// Calendar Helper Routines
// From: http://students.infoiasi.ro/~mishoo/site/calendar.epl#gen4

var calendar = null; // remember the calendar object so that we reuse it and
// avoid creation other calendars.

// This function gets called when the end-user clicks on some date.
function selected(cal, date) {
    cal.sel.value = date; // just update the date in the input field.
    closeHandler(calendar);
}

// And this gets called when the end-user clicks on the _selected_ date,
// or clicks on the "Close" button.  It just hides the calendar without
// destroying it.
function closeHandler(cal) {
    cal.hide();                        // hide the calendar
    cal.sel.date = new Date(cal.date); // remember the date in the input field

    // don't check mousedown on document anymore (used to be able to hide the
    // calendar when someone clicks outside it, see the showCalendar function).
    Calendar.removeEvent(document, "mousedown", checkCalendar);
}

// This gets called when the user presses a mouse button anywhere in the
// document, if the calendar is shown.  If the click was outside the open
// calendar this function closes it.
function checkCalendar(ev) {
    var el = Calendar.is_ie ? Calendar.getElement(ev) : Calendar.getTargetElement(ev);
    for (; el != null; el = el.parentNode)
    // FIXME: allow end-user to click some link without closing the
    // calendar.  Good to see real-time stylesheet change :)
        if (el == calendar.element || el.tagName == "A") break;
    if (el == null) {
        // calls closeHandler which should hide the calendar.
        calendar.callCloseHandler();
    }
}

// This function shows the calendar under the element having the given id.
// It takes care of catching "mousedown" signals on document and hiding the
// calendar if the click was outside.
function showCalendar(id, dateFormat) {
    var el = document.getElementById(id);
    if (calendar != null)
    // we already have some calendar created
        calendar.hide();                 // so we hide it first.
    else {
        // first-time call, create the calendar.
        var cal = new Calendar(true, null, selected, closeHandler);
        calendar = cal;                  // remember it in the global var
        cal.setRange(1920, 2070);        // min/max year allowed.

        cal.create();                    // create popup calendar.

    }
    calendar.sel = el;                 // inform it what input field we use  
    calendar.setDateFormat(convertJavaDateFormat(dateFormat));
    calendar.parseDate(el.value);      // set the date for the new field.
    calendar.showAtElement(el);        // show the calendar below it


    // catch "mousedown" on document
    Calendar.addEvent(document, "mousedown", checkCalendar);
    return false;
}

function convertJavaDateFormat(dateFormat) {
    dateFormat = replaceAll(dateFormat, "MMM", "mm");
    dateFormat = replaceAll(dateFormat, "MM", "m");
    dateFormat = replaceAll(dateFormat, "yyyy", "y");
    return dateFormat;
}

// http://www.rpd.univ.kiev.ua/~mav/tdoc/jcbook/DOSFILES/STRINGS/SUBST.HTM
// Substitute character string c2 for every c1 in aString
function replaceAll(aString, c1, c2) {
    if (aString == "") return aString
    if (c1 == "") return aString

    // avoid infinite recursion when substituting aa for a by
    // providing an offset into the string.
    var argc = replaceAll.arguments.length
    if (argc < 4) { n = 0 } else { n = replaceAll.arguments[3] }

    // find the first occurrence of c1 after the threshold
    var i = aString.indexOf(c1, n)

    // stop recursion and return the current string when c1 not found
    if (i < 0) return aString

    // extract substrings s1 and s2 around the c1
    var s1 = aString.substring(0, i)
    var s2 = aString.substring(i + c1.length, aString.length)

    // recurse with this new string
    return replaceAll(s1 + c2 + s2, c1, c2, (i + c2.length))
}