// 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::CommonWeekOfYear;

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

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

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

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

use crate::calendar::AllowYearZero;

use crate::calendar::CalendarMoment;

use crate::calendar::OrdinalDate;

use crate::calendar::ToFromOrdinalDate;

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

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 std::num::NonZero;

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

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

use num_traits::FromPrimitive;

#[allow(non_snake_case)]

struct SymmetryParams {

    C: i64,

    L: i64,

    K: i64,

}

const NORTHWARD_EQUINOX_PARAMS: SymmetryParams = SymmetryParams {

    C: 293,

    L: 52,

    K: 146,

};

const NORTH_SOLSTICE_PARAMS: SymmetryParams = SymmetryParams {

    C: 389,

    L: 69,

    K: 194,

};

/// Represents a month of the Symmetry calendars

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

pub enum SymmetryMonth {

    January = 1,

    February,

    March,

    April,

    May,

    June,

    July,

    August,

    September,

    October,

    November,

    December,

    /// Only appears in leap years

    Irvember,

}

/// Represents a date in one of the Symmetry calendars

///

/// ## Introduction

///

/// The Symmetry calendars are a collection of calendar systems developed by Dr. Irvin L. Bromberg.

/// Bromberg proposed 2 leap year rules and 2 month length rules, which can be combined to form

/// 4 variants of the Symmetry calendar.

///

/// ## Variants

///

///

/// | `T`       | `U`       | Alias                   | Leap cycle | Quarter length    |

/// |-----------|-----------|-------------------------|------------|-------------------|

/// | [`true`]  | [`true`]  | [`Symmetry454`]         | 293 year   | 4 + 5 + 4 weeks   |

/// | [`false`] | [`true`]  | [`Symmetry010`]         | 293 year   | 30 + 31 + 30 days |

/// | [`true`]  | [`false`] | [`Symmetry454Solstice`] | 389 year   | 4 + 5 + 4 weeks   |

/// | [`false`] | [`false`] | [`Symmetry010Solstice`] | 389 year   | 30 + 31 + 30 days |

///

/// The combinations are summarized in the table above. Columns `T` and `U` are the type parameters.

/// Column Alias refers to the type aliases provided for convenience.

///

/// The placement of leap years  is symmetric within a cycle - the length of the cycle is in

/// column Leap Cycle. The 293 year leap rule approximates the northward equinox, while the 389

/// year rule approximates the north solstice.

///

/// Column Quarter Length refers to how days are distributed within a common year.

/// Symmetry calendars have years split into 4 quarters. Each quarter is composed of

/// 3 months. In Symmetry454 calendars, the months have lengths of 4, 5, and 4 weeks respectively.

/// In Symmetry010 calendars, the months have lenghts of 30, 31, and 30 days respectively.

///

/// ## Irvember

///

/// The Symmetry calendars have leap weeks instead of leap days. The extra week added in a leap

/// year is a standalone thirteenth month called [Irvember](SymmetryMonth::Irvember).

/// Dr. Bromberg suggested an alternative scheme where the extra week is added to

/// December instead of being standalone - however this alternative scheme is **not** implemented.

///

/// ## Bromberg's Warning

///

/// The calculations used in this library mirror Dr. Bromberg's reference documents closely

/// while still being idiomatic Rust. From *Basic Symmetry454 and Symmetry010 Calendar

/// Arithmetic* by Bromberg:

///

/// > Symmetry454 and Symmetry010 calendar arithmetic is very simple, but there is a tendency

/// > for those who are programming their first implementation of these calendars to immediately

/// > cut corners that may suffice for a limited range of dates, or to skip thorough validation

/// > of their implementation.

/// >

/// > Please don’t deviate from the arithmetic outlined herein. Please “stick to the script”.

/// > Don’t try to invent your own arithmetic using novel expressions. There is no reason to do

/// > so, because this arithmetic is in the public domain, royalty free. The algorithm steps

/// > documented herein were carefully designed for efficiency, simplicity, and clarity of

/// > program code, and were thoroughly validated. Cutting corners will most likely result in

/// > harder-to-read programs that are more difficult to maintain and troubleshoot. In all

/// > probability a novel expression intended to “simplify” the arithmetic documented herein

/// > will actually prove to function erroneously under specific circumstances. It is just not

/// > worth wasting the time on the trouble that will make for you.

