// 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::HasLeapYears;

use crate::calendar::prelude::OrdinalDate;

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

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

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

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

use crate::calendar::CalendarMoment;

use crate::calendar::HasEpagemonae;

use crate::clock::ClockTime;

use crate::clock::TimeOfDay;

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::cmp::Ordering;

use std::num::NonZero;

const TRANQUILITY_EPOCH_GREGORIAN: CommonDate = CommonDate {

    year: 1969,

    month: 7,

    day: 20,

};

const NON_MONTH: u8 = 0;

const TRANQUILITY_EPOCH_CLOCK: ClockTime = ClockTime {

    hours: 20,

    minutes: 18,

    seconds: 1.2,

};

/// Represents a month of the Tranquility Calendar

///

/// The Tranquility months are named after famous historical figures.

///

/// Note that the complementary days of the Tranquility calendar year have no

/// month and thus are not represented by TranquilityMonth. When representing an

/// arbitrary day in the Tranquility calendar, use an `Option<TranquilityMonth>` for the

/// the month field.

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

pub enum TranquilityMonth {

    Archimedes = 1,

    Brahe,

    Copernicus,

    Darwin,

    Einstein,

    Faraday,

    Galileo,

    Hippocrates,

    Imhotep,

    Jung,

    Kepler,

    Lavoisier,

    Mendel,

}

const AFTER_H27: i64 = (TranquilityMonth::Hippocrates as i64) * 28;

/// Represents a complementary day of the Tranquility Calendar

///

/// These are a bit more complex than the complementary days of the Positivist

/// or Cotsworth calendars.

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

pub enum TranquilityComplementaryDay {

    /// This is the day of the Apollo 11 moon landing, which is the epoch for

    /// the Tranquility calendar. It is not part of any week, month or year.

    MoonLandingDay = 0,

    /// This is the last day of every year except 1 Before Tranquility. It

    /// is not part of any week or month.

    ArmstrongDay,

    /// This is an extra day added during leap years. It occurs between Hippocrates

    /// 27 and 28. It is not part of any week or month.

    AldrinDay,

}

/// Represents a date in the Tranquility Calendar

///

/// ## Introduction

///

/// The Tranquility calendar was proposed by Jeff Siggins in the July 1989 issue of

/// OMNI magazine. It is used by the Orion's Arm collaborative science fiction project.

/// Hardly anybody else uses the Tranquility calendar - it is so obscure that its Wikipedia

/// page was deleted for lack of notability.

///

/// Siggins' article starts with the following:

/// > Are you tired of that same old calendar, with 12 months of unequal length, and dates

/// > that always fall on different days? Do you forget lunch dates, closing days for real

/// > estate deals, or deadlines for IRA rollovers? When plotting graphs in your fruit fly

/// > experiment, do you ever get confused? Do you wonder why that same vile mood hits on the

/// > fifth of one month and the fifteenth of the next?

/// >

/// > If these problems are yours, you are probably ready for the next step in time accounting,

/// > the Tranquility calendar, designed for a perfection-seeking society, especially the men

/// > and women of science. Inspired by the Apollo 11 manned mission to the moon and developed

/// > for *Omni*, the Tranquility calendar will ease the complexity of scientific calculation,

/// > help astronomers fathom the movements of heavenly spheres, and facilitate high-stakes business.

/// > It will also aid everyday users who simply require a precise, easy-to-follow record of

/// > the events of their lives.

///

/// Unfortunately, despite these lofty goals, the Tranquility Calendar has many edge cases not

/// present in other timekeeping systems, and some aspects of the calendar are poorly documented;

/// this can cause difficulty when implementing software applications.

///

/// ### Year 0

///

/// Year 0 is **not** supported for this implementation of the Tranquility calendar, except as

/// a dummy value for the epoch. See the "Epoch" and "The Curious Case of 1 Before Tranquility"

/// sections for details.

///

/// ## Basic Structure

///

/// The epoch of the Tranquility calendar, known as Moon Landing Day, is an exception to

/// every other rule of the calendar. This also requires some special cases for the year

/// immediately before the epoch, 1 BT. See the "Epoch" section for details. The remainder

/// of this section is about days other than Moon Landing Day.

///

/// ### Months

///

/// From Siggins' article proposing the calendar:

/// > The Tranquility calendar uses a format of 13 months, each with 28 days (four seven-day

/// > weeks), for a total of 364 days. One extra day is added on at the end of the year to make

/// > 365. For leap years, a second extra day is added.

///

/// The months of the Tranquility calendar are named after notable scientists, and are also

/// in alphabetical order. Note that the "second extra day" for leap years is **not** at the

/// end of the year.

///

/// The first day of every Tranquility year is 1 Archimedes, as stated by Siggins:

/// >  The first day of each year is the first day of Archimedes (July 21 on the Gregorian calendar).

///

/// ### Armstrong Day and Aldrin Day

///

/// The two extra days are described as follows by Siggins:

/// > The last day of each Tranquility year is called Armstrong Day. Named for the first human

/// > to step on the moon, Armstrong Day celebrates the anniversary of Moon Landing Day. Thus

/// > July 20, 1970, is the Gregorian equivalent of Armstrong Day, 1 A.T., and July 20, 1989,

/// > is Armstrong Day, 20 A.T.

/// >

/// > Finally, the Tranquility calendar equivalent of leap day is called Aldrin Day. Named for

/// > Armstrong's fellow moon walker, Aldrin Day occurs every four years, with some exceptions.

