Move ical-related stuff to dedicated rustical_ical crate

crates/ical/src/timestamp.rs

@@ -0,0 +1,290 @@
+use crate::IcalProperty;
+
+use super::timezone::CalTimezone;
+use chrono::{DateTime, Duration, Local, NaiveDate, NaiveDateTime, NaiveTime, Utc};
+use chrono_tz::Tz;
+use derive_more::derive::Deref;
+use ical::{
+    parser::{Component, ical::component::IcalTimeZone},
+    property::Property,
+};
+use lazy_static::lazy_static;
+use rustical_xml::{ValueDeserialize, ValueSerialize};
+use std::{collections::HashMap, ops::Add};
+
+lazy_static! {
+    static ref RE_DURATION: regex::Regex = regex::Regex::new(r"^(?<sign>[+-])?P((?P<W>\d+)W)?((?P<D>\d+)D)?(T((?P<H>\d+)H)?((?P<M>\d+)M)?((?P<S>\d+)S)?)?$").unwrap();
+
+    static ref RE_VCARD_DATE_MM_DD: regex::Regex =
+        regex::Regex::new(r"^--(?<m>\d{2})(?<d>\d{2})$").unwrap();
+}
+
+const LOCAL_DATE_TIME: &str = "%Y%m%dT%H%M%S";
+const UTC_DATE_TIME: &str = "%Y%m%dT%H%M%SZ";
+pub const LOCAL_DATE: &str = "%Y%m%d";
+
+#[derive(Debug, thiserror::Error)]
+pub enum CalDateTimeError {
+    #[error(
+        "Timezone has X-LIC-LOCATION property to specify a timezone from the Olson database, however its value {0} is invalid"
+    )]
+    InvalidOlson(String),
+    #[error("TZID {0} does not refer to a valid timezone")]
+    InvalidTZID(String),
+    #[error("Timestamp doesn't exist because of gap in local time")]
+    LocalTimeGap,
+    #[error("Datetime string {0} has an invalid format")]
+    InvalidDatetimeFormat(String),
+    #[error("Could not parse datetime {0}")]
+    ParseError(String),
+    #[error("Duration string {0} has an invalid format")]
+    InvalidDurationFormat(String),
+}
+
+#[derive(Debug, Clone, Deref, PartialEq)]
+pub struct UtcDateTime(DateTime<Utc>);
+
+impl ValueDeserialize for UtcDateTime {
+    fn deserialize(val: &str) -> Result<Self, rustical_xml::XmlError> {
+        let input = <String as ValueDeserialize>::deserialize(val)?;
+        Ok(Self(
+            NaiveDateTime::parse_from_str(&input, UTC_DATE_TIME)
+                .map_err(|_| {
+                    rustical_xml::XmlError::InvalidValue(rustical_xml::ParseValueError::Other(
+                        "Could not parse as UTC timestamp".to_owned(),
+                    ))
+                })?
