((symbol == "+")

                              ? CLOSED_PREFIX : OPENED_PREFIX) + text.trim();

            actuator.firstChild.data = symbol;

            actuator.onclick = actuate;

            item.insertBefore(actuator, item.firstChild);

        }

    }

}



// Props to Simon Willison:

// http://simon.incutio.com/archive/2004/05/26/addLoadEvent

var oldhandler = window.onload;

window.onload = (typeof oldhandler == "function")

    ? function() { oldhandler(); initExpandableLists(); } : initExpandableLists;