/// > The exceptions are the leap days in every 400 years that are dropped to keep the calendar

/// > astronomically precise. Aldrin Day falls between the twenty-seventh and twenty-eighth of

/// > Hippocrates (February 29).

///

/// Siggins explains the Gregorian leap year rule earlier in the article, so we can assume that

/// "the leap days in every 400 years that are dropped" refer to the leap days dropped in

/// Gregorian years divisible by 100 and not by 400.

///

/// The odd placement of Aldrin Day is not explicitly justified in the text. However, implicit

/// in the passage above is the idea that *every* Armstrong Day corresponds to July 20 in the

/// proleptic Gregorian calendar, and *every* Aldrin Day corresponds to February 29. The year

/// lengths are also the same, meaning that there should be a one-to-one relationship between

/// Gregorian dates and Tranquility dates stable across all years (ignoring Moon Landing Day,

/// which replaces one specific Armstrong Day).

///

/// This would also imply that when calculating leap years, we need to apply the Gregorian

/// rule after applying an offset of 1969 or 1970, depending on the date relative to the epoch.

///

/// ## Epoch

///

/// The Tranquility calendar epoch is specific down to the tenth of a second. The day on which

/// the epoch occurs is called Moon Landing Day, and is described as follows by Siggins:

/// > The Tranquility calendar, on the other hand, is based on a recent, well-documented event,

/// > the landing by two American astronauts, Neil Armstrong and Edwin "Buzz" Aldrin, on the

/// > moon. Upon touchdown came those almost mystical words, "Houston ... Tranquility Base here.

/// > The Eagle has landed." Omni's Tranquility calendar starts at the very instant the word

/// > Tranquility was uttered. As one of the most astronomically analyzed moments in scientific

/// > history, our base point can be used to chart the exact position of the earth in

/// > relationship to the moon and other celestial bodies.

/// >

/// > Now for the details of the calendar itself. The day on which the moment of Tranquility

/// > occurred is called Moon Landing Day. It is the central day of the Tranquility calendar

/// > and it stands alone. Not part of any month or year, it has 20 hours, 18 minutes, and 1.2

/// > seconds Before Tranquility (B.T.), and 3 hours, 41 minutes, and 58.8 seconds After

/// > Tranquility (A.T). The Gregorian equivalent of Moon Landing Day is July 20, A.D. 1969.

///

/// We can assume that any date after Moon Landing Day is "After Tranquility" and any day before

/// Moon Landing Day is "Before Tranquility".

///

/// ### The Curious Case of 1 Before Tranquility

///

/// Siggins devoted very little of his article to dates Before Tranquility, and the year

/// immediately preceding Moon Landing Day is particularly confusing.

///

/// Consider the following statements in Siggins' article:

///

/// 1. "The Gregorian equivalent of Moon Landing Day is July 20, A.D. 1969"

/// 2. "The first day of each year is the first day of Archimedes (July 21 on the Gregorian calendar)."

/// 3. "The last day of each Tranquility year is called Armstrong Day."

/// 4. "Armstrong Day celebrates the anniversary of Moon Landing Day."

///

///    a. "July 20, 1970, is the Gregorian equivalent of Armstrong Day, 1 A.T."

///

///    b. "July 20, 1989, is Armstrong Day, 20 A.T."

///

/// First of all, it is not stated whether the year immediately preceding Moon Landing Day is

/// 1 BT or 0 BT - however the full version of Siggins' article in OMNI (with all the

/// images) contains many example dates which imply that 0 BT does not exist. For example,

/// the first airplane flight by Orville and Wilbur Wright at Kitty Hawk is listed as occurring

/// on Faraday 10, 66 BT and 1903 CE. [The exact date of the flight was December 17, 1903](https://airandspace.si.edu/collection-objects/1903-wright-flyer/nasm_A19610048000).

/// The 66th anniversary of the Wright brother's flight would be December 17, 1969 CE which

/// is after Moon Landing Day (as per statement 1 above) and before Armstrong Day, 1 AT (as

/// per statement 4a above) which is the last day of 1 AT (as per statement 3). However,

/// naively calculating 66 BT + 66 = 0 BT would suggest that the year should be 0 BT.

///

/// Based on the math above, we can assume some year BT was skipped, and the most obvious

/// choice is 0 BT. Skipping some other year such as 1 BT, 2 BT or 50 BT would be

/// unintuitive, whereas skipping year 0 is common practice when working with historical dates

/// using the Julian calendar.

///

/// Having established that the year immediately preceding Moon Landing Day is 1 BT, we must

/// figure out what the last day of 1 BT is named.

///

/// All 4 statements above cannot be true for 1 BT, as Armstrong Day, 1 BT would

/// either conflict with Moon Landing Day, not end the year, or not occur on the anniversary

/// of Moon Landing Day. Any implementation of the Tranquility calendar must implement some

/// special case to deal with this situation.

///

/// **This crate assumes that Armstrong Day is skipped in the year 1 BT** The day that

/// would normally be Armstrong Day, 1 BT is Moon Landing Day. The day before Moon Landing

/// Day is Mendel 28, 1 BT - which *would* be the day before Armstrong Day, 1 BT *if*

/// Armstrong Day existed in 1 BT.

///

/// This also seems to be the approach taken by the Orion's Arm Calendar Converter (note that

/// other pages in the Orion's Arm project may differ from the converter).

///

/// ## Representation and Examples

///

/// ### Months

///

/// The months are represented in this crate as [`TranquilityMonth`].

