monorepo/ifc/src/lib.rs

extern crate chrono;
extern crate chrono_tz;

use chrono::{Datelike, NaiveDate};

#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum DayOfWeek {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
    LeapDay,
    YearDay,
}

impl From<DayOfWeek> for String {
    fn from(day: DayOfWeek) -> Self {
        match day {
            DayOfWeek::Sunday => "Sunday",
            DayOfWeek::Monday => "Monday",
            DayOfWeek::Tuesday => "Tuesday",
            DayOfWeek::Wednesday => "Wednesday",
            DayOfWeek::Thursday => "Thursday",
            DayOfWeek::Friday => "Friday",
            DayOfWeek::Saturday => "Saturday",
            DayOfWeek::LeapDay => "LeapDay",
            DayOfWeek::YearDay => "YearDay",
        }
        .to_owned()
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum Month {
    January,
    February,
    March,
    April,
    May,
    June,
    Sol,
    July,
    August,
    September,
    October,
    November,
    December,
}

impl From<u32> for Month {
    fn from(val: u32) -> Month {
        match val {
            1 => Month::January,
            2 => Month::February,
            3 => Month::March,
            4 => Month::April,
            5 => Month::May,
            6 => Month::June,
            7 => Month::Sol,
            8 => Month::July,
            9 => Month::August,
            10 => Month::September,
            11 => Month::October,
            12 => Month::November,
            13 => Month::December,
            _ => panic!("invalid month number"),
        }
    }
}

impl From<Month> for String {
    fn from(val: Month) -> String {
        match val {
            Month::January => "January",
            Month::February => "February",
            Month::March => "March",
            Month::April => "April",
            Month::May => "May",
            Month::June => "June",
            Month::Sol => "Sol",
            Month::July => "July",
            Month::August => "August",
            Month::September => "September",
            Month::October => "October",
            Month::November => "November",
            Month::December => "December",
        }
        .to_owned()
    }
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct IFC {
    year: u32,
    ordinal: u32,
    leap_year: bool,
}

fn is_leap_year(year: i32) -> bool {
    NaiveDate::from_ymd(year, 12, 31).ordinal() == 366
}

impl IFC {
    pub fn ymd(year: u32, month: u8, day: u8) -> IFC {
        let leap_year = is_leap_year(year as i32 - 10000);

        let ordinal = if is_leap_year(year as i32 - 10000) {
            if month == 6 && day == 29 {
                168
            } else if month > 6 {
                (month as u32 - 1) * 28 + (day as u32)
            } else {
                (month as u32 - 1) * 28 + (day as u32) - 1
            }
        } else {
            (month as u32 - 1) * 28 + (day as u32) - 1
        };

        IFC {
            year,
            ordinal,
            leap_year,
        }
    }

    pub fn weekday_ifc(&self) -> DayOfWeek {
        match self.day() % 7 {
            0 => DayOfWeek::Saturday,
            1 => DayOfWeek::Sunday,
            2 => DayOfWeek::Monday,
            3 => DayOfWeek::Tuesday,
            4 => DayOfWeek::Wednesday,
            5 => DayOfWeek::Thursday,
            6 => DayOfWeek::Friday,
            _ => panic!("impossible condition"),
        }
    }

    pub fn month_ifc(&self) -> Month {
        Month::from(self.month())
    }
}

impl From<chrono::Date<chrono::Utc>> for IFC {
    fn from(d: chrono::Date<chrono::Utc>) -> IFC {
        IFC::from(d.naive_utc())
    }
}

impl From<chrono::Date<chrono_tz::Tz>> for IFC {
    fn from(d: chrono::Date<chrono_tz::Tz>) -> IFC {
        IFC::from(d.naive_utc())
    }
}

impl From<chrono::NaiveDate> for IFC {
    fn from(d: NaiveDate) -> IFC {
        //println!("d: {} [{}]", d.format("%Y-%m-%d"), d.ordinal());
        IFC {
            year: (d.year() + 10000) as u32,
            ordinal: d.ordinal0(),
            leap_year: is_leap_year(d.year()),
        }
    }
}