///

/// ## Further reading

/// + Dr. Irvin L. Bromberg

///   + [*Basic Symmetry454 and Symmetry010 Calendar Arithmetic*](https://kalendis.free.nf/Symmetry454-Arithmetic.pdf)

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

pub struct Symmetry<const T: bool, const U: bool>(CommonDate);

/// Symmetry454 calendar with 293 year leap rule

///

/// See [Symmetry] for more details.

pub type Symmetry454 = Symmetry<true, true>;

/// Symmetry010 calendar with 293 year leap rule

///

/// See [Symmetry] for more details.

pub type Symmetry010 = Symmetry<false, true>;

/// Symmetry454 calendar with 389 year leap rule

///

/// See [Symmetry] for more details.

pub type Symmetry454Solstice = Symmetry<true, false>;

/// Symmetry010 calendar with 389 year leap rule

///

/// See [Symmetry] for more details.

pub type Symmetry010Solstice = Symmetry<false, false>;

impl<const T: bool, const U: bool> Symmetry<T, U> {

    fn params() -> SymmetryParams {

        if U {

            NORTHWARD_EQUINOX_PARAMS

        } else {

            NORTH_SOLSTICE_PARAMS

        }

    }

    /// Returns (T, U)

    ///

    /// T is true for Symmetry454 calendars and false for Symmetry010 calendars.

    /// U is true for the 292 year leap cycle and false for the 389 year leap cycle.

    /// See [Symmetry] for more details.

    pub fn mode(self) -> (bool, bool) {

        (T, U)

    }

    /// Returns the fixed day number of a Symmetry year

    pub fn new_year_day_unchecked(sym_year: i32, sym_epoch: i64) -> i64 {

        //LISTING SymNewYearDay (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        let p = Self::params();

        #[allow(non_snake_case)]

        let E = (sym_year - 1) as i64;

        sym_epoch + (364 * E) + (7 * ((p.L * E) + p.K).div_euclid(p.C))

    }

    fn days_before_month_454(sym_month: i64) -> u16 {

        //LISTING DaysBeforeMonth (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        ((28 * (sym_month - 1)) + 7 * sym_month.div_euclid(3)) as u16

    }

    fn days_before_month_010(sym_month: i64) -> u16 {

        //LISTING DaysBeforeMonth (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        ((30 * (sym_month - 1)) + sym_month.div_euclid(3)) as u16

    }

    fn days_before_month(sym_month: u8) -> u16 {

        if T {

            Self::days_before_month_454(sym_month as i64)

        } else {

            Self::days_before_month_010(sym_month as i64)

        }

    }

    fn day_of_year(sym_month: u8, sym_day: u8) -> u16 {

        //LISTING DayOfYear (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        Self::days_before_month(sym_month) + (sym_day as u16)

    }

    fn year_from_fixed(fixed: i64, epoch: i64) -> (i32, i64) {

        //LISTING FixedToSymYear (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        // Tempting to cut "corners here" to avoid floating point.

        // But the notice at the top of the file reminds us to "stick to the script"

        let fixed_date = fixed as f64;

        let sym_epoch = epoch as f64;

        let cycle_mean_year = if U {

            365.0 + (71.0 / 293.0)

        } else {

            365.0 + (94.0 / 389.0)

        };

        let sym_year = ((fixed_date - sym_epoch) / cycle_mean_year).ceil() as i32;

        let start_of_year = Self::new_year_day_unchecked(sym_year, epoch);

        if start_of_year < fixed {

            if (fixed - start_of_year) >= 364 {

                let start_of_next_year = Self::new_year_day_unchecked(sym_year + 1, epoch);

                if fixed >= start_of_next_year {

                    (sym_year + 1, start_of_next_year)

                } else {

                    (sym_year, start_of_year)

                }

            } else {

                (sym_year, start_of_year)

            }

        } else if start_of_year > fixed {

            (

                sym_year - 1,

                Self::new_year_day_unchecked(sym_year - 1, epoch),

            )

        } else {

            (sym_year, start_of_year)

        }

    }

    /// This function is not described by Dr. Bromberg and is not

    /// used in conversion to and from other timekeeping systems.