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let c_1_1 = CommonDate::new(57, 1, 1);

/// let tq_1_1 = Tranquility::try_from_common_date(c_1_1).unwrap();

/// assert_eq!(tq_1_1.try_month().unwrap(), TranquilityMonth::Archimedes);

/// let c_13_28 = CommonDate::new(57, 13, 28);

/// let tq_13_28 = Tranquility::try_from_common_date(c_13_28).unwrap();

/// assert_eq!(tq_13_28.try_month().unwrap(), TranquilityMonth::Mendel);

/// ```

///

/// ### Weekdays

///

/// The days of the Tranquility week are not always the same as the days of the common week.

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

/// use radnelac::day_cycle::*;

///

/// let c = CommonDate::new(-1, 13, 28);

/// let p = Tranquility::try_from_common_date(c).unwrap();

/// assert_eq!(p.weekday().unwrap(), Weekday::Thursday); //Positivist week

/// assert_eq!(p.convert::<Weekday>(), Weekday::Saturday); //Common week

/// ```

///

/// ### Armstrong Day and Aldrin Day

///

/// The epagomenal days of a Tranquility year are represented as [`TranquilityComplementaryDay`].

/// When converting to and from a [`CommonDate`](crate::calendar::CommonDate), the epagomenal

/// days are treated as month 0.

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let c_arm = CommonDate::new(31, 0, 1);

/// let tq_arm = Tranquility::try_from_common_date(c_arm).unwrap();

/// assert!(tq_arm.try_month().is_none());

/// assert_eq!(tq_arm.epagomenae().unwrap(), TranquilityComplementaryDay::ArmstrongDay);

/// assert!(tq_arm.weekday().is_none());

///

/// let c_ald = CommonDate::new(31, 0, 2);

/// let tq_ald = Tranquility::try_from_common_date(c_ald).unwrap();

/// assert!(tq_ald.try_month().is_none());

/// assert_eq!(tq_ald.epagomenae().unwrap(), TranquilityComplementaryDay::AldrinDay);

/// assert!(tq_ald.weekday().is_none());

/// ```

///

/// Armstrong Day is at the end of a year (except the year 1 BT).

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let tq_end_31 = Tranquility::try_year_end(31).unwrap();

/// assert_eq!(tq_end_31.epagomenae().unwrap(), TranquilityComplementaryDay::ArmstrongDay);

/// let tq_end_1 = Tranquility::try_year_end(-1).unwrap();

/// assert!(tq_end_1.epagomenae().is_none());

/// ```

///

/// Aldrin Day is between 27 and 28 Hippocrates in a leap year. Note that leap years occur

/// at the same time as proleptic Gregorian leap years and Aldrin Day is always February 28

/// in the proleptic Gregorian calendar.

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let g_list = [

///     Gregorian::try_new(2024, GregorianMonth::February, 28).unwrap(),

///     Gregorian::try_new(2024, GregorianMonth::February, 29).unwrap(),

///     Gregorian::try_new(2024, GregorianMonth::March, 1).unwrap(),

/// ];

///

/// let tq_list = [

///     g_list[0].convert::<Tranquility>(),

///     g_list[1].convert::<Tranquility>(),

///     g_list[2].convert::<Tranquility>(),

/// ];

///

/// // Before Aldrin Day

/// assert_eq!(tq_list[0].year(), 55);

/// assert_eq!(tq_list[0].day(), 27);

/// assert_eq!(tq_list[0].try_month().unwrap(), TranquilityMonth::Hippocrates);

/// // Aldrin Day

/// assert_eq!(tq_list[1].year(), 55);

/// assert_eq!(tq_list[1].epagomenae().unwrap(), TranquilityComplementaryDay::AldrinDay);

/// assert!(tq_list[1].try_month().is_none());

/// // After Aldrin Day

/// assert_eq!(tq_list[2].year(), 55);

/// assert_eq!(tq_list[2].day(), 28);

/// assert_eq!(tq_list[2].try_month().unwrap(), TranquilityMonth::Hippocrates);

/// ```

///

/// ### Moon Landing Day

///

/// Moon Landing Day technically does not have any year, month or weekday. However it is

/// sometimes represented using the dummy year and month value `0`. The corresponding Gregorian

/// date is July 20, 1969.

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let g = Gregorian::try_new(1969, GregorianMonth::July, 20).unwrap();

/// let tq = g.convert::<Tranquility>();

/// assert_eq!(tq.year(), 0);

/// assert_eq!(tq.epagomenae().unwrap(), TranquilityComplementaryDay::MoonLandingDay);

/// assert!(tq.try_month().is_none());

/// assert!(tq.weekday().is_none());

/// assert_eq!(tq.to_common_date(), CommonDate::new(0, 0, 0));

/// ```

///

/// Moon Landing Day is between Mendel 28, 1 BT and Archimedes 1, 1 AT.

///

/// ```

/// use radnelac::calendar::*;

/// use radnelac::day_count::*;

///

/// let g_list = [

///     Gregorian::try_new(1969, GregorianMonth::July, 19).unwrap(),

///     Gregorian::try_new(1969, GregorianMonth::July, 20).unwrap(),

///     Gregorian::try_new(1969, GregorianMonth::July, 21).unwrap(),

/// ];

///

/// let tq_list = [

///     g_list[0].convert::<Tranquility>(),

///     g_list[1].convert::<Tranquility>(),

///     g_list[2].convert::<Tranquility>(),

/// ];

///

/// // Before Moon Landing Day

/// assert_eq!(tq_list[0].year(), -1);

/// assert_eq!(tq_list[0].day(), 28);

/// assert_eq!(tq_list[0].try_month().unwrap(), TranquilityMonth::Mendel);

/// // Moon Landing Day

/// assert_eq!(tq_list[1].epagomenae().unwrap(), TranquilityComplementaryDay::MoonLandingDay);

/// // After Moon Landing Day

/// assert_eq!(tq_list[2].year(), 1);

/// assert_eq!(tq_list[2].day(), 1);

/// assert_eq!(tq_list[2].try_month().unwrap(), TranquilityMonth::Archimedes);

/// ```

///

/// The epoch of the Tranquility calendar is specific to the tenth of a second. To check if

/// a specific point in time is before or after the epoch, callers should use [`TranquilityMoment`].

