213 lines
8.9 KiB
Zig
213 lines
8.9 KiB
Zig
// From https://gist.github.com/WoodyAtHome/3ef50b17f0fa2860ac52b97af12f8d15
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// Translated from German. We don't need any local time for this use case, and conversion
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// really requires the TZ DB.
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const std = @import("std");
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const log = std.log.scoped(.date);
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const zeit = @import("zeit");
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pub const DateTime = struct {
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day: u8,
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month: u8,
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year: u16,
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hour: u8,
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minute: u8,
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second: u8,
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pub fn fromInstant(val: zeit.Instant) DateTime {
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return fromTime(val.time());
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}
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pub fn fromTime(val: zeit.Time) DateTime {
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return DateTime{
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.day = val.day,
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.month = @intFromEnum(val.month),
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.year = @intCast(val.year),
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.hour = val.hour,
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.minute = val.minute,
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.second = val.second,
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};
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}
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pub fn time(self: DateTime) zeit.Time {
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return zeit.Time{
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.day = @intCast(self.day),
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.month = @enumFromInt(self.month),
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.year = self.year,
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.hour = @intCast(self.hour),
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.minute = @intCast(self.minute),
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.second = @intCast(self.second),
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};
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}
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pub fn instant(self: DateTime) !zeit.Instant {
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return try zeit.instant(.{ .source = .{ .time = self.time() } });
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}
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};
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const SECONDS_PER_DAY = 86400; //* 24* 60 * 60 */
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const DAYS_PER_YEAR = 365; //* Normal year (no leap year) */
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pub fn timestampToDateTime(timestamp: zeit.Seconds) DateTime {
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const ins = zeit.instant(.{ .source = .{ .unix_timestamp = timestamp } }) catch @panic("Failed to create instant from timestamp");
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return DateTime.fromInstant(ins);
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}
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pub fn parseEnglishToTimestamp(data: []const u8) !i64 {
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return try dateTimeToTimestamp(try parseEnglishToDateTime(data));
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}
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/// Converts a string to a timestamp value. May not handle dates before the
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/// epoch. Dates should look like "Fri, 03 Jun 2022 18:12:36 GMT"
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pub fn parseEnglishToDateTime(data: []const u8) !DateTime {
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const ins = try zeit.instant(.{ .source = .{ .rfc1123 = data } });
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return DateTime.fromInstant(ins);
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}
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pub fn parseIso8601ToTimestamp(data: []const u8) !i64 {
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return try dateTimeToTimestamp(try parseIso8601ToDateTime(data));
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}
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const IsoParsingState = enum { Start, Year, Month, Day, Hour, Minute, Second, Millisecond, End };
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/// Converts a string to a timestamp value. May not handle dates before the
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/// epoch
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pub fn parseIso8601ToDateTime(data: []const u8) !DateTime {
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// Basic format YYYYMMDDThhmmss
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if (data.len == "YYYYMMDDThhmmss".len and data[8] == 'T')
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return try parseIso8601BasicFormatToDateTime(data);
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if (data.len == "YYYYMMDDThhmmssZ".len and data[8] == 'T')
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return try parseIso8601BasicFormatToDateTime(data);
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var start: usize = 0;
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var state = IsoParsingState.Start;
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// Anything not explicitly set by our string would be 0
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var rc = DateTime{ .year = 0, .month = 0, .day = 0, .hour = 0, .minute = 0, .second = 0 };
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var zulu_time = false;
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for (data, 0..) |ch, i| {
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switch (ch) {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9' => {
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if (state == .Start) state = .Year;
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},
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'?', '~', '%' => {
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// These characters all specify the type of time (approximate, etc)
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// and we will ignore
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},
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'.', '-', ':', 'T' => {
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// State transition
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// We're going to coerce and this might not go well, but we
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// want the compiler to create checks, so we'll turn on
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// runtime safety for this block, forcing checks in ReleaseSafe
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// ReleaseFast modes.
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const next_state = try endIsoState(state, &rc, data[start..i]);
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state = next_state;
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start = i + 1;
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},
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'Z' => zulu_time = true,
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else => {
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log.err("Invalid character: {c}", .{ch});
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return error.InvalidCharacter;
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},
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}
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}
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if (!zulu_time) return error.LocalTimeNotSupported;
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// We know we have a Z at the end of this, so let's grab the last bit
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// of the string, minus the 'Z', and fly, eagles, fly!
