Date

const Date = struct {
    /// example: 1999
    year: u16,
    /// range: 1 to 12
    month: u8,
    /// range: 1 to 31
    day: u8,
    /// range: 0 to 59
    hour: u8,
    /// range: 0 to 59
    minute: u8,
    /// range: 0 to 59
    second: u8,

    /// Convert to number of seconds since epoch.
    pub fn toSeconds(date: Date) u64 {
        var sec: u64 = 0;

        {
            var year: u16 = 1970;
            while (year < date.year) : (year += 1) {
                const days: u64 = std.time.epoch.getDaysInYear(year);
                sec += days * std.time.epoch.secs_per_day;
            }
        }

        {
            var month: u4 = 1;
            while (month < date.month) : (month += 1) {
                const days: u64 = std.time.epoch.getDaysInMonth(
                    date.year,
                    @fromBackingInt(@intCast(month)),
                );
                sec += days * std.time.epoch.secs_per_day;
            }
        }

        sec += (date.day - 1) * @as(u64, std.time.epoch.secs_per_day);
        sec += date.hour * @as(u64, 60 * 60);
        sec += date.minute * @as(u64, 60);
        sec += date.second;

        return sec;
    }
}