///

/// ## Inconsistencies with Other Implementations

///

/// The assumptions regarding 0 BT and 1 BT could differ from other implementations.

///

/// ## Further reading

/// + Orion's Arm

///   + ["Encyclopaedia Galactica"](https://www.orionsarm.com/eg-article/48c6d4c3d54cf/)

///   + [Calendar Converter](https://www.orionsarm.com/xcms.php?r=oa-calendar-converter)

/// + [Wikipedia Deletion Log](https://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Tranquility_Calendar)

/// + [Archived Wikipedia article](https://web.archive.org/web/20180818233025/https://en.wikipedia.org/wiki/Tranquility_calendar)

/// + Archived copies of Jeff Siggins' article for OMNI

///   + [archive.org copy of mithrandir.com](https://web.archive.org/web/20161025042320/http://www.mithrandir.com/Tranquility/tranquilityArticle.html)

///   + [archive.org copy of OMNI July 1989, pages 63, 64](https://archive.org/details/omni-archive/OMNI_1989_07/page/n63/mode/2up)

///   + [archive.org copy of OMNI July 1989, pages 65, 66](https://archive.org/details/omni-archive/OMNI_1989_07/page/n65/mode/2up)

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

pub struct Tranquility(CommonDate);

impl Tranquility {

    pub fn prior_elapsed_days(year: i32) -> i64 {

        if year == 0 {

            TranquilityMoment::epoch().get_day_i() - 1

        } else {

            let y = if year < 0 { 
year + 13.95k
 } else { 
year3.36k
 };

            let prior_g = Gregorian::try_from_common_date(CommonDate {

                year: (y - 1) + TRANQUILITY_EPOCH_GREGORIAN.year,

                month: TRANQUILITY_EPOCH_GREGORIAN.month,

                day: TRANQUILITY_EPOCH_GREGORIAN.day,

            })

            .expect("Month and day known to be valid.");

            prior_g.to_fixed().get_day_i()

        }

    }

}

impl ToFromOrdinalDate for Tranquility {

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

        let correction = if TranquilityMoment::is_leap(ord.year) {

            1

        } else {

            0

        };

        if ord.day_of_year > 0 && 
ord.day_of_year <= (365 + correction)1.02k
 {

            Ok(())

        } else {

            Err(CalendarError::InvalidDayOfYear)

        }

    }

    fn ordinal_from_fixed(fixed_date: Fixed) -> OrdinalDate {

        //Common

        //Gregorian:   (jan1).....(feb28)(mar1).....(jul20)(jul21).....(dec31)

        //Greg  ord:   (1)...........(59)(60).........(201)(202).........(365)

        //Tranquility: (far25)....(hip27)(hip28)......(arm)(arc1)......(far24)

        //Tran  ord:   (165)........(223)(224)........(365)(1)...........(164)

        //Leap

        //Gregorian:   (jan1).....(feb29)(mar1).....(jul20)(jul21).....(dec31)

        //Greg  ord:   (1)...........(60)(61).........(202)(203).........(366)

        //Tranquility: (far25)......(ald)(hip28)......(arm)(arc1)......(far24)

        //Tran  ord:   (165)........(224)(225)........(366)(1)...........(164)

        const ORDINAL_SHIFT: i64 = ((TranquilityMonth::Faraday as i64) * 28) - 4;

        let g_ord = Gregorian::ordinal_from_fixed(fixed_date);

        let g_doy_shift = (g_ord.day_of_year as i64) + ORDINAL_SHIFT;

        let g_len = if Gregorian::is_leap(g_ord.year) {

            366

        } else {

            365

        };

        let tq_doy = g_doy_shift.adjusted_remainder(g_len);

        let y_approx_0 = g_ord.year - TRANQUILITY_EPOCH_GREGORIAN.year;

        let correct_0 = if tq_doy <= ORDINAL_SHIFT { 
14.06k
 } else { 
04.91k
 };

        let y_approx_1 = y_approx_0 + correct_0;

        let year = if y_approx_1 < 1 {

            y_approx_1 - 1

        } else {

            y_approx_1

        };

        if year == -1 && 
tq_doy == 365119
 {

            OrdinalDate {

                year: 0,

                day_of_year: 1,

            }

        } else {

            OrdinalDate {

                year: year,

                day_of_year: tq_doy as u16,

            }

        }

    }

    fn to_ordinal(self) -> OrdinalDate {

        let comp_count = Self::epagomenae_count(self.0.year) as i64;

        let ordinal_day = match self.epagomenae() {

            Some(TranquilityComplementaryDay::MoonLandingDay) => 1,

            Some(TranquilityComplementaryDay::ArmstrongDay) => 364 + comp_count,

            Some(TranquilityComplementaryDay::AldrinDay) => AFTER_H27,

            None => {

                let month = self.0.month as i64;

                let day = self.0.day as i64;

                let approx = ((month - 1) * 28) + day;

                let correction = if approx < AFTER_H27 || 
comp_count < 25.05k
 {

                    0

                } else {

                    1

                };

                approx + correction

            }

        };

