1 files changed, 87 insertions, 0 deletions
diff --git a/src/time.rs b/src/time.rs
new file mode 100644
index 0000000..534cb34
--- /dev/null
+++ b/src/time.rs
@@ -0,0 +1,87 @@
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+
+#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+pub struct Timestamp(pub SystemTime);
+
+impl Timestamp {
+    pub const ZERO: Timestamp = Timestamp(UNIX_EPOCH);
+
+    pub fn now() -> Timestamp {
+        return Timestamp(SystemTime::now());
+    }
+
+    pub fn duration_since(self, earlier: Timestamp) -> Result<Duration, std::time::SystemTimeError> {
+        return self.0.duration_since(earlier.0);
+    }
+}
+
+impl std::ops::Add<Duration> for Timestamp {
+    type Output = Timestamp;
+    fn add(self, rhs: Duration) -> Timestamp {
+        return Timestamp(self.0 + rhs);
+    }
+}
+
+impl std::ops::Sub<Duration> for Timestamp {
+    type Output = Timestamp;
+    fn sub(self, rhs: Duration) -> Timestamp {
+        return Timestamp(self.0 - rhs);
+    }
+}
+
+fn is_leap_year(y: u64) -> bool {
+    return (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0);
+}
+
+fn days_in_month(y: u64, m: u64) -> u64 {
+    match m {
+        1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
+        4 | 6 | 9 | 11 => 30,
+        2 => if is_leap_year(y) { 29 } else { 28 },
+        _ => panic!("invalid month"),
+    }
+}
+
+pub fn secs_to_ymd_hms(mut secs: u64) -> (u64, u64, u64, u64, u64, u64) {
+    let s = secs % 60;
+    secs /= 60;
+    let min = secs % 60;
+    secs /= 60;
+    let h = secs % 24;
+    let mut days = secs / 24;
+
+    let mut y = 1970u64;
+    loop {
+        let days_in_year = if is_leap_year(y) { 366 } else { 365 };
+        if days < days_in_year {
+            break;
+        }
+        days -= days_in_year;
+        y += 1;
+    }
+
+    let mut mo = 1u64;
+    loop {
+        let dim = days_in_month(y, mo);
+        if days < dim {
+            break;
+        }
+        days -= dim;
+        mo += 1;
+    }
+
+    let day = days + 1;
+    return (y, mo, day, h, min, s);
+}
+
+pub fn ymd_hms_to_secs(y: u64, m: u64, d: u64, h: u64, min: u64, s: u64) -> u64 {
+    let mut days = 0u64;
+    for year in 1970..y {
+        days += if is_leap_year(year) { 366 } else { 365 };
+    }
+    for month in 1..m {
+        days += days_in_month(y, month);
+    }
+    days += d - 1;
+    return days * 86400 + h * 3600 + min * 60 + s;
+}