impl Datelike for IFC {
    fn year(&self) -> i32 {
        self.year as i32
    }
    fn month(&self) -> u32 {
        self.month0() + 1
    }
    fn month0(&self) -> u32 {
        if self.leap_year && self.ordinal == 365 {
            12
        } else if self.leap_year && self.ordinal == 168 {
            5
        } else {
            self.ordinal / 28
        }
    }
    fn day(&self) -> u32 {
        self.day0() + 1
    }
    fn day0(&self) -> u32 {
        if self.leap_year {
            if self.ordinal == 365 {
                28
            } else if self.ordinal == 168 {
                28
            } else if self.ordinal > 168 {
                (self.ordinal - 1).rem_euclid(28) as u32
            } else {
                self.ordinal.rem_euclid(28) as u32
            }
        } else {
            if self.ordinal == 364 {
                28
            } else {
                self.ordinal.rem_euclid(28) as u32
            }
        }
    }
    fn ordinal(&self) -> u32 {
        self.ordinal + 1
    }
    fn ordinal0(&self) -> u32 {
        self.ordinal
    }
    fn weekday(&self) -> chrono::Weekday {
        if self.day0() == 28 {
            chrono::Weekday::Sat
        } else {
            match self.day0().rem_euclid(7) {
                0 => chrono::Weekday::Sun,
                1 => chrono::Weekday::Mon,
                2 => chrono::Weekday::Tue,
                3 => chrono::Weekday::Wed,
                4 => chrono::Weekday::Thu,
                5 => chrono::Weekday::Fri,
                6 => chrono::Weekday::Sat,
                _ => panic!("rem_euclid should not return anything outside the 0..6 range"),
            }
        }
    }
    fn iso_week(&self) -> chrono::IsoWeek {
        panic!("iso_week is not implemented because chrono does not expose any constructors for IsoWeek!");
    }
    fn with_year(&self, year: i32) -> Option<IFC> {
        Some(IFC {
            year: (year as u32) + 10000,
            ordinal: self.ordinal,
            leap_year: is_leap_year(year),
        })
    }
    fn with_month(&self, month: u32) -> Option<IFC> {
        Some(IFC::ymd(self.year, month as u8, self.day() as u8))
    }
    fn with_month0(&self, month: u32) -> Option<IFC> {
        Some(IFC::ymd(self.year, month as u8 + 1, self.day() as u8))
    }
    fn with_day(&self, day: u32) -> Option<IFC> {
        Some(IFC::ymd(self.year, self.month() as u8, day as u8))
    }
    fn with_day0(&self, day: u32) -> Option<IFC> {
        Some(IFC::ymd(self.year, self.month() as u8, day as u8 + 1))
    }
    fn with_ordinal(&self, ordinal: u32) -> Option<IFC> {
        Some(IFC {
            year: self.year,
            ordinal,
            leap_year: self.leap_year,
        })
    }
    fn with_ordinal0(&self, ordinal: u32) -> Option<IFC> {
        Some(IFC {
            year: self.year,
            ordinal: ordinal + 1,
            leap_year: self.leap_year,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use chrono::NaiveDate;

    #[test]
    fn check_start_of_month() {
        assert_eq!(
            IFC::ymd(12019, 1, 1),
            IFC {
                year: 12019,
                ordinal: 0,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 2, 1),
            IFC {
                year: 12019,
                ordinal: 28,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 3, 1),
            IFC {
                year: 12019,
                ordinal: 56,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 4, 1),
            IFC {
                year: 12019,
                ordinal: 84,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 5, 1),
            IFC {
                year: 12019,
                ordinal: 112,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 6, 1),
            IFC {
                year: 12019,
                ordinal: 140,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 7, 1),
            IFC {
                year: 12019,
                ordinal: 168,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 8, 1),
            IFC {
                year: 12019,
                ordinal: 196,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 9, 1),
            IFC {
                year: 12019,
                ordinal: 224,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 10, 1),
            IFC {
                year: 12019,
                ordinal: 252,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 11, 1),
            IFC {
                year: 12019,
                ordinal: 280,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 12, 1),
            IFC {
                year: 12019,
                ordinal: 308,
                leap_year: false
            }
        );
        assert_eq!(
            IFC::ymd(12019, 13, 1),
            IFC {
                year: 12019,
                ordinal: 336,
                leap_year: false
            }
        );
    }