        OrdinalDate {

            year: self.0.year,

            day_of_year: ordinal_day as u16,

        }

    }

    fn from_ordinal_unchecked(ord: OrdinalDate) -> Self {

        let date_tq = match (

            ord.day_of_year as i64,

            ord.year,

            TranquilityMoment::is_leap(ord.year),

        ) {

            (_, 0, _) => CommonDate::new(0, NON_MONTH, 0),

            (365, _, false) => CommonDate::new(ord.year, NON_MONTH, 1),

            (366, _, true) => CommonDate::new(ord.year, NON_MONTH, 1),

            (AFTER_H27, _, true) => CommonDate::new(ord.year, NON_MONTH, 2),

            (doy, y, is_leap) => {

                let correction = if doy < AFTER_H27 || 
!is_leap3.03k
 { 
07.96k
 } else { 
1723
 };

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

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

                debug_assert!(month > 0 && month < 14, 
"doy: {}, y: {}"0
, doy, y);

                CommonDate::new(y, month, day)

            }

        };

        Tranquility(date_tq)

    }

}

impl PartialOrd for Tranquility {

    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {

        if self == other {

            Some(Ordering::Equal)

        } else {

            let self_ord = self.to_ordinal();

            let other_ord = other.to_ordinal();

            self_ord.partial_cmp(&other_ord)

        }

    }

}

impl HasEpagemonae<TranquilityComplementaryDay> for Tranquility {

    fn epagomenae(self) -> Option<TranquilityComplementaryDay> {

        if self.0.month == NON_MONTH {

            TranquilityComplementaryDay::from_u8(self.0.day)

        } else {

            None

        }

    }

    fn epagomenae_count(p_year: i32) -> u8 {

        if Self::is_leap(p_year) {

            2

        } else if p_year == -1 {

            //Armstrong Day replaced by Moon Landing Day

            0

        } else {

            1

        }

    }

}

impl Perennial<TranquilityMonth, Weekday> for Tranquility {

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

        if self.epagomenae().is_some() {

            None

        } else {

            Weekday::from_i64(((self.0.day as i64) + 4).modulus(7))

        }

    }

    fn days_per_week() -> u8 {

        7

    }

    fn weeks_per_month() -> u8 {

        4

    }

}

impl HasLeapYears for Tranquility {

    fn is_leap(t_year: i32) -> bool {

        if t_year > 0 {

            Gregorian::is_leap(t_year + TRANQUILITY_EPOCH_GREGORIAN.year)

        } else if t_year < 0 {

            Gregorian::is_leap(t_year + TRANQUILITY_EPOCH_GREGORIAN.year + 1)

        } else {

            false

        }

    }

}

impl CalculatedBounds for Tranquility {}

impl Epoch for Tranquility {

    fn epoch() -> Fixed {

        let date = Gregorian::try_from_common_date(TRANQUILITY_EPOCH_GREGORIAN)

            .expect("Epoch known to be valid")

            .to_fixed();

        let time = TimeOfDay::try_from_clock(TRANQUILITY_EPOCH_CLOCK).expect("Known valid");

        Fixed::new(date.get() + time.get())

    }

}

impl FromFixed for Tranquility {

    fn from_fixed(date: Fixed) -> Tranquility {

        let ord = Tranquility::ordinal_from_fixed(date);

        Tranquility::from_ordinal_unchecked(ord)

    }

}

impl ToFixed for Tranquility {

    fn to_fixed(self) -> Fixed {

        let ord = self.to_ordinal();

        let offset_prior = Tranquility::prior_elapsed_days(ord.year);

        Fixed::new((offset_prior as f64) + (ord.day_of_year as f64))

    }

}

impl ToFromCommonDate<TranquilityMonth> for Tranquility {

    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 > 13 {

            Err(CalendarError::InvalidMonth)

        } else if date.month == NON_MONTH {

            if date.day == 0 && 
date.year == 02
 {

                Ok(())

            } else if date.day == 1 && 
date.year != 02.06k
 && 
date.year != -12.06k
 {

                Ok(())

            } else if date.day == 2 && date.year != 0 && Self::is_leap(date.year) {

                Ok(())

            } else {

                Err(CalendarError::InvalidDay)

            }

        } else if date.day < 1 || 
date.day > 2820.6k
 {

            Err(CalendarError::InvalidDay)

        } else if date.year == 0 {

            //Only for Moon Landing Day, as above

            Err(CalendarError::InvalidYear)

        } else {

            Ok(())

        }

    }

    fn year_start_date(year: i32) -> CommonDate {

        if year == 0 {

            CommonDate::new(

                year,

                NON_MONTH,

                TranquilityComplementaryDay::MoonLandingDay as u8,

            )

        } else {

            CommonDate::new(year, 1, 1)

        }

    }

    fn year_end_date(year: i32) -> CommonDate {

        if year == 0 {

            CommonDate::new(

                year,

                NON_MONTH,

                TranquilityComplementaryDay::MoonLandingDay as u8,

            )

        } else if year == -1 {

            CommonDate::new(year, TranquilityMonth::Mendel as u8, 28)

        } else {

            CommonDate::new(

                year,

                NON_MONTH,

                TranquilityComplementaryDay::ArmstrongDay as u8,

            )

