Initial commit

src/sync/import_imap/internaldate.rs

@@ -0,0 +1,152 @@
+/*
+ * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR MIT
+ */
+
+use crate::error::Error;
+
+pub fn imap_internaldate_to_rfc3339(s: &str) -> Result<String, Error> {
+    let s = s.trim_start_matches(' ').trim_end();
+    let (day, rest) = s
+        .split_once('-')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: missing day in {s:?}")))?;
+    let (mon, rest) = rest
+        .split_once('-')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: missing month in {s:?}")))?;
+    let (year, rest) = rest
+        .split_once(' ')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: missing year in {s:?}")))?;
+    let (time, zone) = rest
+        .split_once(' ')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: missing zone in {s:?}")))?;
+    let (h, ms) = time
+        .split_once(':')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: bad time {time:?}")))?;
+    let (m, sec) = ms
+        .split_once(':')
+        .ok_or_else(|| Error::Partial(format!("INTERNALDATE: bad time {time:?}")))?;
+    let day: u32 = day
+        .trim()
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE day {day:?}: {e}")))?;
+    let mon_idx = month_to_num(mon)?;
+    let year: i32 = year
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE year {year:?}: {e}")))?;
+    let h: u32 = h
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE hour {h:?}: {e}")))?;
+    let m: u32 = m
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE minute {m:?}: {e}")))?;
+    let sec: u32 = sec
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE second {sec:?}: {e}")))?;
+    let (sign, hh, mm) = parse_zone(zone)?;
+    let mut out = String::with_capacity(32);
+    use std::fmt::Write;
+    let _ = write!(
+        &mut out,
+        "{year:04}-{mon_idx:02}-{day:02}T{h:02}:{m:02}:{sec:02}"
+    );
+    if hh == 0 && mm == 0 {
+        out.push('Z');
+    } else {
+        let _ = write!(&mut out, "{sign}{hh:02}:{mm:02}");
+    }
+    Ok(out)
+}
+
+fn month_to_num(s: &str) -> Result<u32, Error> {
+    let m = match s {
+        "Jan" => 1,
+        "Feb" => 2,
+        "Mar" => 3,
+        "Apr" => 4,
+        "May" => 5,
+        "Jun" => 6,
+        "Jul" => 7,
+        "Aug" => 8,
+        "Sep" => 9,
+        "Oct" => 10,
+        "Nov" => 11,
+        "Dec" => 12,
+        other => return Err(Error::Partial(format!("INTERNALDATE month {other:?}"))),
+    };
+    Ok(m)
+}
+
+fn parse_zone(s: &str) -> Result<(char, u32, u32), Error> {
+    let s = s.trim();
+    if s.len() != 5 {
+        return Err(Error::Partial(format!("INTERNALDATE zone {s:?}")));
+    }
+    let sign = s.as_bytes()[0] as char;
+    if sign != '+' && sign != '-' {
+        return Err(Error::Partial(format!("INTERNALDATE zone sign {sign}")));
+    }
+    let hh: u32 = s[1..3]
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE zone hour: {e}")))?;
+    let mm: u32 = s[3..5]
+        .parse()
+        .map_err(|e| Error::Partial(format!("INTERNALDATE zone min: {e}")))?;
+    Ok((sign, hh, mm))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn utc_zone_becomes_z() {
+        assert_eq!(
+            imap_internaldate_to_rfc3339("17-Jul-1996 02:44:25 +0000").unwrap(),
+            "1996-07-17T02:44:25Z"
+        );
+    }
+
+    #[test]
+    fn positive_offset_preserved() {
+        assert_eq!(
+            imap_internaldate_to_rfc3339("17-Jul-1996 02:44:25 +0200").unwrap(),
+            "1996-07-17T02:44:25+02:00"
+        );
+    }
+
+    #[test]
+    fn negative_offset_preserved() {
+        assert_eq!(
+            imap_internaldate_to_rfc3339("17-Jul-1996 02:44:25 -0700").unwrap(),
+            "1996-07-17T02:44:25-07:00"
+        );
+    }
+
+    #[test]
+    fn single_digit_day_padded() {
+        assert_eq!(
+            imap_internaldate_to_rfc3339("5-Jan-2024 09:05:01 +0000").unwrap(),
+            "2024-01-05T09:05:01Z"
+        );
+    }
+
+    #[test]
+    fn leading_space_single_digit_day() {
+        assert_eq!(
+            imap_internaldate_to_rfc3339(" 5-Jan-2024 09:05:01 +0000").unwrap(),
+            "2024-01-05T09:05:01Z"
+        );
+    }
+
+    #[test]
+    fn invalid_month_errors() {
+        assert!(imap_internaldate_to_rfc3339("1-XYZ-2024 00:00:00 +0000").is_err());
+    }
+
+    #[test]
+    fn malformed_input_errors() {
+        assert!(imap_internaldate_to_rfc3339("garbage").is_err());
+        assert!(imap_internaldate_to_rfc3339("17-Jul-1996").is_err());
+    }
+}