(function () {
    var _MONTHS_ = ['január', 'február', 'március', 'április', 'május', 'június', 'július', 'augusztus', 'szeptember', 'október', 'november', 'december'];
    var _DAYS_ = ['vasárnap', 'hétfő', 'kedd', 'szerda', 'csütörtök', 'péntek', 'szombat'];

    var syncTimeout;
    var clockTimeout;
    var correct = 0;

    function getSyncedDateTime() {
        return new Date(new Date().getTime() - correct);
    }

    function fillZero(param) {
        return param < 10 ? '0' + String(param) : String(param);
    }

    function sync() {
        clearTimeout(syncTimeout);

        var started;
        var latency;

        var syncRequest = new XMLHttpRequest();

        syncRequest.onreadystatechange = function () {
            switch (syncRequest.readyState) {
                case XMLHttpRequest.OPENED:
                    started = new Date().getTime();

                    break;

                case XMLHttpRequest.HEADERS_RECEIVED:
                    latency = (new Date().getTime() - started) / 2;

                    break;

                case XMLHttpRequest.DONE:
                    correct = new Date().getTime() - (parseInt(syncRequest.responseText) + latency);

                    syncTimeout = setTimeout(sync, 10000);

                    break;
            }
        }

        syncRequest.open('GET', 'getTime.php', true);
        syncRequest.send();
    }

    function clock() {
        var dateTime = getSyncedDateTime();

        document.getElementById('year').innerHTML = dateTime.getFullYear();
        document.getElementById('month').innerHTML = _MONTHS_[dateTime.getMonth()];
        document.getElementById('date').innerHTML = dateTime.getDate();
        document.getElementById('day').innerHTML = _DAYS_[dateTime.getDay()];
        document.getElementById('time').innerHTML = fillZero(dateTime.getHours()) + ':' + fillZero(dateTime.getMinutes()) + ':' + fillZero(dateTime.getSeconds());

        if (Math.abs(correct) < 100) {
            document.getElementById('correct').style.display = 'none';
        } else {
            document.getElementById('correct').style.display = 'block';
            document.getElementById('correct_seconds').innerHTML = (correct > 0 ? '+' : '') + (correct / 1000).toFixed(1);
        }

        clockTimeout = setTimeout(clock, 100);
    }

    document.getElementsByTagName('main')[0].ondblclick = function () {
        sync();
    }

    clock();
    sync();
})();