var timerID = null;
var timerRunning = false;

var timerDay = 0;
var timerHour = 0;
var timerMinute = 0;
var timerSecond = 0;

function runtime() {
    if (timerRunning) {
        timerSecond = timerSecond - 1;

        if (timerSecond < 0) {
            timerSecond = 60 + timerSecond;
            timerMinute = timerMinute - 1;
        }
        if (timerMinute < 0) {
            timerMinute = 60 + timerMinute;
            timerHour = timerHour - 1;
        }
        if (timerHour < 0) {
            timerHour = 24 + timerHour;
            timerDay = timerDay - 1;
        }
        if (timerDay < 0) {
            stoptimer();
            try {
                timer_over();
            } catch (e) { }
            return;
        }
        try {
            timer_show(timerDay, timerHour, timerMinute, timerSecond);
        } catch (e) { }  
        timerID = setTimeout("runtime()", 1000);
    }
}

function stoptimer() {
    timerRunning = false;
    if (timerRunning)
        clearTimeout(timerID);
}

function startimer(day, hour, minute, second) {
    if (timerID)
        clearTimeout(timerID);
    stoptimer();

    timerDay = day;
    timerHour = hour;
    timerMinute = minute;
    timerSecond = second;

    timerRunning = true;
    runtime();
}