        }

    }

    fn month_length(_year: i32, _month: TranquilityMonth) -> u8 {

        28

    }

}

impl Quarter for Tranquility {

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

        match (self.try_week_of_year(), self.epagomenae()) {

            (None, Some(TranquilityComplementaryDay::MoonLandingDay)) => NonZero::new(4).unwrap(),

            (None, Some(TranquilityComplementaryDay::ArmstrongDay)) => NonZero::new(4).unwrap(),

            (None, Some(TranquilityComplementaryDay::AldrinDay)) => NonZero::new(3).unwrap(),

            (Some(w), None) => NonZero::new((w - 1) / 13 + 1).expect("w > 0"),

            (_, _) => unreachable!(),

        }

    }

}

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

pub type TranquilityMoment = CalendarMoment<Tranquility>;

impl TranquilityMoment {

    pub fn is_after_tranquility(self) -> bool {

        if self.date().0.year == 0 {

            self.time_of_day() > TRANQUILITY_EPOCH_CLOCK

        } else {

            self.date().0.year > 0

        }

    }

}

#[cfg(test)]

mod tests {

    use super::*;

    //use crate::calendar::Julian;

    use crate::day_count::RataDie;

    use crate::day_count::FIXED_MAX;

    use crate::day_count::FIXED_MIN;

    use proptest::proptest;

    #[test]

    fn moon_landing_edge_cases() {

        let f0 = TranquilityMoment::epoch();

        let q0 = TranquilityMoment::from_fixed(f0);

        let c = CommonDate::new(0, 0, 0);

        assert_eq!(q0.to_common_date(), c);

        let f1 = q0.to_fixed();

        assert_eq!(f0, f1);

        assert_eq!(c, TranquilityMoment::year_end_date(0));

        assert_eq!(c, TranquilityMoment::year_start_date(0));

    }

    #[test]

    fn one_bt_edge_cases() {

        let c = CommonDate::new(-1, 13, 28);

        assert_eq!(c, TranquilityMoment::year_end_date(-1));

    }

    #[test]

    fn obvious_conversions_from_gregorian() {

        let d_list = [

            // Moon Landing Day

            (CommonDate::new(1969, 7, 20), CommonDate::new(0, 0, 0)),

            // Near Moon Landing Day

            (CommonDate::new(1969, 6, 30), CommonDate::new(-1, 13, 9)),

            (CommonDate::new(1969, 7, 1), CommonDate::new(-1, 13, 10)),

            (CommonDate::new(1969, 7, 9), CommonDate::new(-1, 13, 18)),

            (CommonDate::new(1969, 7, 19), CommonDate::new(-1, 13, 28)),

            (CommonDate::new(1969, 7, 21), CommonDate::new(1, 1, 1)),

            (CommonDate::new(1969, 7, 31), CommonDate::new(1, 1, 11)),

            (CommonDate::new(1969, 8, 1), CommonDate::new(1, 1, 12)),

            // Armstrong Day

            (CommonDate::new(1965, 7, 20), CommonDate::new(-5, 0, 1)),

            (CommonDate::new(1968, 7, 20), CommonDate::new(-2, 0, 1)),

            (CommonDate::new(1970, 7, 20), CommonDate::new(1, 0, 1)),

            (CommonDate::new(1989, 7, 20), CommonDate::new(20, 0, 1)), //in Siggins' article

            (CommonDate::new(1995, 7, 20), CommonDate::new(26, 0, 1)),

            (CommonDate::new(1995, 7, 21), CommonDate::new(27, 1, 1)),

            (CommonDate::new(2000, 7, 20), CommonDate::new(31, 0, 1)),

            (CommonDate::new(2020, 7, 20), CommonDate::new(51, 0, 1)),

            (CommonDate::new(2025, 7, 20), CommonDate::new(56, 0, 1)),

            // Aldrin Day

            (CommonDate::new(1968, 2, 29), CommonDate::new(-2, 0, 2)),

            (CommonDate::new(1972, 2, 29), CommonDate::new(3, 0, 2)),

            (CommonDate::new(2000, 2, 29), CommonDate::new(31, 0, 2)),

        ];

        for 
pair20
 in d_list {

            let dg = Gregorian::try_from_common_date(pair.0).unwrap().to_fixed();

            let dq = TranquilityMoment::try_from_common_date(pair.1)

                .unwrap()

                .to_fixed();

            assert_eq!(dq.get_day_i(), dg.get_day_i());

        }

    }

    #[test]

    fn article_examples() {

        let d_list = [

            // From Siggins' article

            // 21, 1, 3

            // Beginning of the Perseid meteor showers (1989)

            // ???

            // Louise Brown, first test-tube baby, is born (1978)

            // 1978-07-25 https://en.wikipedia.org/wiki/Louise_Brown

            (CommonDate::new(1978, 7, 25), CommonDate::new(10, 1, 5)),

            // NASA established and funded by Congress (1958)

            // 1958-07-29 https://en.wikipedia.org/wiki/NASA

            (CommonDate::new(1958, 7, 29), CommonDate::new(-11, 1, 9)),

            // Explorer VI transmits first picture of Earth from space (1959)

            // 1959-08-14 https://en.wikipedia.org/wiki/Explorer_6

            // (CommonDate::new(1959, 8, 14), CommonDate::new(-10, 1, 18)), //Incorrect???