    #[test]
    fn check_start_of_month_leap_year() {
        assert_eq!(
            IFC::ymd(12020, 1, 1),
            IFC {
                year: 12020,
                ordinal: 0,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 2, 1),
            IFC {
                year: 12020,
                ordinal: 28,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 3, 1),
            IFC {
                year: 12020,
                ordinal: 56,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 4, 1),
            IFC {
                year: 12020,
                ordinal: 84,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 5, 1),
            IFC {
                year: 12020,
                ordinal: 112,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 6, 1),
            IFC {
                year: 12020,
                ordinal: 140,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 6, 29),
            IFC {
                year: 12020,
                ordinal: 168,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 7, 1),
            IFC {
                year: 12020,
                ordinal: 169,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 8, 1),
            IFC {
                year: 12020,
                ordinal: 197,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 9, 1),
            IFC {
                year: 12020,
                ordinal: 225,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 10, 1),
            IFC {
                year: 12020,
                ordinal: 253,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 11, 1),
            IFC {
                year: 12020,
                ordinal: 281,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 12, 1),
            IFC {
                year: 12020,
                ordinal: 309,
                leap_year: true
            }
        );
        assert_eq!(
            IFC::ymd(12020, 13, 1),
            IFC {
                year: 12020,
                ordinal: 337,
                leap_year: true
            }
        );
    }
    #[test]
    fn it_matches_january_1() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 1, 1)),
            IFC::ymd(12019, 1, 1)
        );
    }

    #[test]
    fn it_matches_february_1() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 1, 29)),
            IFC::ymd(12019, 2, 1)
        );
    }

    #[test]
    fn it_matches_sol_1() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 6, 18)),
            IFC::ymd(12019, 7, 1)
        );
    }

    #[test]
    fn it_matches_year_day() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 12, 31)),
            IFC::ymd(12019, 13, 29)
        );
    }

    #[test]
    fn it_matches_leap_day() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 6, 18)),
            IFC::ymd(12019, 7, 1),
        );
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 6, 17)),
            IFC::ymd(12020, 6, 29),
        );
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 6, 18)),
            IFC::ymd(12020, 7, 1),
        );
        assert_ne!(IFC::ymd(12020, 6, 29), IFC::ymd(12020, 7, 1));
    }

    #[test]
    fn it_handles_gregorian_leap_day() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2019, 3, 1)),
            IFC::ymd(12019, 3, 4)
        );
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 2, 29)),
            IFC::ymd(12020, 3, 4)
        );
    }

    #[test]
    fn it_handles_days_between_leap_days() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 4, 8)),
            IFC::ymd(12020, 4, 15),
        );
    }

    #[test]
    fn it_handles_days_after_ifc_leap_day() {
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 10, 8)),
            IFC::ymd(12020, 11, 1),
        );
    }

    #[test]
    fn it_matches_year_day_in_leap_year() {
        assert_eq!(NaiveDate::from_ymd(2020, 12, 31).ordinal(), 366);
        assert_eq!(
            IFC::from(NaiveDate::from_ymd(2020, 12, 31)),
            IFC::ymd(12020, 13, 29)
        );
    }

    #[test]
    fn it_reports_correct_month() {
        assert_eq!(IFC::ymd(12019, 1, 1).month(), 1);
        assert_eq!(IFC::ymd(12019, 1, 1).month0(), 0);

        assert_eq!(IFC::ymd(12020, 6, 28).month(), 6);
        assert_eq!(IFC::ymd(12020, 6, 28).month0(), 5);

        assert_eq!(IFC::ymd(12020, 7, 1).month(), 7);
        assert_eq!(IFC::ymd(12020, 7, 1).month0(), 6);

        assert_eq!(IFC::ymd(12019, 13, 1).month(), 13);
        assert_eq!(IFC::ymd(12019, 13, 1).month0(), 12);
    }

