Expand gix-date baseline tests and implement missing Git date formats

gix-date/src/parse/function.rs

@@ -0,0 +1,182 @@
+use std::{str::FromStr, time::SystemTime};
+
+use jiff::{civil::Date, fmt::rfc2822, tz::TimeZone, Zoned};
+
+use crate::parse::git::parse_git_date_format;
+use crate::parse::raw::parse_raw;
+use crate::{
+    parse::{relative, Error},
+    time::format::{DEFAULT, GITOXIDE, ISO8601, ISO8601_STRICT, SHORT},
+    OffsetInSeconds, SecondsSinceUnixEpoch, Time,
+};
+
+/// Parse `input` as any time that Git can parse when inputting a date.
+///
+/// ## Examples
+///
+/// ### 1. SHORT Format
+///
+/// *   `2018-12-24`
+/// *   `1970-01-01`
+/// *   `1950-12-31`
+/// *   `2024-12-31`
+///
+/// ### 2. RFC2822 Format
+///
+/// *   `Thu, 18 Aug 2022 12:45:06 +0800`
+/// *   `Mon Oct 27 10:30:00 2023 -0800`
+///
+/// ### 3. GIT_RFC2822 Format
+///
+/// *   `Thu, 8 Aug 2022 12:45:06 +0800`
+/// *   `Mon Oct 27 10:30:00 2023 -0800` (Note the single-digit day)
+///
+/// ### 4. ISO8601 Format
+///
+/// *   `2022-08-17 22:04:58 +0200`
+/// *   `1970-01-01 00:00:00 -0500`
+///
+/// ### 5. ISO8601_STRICT Format
+///
+/// *   `2022-08-17T21:43:13+08:00`
+///
+/// ### 6. UNIX Timestamp (Seconds Since Epoch)
+///
+/// *   `123456789`
+/// *   `0` (January 1, 1970 UTC)
+/// *   `-1000`
+/// *   `1700000000`
+///
+/// ### 7. Commit Header Format
+///
+/// *   `1745582210 +0200`
+/// *   `1660874655 +0800`
+/// *   `-1660874655 +0800`
+///
+/// See also the [`parse_header()`].
+///
+/// ### 8. GITOXIDE Format
+///
+/// *   `Thu Sep 04 2022 10:45:06 -0400`
+/// *   `Mon Oct 27 2023 10:30:00 +0000`
+///
+/// ### 9. DEFAULT Format
+///
+/// *   `Thu Sep 4 10:45:06 2022 -0400`
+/// *   `Mon Oct 27 10:30:00 2023 +0000`
+///
+/// ### 10. Relative Dates (e.g., "2 minutes ago", "1 hour from now")
+///
+/// These dates are parsed *relative to a `now` timestamp*. The examples depend entirely on the value of `now`.
+/// If `now` is October 27, 2023 at 10:00:00 UTC:
+///     *   `2 minutes ago` (October 27, 2023 at 09:58:00 UTC)
+///     *   `3 hours ago` (October 27, 2023 at 07:00:00 UTC)
+pub fn parse(input: &str, now: Option<SystemTime>) -> Result<Time, Error> {
+    Ok(if let Ok(val) = Date::strptime(SHORT.0, input) {
+        let val = val
+            .to_zoned(TimeZone::UTC)
+            .map_err(|_| Error::InvalidDateString { input: input.into() })?;
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = rfc2822_relaxed(input) {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = strptime_relaxed(ISO8601.0, input) {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = strptime_relaxed(ISO8601_STRICT.0, input) {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = strptime_relaxed(GITOXIDE.0, input) {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = strptime_relaxed(DEFAULT.0, input) {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Ok(val) = SecondsSinceUnixEpoch::from_str(input) {
+        Time::new(val, 0)
+    } else if let Some(val) = parse_git_date_format(input) {
+        val
+    } else if let Some(val) = relative::parse(input, now).transpose()? {
+        Time::new(val.timestamp().as_second(), val.offset().seconds())
+    } else if let Some(val) = parse_raw(input) {
+        // Format::Raw
+        val
+    } else {
+        return Err(Error::InvalidDateString { input: input.into() });
+    })
+}
+
+/// Unlike [`parse()`] which handles all kinds of input, this function only parses the commit-header format
+/// like `1745582210 +0200`.
+///
+/// Note that failure to parse the time zone isn't fatal, instead it will default to `0`. To know if
+/// the time is wonky, serialize the return value to see if it matches the `input.`
+pub fn parse_header(input: &str) -> Option<Time> {
+    pub enum Sign {
+        Plus,
+        Minus,
+    }
+    fn parse_offset(offset: &str) -> Option<OffsetInSeconds> {
+        if (offset.len() != 5) && (offset.len() != 7) {
+            return None;
+        }
+        let sign = match offset.get(..1)? {
+            "-" => Some(Sign::Minus),
+            "+" => Some(Sign::Plus),
+            _ => None,
+        }?;
+        if offset.as_bytes().get(1).is_some_and(|b| !b.is_ascii_digit()) {
+            return None;
+        }
+        let hours: i32 = offset.get(1..3)?.parse().ok()?;
+        let minutes: i32 = offset.get(3..5)?.parse().ok()?;
+        let offset_seconds: i32 = if offset.len() == 7 {
+            offset.get(5..7)?.parse().ok()?
+        } else {
+            0
+        };
+        let mut offset_in_seconds = hours * 3600 + minutes * 60 + offset_seconds;
+        if matches!(sign, Sign::Minus) {
+            offset_in_seconds *= -1;
+        }
+        Some(offset_in_seconds)
+    }
+
+    if input.contains(':') {
+        return None;
+    }
+    let mut split = input.split_whitespace();
+    let seconds = split.next()?;
+    let seconds = match seconds.parse::<SecondsSinceUnixEpoch>() {
+        Ok(s) => s,
+        Err(_err) => {
+            // Inefficient, but it's not the common case.
+            let first_digits: String = seconds.chars().take_while(char::is_ascii_digit).collect();
+            first_digits.parse().ok()?
+        }
+    };
+    let offset = match split.next() {
+        None => 0,
+        Some(offset) => {
+            if split.next().is_some() {
+                0
+            } else {
+                parse_offset(offset).unwrap_or_default()
+            }
+        }
+    };
+    let time = Time { seconds, offset };
+    Some(time)
+}
+
+/// This is just like `Zoned::strptime`, but it allows parsing datetimes
+/// whose weekdays are inconsistent with the date. While the day-of-week
+/// still must be parsed, it is otherwise ignored. This seems to be
+/// consistent with how `git` behaves.
+fn strptime_relaxed(fmt: &str, input: &str) -> Result<Zoned, jiff::Error> {
+    let mut tm = jiff::fmt::strtime::parse(fmt, input)?;
+    tm.set_weekday(None);
+    tm.to_zoned()
+}
+
+/// This is just like strptime_relaxed, except for RFC 2822 parsing.
+/// Namely, it permits the weekday to be inconsistent with the date.
+fn rfc2822_relaxed(input: &str) -> Result<Zoned, jiff::Error> {
+    static P: rfc2822::DateTimeParser = rfc2822::DateTimeParser::new().relaxed_weekday(true);
+    P.parse_zoned(input)
+}