Allow for minutes in TimeZone offsets

src/main.zig

@@ -135,37 +135,95 @@ pub const TimeZoneTag = enum(u1) {
     offset,
 };
 
-pub const TimeZone = union(TimeZoneTag) {
-    utc: void,
-    offset: i8,
+pub const Sign = enum(u1) {
+    positive,
+    negative,
+};
+
+pub const HoursMinutes = struct {
+    hours: u4,
+    minutes: ?u6,
+};
+
+pub const Offset = union(Sign) {
+    positive: HoursMinutes,
+    negative: HoursMinutes,
 
     const Self = @This();
 
-    pub fn new(offset: ?i8) ?Self {
-        return if (offset) |ofs| blk: {
-            if (ofs < -12 or ofs > 12) {
-                break :blk null;
-            } else if (ofs == 0) {
-                break :blk .utc;
-            } else {
-                break :blk Self{ .offset = ofs };
+    fn new(hours: i8, minutes: ?u6) ?Self {
+        if (hours > 12 or hours < -12) {
+            return null;
         }
-        } else .utc;
+        if (minutes) |m| {
+            if (m > 59) return null;
+            if (hours == 0 and m == 0) return null;
+        } else if (hours == 0) return null;
+        if (hours < 0) {
+            const h = @intCast(u4, @as(i8, hours) * -1);
+            return Self{ .negative = .{ .hours = h, .minutes = minutes } };
+        } else {
+            return Self{ .positive = .{ .hours = @intCast(u4, hours), .minutes = minutes } };
+        }
+    }
+
+    fn as_seconds(self: Self) i64 {
+        return switch (self) {
+            .positive => |ofs| blk: {
+                var seconds = @as(i64, ofs.hours) * 3600;
+                if (ofs.minutes) |m| seconds += (@as(i64, m) * 60);
+                break :blk seconds;
+            },
+            .negative => |ofs| blk: {
+                var seconds = @as(i64, ofs.hours) * 3600;
+                if (ofs.minutes) |m| seconds += (@as(i64, m) * 60);
+                break :blk seconds * -1;
+            },
+        };
+    }
+};
+
+test "new offsets" {
+    try testing.expectEqual(Offset.new(-5, null), Offset{ .negative = .{ .hours = 5, .minutes = null } });
+    try testing.expectEqual(Offset.new(3, null), Offset{ .positive = .{ .hours = 3, .minutes = null } });
+}
+
+test "as seconds" {
+    try testing.expectEqual(Offset.new(-4, 30).?.as_seconds(), -16200);
+    try testing.expectEqual(Offset.new(3, null).?.as_seconds(), 10800);
+}
+
+pub const TimeZone = union(TimeZoneTag) {
+    utc: void,
+    offset: Offset,
+
+    const Self = @This();
+
+    pub fn new(hours: ?i8, minutes: ?u6) ?Self {
+        return if (hours) |h| blk: {
+            if (h == 0) {
+                break :blk .utc;
+            } else if (Offset.new(h, minutes)) |ofs| {
+                break :blk Self{ .offset = ofs };
+            } else {
+                break :blk null;
+            }
+        } else if (minutes) |m| Self{ .offset = Offset.new(0, m).? } else .utc;
     }
 };
 
 test "new timezone" {
-    const tz = TimeZone.new(-5).?;
+    const tz = TimeZone.new(-5, null).?;
     try testing.expectEqual(@as(TimeZoneTag, tz), .offset);
     switch (tz) {
-        .offset => |ofs| try testing.expectEqual(ofs, -5),
+        .offset => |ofs| try testing.expectEqual(ofs, Offset{ .negative = .{ .hours = 5, .minutes = null } }),
         else => unreachable,
     }
 }
 
 test "new timezone utc" {
-    const tz0 = TimeZone.new(null).?;
-    const tz1 = TimeZone.new(0).?;
+    const tz0 = TimeZone.new(null, null).?;
+    const tz1 = TimeZone.new(0, null).?;
     try testing.expectEqual(@as(TimeZoneTag, tz0), .utc);
     try testing.expectEqual(@as(TimeZoneTag, tz1), .utc);
 }
@@ -186,7 +244,7 @@ pub const DateTime = struct {
         return self.year.get();
     }
 
-    pub fn getOffset(self: Self) ?i8 {
+    pub fn getOffset(self: Self) ?Offset {
         return switch (self.tz) {
             .utc => null,
             .offset => |ofs| ofs,
@@ -203,7 +261,7 @@ test "get year" {
         .minute = 5,
         .second = 14,
         .nanos = null,
-        .tz = TimeZone.new(-5).?,
+        .tz = TimeZone.new(-5, null).?,
     };
     try testing.expectEqual(dt.getYear(), 2023);
 }
@@ -217,7 +275,7 @@ test "get offset" {
         .minute = 5,
         .second = 14,
         .nanos = null,
-        .tz = TimeZone.new(-5).?,
+        .tz = TimeZone.new(-5, null).?,
     };
-    try testing.expectEqual(dt.getOffset().?, -5);
+    try testing.expectEqual(dt.getOffset().?, Offset{ .negative = .{ .hours = 5, .minutes = null } });
 }