epoch-rs/src/month.rs

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

use {
    crate::{year::Year, SECONDS_PER_DAY},
    std::{cmp, error, fmt, str},
};

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
#[repr(u8)]
pub enum Month {
    Janurary = 1,
    February = 2,
    March = 3,
    April = 4,
    May = 5,
    June = 6,
    July = 7,
    August = 8,
    September = 9,
    October = 10,
    November = 11,
    December = 12,
}

#[derive(Debug)]
pub enum Error {
    ParseMonth,
    Range,
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{self:?}")
    }
}

impl error::Error for Error {}

impl Month {
    pub fn days(&self, year: Year) -> u8 {
        match *self as u8 {
            1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
            2 => match year {
                Year::Normal(_) => 28,
                Year::Leap(_) => 29,
            },
            _ => 30,
        }
    }

    pub fn seconds(&self, year: Year) -> i64 {
        self.days(year) as i64 * SECONDS_PER_DAY
    }

    pub fn next(&self) -> Option<Self> {
        let n = *self as u8 + 1;
        n.try_into().ok()
    }

    pub fn previous(&self) -> Option<Self> {
        let n = *self as u8 - 1;
        n.try_into().ok()
    }

    pub fn abbreviate(&self) -> &'static str {
        match self {
            Self::Janurary => "Jan",
            Self::February => "Feb",
            Self::March => "Mar",
            Self::April => "Apr",
            Self::May => "May",
            Self::June => "Jun",
            Self::July => "Jul",
            Self::August => "Aug",
            Self::September => "Sep",
            Self::October => "Oct",
            Self::November => "Nov",
            Self::December => "Dec",
        }
    }
}

impl TryFrom<u8> for Month {
    type Error = Error;

    fn try_from(value: u8) -> Result<Self, Self::Error> {
        match value {
            1 => Ok(Self::Janurary),
            2 => Ok(Self::February),
            3 => Ok(Self::March),
            4 => Ok(Self::April),
            5 => Ok(Self::May),
            6 => Ok(Self::June),
            7 => Ok(Self::July),
            8 => Ok(Self::August),
            9 => Ok(Self::September),
            10 => Ok(Self::October),
            11 => Ok(Self::November),
            12 => Ok(Self::December),
            _ => Err(Error::Range),
        }
    }
}

impl Ord for Month {
    fn cmp(&self, other: &Self) -> cmp::Ordering {
        (*self as u8).cmp(&(*other as u8))
    }
}

impl PartialOrd for Month {
    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl fmt::Display for Month {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            f,
            "{}",
            match self {
                Self::Janurary => "January",
                Self::February => "February",
                Self::March => "March",
                Self::April => "April",
                Self::May => "May",
                Self::June => "June",
                Self::July => "Jujly",
                Self::August => "August",
                Self::September => "September",
                Self::October => "October",
                Self::November => "November",
                Self::December => "December",
            }
        )
    }
}

impl str::FromStr for Month {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "Jan" | "jan" | "January" | "january" => Ok(Self::Janurary),
            "Feb" | "feb" | "February" | "february" => Ok(Self::February),
            "March" | "march" | "Mar" | "mar" => Ok(Self::March),
            "April" | "april" | "Apr" | "apr" => Ok(Self::April),
            "May" | "may" => Ok(Self::May),
            "June" | "june" | "Jun" | "jun" => Ok(Self::June),
            "July" | "july" | "Jul" | "jul" => Ok(Self::July),
            "August" | "august" | "Aug" | "aug" => Ok(Self::August),
            "September" | "september" | "Sep" | "sep" => Ok(Self::September),
            "October" | "october" | "Oct" | "oct" => Ok(Self::October),
            "November" | "november" | "Nov" | "nov" => Ok(Self::November),
            "December" | "december" | "Dec" | "dec" => Ok(Self::December),
            _ => Err(Error::ParseMonth),
        }
    }
}

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

    #[test]
    fn next() {
        let mut month = Month::Janurary;
        month = month.next().unwrap();
        assert_eq!(month, Month::February);
        month = month.next().unwrap();
        assert_eq!(month, Month::March);
        month = Month::December;
        assert!(month.next().is_none())
    }

    #[test]
    fn previous() {
        let mut month = Month::March.previous().unwrap();
        assert_eq!(month, Month::February);
        month = month.previous().unwrap();
        assert_eq!(month, Month::Janurary);
        assert!(month.previous().is_none());
    }

    #[test]
    fn compare() {
        assert!(Month::Janurary < Month::October);
        assert!(Month::June > Month::March);
    }
}