    #[test]
    fn it_reports_correct_day() {
        assert_eq!(IFC::ymd(12019, 1, 1).day(), 1);
        assert_eq!(IFC::ymd(12019, 1, 1).day0(), 0);

        assert_eq!(IFC::ymd(12020, 3, 1).day(), 1);
        assert_eq!(IFC::ymd(12020, 3, 1).day0(), 0);

        assert_eq!(IFC::ymd(12020, 6, 28).day(), 28);
        assert_eq!(IFC::ymd(12020, 6, 28).day0(), 27);

        assert_eq!(IFC::ymd(12020, 7, 1).day(), 1);
        assert_eq!(IFC::ymd(12020, 7, 1).day0(), 0);

        assert_eq!(IFC::ymd(12019, 13, 1).day(), 1);
        assert_eq!(IFC::ymd(12019, 13, 1).day0(), 0);

        assert_eq!(IFC::ymd(12019, 13, 29).day(), 29);
        assert_eq!(IFC::ymd(12019, 13, 29).day0(), 28);
    }

    #[test]
    fn it_reports_correct_month_in_leap_year() {
        assert_eq!(IFC::ymd(12020, 1, 1).month(), 1);
        assert_eq!(IFC::ymd(12020, 1, 1).month0(), 0);

        assert_eq!(IFC::ymd(12020, 3, 1).month(), 3);
        assert_eq!(IFC::ymd(12020, 3, 1).month0(), 2);

        assert_eq!(IFC::ymd(12020, 6, 29).month(), 6);
        assert_eq!(IFC::ymd(12020, 6, 29).month0(), 5);

        assert_eq!(IFC::ymd(12020, 7, 1).month(), 7);
        assert_eq!(IFC::ymd(12020, 7, 1).month0(), 6);
    }

    #[test]
    fn it_reports_correct_day_in_leap_year() {
        assert_eq!(IFC::ymd(12019, 1, 1).day(), 1);
        assert_eq!(IFC::ymd(12019, 1, 1).day0(), 0);

        assert_eq!(IFC::ymd(12020, 6, 28).day(), 28);
        assert_eq!(IFC::ymd(12020, 6, 28).day0(), 27);

        assert_eq!(IFC::ymd(12020, 6, 29).day(), 29);
        assert_eq!(IFC::ymd(12020, 6, 29).day0(), 28);

        assert_eq!(IFC::ymd(12020, 7, 1).day(), 1);
        assert_eq!(IFC::ymd(12020, 7, 1).day0(), 0);

        assert_eq!(IFC::ymd(12019, 13, 1).day(), 1);
        assert_eq!(IFC::ymd(12019, 13, 1).day0(), 0);

        assert_eq!(IFC::ymd(12019, 13, 29).day(), 29);
        assert_eq!(IFC::ymd(12019, 13, 29).day0(), 28);
    }

    #[test]
    fn it_reports_correct_day_of_week() {
        assert_eq!(IFC::ymd(12019, 1, 1).weekday(), chrono::Weekday::Sun);
        assert_eq!(IFC::ymd(12019, 6, 1).weekday(), chrono::Weekday::Sun);
        assert_eq!(IFC::ymd(12019, 6, 28).weekday(), chrono::Weekday::Sat);
        assert_eq!(IFC::ymd(12019, 7, 1).weekday(), chrono::Weekday::Sun);
        assert_eq!(IFC::ymd(12019, 13, 28).weekday(), chrono::Weekday::Sat);
        assert_eq!(IFC::ymd(12019, 13, 29).weekday(), chrono::Weekday::Sat);

        assert_eq!(IFC::ymd(12020, 6, 28).weekday(), chrono::Weekday::Sat);
        assert_eq!(IFC::ymd(12020, 6, 29).weekday(), chrono::Weekday::Sat);
        assert_eq!(IFC::ymd(12020, 7, 1).weekday(), chrono::Weekday::Sun);
        assert_eq!(IFC::ymd(12020, 13, 28).weekday(), chrono::Weekday::Sat);
        assert_eq!(IFC::ymd(12020, 13, 29).weekday(), chrono::Weekday::Sat);
    }
}