    /// Instead it is used for checking if a [CommonDate] is valid.

    pub fn days_in_month(month: SymmetryMonth) -> u8 {

        if month == SymmetryMonth::Irvember {

            7

        } else if T {

            (28 + (7 * ((month as u8).modulus(3).div_euclid(2)))) as u8

        } else {

            (30 + (month as u8).modulus(3).div_euclid(2)) as u8

        }

    }

}

impl<const T: bool, const U: bool> AllowYearZero for Symmetry<T, U> {}

impl<const T: bool, const U: bool> ToFromOrdinalDate for Symmetry<T, U> {

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

        // Not described by Dr. Bromberg

        let new_year_0 = Self::new_year_day_unchecked(ord.year, Self::epoch().get_day_i());

        let new_year_1 = Self::new_year_day_unchecked(ord.year + 1, Self::epoch().get_day_i());

        let diff = new_year_1 - new_year_0;

        if (ord.day_of_year as i64) < 1 || 
(ord.day_of_year as i64) > diff4.09k
 {

            Err(CalendarError::InvalidDayOfYear)

        } else {

            Ok(())

        }

    }

    fn ordinal_from_fixed(fixed_date: Fixed) -> OrdinalDate {

        //LISTING FixedToSym (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        //Only the SymYear and DayOfYear terms.

        let date = fixed_date.get_day_i();

        let (sym_year, start_of_year) = Self::year_from_fixed(date, Self::epoch().get_day_i());

        let day_of_year = (date - start_of_year + 1) as u16;

        OrdinalDate {

            year: sym_year,

            day_of_year: day_of_year,

        }

    }

    fn to_ordinal(self) -> OrdinalDate {

        OrdinalDate {

            year: self.0.year,

            day_of_year: Self::day_of_year(self.0.month, self.0.day),

        }

    }

    fn from_ordinal_unchecked(ord: OrdinalDate) -> Self {

        //LISTING FixedToSym (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        // Originally second part of from_fixed

        let (sym_year, day_of_year) = (ord.year, ord.day_of_year);

        // Thank Ferris for div_ceil

        let week_of_year = day_of_year.div_ceil(7);

        debug_assert!(week_of_year > 0 && week_of_year < 54);

        let quarter = (4 * week_of_year).div_ceil(53);

        debug_assert!(quarter > 0 && quarter < 5);

        let day_of_quarter = day_of_year - (91 * (quarter - 1));

        let week_of_quarter = day_of_quarter.div_ceil(7);

        let month_of_quarter = if T {

            (2 * week_of_quarter).div_ceil(9)

        } else {

            (2 * day_of_quarter).div_ceil(61)

        };

        let sym_month = (3 * (quarter - 1) + month_of_quarter) as u8;

        // Skipping optionals

        let sym_day = (day_of_year - Self::days_before_month(sym_month)) as u8;

        Self(CommonDate::new(sym_year, sym_month, sym_day))

    }

}

impl<const T: bool, const U: bool> HasLeapYears for Symmetry<T, U> {

    fn is_leap(sym_year: i32) -> bool {

        //LISTING isSymLeapYear (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        let p = Self::params();

        let sym_year = sym_year as i64;

        ((p.L * sym_year) + p.K).modulus(p.C) < p.L

    }

}

impl<const T: bool, const U: bool> CalculatedBounds for Symmetry<T, U> {}

impl<const T: bool, const U: bool> Epoch for Symmetry<T, U> {

    fn epoch() -> Fixed {

        Gregorian::epoch()

    }

}

impl<const T: bool, const U: bool> FromFixed for Symmetry<T, U> {

    fn from_fixed(fixed_date: Fixed) -> Symmetry<T, U> {

        //LISTING FixedToSym (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        // Compared to Dr. Bromberg's original, this function is split in two

        let ord = Self::ordinal_from_fixed(fixed_date);

        Self::from_ordinal_unchecked(ord)

