// This Source Code Form is subject to the terms of the Mozilla Public

// License, v. 2.0. If a copy of the MPL was not distributed with this

// file, You can obtain one at https://mozilla.org/MPL/2.0/.

use crate::calendar::gregorian::Gregorian;

use crate::calendar::prelude::CommonDate;

use crate::calendar::prelude::GuaranteedMonth;

use crate::calendar::prelude::HasLeapYears;

use crate::calendar::prelude::Perennial;

use crate::calendar::prelude::Quarter;

use crate::calendar::prelude::ToFromCommonDate;

use crate::calendar::prelude::ToFromOrdinalDate;

use crate::calendar::AllowYearZero;

use crate::calendar::CalendarMoment;

use crate::calendar::HasIntercalaryDays;

use crate::calendar::OrdinalDate;

use crate::common::error::CalendarError;

use crate::common::math::TermNum;

use crate::day_count::BoundedDayCount;

use crate::day_count::CalculatedBounds;

use crate::day_count::Epoch;

use crate::day_count::Fixed;

use crate::day_count::FromFixed;

use crate::day_count::ToFixed;

use crate::day_cycle::Weekday;

#[allow(unused_imports)] //FromPrimitive is needed for derive

use num_traits::FromPrimitive;

use std::num::NonZero;

/// Represents a month in the Cotsworth Calendar

#[derive(Debug, PartialEq, PartialOrd, Clone, Copy, FromPrimitive, ToPrimitive)]

pub enum CotsworthMonth {

    January = 1,

    February,

    March,

    April,

    May,

    June,

    Sol,

    July,

    August,

    September,

    October,

    November,

    December,

}

/// Represents a complementary day of the Cotsworth Calendar

#[derive(Debug, PartialEq, PartialOrd, Clone, Copy, FromPrimitive, ToPrimitive)]

pub enum CotsworthComplementaryDay {

    /// The day that ends every year of the Cotsworth Calendar.

    /// This is also represented as December 29. It is not part of any week.

    YearDay = 1,

    /// The extra day added in leap years of the Cotsworth Calendar.

    /// This is also represented as June 29. It is not part of any week.

    LeapDay,

}

/// Represents a date in the Cotsworth calendar

/// (ie. International Fixed Calendar, Eastman plan, Yearal)

///

/// This calendar was originally designed by Moses B Cotsworth.

/// George Eastman instituted its use within the Eastman Kodak Company from 1928 to 1989.

///

/// ## Further reading

/// + [Wikipedia](https://en.wikipedia.org/wiki/Cotsworth_calendar)

/// + ["Nation's Business" May 1926](https://www.freexenon.com/wp-content/uploads/2018/07/The-Importance-of-Calendar-Reform-to-the-Business-World-George-Eastman.pdf)

///   + "The Importance of Calendar Reform to the Business World"

///   + by George Eastman, President, Eastman Kodak Company

#[derive(Debug, PartialEq, PartialOrd, Clone, Copy)]

pub struct Cotsworth(CommonDate);

impl AllowYearZero for Cotsworth {}

impl ToFromOrdinalDate for Cotsworth {

    fn valid_ordinal(ord: OrdinalDate) -> Result<(), CalendarError> {

        Gregorian::valid_ordinal(ord)

    }

    fn ordinal_from_fixed(fixed_date: Fixed) -> OrdinalDate {

        Gregorian::ordinal_from_fixed(fixed_date)

    }

    fn to_ordinal(self) -> OrdinalDate {

        let approx_m = ((self.0.month as i64) - 1) * 28;

        let offset_m = if self.0.month > 6 && 
Cotsworth::is_leap4.91k
(
self.0.year4.91k
) {

            approx_m + 1

        } else {

            approx_m

        };

        let doy = (offset_m as u16) + (self.0.day as u16);

