1use std::time::{SystemTime, UNIX_EPOCH};
5
6pub fn rfc3339(unix_secs: u64) -> String {
8 let days = (unix_secs / 86_400) as i64;
9 let secs = unix_secs % 86_400;
10 let z = days + 719_468;
13 let era = z.div_euclid(146_097);
14 let doe = z.rem_euclid(146_097);
15 let yoe = (doe - doe / 1460 + doe / 36_524 - doe / 146_096) / 365;
16 let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
17 let mp = (5 * doy + 2) / 153;
18 let d = doy - (153 * mp + 2) / 5 + 1;
19 let m = if mp < 10 { mp + 3 } else { mp - 9 };
20 let y = yoe + era * 400 + i64::from(m <= 2);
21 format!(
22 "{y:04}-{m:02}-{d:02}T{:02}:{:02}:{:02}Z",
23 secs / 3600,
24 secs / 60 % 60,
25 secs % 60
26 )
27}
28
29pub fn now() -> String {
30 rfc3339(
31 SystemTime::now()
32 .duration_since(UNIX_EPOCH)
33 .map_or(0, |d| d.as_secs()),
34 )
35}
36
37#[cfg(test)]
38mod tests {
39 #[test]
40 fn known_dates() {
41 assert_eq!(super::rfc3339(0), "1970-01-01T00:00:00Z");
42 assert_eq!(super::rfc3339(951_782_400), "2000-02-29T00:00:00Z");
43 assert_eq!(super::rfc3339(1_792_281_600), "2026-10-18T00:00:00Z");
44 }
45}