I should probably make more commits

src/datetime.rs

@@ -0,0 +1,112 @@
+use std::time::SystemTime;
+
+use chrono::{DateTime, Datelike, NaiveDate, NaiveTime, Timelike, Utc};
+
+#[derive(Debug)]
+pub struct Date {
+    repr: u16,
+}
+
+impl Date {
+    pub fn new(repr: u16) -> anyhow::Result<Date> {
+        let date = Date { repr };
+
+        anyhow::ensure!(date.day() <= 31, "invalid day for date: {} (0x{:#X})", date.day(), repr);
+        anyhow::ensure!(
+            date.month() <= 12,
+            "invalid month for date: {} (0x{:#X})",
+            date.month(),
+            repr
+        );
+
+        Ok(date)
+    }
+
+    pub fn from_day_month_year(day: u8, month: u8, year: u16) -> anyhow::Result<Date> {
+        anyhow::ensure!(day <= 31, "invalid day: {}", day);
+        anyhow::ensure!(month <= 12, "invalid month: {}", month);
+        anyhow::ensure!(1980 <= year && year <= 2107, "invalid year: {}", year);
+
+        let repr = day as u16 | (month as u16) << 4 | (year - 1980) << 8;
+
+        Ok(Date { repr })
+    }
+
+    pub fn from_system_time(time: SystemTime) -> anyhow::Result<Date> {
+        let datetime: DateTime<Utc> = time.into();
+
+        let date = datetime.date_naive();
+
+        Date::from_day_month_year(
+            date.day() as u8,
+            date.month0() as u8 + 1,
+            date.year_ce().1 as u16,
+        )
+    }
+
+    pub fn day(&self) -> u8 {
+        (self.repr & 0x1F) as u8
+    }
+
+    pub fn month(&self) -> u8 {
+        ((self.repr & 0x1E0) >> 5) as u8
+    }
+
+    pub fn year(&self) -> u16 {
+        ((self.repr & 0xFE00) >> 9) as u16 + 1980
+    }
+
+    pub fn to_naive_date(&self) -> NaiveDate {
+        NaiveDate::from_ymd_opt(self.year() as i32, self.month() as u32, self.day() as u32).unwrap()
+    }
+}
+
+#[derive(Debug)]
+pub struct Time {
+    repr: u16,
+}
+
+impl Time {
+    pub fn new(time: u16) -> anyhow::Result<Time> {
+        let time = Time { repr: time };
+
+        Ok(time)
+    }
+
+    pub fn from_seconds_minutes_hours(seconds: u8, minutes: u8, hours: u8) -> anyhow::Result<Time> {
+        anyhow::ensure!(seconds <= 58 && seconds % 2 == 0, "invalid seconds: {}", seconds);
+        anyhow::ensure!(minutes <= 59, "invalid minutes: {}", minutes);
+        anyhow::ensure!(hours <= 23, "invalid hours: {}", hours);
+
+        let repr = (seconds >> 1) as u16 | (minutes as u16) << 5 | (hours as u16) << 11;
+
+        Ok(Time { repr })
+    }
+
+    pub fn from_system_time(time: SystemTime) -> anyhow::Result<Time> {
+        let datetime: DateTime<Utc> = time.into();
+
+        let time = datetime.time();
+
+        let seconds = (time.second() as u8) & !0x01;
+
+        Time::from_seconds_minutes_hours(seconds, time.minute() as u8, time.hour() as u8)
+    }
+
+    pub fn second(&self) -> u8 {
+        2 * (self.repr & 0x1F) as u8
+    }
+
+    pub fn minute(&self) -> u8 {
+        ((self.repr >> 5) & 0x3F) as u8
+    }
+
+    pub fn hour(&self) -> u8 {
+        ((self.repr >> 11) & 0x1F) as u8
+    }
+
+    pub fn to_naive_time(&self) -> NaiveTime {
+        NaiveTime::from_hms_opt(self.hour() as u32, self.minute() as u32, self.second() as u32)
+            .unwrap()
+    }
+}