    }

}

impl<const T: bool, const U: bool> ToFixed for Symmetry<T, U> {

    fn to_fixed(self) -> Fixed {

        //LISTING SymToFixed (*Basic Symmetry454 and Symmetry010 Calendar Arithmetic* by Dr. Irvin L. Bromberg)

        let new_year_day = Self::new_year_day_unchecked(self.0.year, Self::epoch().get_day_i());

        let day_of_year = Self::day_of_year(self.0.month, self.0.day) as i64;

        Fixed::cast_new(new_year_day + day_of_year - 1)

    }

}

impl<const T: bool, const U: bool> ToFromCommonDate<SymmetryMonth> for Symmetry<T, U> {

    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> {

        let month_opt = SymmetryMonth::from_u8(date.month);

        if month_opt.is_none() {

            Err(CalendarError::InvalidMonth)

        } else if date.day < 1 {

            Err(CalendarError::InvalidDay)

        } else if date.day > Self::days_in_month(month_opt.unwrap()) {

            Err(CalendarError::InvalidDay)

        } else {

            Ok(())

        }

    }

    fn year_end_date(year: i32) -> CommonDate {

        let m = if Self::is_leap(year) {

            SymmetryMonth::Irvember

        } else {

            SymmetryMonth::December

        };

        CommonDate::new(year, m as u8, Self::days_in_month(m))

    }

}

impl<const T: bool, const U: bool> Quarter for Symmetry<T, U> {

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

        match self.month() {

            SymmetryMonth::Irvember => NonZero::new(4 as u8).unwrap(),

            m => NonZero::new((((m as u8) - 1) / 3) + 1).expect("(m-1)/3 > -1"),

        }

    }

}

impl<const T: bool, const U: bool> GuaranteedMonth<SymmetryMonth> for Symmetry<T, U> {}

impl<const T: bool, const U: bool> CommonWeekOfYear<SymmetryMonth> for Symmetry<T, U> {}

/// Represents a date *and time* in the Symmetry454 Calendar

pub type Symmetry454Moment = CalendarMoment<Symmetry454>;

/// Represents a date *and time* in the Symmetry010 Calendar

pub type Symmetry010Moment = CalendarMoment<Symmetry010>;

/// Represents a date *and time* in the Symmetry454 Calendar (solstice-approximating)

pub type Symmetry454SolsticeMoment = CalendarMoment<Symmetry454Solstice>;

/// Represents a date *and time* in the Symmetry010 Calendar (solstice-approximating)

pub type Symmetry010SolsticeMoment = CalendarMoment<Symmetry010Solstice>;

#[cfg(test)]

mod tests {

    use super::*;

    use crate::day_count::RataDie;

    use crate::day_count::FIXED_MAX;

    use crate::day_cycle::Weekday;

    use proptest::proptest;

    const MAX_YEARS: i32 = (FIXED_MAX / 365.25) as i32;

    #[test]

    fn is_leap_example() {

        assert!(Symmetry454::is_leap(2009));

        assert!(Symmetry454::is_leap(2015));

        assert!(Symmetry010::is_leap(2009));

        assert!(Symmetry010::is_leap(2015));

        assert!(!Symmetry454Solstice::is_leap(2009));

        assert!(!Symmetry010Solstice::is_leap(2009));

        assert!(Symmetry454Solstice::is_leap(2010));

        assert!(Symmetry010Solstice::is_leap(2016));

    }

    #[test]

    fn new_year_day_example() {

        assert_eq!(Symmetry454::new_year_day_unchecked(2010, 1), 733776);

        assert_eq!(Symmetry010::new_year_day_unchecked(2010, 1), 733776);

        assert_eq!(Symmetry454Solstice::new_year_day_unchecked(2010, 1), 733769);

        assert_eq!(Symmetry010Solstice::new_year_day_unchecked(2010, 1), 733769);

