1 files changed, 138 insertions, 0 deletions
diff --git a/aero-ical/src/parser.rs b/aero-ical/src/parser.rs
new file mode 100644
index 0000000..4354737
--- /dev/null
+++ b/aero-ical/src/parser.rs
@@ -0,0 +1,138 @@
+use chrono::TimeDelta;
+
+use nom::IResult;
+use nom::branch::alt;
+use nom::bytes::complete::{tag, tag_no_case};
+use nom::combinator::{value, opt, map, map_opt};
+use nom::sequence::{pair, tuple};
+use nom::character::complete as nomchar;
+
+use aero_dav::caltypes as cal;
+
+//@FIXME too simple, we have 4 cases in practices:
+// - floating datetime
+// - floating datetime with a tzid as param so convertible to tz datetime
+// - utc datetime
+// - floating(?) date (without time)
+pub fn date_time(dt: &str) -> Option<chrono::DateTime<chrono::Utc>> {
+    tracing::trace!(raw_time = dt, "VEVENT raw time");
+    let tmpl = match dt.chars().last() {
+        Some('Z') => cal::UTC_DATETIME_FMT,
+        Some(_) => {
+            tracing::warn!(raw_time=dt, "floating datetime is not properly supported yet");
+            cal::FLOATING_DATETIME_FMT
+        },
+        None => return None
+    };
+
+    chrono::NaiveDateTime::parse_from_str(dt, tmpl)
+        .ok()
+        .map(|v| v.and_utc())
+}
+
+/// RFC3389 Duration Value
+///
+/// ```abnf
+/// dur-value  = (["+"] / "-") "P" (dur-date / dur-time / dur-week)
+/// dur-date   = dur-day [dur-time]
+/// dur-time   = "T" (dur-hour / dur-minute / dur-second)
+/// dur-week   = 1*DIGIT "W"
+/// dur-hour   = 1*DIGIT "H" [dur-minute]
+/// dur-minute = 1*DIGIT "M" [dur-second]
+/// dur-second = 1*DIGIT "S"
+/// dur-day    = 1*DIGIT "D"
+/// ```
+pub fn dur_value(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(tuple((
+        dur_sign, 
+        tag_no_case("P"), 
+        alt((
+            dur_date,
+            dur_time,
+            dur_week,
+        ))
+    )), |(sign, _, delta)| {
+        delta.checked_mul(sign)
+    })(text)
+}
+
+fn dur_sign(text: &str) -> IResult<&str, i32> {
+    map(opt(alt((value(1, tag("+")), value(-1, tag("-"))))), |x| x.unwrap_or(1))(text)
+}
+fn dur_date(text: &str) -> IResult<&str, TimeDelta> {
+    map(pair(dur_day, opt(dur_time)), |(day, time)| day + time.unwrap_or(TimeDelta::zero()))(text)
+}
+fn dur_time(text: &str) -> IResult<&str, TimeDelta> {
+    map(pair(tag_no_case("T"), alt((dur_hour, dur_minute, dur_second))), |(_, x)| x)(text)
+}
+fn dur_week(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(pair(nomchar::i64, tag_no_case("W")), |(i, _)| TimeDelta::try_weeks(i))(text)
+}
+fn dur_day(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(pair(nomchar::i64, tag_no_case("D")), |(i, _)| TimeDelta::try_days(i))(text)
+}
+fn dur_hour(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(tuple((nomchar::i64, tag_no_case("H"), opt(dur_minute))), |(i, _, mm)| {
+        TimeDelta::try_hours(i).map(|hours| hours + mm.unwrap_or(TimeDelta::zero()))
+    })(text)
+}
+fn dur_minute(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(tuple((nomchar::i64, tag_no_case("M"), opt(dur_second))), |(i, _, ms)| {
+        TimeDelta::try_minutes(i).map(|min| min + ms.unwrap_or(TimeDelta::zero()))
+    })(text)
+}
+fn dur_second(text: &str) -> IResult<&str, TimeDelta> {
+    map_opt(pair(nomchar::i64, tag_no_case("S")), |(i, _)| TimeDelta::try_seconds(i))(text)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rfc5545_example1() {
+        // A duration of 15 days, 5 hours, and 20 seconds would be:
+        let to_parse = "P15DT5H0M20S";
+        let (_, time_delta) = dur_value(to_parse).unwrap();
+        assert_eq!(
+            time_delta, 
+            TimeDelta::try_days(15).unwrap() + TimeDelta::try_hours(5).unwrap() + TimeDelta::try_seconds(20).unwrap());
+    }
+
+    #[test]
+    fn rfc5545_example2() {
+        // A duration of 7 weeks would be:
+        let to_parse = "P7W";
+        let (_, time_delta) = dur_value(to_parse).unwrap();
+        assert_eq!(
+            time_delta, 
+            TimeDelta::try_weeks(7).unwrap()
+        );
+    }
+
+    #[test]
+    fn rfc4791_example1()  {
+        // 10 minutes before
+        let to_parse = "-PT10M";
+
+        let (_, time_delta) = dur_value(to_parse).unwrap();
+        assert_eq!(
+            time_delta, 
+            TimeDelta::try_minutes(-10).unwrap()
+        );
+    }
+
+
+    #[test]
+    fn ical_org_example1() {
+        // The following example is for a "VALARM" calendar component that specifies an email alarm 
+        // that will trigger 2 days before the scheduled due DATE-TIME of a to-do with which it is associated.
+        let to_parse = "-P2D";
+
+        let (_, time_delta) = dur_value(to_parse).unwrap();
+        assert_eq!(
+            time_delta, 
+            TimeDelta::try_days(-2).unwrap()
+        );
+    }
+}