calcDuration() {
        let duration = dayjs.utc(this.end_time, "HH:mm").diff(dayjs.utc(this.start_time, "HH:mm"), "second");
        // Add 24hours if it is across day
        if (duration < 0) {
            duration += 24 * 3600;
        }
        return duration;
    }
Get the duration of maintenance in seconds
@returns {number} Duration of maintenance