        OrdinalDate {

            year: self.0.year,

            day_of_year: doy,

        }

    }

    fn from_ordinal_unchecked(ord: OrdinalDate) -> Self {

        const LEAP_DAY_ORD: u16 = (6 * 28) + 1;

        let result = match (ord.day_of_year, Cotsworth::is_leap(ord.year)) {

            (366, true) => CommonDate::new(ord.year, 13, 29),

            (365, false) => CommonDate::new(ord.year, 13, 29),

            (LEAP_DAY_ORD, true) => CommonDate::new(ord.year, 6, 29),

            (doy, is_leap) => {

                let correction = if doy < LEAP_DAY_ORD || 
!is_leap4.51k
 { 
07.69k
 } else { 
1979
 };

                let month = ((((doy - correction) - 1) as i64).div_euclid(28) + 1) as u8;

                let day = ((doy - correction) as i64).adjusted_remainder(28) as u8;

                CommonDate::new(ord.year, month, day)

            }

        };

        Cotsworth(result)

    }

}

impl HasIntercalaryDays<CotsworthComplementaryDay> for Cotsworth {

    fn complementary(self) -> Option<CotsworthComplementaryDay> {

        if self.0.day == 29 && 
self.0.month == (CotsworthMonth::December as u8)6
 {

            Some(CotsworthComplementaryDay::YearDay)

        } else if self.0.day == 29 && 
self.0.month == (CotsworthMonth::June as u8)2
 {

            Some(CotsworthComplementaryDay::LeapDay)

        } else {

            None

        }

    }

    fn complementary_count(p_year: i32) -> u8 {

        if Cotsworth::is_leap(p_year) {

            2

        } else {

            1

        }

    }

}

impl Perennial<CotsworthMonth, Weekday> for Cotsworth {

    fn weekday(self) -> Option<Weekday> {

        if self.complementary().is_some() {

            None

        } else {

            Weekday::from_i64(((self.0.day as i64) - 1).modulus(7))

        }

    }

    fn days_per_week() -> u8 {

        7

    }

    fn weeks_per_month() -> u8 {

        4

    }

}

impl HasLeapYears for Cotsworth {

    fn is_leap(c_year: i32) -> bool {

        Gregorian::is_leap(c_year)

    }

}

impl CalculatedBounds for Cotsworth {}

impl Epoch for Cotsworth {

    fn epoch() -> Fixed {

        Gregorian::epoch()

    }

}

impl FromFixed for Cotsworth {

    fn from_fixed(fixed_date: Fixed) -> Cotsworth {

        let ord = Self::ordinal_from_fixed(fixed_date);

        Self::from_ordinal_unchecked(ord)

    }

}

impl ToFixed for Cotsworth {

    fn to_fixed(self) -> Fixed {

        let offset_y = Gregorian::try_year_start(self.0.year)

            .expect("Year known to be valid")

            .to_fixed()

            .get_day_i()

            - 1;

        let ord = self.to_ordinal();

        Fixed::cast_new(offset_y + (ord.day_of_year as i64))

    }

}

impl ToFromCommonDate<CotsworthMonth> for Cotsworth {

    fn to_common_date(self) -> CommonDate {

        self.0

    }

    fn from_common_date_unchecked(date: CommonDate) -> Self {

        debug_assert!(Self::valid_ymd(date).is_ok());

        Self(date)

    }

    fn valid_ymd(date: CommonDate) -> Result<(), CalendarError> {

        if date.month < 1 || 
date.month > 1324.1k
 {

            Err(CalendarError::InvalidMonth)

        } else if date.day < 1 || 
date.day > 2923.4k
 {

            Err(CalendarError::InvalidDay)

        } else if date.day == 29 {

            if date.month == 13 || (
Cotsworth::is_leap360
(
date.year360
) && 
date.month == 6360
) {

                Ok(())

            } else {

                Err(CalendarError::InvalidDay)

            }

        } else {

            Ok(())

        }

    }

    fn year_end_date(year: i32) -> CommonDate {

        CommonDate::new(year, CotsworthMonth::December as u8, 29)

    }

}

impl Quarter for Cotsworth {

    fn quarter(self) -> NonZero<u8> {

        let m = self.to_common_date().month;

        if m == 13 {

            NonZero::new(4 as u8).expect("4 != 0")

        } else {

            NonZero::new(((m - 1) / 3) + 1).expect("(m-1)/3 > -1")

        }

    }

}

impl GuaranteedMonth<CotsworthMonth> for Cotsworth {}

/// Represents a date *and time* in the Cotsworth Calendar

pub type CotsworthMoment = CalendarMoment<Cotsworth>;