    }

    #[test]

    fn days_before_month() {

        assert_eq!(Symmetry454::days_before_month(1), 0);

        assert_eq!(Symmetry454::days_before_month(13), 364);

        assert_eq!(Symmetry454::days_before_month(6), 154);

        assert_eq!(Symmetry010::days_before_month(1), 0);

        assert_eq!(Symmetry010::days_before_month(13), 364);

        assert_eq!(Symmetry010::days_before_month(6), 152);

        assert_eq!(Symmetry454Solstice::days_before_month(1), 0);

        assert_eq!(Symmetry454Solstice::days_before_month(13), 364);

        assert_eq!(Symmetry454Solstice::days_before_month(6), 154);

        assert_eq!(Symmetry010Solstice::days_before_month(1), 0);

        assert_eq!(Symmetry010Solstice::days_before_month(13), 364);

        assert_eq!(Symmetry010Solstice::days_before_month(6), 152);

    }

    #[test]

    fn day_of_year() {

        assert_eq!(Symmetry454::day_of_year(6, 17), 171);

        assert_eq!(Symmetry010::day_of_year(6, 17), 169);

        assert_eq!(Symmetry454Solstice::day_of_year(6, 17), 171);

        assert_eq!(Symmetry010Solstice::day_of_year(6, 17), 169);

    }

    #[test]

    fn to_fixed() {

        assert_eq!(

            Symmetry454::try_from_common_date(CommonDate::new(2009, 4, 5))

                .unwrap()

                .to_fixed()

                .get_day_i(),

            733500

        );

        assert_eq!(

            Symmetry010::try_from_common_date(CommonDate::new(2009, 4, 5))

                .unwrap()

                .to_fixed()

                .get_day_i(),

            733500

        );

        assert_eq!(

            Symmetry454Solstice::try_from_common_date(CommonDate::new(2009, 4, 5))

                .unwrap()

                .to_fixed()

                .get_day_i(),

            733500

        );

        assert_eq!(

            Symmetry010Solstice::try_from_common_date(CommonDate::new(2009, 4, 5))

                .unwrap()

                .to_fixed()

                .get_day_i(),

            733500

        );

    }

    #[test]

    fn year_from_fixed() {

        assert_eq!(Symmetry454::year_from_fixed(733649, 1), (2009, 733405));

        assert_eq!(Symmetry010::year_from_fixed(733649, 1), (2009, 733405));

        assert_eq!(Symmetry454::year_from_fixed(733406, 1), (2009, 733405));

        assert_eq!(Symmetry010::year_from_fixed(733406, 1), (2009, 733405));

        assert_eq!(Symmetry454::year_from_fixed(733774, 1).0, 2009);

        assert_eq!(Symmetry010::year_from_fixed(733774, 1).0, 2009);

    }

    #[test]