            // USSR explodes its first hydrogen bomb (1953)

            // 1953-08-12 https://en.wikipedia.org/wiki/RDS-6s

            (CommonDate::new(1953, 8, 12), CommonDate::new(-16, 1, 23)),

            // Lunar eclipse (1989)

            // 1989-08-17 https://en.wikipedia.org/wiki/August_1989_lunar_eclipse

            (CommonDate::new(1989, 8, 17), CommonDate::new(21, 1, 28)),

            // Launch of Voyager 2, space-craft for planetary exploration (1977)

            // 1977-08-20 https://en.wikipedia.org/wiki/Voyager_2

            (CommonDate::new(1977, 8, 20), CommonDate::new(9, 2, 3)),

            // Pliny the Elder dies in eruption of Vesuvius at Pompeii (79)

            // 79-08-24 https://en.wikipedia.org/wiki/Eruption_of_Mount_Vesuvius_in_79_AD

            // Actual date seems controversial, additionally shouldn't this be Julian?

            (CommonDate::new(79, 8, 24), CommonDate::new(-1890, 2, 7)),

            // Partial solar eclipse (1989)

            // 1989-08-31 wiki:https://en.wikipedia.org/wiki/Solar_eclipse_of_August_31,_1989

            (CommonDate::new(1989, 8, 31), CommonDate::new(21, 2, 14)),

            // Viking 2 lands near polar cap of Mars, sends photos of Earth (1976)

            // 1976-09-03 wiki:https://en.wikipedia.org/wiki/Viking_2

            (CommonDate::new(1976, 9, 3), CommonDate::new(8, 2, 17)),

            // Charles Darwin, in a letter to American botanist Asa Gray, propounds the law of evolution of species by means of natural selection (1857)

            // 1857-09-05 wiki:https://en.wikipedia.org/wiki/Charles_Darwin

            (CommonDate::new(1857, 9, 5), CommonDate::new(-112, 2, 19)),

            // First privately owned rocket launched by Space Services, Inc., of the USA (1982)

            // 1982-09-09 wiki:https://en.wikipedia.org/wiki/Conestoga_(rocket)

            (CommonDate::new(1982, 9, 9), CommonDate::new(14, 2, 23)),

            // 16, 2, 28

            // First solo balloon flight across the Atlantic Ocean embarks from Maine, arrives 86 hours later (1984)

            // ???

            // Autumnal equinox. The serpent of light appears on the pyramid at Chichen Itza Mexico (1989)

            // 1989-09-23 https://www.timeanddate.com/calendar/seasons.html?year=1950&n=1440

            (CommonDate::new(1989, 9, 23), CommonDate::new(21, 3, 9)),

            // "Blue sun," a 200-mile-wide blanket of smoke, caused by forest fires in Alberta and British Columbia, Canada (1950)

            // 1950-09-24 https://en.wikipedia.org/wiki/Chinchaga_fire (black sunday)

            // (CommonDate::new(1950, 9, 24), CommonDate::new(-19, 3, 12)), //Incorrect?

            // Shuttle Discovery launched, first manned US craft since the Challenger (1988)

            // 1988-09-29 https://en.wikipedia.org/wiki/STS-26

            (CommonDate::new(1988, 9, 29), CommonDate::new(20, 3, 15)),

            // 21, 3, 16

            // First day of year 5750 on the Judaic calendar (1989)

            // ???

            // Sputnik 1, first successful man-made satellite, is launched by the USSR (1957)

            // 1957-10-04 https://en.wikipedia.org/wiki/Sputnik_1

            (CommonDate::new(1957, 10, 4), CommonDate::new(-12, 3, 20)),

            // -302, 3, 25

            // Antonie van Leeuwenhoek announces discovery of microorganisms (1667)

            // ???

            // Christopher Columbus lands in the Bahamas (1492)

            // 1492-10-12 https://en.wikipedia.org/wiki/Voyages_of_Christopher_Columbus

            (CommonDate::new(1492, 10, 12), CommonDate::new(-477, 3, 28)), //Apparently not Julian

            // USAF Chaptain Charles Yeager becomes first human to fly faster than the speed of sound

            // 1947-10-14 https://en.wikipedia.org/wiki/Bell_X-1

            (CommonDate::new(1947, 10, 14), CommonDate::new(-22, 4, 2)),

            // -123, 4, 4

            // First public operation using ether as an anesthetic is performed at Massachusetts General Hospital

            // ???

            // Thomas Edison invents incandescent electric lamp (1879)

            // 1879-10-22 https://en.wikipedia.org/wiki/Incandescent_light_bulb

            // (CommonDate::new(1879, 10, 22), CommonDate::new(-90, 4, 9)), //Incorrect?

            // The first recorded parachute descent, from a balloon (1797) (1st Brumaire, Year VI of the Republican calendar)

            // 1797-10-22 https://en.wikipedia.org/wiki/Andr%C3%A9-Jacques_Garnerin

            (CommonDate::new(1797, 10, 22), CommonDate::new(-172, 4, 10)),

            // -10, 4, 15

            // The Soviet Union releases the first pictures of the far side of the moon, taken by Lunik 3 (1959)

            // ??? 1959-10-07 wiki:https://en.wikipedia.org/wiki/Luna_3

            // Laika, a Russian dog, becomes the first "higher" animal in space (1957)

            // 1957-11-03 https://en.wikipedia.org/wiki/Sputnik_2

            (CommonDate::new(1957, 11, 3), CommonDate::new(-12, 4, 22)),

            // Archaeologist Howard Carter discovers tomb of King Tut at Luxor, Egypt (1922)

            // 1992-11-04 https://en.wikipedia.org/wiki/Discovery_of_the_tomb_of_Tutankhamun

            (CommonDate::new(1922, 11, 4), CommonDate::new(-47, 4, 23)),

            // 25, 4, 28

            // The next transit of the planet Mercury across the face of the sun (1993)