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_ = try endIsoState(state, &rc, data[start .. data.len - 1]);
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return rc;
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}
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fn parseIso8601BasicFormatToDateTime(data: []const u8) !DateTime {
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return DateTime{
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.year = try std.fmt.parseUnsigned(u16, data[0..4], 10),
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.month = try std.fmt.parseUnsigned(u8, data[4..6], 10),
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.day = try std.fmt.parseUnsigned(u8, data[6..8], 10),
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.hour = try std.fmt.parseUnsigned(u8, data[9..11], 10),
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.minute = try std.fmt.parseUnsigned(u8, data[11..13], 10),
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.second = try std.fmt.parseUnsigned(u8, data[13..15], 10),
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};
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}
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fn endIsoState(current_state: IsoParsingState, date: *DateTime, prev_data: []const u8) !IsoParsingState {
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var next_state: IsoParsingState = undefined;
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log.debug("endIsoState. Current state '{}', data: {s}", .{ current_state, prev_data });
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// Using two switches is slightly less efficient, but more readable
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switch (current_state) {
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.Start, .End => return error.IllegalStateTransition,
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.Year => next_state = .Month,
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.Month => next_state = .Day,
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.Day => next_state = .Hour,
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.Hour => next_state = .Minute,
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.Minute => next_state = .Second,
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.Second => next_state = .Millisecond,
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.Millisecond => next_state = .End,
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}
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// TODO: This won't handle signed, which Iso supports. For now, let's fail
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// explictly
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switch (current_state) {
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.Year => date.year = try std.fmt.parseUnsigned(u16, prev_data, 10),
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.Month => date.month = try std.fmt.parseUnsigned(u8, prev_data, 10),
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.Day => date.day = try std.fmt.parseUnsigned(u8, prev_data, 10),
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.Hour => date.hour = try std.fmt.parseUnsigned(u8, prev_data, 10),
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.Minute => date.minute = try std.fmt.parseUnsigned(u8, prev_data, 10),
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.Second => date.second = try std.fmt.parseUnsigned(u8, prev_data, 10),
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.Millisecond => {}, // We'll throw that away - our granularity is 1 second
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.Start, .End => return error.InvalidState,
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}
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return next_state;
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}
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pub fn dateTimeToTimestamp(datetime: DateTime) !zeit.Seconds {
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return (try datetime.instant()).unixTimestamp();
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}
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const DateTimeToTimestampError = error{
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DateTimeOutOfRange,
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};
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fn printDateTime(dt: DateTime) void {
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log.debug("{:0>4}-{:0>2}-{:0>2}T{:0>2}:{:0>2}:{:0<2}Z", .{
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dt.year,
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dt.month,
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dt.day,
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dt.hour,
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dt.minute,
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dt.second,
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});
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}
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pub fn printNowUtc() void {
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printDateTime(timestampToDateTime(std.time.timestamp()));
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}
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test "Convert timestamp to datetime" {
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printDateTime(timestampToDateTime(std.time.timestamp()));
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try std.testing.expectEqual(DateTime{ .year = 2020, .month = 8, .day = 28, .hour = 9, .minute = 32, .second = 27 }, timestampToDateTime(1598607147));
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try std.testing.expectEqual(DateTime{ .year = 2020, .month = 11, .day = 1, .hour = 5, .minute = 6, .second = 7 }, timestampToDateTime(1604207167));
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// Get time for date: https://wtools.io/convert-date-time-to-unix-time
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try std.testing.expectEqual(DateTime{ .year = 2015, .month = 8, .day = 30, .hour = 12, .minute = 36, .second = 0 }, timestampToDateTime(1440938160));
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}
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test "Convert datetime to timestamp" {
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try std.testing.expectEqual(@as(i64, 1598607147), try dateTimeToTimestamp(DateTime{ .year = 2020, .month = 8, .day = 28, .hour = 9, .minute = 32, .second = 27 }));
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try std.testing.expectEqual(@as(i64, 1604207167), try dateTimeToTimestamp(DateTime{ .year = 2020, .month = 11, .day = 1, .hour = 5, .minute = 6, .second = 7 }));
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try std.testing.expectEqual(@as(i64, 1440938160), try dateTimeToTimestamp(DateTime{ .year = 2015, .month = 8, .day = 30, .hour = 12, .minute = 36, .second = 0 }));
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}
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test "Convert ISO8601 string to timestamp" {
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try std.testing.expectEqual(DateTime{ .year = 2020, .month = 8, .day = 28, .hour = 9, .minute = 32, .second = 27 }, try parseIso8601ToDateTime("20200828T093227"));
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try std.testing.expectEqual(DateTime{ .year = 2020, .month = 8, .day = 28, .hour = 9, .minute = 32, .second = 27 }, try parseIso8601ToDateTime("2020-08-28T9:32:27Z"));
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try std.testing.expectEqual(DateTime{ .year = 2020, .month = 11, .day = 1, .hour = 5, .minute = 6, .second = 7 }, try parseIso8601ToDateTime("2020-11-01T5:06:7Z"));
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try std.testing.expectEqual(DateTime{ .year = 2015, .month = 8, .day = 30, .hour = 12, .minute = 36, .second = 0 }, try parseIso8601ToDateTime("2015-08-30T12:36:00.000Z"));
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}
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test "Convert datetime to timestamp before 1970" {
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try std.testing.expectEqual(@as(i64, -449392815), try dateTimeToTimestamp(DateTime{ .year = 1955, .month = 10, .day = 5, .hour = 16, .minute = 39, .second = 45 }));
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}
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test "Convert whatever AWS is sending us to timestamp" {
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const string_date = "Fri, 03 Jun 2022 18:12:36 GMT";
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try std.testing.expectEqual(DateTime{ .year = 2022, .month = 6, .day = 3, .hour = 18, .minute = 12, .second = 36 }, try parseEnglishToDateTime(string_date));
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}
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