+                .and_utc(),
+        ))
+    }
+}
+
+impl ValueSerialize for UtcDateTime {
+    fn serialize(&self) -> String {
+        format!("{}", self.0.format(UTC_DATE_TIME))
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum CalDateTime {
+    // Form 1, example: 19980118T230000 -> Local
+    // Form 2, example: 19980119T070000Z -> UTC
+    // Form 3, example: TZID=America/New_York:19980119T020000 -> Olson
+    // https://en.wikipedia.org/wiki/Tz_database
+    DateTime(DateTime<CalTimezone>),
+    Date(NaiveDate),
+}
+
+impl From<DateTime<Local>> for CalDateTime {
+    fn from(value: DateTime<Local>) -> Self {
+        CalDateTime::DateTime(value.with_timezone(&CalTimezone::Local))
+    }
+}
+
+impl From<DateTime<Utc>> for CalDateTime {
+    fn from(value: DateTime<Utc>) -> Self {
+        CalDateTime::DateTime(value.with_timezone(&CalTimezone::Utc))
+    }
+}
+
+impl Add<Duration> for CalDateTime {
+    type Output = Self;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        match self {
+            Self::DateTime(datetime) => Self::DateTime(datetime + duration),
+            Self::Date(date) => Self::DateTime(
+                date.and_time(NaiveTime::default())
+                    .and_local_timezone(CalTimezone::Local)
+                    .earliest()
+                    .expect("Local timezone has constant offset")
+                    + duration,
+            ),
+        }
+    }
+}
+
+impl CalDateTime {
+    pub fn parse_prop(
+        prop: &Property,
+        timezones: &HashMap<String, IcalTimeZone>,
+    ) -> Result<Option<Self>, CalDateTimeError> {
+        let prop_value = if let Some(value) = prop.value.as_ref() {
+            value
+        } else {
+            return Ok(None);
+        };
+
+        // Use the TZID parameter from the property
+        let timezone = if let Some(tzid) = prop.get_tzid() {
+            if let Some(timezone) = timezones.get(tzid) {
+                // X-LIC-LOCATION is often used to refer to a standardised timezone from the Olson
+                // database
+                if let Some(olson_name) = timezone
+                    .get_property("X-LIC-LOCATION")
+                    .map(|prop| prop.value.to_owned())
+                    .unwrap_or_default()
+                {
+                    if let Ok(tz) = olson_name.parse::<Tz>() {
+                        Some(tz)
+                    } else {
+                        return Err(CalDateTimeError::InvalidOlson(olson_name));
+                    }
+                } else {
+                    // If the TZID matches a name from the Olson database (e.g. Europe/Berlin) we
+                    // guess that we can just use it
+                    tzid.parse::<Tz>().ok()
+                    // TODO: If None: Too bad, we need to manually parse it
+                    // For now it's just treated as localtime
+                }
+            } else {
+                // TZID refers to timezone that does not exist
+                return Err(CalDateTimeError::InvalidTZID(tzid.to_string()));
+            }
+        } else {
+            // No explicit timezone specified.
+            // This is valid and will be localtime or UTC depending on the value
+            None
+        };
+
+        Self::parse(prop_value, timezone).map(Some)
+    }
+
+    pub fn format(&self) -> String {
+        match self {
+            Self::DateTime(datetime) => match datetime.timezone() {
+                CalTimezone::Utc => datetime.format(UTC_DATE_TIME).to_string(),
+                _ => datetime.format(LOCAL_DATE_TIME).to_string(),
+            },
+            Self::Date(date) => date.format(LOCAL_DATE).to_string(),
+        }
+    }
+
+    pub fn date(&self) -> NaiveDate {
+        match self {
+            Self::DateTime(datetime) => datetime.date_naive(),
+            Self::Date(date) => date.to_owned(),
+        }
+    }
+
+    pub fn parse(value: &str, timezone: Option<Tz>) -> Result<Self, CalDateTimeError> {
+        if let Ok(datetime) = NaiveDateTime::parse_from_str(value, LOCAL_DATE_TIME) {
+            if let Some(timezone) = timezone {
+                return Ok(CalDateTime::DateTime(
+                    datetime
