var NS4 = (navigator.appName === "Netscape" && parseInt(navigator.appVersion, 10) < 5);

function createOption(theText, theValue, theCategory) {
    var newOpt = document.createElement('option');
    newOpt.text = theText;
    newOpt.value = theValue;
    newOpt.setAttribute("data-category", theCategory);
    return newOpt;
}

function addOption(theSel, newOpt)
{
    var theCategory, opt_groups, i;
    theCategory = newOpt.getAttribute("data-category");
    theSel = $(theSel);
    if (theCategory && (theSel.childElements().length > 0) && theSel.down(0).tagName === "OPTGROUP") { // add the opt to the given category
        opt_groups = theSel.childElements();
        for (i = 0; i < opt_groups.length; i += 1) {
            if (opt_groups[i].getAttribute("data-category") === theCategory) {
                opt_groups[i].appendChild(newOpt);
                break;
            }
        }
    }
    else { // no category given, just add the opt to the end of the select list
        theSel.appendChild(newOpt);
    }
}

function swapOptions(theSel, index1, index2)
{
    theSel = $(theSel);
    var text, value, category;
    text = theSel.options[index1].text;
    value = theSel.options[index1].value;
    category = theSel.options[index1].getAttribute("data-category");
    theSel.options[index1].text = theSel.options[index2].text;
    theSel.options[index1].value = theSel.options[index2].value;
    theSel.options[index1].setAttribute("data-category", theSel.options[index2].getAttribute("data-category"));
    theSel.options[index2].text = text;
    theSel.options[index2].value = value;
    theSel.options[index2].setAttribute("data-category", category);
}

function deleteOption(theSel, theIndex)
{
    theSel = $(theSel);
    var selLength = theSel.length;
    if (selLength > 0)
    {
        theSel.options[theIndex] = null;
    }
}

// Returns true if the given select-box has optgroups.
// We assume that a possibly present optgroup is the first child element of the select-box.
function has_optgroups(theSel) {
    theSel = $(theSel);
    return (theSel.childElements().length > 0) && (theSel.down(0).tagName === "OPTGROUP");
}

// Compares two option elements (return -1 if a < b, if not return 1).
// If those elements have a 'data-sort_by' attribute, we compare that attribute.
// If this is not the case we just compare their labels.
function compareOptions(a, b) {
    var a_cmp, b_cmp;
    a_cmp = a.getAttribute("data-sort_by") ? a.getAttribute("data-sort_by") : a.text.toLowerCase();
    b_cmp = b.getAttribute("data-sort_by") ? b.getAttribute("data-sort_by") : b.text.toLowerCase();
    return (a_cmp < b_cmp) ? -1 : 1;
}

// Sorts all elements of the given select-box.
// If that select-box contains optgroups, the options are sorted for each optgroup separately.
function sortOptions(theSel) {
    theSel = $(theSel);
    if (has_optgroups(theSel)) {
        // handle each optgroup separately
        theSel.childElements().each(function (group) {
            var sorted_elements;
            // get all elements of this optgroup and sort them
            sorted_elements = $A(group.childElements()).sort(compareOptions);
            // make optgroup empty
            $A(group.childElements()).each(function (o) {
                $(o).remove();
            });
            // insert sorted elements into opgroup
            sorted_elements.each(function (o) {
                $(group).insert({'bottom' : o});
            });
        });
    }
    else {
        // there is no optgroup, so just sort the options
        $A(theSel.options).sort(compareOptions).each(function (o, i) {
            theSel.options[i] = o;
        });
    }
}

function moveOptions(theSelFrom, theSelTo)
{
    var selLength, selectedText, selectedValues, selectedCategories, selectedCount, i;
    theSelFrom = $(theSelFrom);
    theSelTo = $(theSelTo);
    selLength = theSelFrom.length;
    selectedText = [];
    selectedValues = [];
    selectedCategories = [];
    selectedCount = 0;

    for (i = selLength - 1; i >= 0; i -= 1) {
        if (theSelFrom.options[i].selected)
        {
            addOption(theSelTo, theSelFrom.options[i].cloneNode(true));
            deleteOption(theSelFrom, i);
        }
    }

    if (has_optgroups(theSelTo)) {
        sortOptions(theSelTo);
    }
    if (NS4) {
        history.go(0);
    }
}

function moveOptionUp(theSel) {
    theSel = $(theSel);
    var index = theSel.selectedIndex;
    if (index > 0) {
        swapOptions(theSel, index - 1, index);
        theSel.selectedIndex = index - 1;
    }
}

function moveOptionDown(theSel) {
    theSel = $(theSel);
    var index = theSel.selectedIndex;
    if (index < theSel.length - 1) {
        swapOptions(theSel, index, index + 1);
        theSel.selectedIndex = index + 1;
    }
}

function selectAllOptions(select)
{
    select = $(select);
    for (var i = 0; i < select.options.length; i += 1) {
        select.options[i].selected = true;
    }
}