Basic timezones

2 files changed, 81 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index d3b0e30..12b7225 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,7 @@ mod date;
 mod datetime;
 mod month;
 mod time;
+pub mod timezone;
 mod weekday;
 mod year;
 
diff --git a/src/timezone.rs b/src/timezone.rs
new file mode 100644
index 0000000..8401631
--- /dev/null
+++ b/src/timezone.rs
@@ -0,0 +1,80 @@
+use crate::NaiveDateTime;
+use core::convert::Infallible;
+
+/// A type that can be used to represent a TimeZone
+pub trait TimeZone {
+	type Err;
+
+	fn utc_offset(&self, date_time: NaiveDateTime) -> Result<UtcOffset, Self::Err>;
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+/// The UTC time zone
+pub struct Utc;
+
+impl TimeZone for Utc {
+	type Err = Infallible;
+
+	fn utc_offset(&self, _: NaiveDateTime) -> Result<UtcOffset, Self::Err> {
+		Ok(UtcOffset::UTC)
+	}
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
+/// A timezone with a fixed offset from UTC
+pub struct UtcOffset {
+	offset_seconds: i32,
+}
+
+impl UtcOffset {
+	/// The UTC Timezone, represented as an offset
+	pub const UTC: Self = Self { offset_seconds: 0 };
+
+	// TODO validation
+
+	/// Makes a new `UtcOffset` timezone with the given timezone difference.
+	/// A positive number is the Eastern hemisphere. A negative number is the
+	/// Western hemisphere.
+	///
+	/// # Safety
+	///
+	/// A value with an absolute value greater than or equal to 86,400 results
+	/// in undefined behavior
+	pub const unsafe fn from_seconds_unchecked(seconds: i32) -> Self {
+		Self {
+			offset_seconds: seconds,
+		}
+	}
+
+	/// Makes a new `UtcOffset` timezone with the given timezone difference.
+	/// A positive number is the Eastern hemisphere. A negative number is the
+	/// Western hemisphere.
+	///
+	/// # Safety
+	///
+	/// A value with an absolute value greater than or equal to 24 results
+	/// in undefined behavior
+	pub const unsafe fn from_hours_unchecked(hours: i8) -> Self {
+		Self::from_seconds_unchecked(hours as i32 * 3600)
+	}
+
+	/// The number of hours this timezone is ahead of UTC. THis number is
+	/// negative if the timezone is in the Western hemisphere
+	pub fn hours_ahead(self) -> f32 {
+		self.offset_seconds as f32 / 3600.0
+	}
+
+	/// The number of seconds this timezone is ahead of UTC. This number is
+	/// negative if the timezone is in the Western hemisphere
+	pub const fn seconds_ahead(self) -> i32 {
+		self.offset_seconds
+	}
+}
+
+impl TimeZone for UtcOffset {
+	type Err = Infallible;
+
+	fn utc_offset(&self, _: NaiveDateTime) -> Result<UtcOffset, Self::Err> {
+		Ok(*self)
+	}
+}