+                        .and_local_timezone(timezone.into())
+                        .earliest()
+                        .ok_or(CalDateTimeError::LocalTimeGap)?,
+                ));
+            }
+            return Ok(CalDateTime::DateTime(
+                datetime
+                    .and_local_timezone(CalTimezone::Local)
+                    .earliest()
+                    .ok_or(CalDateTimeError::LocalTimeGap)?,
+            ));
+        }
+
+        if let Ok(datetime) = NaiveDateTime::parse_from_str(value, UTC_DATE_TIME) {
+            return Ok(datetime.and_utc().into());
+        }
+        if let Ok(date) = NaiveDate::parse_from_str(value, LOCAL_DATE) {
+            return Ok(CalDateTime::Date(date));
+        }
+
+        if let Ok(date) = NaiveDate::parse_from_str(value, "%Y-%m-%d") {
+            return Ok(CalDateTime::Date(date));
+        }
+        if let Ok(date) = NaiveDate::parse_from_str(value, "%Y%m%d") {
+            return Ok(CalDateTime::Date(date));
+        }
+        if let Some(captures) = RE_VCARD_DATE_MM_DD.captures(value) {
+            // Because 1972 is a leap year
+            let year = 1972;
+            // Cannot fail because of the regex
+            let month = captures.name("m").unwrap().as_str().parse().ok().unwrap();
+            let day = captures.name("d").unwrap().as_str().parse().ok().unwrap();
+
+            return Ok(CalDateTime::Date(
+                NaiveDate::from_ymd_opt(year, month, day)
+                    .ok_or(CalDateTimeError::ParseError(value.to_string()))?,
+            ));
+        }
+
+        Err(CalDateTimeError::InvalidDatetimeFormat(value.to_string()))
+    }
+
+    pub fn utc(&self) -> DateTime<Utc> {
+        match &self {
+            CalDateTime::DateTime(datetime) => datetime.to_utc(),
+            CalDateTime::Date(date) => date.and_time(NaiveTime::default()).and_utc(),
+        }
+    }
+}
+
+impl From<CalDateTime> for DateTime<Utc> {
+    fn from(value: CalDateTime) -> Self {
+        value.utc()
+    }
+}
+
+pub fn parse_duration(string: &str) -> Result<Duration, CalDateTimeError> {
+    let captures = RE_DURATION
+        .captures(string)
+        .ok_or(CalDateTimeError::InvalidDurationFormat(string.to_string()))?;
+
+    let mut duration = Duration::zero();
+    if let Some(weeks) = captures.name("W") {
+        duration += Duration::weeks(weeks.as_str().parse().unwrap());
+    }
+    if let Some(days) = captures.name("D") {
+        duration += Duration::days(days.as_str().parse().unwrap());
+    }
+    if let Some(hours) = captures.name("H") {
+        duration += Duration::hours(hours.as_str().parse().unwrap());
+    }
+    if let Some(minutes) = captures.name("M") {
+        duration += Duration::minutes(minutes.as_str().parse().unwrap());
+    }
+    if let Some(seconds) = captures.name("S") {
+        duration += Duration::seconds(seconds.as_str().parse().unwrap());
+    }
+    if let Some(sign) = captures.name("sign") {
+        if sign.as_str() == "-" {
+            duration = -duration;
+        }
+    }
+
+    Ok(duration)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{CalDateTime, parse_duration};
+    use chrono::{Duration, NaiveDate};
+
+    #[test]
+    fn test_parse_duration() {
+        assert_eq!(parse_duration("P12W").unwrap(), Duration::weeks(12));
+        assert_eq!(parse_duration("P12D").unwrap(), Duration::days(12));
+        assert_eq!(parse_duration("PT12H").unwrap(), Duration::hours(12));
+        assert_eq!(parse_duration("PT12M").unwrap(), Duration::minutes(12));
+        assert_eq!(parse_duration("PT12S").unwrap(), Duration::seconds(12));
+    }
+
+    #[test]
+    fn test_vcard_date() {
+        assert_eq!(
+            CalDateTime::parse("19850412", None).unwrap(),
+            CalDateTime::Date(NaiveDate::from_ymd_opt(1985, 4, 12).unwrap())
+        );
+        assert_eq!(
+            CalDateTime::parse("1985-04-12", None).unwrap(),
+            CalDateTime::Date(NaiveDate::from_ymd_opt(1985, 4, 12).unwrap())
+        );
+        assert_eq!(
+            CalDateTime::parse("--0412", None).unwrap(),
+            CalDateTime::Date(NaiveDate::from_ymd_opt(1972, 4, 12).unwrap())
+        );
+    }
+}