    fn example_data() {

        let d_list = [

            (

                -44444 as i32,

                CommonDate::new(-121, 4, 27),

                CommonDate::new(-121, 4, 27),

                CommonDate::new(-121, 4, 27),

                CommonDate::new(-121, 4, 27),

            ),

            (

                -33333 as i32,

                CommonDate::new(-91, 9, 22),

                CommonDate::new(-91, 9, 24),

                CommonDate::new(-91, 9, 22),

                CommonDate::new(-91, 9, 24),

            ),

            (

                44444 as i32,

                CommonDate::new(122, 9, 8),

                CommonDate::new(122, 9, 10),

                CommonDate::new(122, 9, 8),

                CommonDate::new(122, 9, 10),

            ),

            (

                648491 as i32,

                CommonDate::new(1776, 7, 4),

                CommonDate::new(1776, 7, 4),

                CommonDate::new(1776, 7, 4),

                CommonDate::new(1776, 7, 4),

            ),

            (

                681724 as i32,

                CommonDate::new(1867, 7, 1),

                CommonDate::new(1867, 7, 1),

                CommonDate::new(1867, 7, 1),

                CommonDate::new(1867, 7, 1),

            ),

            (

                711058 as i32,

                CommonDate::new(1947, 10, 26),

                CommonDate::new(1947, 10, 26),

                CommonDate::new(1947, 10, 26),

                CommonDate::new(1947, 10, 26),

            ),

            (

                728515 as i32,

                CommonDate::new(1995, 8, 11),

                CommonDate::new(1995, 8, 9),

                CommonDate::new(1995, 8, 11),

                CommonDate::new(1995, 8, 9),

            ),

            (

                730179 as i32,

                CommonDate::new(2000, 2, 30),

                CommonDate::new(2000, 2, 28),

                CommonDate::new(2000, 2, 30),

                CommonDate::new(2000, 2, 28),

            ),

            (

                731703 as i32,

                CommonDate::new(2004, 5, 7),

                CommonDate::new(2004, 5, 5),

                CommonDate::new(2004, 5, 7),

                CommonDate::new(2004, 5, 5),

            ),

            (

                731946 as i32,

                CommonDate::new(2004, 13, 5),

                CommonDate::new(2004, 13, 5),

                CommonDate::new(2005, 1, 5),

                CommonDate::new(2005, 1, 5),

            ),

            (

                737475 as i32,

                CommonDate::new(2020, 2, 25),

                CommonDate::new(2020, 2, 23),

                CommonDate::new(2020, 2, 25),

                CommonDate::new(2020, 2, 23),

            ),

            (

                811236 as i32,

                CommonDate::new(2222, 2, 6),

                CommonDate::new(2222, 2, 4),

                CommonDate::new(2222, 2, 6),

                CommonDate::new(2222, 2, 4),

            ),

            (

                1217048 as i32,

                CommonDate::new(3333, 2, 35),

                CommonDate::new(3333, 3, 2),

                CommonDate::new(3333, 2, 35),

                CommonDate::new(3333, 3, 2),

            ),

        ];

        for 
item13
 in d_list {

            let rd = RataDie::new(item.0 as f64);

            let s454q = Symmetry454::try_from_common_date(item.1).unwrap();

            let s010q = Symmetry010::try_from_common_date(item.2).unwrap();

            let s454s = Symmetry454Solstice::try_from_common_date(item.3).unwrap();

            let s010s = Symmetry010Solstice::try_from_common_date(item.4).unwrap();

            assert_eq!(rd.to_fixed(), s454q.to_fixed());

            assert_eq!(rd.to_fixed(), s010q.to_fixed());

            assert_eq!(rd.to_fixed(), s454s.to_fixed());

            assert_eq!(rd.to_fixed(), s010s.to_fixed());

        }

    }

    proptest! {

        #[test]

        fn month_start_on_monday_454(year in -MAX_YEARS..MAX_YEARS, month in 1..12) {

            let c = CommonDate::new(year as i32, month as u8, 1);

            let d = Symmetry454::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Monday);

            let d = Symmetry454Solstice::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Monday);

        }

        #[test]

        fn month_end_on_sunday_454(year in -MAX_YEARS..MAX_YEARS, month in 1..12) {

            let m = SymmetryMonth::from_i32(month).unwrap();

            let c = CommonDate::new(year as i32, month as u8, Symmetry454::days_in_month(m));

            let d = Symmetry454::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Sunday);

            let d = Symmetry454Solstice::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Sunday);

        }

        #[test]

        fn no_friday_13_454(year in -MAX_YEARS..MAX_YEARS, month in 1..12) {

            let c = CommonDate::new(year as i32, month as u8, 13);

            let d = Symmetry454::try_from_common_date(c).unwrap();

            assert_ne!(d.convert::<Weekday>(), Weekday::Friday);

            let d = Symmetry454Solstice::try_from_common_date(c).unwrap();

            assert_ne!(d.convert::<Weekday>(), Weekday::Friday);

        }

        #[test]

        fn year_start_on_monday_010(year in -MAX_YEARS..MAX_YEARS) {

            let c = CommonDate::new(year as i32, 1, 1);

            let d = Symmetry010::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Monday);

            let d = Symmetry010Solstice::try_from_common_date(c).unwrap();

            assert_eq!(d.convert::<Weekday>(), Weekday::Monday);

        }

        #[test]

        fn no_friday_13_010(year in -MAX_YEARS..MAX_YEARS, month in 1..12) {

            let c = CommonDate::new(year as i32, month as u8, 13);

            let d = Symmetry010::try_from_common_date(c).unwrap();

            assert_ne!(d.convert::<Weekday>(), Weekday::Friday);

            let d = Symmetry010Solstice::try_from_common_date(c).unwrap();

            assert_ne!(d.convert::<Weekday>(), Weekday::Friday);

        }

    }

}