/*
Copyright 2020-2023, Savanni D'Gerinel <savanni@luminescent-dreams.com>
This file is part of the Luminescent Dreams Tools.
Luminescent Dreams Tools is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Luminescent Dreams Tools is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Lumeto. If not, see <https://www.gnu.org/licenses/>.
*/
extern crate chrono;
extern crate chrono_tz;
use chrono::SecondsFormat;
use chrono_tz::Etc::UTC;
use serde::de::{self, Deserialize, Deserializer, Visitor};
use serde::ser::{Serialize, Serializer};
use std::{fmt, str::FromStr};
/// This is a wrapper around date time objects, using timezones from the chroon-tz database and
/// providing string representation and parsing of the form "<RFC3339> <Timezone Name>", i.e.,
/// "2019-05-15T14:30:00Z US/Central". The to_string method, and serde serialization will
/// produce a string of this format. The parser will accept an RFC3339-only string of the forms
/// "2019-05-15T14:30:00Z", "2019-05-15T14:30:00+00:00", and also an "RFC3339 Timezone Name"
/// string.
///
/// The function here is to generate as close to unambiguous time/date strings, (for earth's
/// gravitational frame of reference), as possible. Clumping together the time, offset from UTC,
/// and the named time zone allows future parsers to know the exact interpretation of the time in
/// the frame of reference of the original recording.
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct DateTimeTz(pub chrono::DateTime<chrono_tz::Tz>);
impl fmt::Display for DateTimeTz {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
if self.0.timezone() == UTC {
write!(f, "{}", self.0.to_rfc3339_opts(SecondsFormat::Secs, true))
} else {
write!(
f,
"{} {}",
self.0
.with_timezone(&chrono_tz::Etc::UTC)
.to_rfc3339_opts(SecondsFormat::Secs, true,),
self.0.timezone().name()
)
}
}
}
impl DateTimeTz {
pub fn map<F>(&self, f: F) -> DateTimeTz
where
F: FnOnce(chrono::DateTime<chrono_tz::Tz>) -> chrono::DateTime<chrono_tz::Tz>,
{
DateTimeTz(f(self.0))
}
}
impl std::str::FromStr for DateTimeTz {
type Err = chrono::ParseError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let v: Vec<&str> = s.split_terminator(' ').collect();
if v.len() == 2 {
let tz = v[1].parse::<chrono_tz::Tz>().unwrap();
chrono::DateTime::parse_from_rfc3339(v[0]).map(|ts| DateTimeTz(ts.with_timezone(&tz)))
} else {
chrono::DateTime::parse_from_rfc3339(v[0]).map(|ts| DateTimeTz(ts.with_timezone(&UTC)))
}
}
}
impl From<chrono::DateTime<chrono_tz::Tz>> for DateTimeTz {
fn from(dt: chrono::DateTime<chrono_tz::Tz>) -> DateTimeTz {
DateTimeTz(dt)
}
}
struct DateTimeTzVisitor;
impl<'de> Visitor<'de> for DateTimeTzVisitor {
type Value = DateTimeTz;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a string date time representation that can be parsed")
}
fn visit_str<E: de::Error>(self, s: &str) -> Result<Self::Value, E> {
DateTimeTz::from_str(s).or(Err(E::custom(
"string is not a parsable datetime representation".to_owned(),
)))
}
}
impl Serialize for DateTimeTz {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
serializer.serialize_str(&self.to_string())
}
}
impl<'de> Deserialize<'de> for DateTimeTz {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
deserializer.deserialize_str(DateTimeTzVisitor)
}
}
#[cfg(test)]
mod test {
extern crate serde_json;
use super::*;
use chrono::TimeZone;
use chrono_tz::America::Phoenix;
use chrono_tz::Etc::UTC;
use chrono_tz::US::{Arizona, Central};
use std::str::FromStr;
#[test]
fn it_creates_timestamp_with_z() {
let t = DateTimeTz(UTC.with_ymd_and_hms(2019, 5, 15, 12, 0, 0).unwrap());
assert_eq!(t.to_string(), "2019-05-15T12:00:00Z");
}
#[test]
fn it_parses_utc_rfc3339_z() {
let t = DateTimeTz::from_str("2019-05-15T12:00:00Z").unwrap();
assert_eq!(
t,
DateTimeTz(UTC.with_ymd_and_hms(2019, 5, 15, 12, 0, 0).unwrap())
);
}
#[test]
fn it_parses_rfc3339_with_offset() {
let t = DateTimeTz::from_str("2019-05-15T12:00:00-06:00").unwrap();
assert_eq!(
t,
DateTimeTz(UTC.with_ymd_and_hms(2019, 5, 15, 18, 0, 0).unwrap())
);
}
#[test]
fn it_parses_rfc3339_with_tz() {
let t = DateTimeTz::from_str("2019-06-15T19:00:00Z US/Arizona").unwrap();
assert_eq!(
t,
DateTimeTz(UTC.with_ymd_and_hms(2019, 6, 15, 19, 0, 0).unwrap())
);
assert_eq!(
t,
DateTimeTz(Arizona.with_ymd_and_hms(2019, 6, 15, 12, 0, 0).unwrap())
);
assert_eq!(
t,
DateTimeTz(Central.with_ymd_and_hms(2019, 6, 15, 14, 0, 0).unwrap())
);
assert_eq!(t.to_string(), "2019-06-15T19:00:00Z US/Arizona");
}
#[derive(Serialize)]
struct DemoStruct {
id: String,
dt: DateTimeTz,
}
// I used Arizona here specifically because large parts of Arizona do not honor DST, and so
// that adds in more ambiguity of the -0700 offset with Pacific time.
#[test]
fn it_json_serializes() {
let t = DateTimeTz::from_str("2019-06-15T19:00:00Z America/Phoenix").unwrap();
assert_eq!(
serde_json::to_string(&t).unwrap(),
"\"2019-06-15T19:00:00Z America/Phoenix\""
);
let demo = DemoStruct {
id: String::from("abcdefg"),
dt: t,
};
assert_eq!(
serde_json::to_string(&demo).unwrap(),
"{\"id\":\"abcdefg\",\"dt\":\"2019-06-15T19:00:00Z America/Phoenix\"}"
);
}
#[test]
fn it_json_parses() {
let t =
serde_json::from_str::<DateTimeTz>("\"2019-06-15T19:00:00Z America/Phoenix\"").unwrap();
assert_eq!(
t,
DateTimeTz(Phoenix.with_ymd_and_hms(2019, 6, 15, 12, 0, 0).unwrap())
);
}
}