/* Baby Buddy Timer
 *
 * Uses a supplied ID to run a timer. The element using the ID must have
 * three children with the following classes:
 *  * timer-seconds
 *  * timer-minutes
 *  * timer-hours
 */
BabyBuddy.Timer = function ($) {
    var runIntervalId = null;
    var timerId = null;
    var timerElement = null;
    var lastUpdate = moment();

    var Timer = {
        run: function(timer_id, element_id) {
            timerId = timer_id;
            timerElement = $('#' + element_id);

            if (timerElement.length == 0) {
                console.error('BBTimer: Timer element not found.');
                return false;
            }

            if (timerElement.find('.timer-seconds').length == 0
                || timerElement.find('.timer-minutes').length == 0
                || timerElement.find('.timer-hours').length == 0) {
                console.error('BBTimer: Element does not contain expected children.');
                return false;
            }

            runIntervalId = setInterval(this.tick, 1000);

            // If the page just came in to view, update the timer data with the
            // current actual duration. This will (potentially) help mobile
            // phones that lock with the timer page open.
            Visibility.change(function (e, state) {
                if (state == 'visible' && moment().diff(lastUpdate) > 2000) {
                    clearInterval(runIntervalId);
                    Timer.update();
                    runIntervalId = setInterval(Timer.tick, 1000);
                }
            });
        },

        tick: function() {
            var s = timerElement.find('.timer-seconds');
            var seconds = Number(s.text());
            if (seconds < 59) {
                s.text(seconds + 1);
                return;
            }
            else {
                s.text(0);
            }

            var m = timerElement.find('.timer-minutes');
            var minutes = Number(m.text());
            if (minutes < 59) {
                m.text(minutes + 1);
                return;
            }
            else {
                m.text(0);
            }

            var h = timerElement.find('.timer-hours');
            var hours = Number(h.text());
            h.text(hours + 1);
        },

        update: function() {
            $.get('/api/timers/' + timerId + '/', function(data) {
                if (data && 'duration' in data) {
                    var duration = moment.duration(data.duration);
                    timerElement.find('.timer-hours').text(duration.hours());
                    timerElement.find('.timer-minutes').text(duration.minutes());
                    timerElement.find('.timer-seconds').text(duration.seconds());
                    lastUpdate = moment();
                }
            });
        }
    };

    return Timer;
}(jQuery);