use chrono::prelude::*; use lazy_static::lazy_static; use serde_derive::{Deserialize, Serialize}; use std::collections::HashMap; // http://astropixels.com/ephemeris/soleq2001.html const SOLSTICE_TEXT: &str = " 2001 Mar 20 13:31 Jun 21 07:38 Sep 22 23:05 Dec 21 19:22 2002 Mar 20 19:16 Jun 21 13:25 Sep 23 04:56 Dec 22 01:15 2003 Mar 21 01:00 Jun 21 19:11 Sep 23 10:47 Dec 22 07:04 2004 Mar 20 06:49 Jun 21 00:57 Sep 22 16:30 Dec 21 12:42 2005 Mar 20 12:34 Jun 21 06:46 Sep 22 22:23 Dec 21 18:35 2006 Mar 20 18:25 Jun 21 12:26 Sep 23 04:04 Dec 22 00:22 2007 Mar 21 00:07 Jun 21 18:06 Sep 23 09:51 Dec 22 06:08 2008 Mar 20 05:49 Jun 21 00:00 Sep 22 15:45 Dec 21 12:04 2009 Mar 20 11:44 Jun 21 05:45 Sep 22 21:18 Dec 21 17:47 2010 Mar 20 17:32 Jun 21 11:28 Sep 23 03:09 Dec 21 23:38 2011 Mar 20 23:21 Jun 21 17:16 Sep 23 09:05 Dec 22 05:30 2012 Mar 20 05:15 Jun 20 23:08 Sep 22 14:49 Dec 21 11:12 2013 Mar 20 11:02 Jun 21 05:04 Sep 22 20:44 Dec 21 17:11 2014 Mar 20 16:57 Jun 21 10:52 Sep 23 02:30 Dec 21 23:03 2015 Mar 20 22:45 Jun 21 16:38 Sep 23 08:20 Dec 22 04:48 2016 Mar 20 04:31 Jun 20 22:35 Sep 22 14:21 Dec 21 10:45 2017 Mar 20 10:29 Jun 21 04:25 Sep 22 20:02 Dec 21 16:29 2018 Mar 20 16:15 Jun 21 10:07 Sep 23 01:54 Dec 21 22:22 2019 Mar 20 21:58 Jun 21 15:54 Sep 23 07:50 Dec 22 04:19 2020 Mar 20 03:50 Jun 20 21:43 Sep 22 13:31 Dec 21 10:03 2021 Mar 20 09:37 Jun 21 03:32 Sep 22 19:21 Dec 21 15:59 2022 Mar 20 15:33 Jun 21 09:14 Sep 23 01:04 Dec 21 21:48 2023 Mar 20 21:25 Jun 21 14:58 Sep 23 06:50 Dec 22 03:28 2024 Mar 20 03:07 Jun 20 20:51 Sep 22 12:44 Dec 21 09:20 2025 Mar 20 09:02 Jun 21 02:42 Sep 22 18:20 Dec 21 15:03 2026 Mar 20 14:46 Jun 21 08:25 Sep 23 00:06 Dec 21 20:50 2027 Mar 20 20:25 Jun 21 14:11 Sep 23 06:02 Dec 22 02:43 2028 Mar 20 02:17 Jun 20 20:02 Sep 22 11:45 Dec 21 08:20 2029 Mar 20 08:01 Jun 21 01:48 Sep 22 17:37 Dec 21 14:14 2030 Mar 20 13:51 Jun 21 07:31 Sep 22 23:27 Dec 21 20:09 2031 Mar 20 19:41 Jun 21 13:17 Sep 23 05:15 Dec 22 01:56 2032 Mar 20 01:23 Jun 20 19:09 Sep 22 11:11 Dec 21 07:57 2033 Mar 20 07:23 Jun 21 01:01 Sep 22 16:52 Dec 21 13:45 2034 Mar 20 13:18 Jun 21 06:45 Sep 22 22:41 Dec 21 19:35 2035 Mar 20 19:03 Jun 21 12:33 Sep 23 04:39 Dec 22 01:31 2036 Mar 20 01:02 Jun 20 18:31 Sep 22 10:23 Dec 21 07:12 2037 Mar 20 06:50 Jun 21 00:22 Sep 22 16:13 Dec 21 13:08 2038 Mar 20 12:40 Jun 21 06:09 Sep 22 22:02 Dec 21 19:01 2039 Mar 20 18:32 Jun 21 11:58 Sep 23 03:50 Dec 22 00:41 2040 Mar 20 00:11 Jun 20 17:46 Sep 22 09:44 Dec 21 06:33 2041 Mar 20 06:07 Jun 20 23:37 Sep 22 15:27 Dec 21 12:19 2042 Mar 20 11:53 Jun 21 05:16 Sep 22 21:11 Dec 21 18:04 2043 Mar 20 17:29 Jun 21 10:59 Sep 23 03:07 Dec 22 00:02 2044 Mar 19 23:20 Jun 20 16:50 Sep 22 08:47 Dec 21 05:43 2045 Mar 20 05:08 Jun 20 22:34 Sep 22 14:33 Dec 21 11:36 2046 Mar 20 10:58 Jun 21 04:15 Sep 22 20:22 Dec 21 17:28 2047 Mar 20 16:52 Jun 21 10:02 Sep 23 02:07 Dec 21 23:07 2048 Mar 19 22:34 Jun 20 15:54 Sep 22 08:01 Dec 21 05:02 2049 Mar 20 04:28 Jun 20 21:47 Sep 22 13:42 Dec 21 10:51 2050 Mar 20 10:20 Jun 21 03:33 Sep 22 19:29 Dec 21 16:39 "; #[derive(Clone, Copy, Debug, Serialize, Deserialize)] pub struct YearlyEvents { pub year: i32, pub spring_equinox: chrono::DateTime, pub summer_solstice: chrono::DateTime, pub autumn_equinox: chrono::DateTime, pub winter_solstice: chrono::DateTime, } #[derive(Clone, Copy, Debug, Serialize, Deserialize)] pub enum Event { SpringEquinox(chrono::DateTime), SummerSolstice(chrono::DateTime), AutumnEquinox(chrono::DateTime), WinterSolstice(chrono::DateTime), } impl Event { pub fn date(&self) -> chrono::DateTime { match *self { Event::SpringEquinox(d) => d, Event::SummerSolstice(d) => d, Event::AutumnEquinox(d) => d, Event::WinterSolstice(d) => d, } } } fn parse_time<'a>( year: &str, iter: impl Iterator, ) -> chrono::DateTime { let parts = iter.collect::>(); let p = format!("{} {} {} {}", year, parts[0], parts[1], parts[2]); NaiveDateTime::parse_from_str(&p, "%Y %b %d %H:%M") .unwrap() .and_utc() } fn parse_line(year: &str, rest: &[&str]) -> YearlyEvents { let spring = parse_time(year, rest.iter().take(3).cloned()); let summer = parse_time(year, rest.iter().skip(3).take(3).cloned()); let autumn = parse_time(year, rest.iter().skip(6).take(3).cloned()); let winter = parse_time(year, rest.iter().skip(9).take(3).cloned()); YearlyEvents { year: year.parse::().unwrap(), spring_equinox: spring, summer_solstice: summer, autumn_equinox: autumn, winter_solstice: winter, } } fn parse_events() -> Vec> { SOLSTICE_TEXT .lines() .map(|line| { match line .split(' ') .filter(|elem| !elem.is_empty()) .collect::>() .as_slice() { [year, rest @ ..] => Some(parse_line(year, rest)), _ => None, } }) .collect() } pub struct Solstices(HashMap); impl Solstices { pub fn yearly_events(&self, year: i32) -> Option { self.0.get(&year).copied() } pub fn next_event(&self, date: chrono::DateTime) -> Option { let year_events = self.0.get(&date.year()); match year_events { Some(year_events) => { if date <= year_events.spring_equinox { Some(Event::SpringEquinox(year_events.spring_equinox)) } else if date <= year_events.summer_solstice { Some(Event::SummerSolstice(year_events.summer_solstice)) } else if date <= year_events.autumn_equinox { Some(Event::AutumnEquinox(year_events.autumn_equinox)) } else if date <= year_events.winter_solstice { Some(Event::WinterSolstice(year_events.winter_solstice)) } else { self.0 .get(&(date.year() + 1)) .map(|_| Event::SpringEquinox(year_events.spring_equinox)) } } None => None, } } } impl From>> for Solstices { fn from(event_list: Vec>) -> Self { Solstices(event_list.iter().fold(HashMap::new(), |mut m, record| { match record { Some(record) => { m.insert(record.year, *record); } None => (), } m })) } } lazy_static! { pub static ref EVENTS: Solstices = Solstices::from(parse_events()); } #[cfg(test)] mod test { use chrono::{NaiveDate, NaiveDateTime}; #[test] fn it_can_parse_a_solstice_time() { let p = "2001 Mar 20 13:31".to_owned(); let parsed_date = NaiveDateTime::parse_from_str(&p, "%Y %b %d %H:%M") .unwrap() .and_utc(); assert_eq!( parsed_date, NaiveDate::from_ymd_opt(2001, 03, 20) .unwrap() .and_hms_opt(13, 31, 0) .unwrap() .and_utc() ); } }