1 files changed, 79 insertions, 0 deletions
diff --git a/src/timestamp.rs b/src/timestamp.rs
new file mode 100644
index 0000000..ea8f2e1
--- /dev/null
+++ b/src/timestamp.rs
@@ -0,0 +1,79 @@
+use crate::{Date, NaiveDateTime};
+
+#[derive(Clone, Copy, Eq, PartialEq, Hash, Debug)]
+pub struct UnixTimestamp {
+	seconds: i64,
+	nanoseconds: u32,
+}
+
+impl UnixTimestamp {
+	#[must_use]
+	pub const fn new(seconds: i64, nanoseconds: u32) -> Self {
+		Self {
+			seconds,
+			nanoseconds,
+		}
+	}
+
+	#[must_use]
+	pub const fn seconds_since_unix_epoch(self) -> i64 {
+		self.seconds
+	}
+
+	#[must_use]
+	pub const fn nanosecond(self) -> u32 {
+		self.nanoseconds
+	}
+
+	#[must_use]
+	pub const fn add_seconds_overflowing(self, seconds: i64) -> (Self, bool) {
+		// TODO overflowing goes first
+		let (seconds, overflowing) = self.seconds.overflowing_add(seconds as i64);
+
+		let timestamp = Self::new(seconds, self.nanoseconds);
+		(timestamp, overflowing)
+	}
+
+	#[must_use]
+	pub const fn add_nanoseconds_overflowing(self, nanoseconds: i64) -> (Self, bool) {
+		let total_nanos = (self.nanoseconds as i64 + nanoseconds) % 1_000_000_000;
+		let total_nanos = total_nanos + (1_000_000_000 * total_nanos.is_negative() as i64);
+		let added_seconds = (self.nanoseconds as i64 + nanoseconds) / 1_000_000_000;
+		let total_seconds = (self.seconds as i64 + added_seconds) % 60;
+		let overflow = 0 > total_seconds;
+		let total_seconds = total_seconds + (60 * total_seconds.is_negative() as i64);
+
+		let timestamp = Self::new(total_seconds, total_nanos as u32);
+		(timestamp, overflow)
+	}
+}
+
+impl From<NaiveDateTime> for UnixTimestamp {
+	fn from(ndt: NaiveDateTime) -> Self {
+		const UNIX_EPOCH_DAYS: i64 = Date::UNIX_EPOCH.days_after_common_era();
+		// TODO don't require the .date()
+		let days = (ndt.date().days_after_common_era() - UNIX_EPOCH_DAYS) as i64;
+		let seconds = days * 86_400 + i64::from(ndt.time().seconds_from_midnight());
+		let nanoseconds = ndt.nanosecond();
+
+		Self::new(seconds, nanoseconds)
+	}
+}
+
+impl PartialOrd for UnixTimestamp {
+	fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+		match self.seconds.partial_cmp(&other.seconds) {
+			Some(core::cmp::Ordering::Equal) => self.nanoseconds.partial_cmp(&other.nanoseconds),
+			ord => ord,
+		}
+	}
+}
+
+impl Ord for UnixTimestamp {
+	fn cmp(&self, other: &Self) -> core::cmp::Ordering {
+		match self.seconds.cmp(&other.seconds) {
+			core::cmp::Ordering::Equal => self.nanoseconds.cmp(&other.nanoseconds),
+			ord => ord,
+		}
+	}
+}