            // ??? 1993-11-06 https://en.m.wikipedia.org/wiki/Transit_of_Mercury

            // The first coast-to-coast direct-dial telephone service begins, Englewood, New Jersey (1951)

            // 1951-11-10 https://en.wikipedia.org/wiki/Englewood,_New_Jersey

            (CommonDate::new(1951, 11, 10), CommonDate::new(-18, 5, 1)),

            // Voyager 1 nears Saturn; photos reveal three new moons (1980)

            // 1980-11-12 https://en.wikipedia.org/wiki/Voyager_1

            (CommonDate::new(1980, 11, 12), CommonDate::new(12, 5, 3)),

            // -3, 5, 8

            // The densest meteor shower ever recorded (1966)

            // ???

            // -63, 5, 13

            // SOS adopted as the international distress call (1906)

            // ??? 1906-11-03 wiki:https://en.wikipedia.org/wiki/SOS

            // Charles Darwin's The Origin of Species is published (1859)

            // 1859-11-24 https://en.wikipedia.org/wiki/On_the_Origin_of_Species

            (CommonDate::new(1859, 11, 24), CommonDate::new(-110, 5, 15)),

            // -23, 5, 28

            // Percy Spencer patents the microwave oven (1946)

            // ??? 1945-10-08 wiki:https://en.wikipedia.org/wiki/Percy_Spencer

            // Anethesia used for first time to perform a dental extraction (1844)

            //1844-12-10 https://en.wikipedia.org/wiki/History_of_general_anesthesia

            // (CommonDate::new(1844, 12, 10), CommonDate::new(-125, 6, 4)), // Incorrect??

            // -22, 6, 5

            // John Bardeen, Walter Brattain, and William Shockley invent the transistor (1947)

            // ??? 1947-(11-17 to 12-23) wiki:https://en.wikipedia.org/wiki/Transistor

            // The first airplane flight by Orville and Wilbur Wright, Kitty Hawk, North Carolina (1903)

            //1903-12-17 https://en.wikipedia.org/wiki/Wright_Flyer

            (CommonDate::new(1903, 12, 17), CommonDate::new(-66, 6, 10)),

            // Winter solstice (1989)

            //1989-12-21 https://aa.usno.navy.mil/calculated/seasons?year=1989&tz=0.00&tz_sign=-1&tz_label=false&dst=false&submit=Get+Data

            (CommonDate::new(1989, 12, 21), CommonDate::new(21, 6, 14)),

            // 6, 6, 17

            // The discovery of Lucy, fossil remains of an early female hominid, in Ethiopia (1974)

            // ???

            // New Year's Day on both the Gregorian Calendar (1990) and Japanese calendar (2651)

            // 1990-01-01 by definition

            (CommonDate::new(1990, 1, 1), CommonDate::new(21, 6, 25)),

            // 21, 6, 28

            // The earth is at its farthest distance from the sun (aphelion) (1990)

            // ??? 1990-01-04 is the perihelion wiki:https://aa.usno.navy.mil/calculated/seasons?year=1990&tz=0.00&tz_sign=-1&tz_label=false&dst=false&submit=Get+Data

            // Galileo discovers the moons of Jupiter (1610)

            // 1610-01-07 https://en.wikipedia.org/wiki/Galileo_Galilei

            (CommonDate::new(1610, 1, 7), CommonDate::new(-360, 7, 3)),

            // 16, 7, 9

            // Ornithologists count 1350 great white cranes at Poyand Lake in China, the most ever recorded (1985)

            // ???

            // Earthquake changes course of the Mississippi River (1812)

            // 1812-01-23 https://en.wikipedia.org/wiki/1811%E2%80%931812_New_Madrid_earthquakes

            (CommonDate::new(1812, 1, 23), CommonDate::new(-158, 7, 19)),

            // Annular eclipse of the sun (1990)

            // 1990-01-26 wiki:https://en.wikipedia.org/wiki/List_of_solar_eclipses_in_the_20th_century

            (CommonDate::new(1990, 1, 26), CommonDate::new(21, 7, 22)),

            // Apollo 1 fire kills US astronauts Gus Grissom, Ed White, and Roger Chaffee (1967)

            //1967-01-27 https://en.wikipedia.org/wiki/Apollo_1

            (CommonDate::new(1967, 1, 27), CommonDate::new(-3, 7, 23)),

            // The space shuttle Challenger explodes, killing seven American astronauts (1986)

            //1986-01-28 https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster

            (CommonDate::new(1986, 1, 28), CommonDate::new(17, 7, 24)),

            // Explorer 1, the first US satellite, is launched (1958)

            //1958-02-01 https://en.wikipedia.org/wiki/Explorer_1

            // (CommonDate::new(1958, 2, 1), CommonDate::new(-12, 7, 27)), //Incorrect??

            // Soviet Luna 9 makes first successful soft landing on the moon (1966)

            //1966-02-03 https://en.wikipedia.org/wiki/Luna_9

            (CommonDate::new(1966, 2, 3), CommonDate::new(-4, 8, 2)),

            // Two US astronauts become first humans to fly untethered in space (1984)

            //1984-02-07 https://en.wikipedia.org/wiki/STS-41-B

            // Launch date instead of untethered spacewalk date!

            (CommonDate::new(1984, 2, 3), CommonDate::new(15, 8, 2)),

            // Total lunar eclipse (1990)

            //1990-02-09 https://en.wikipedia.org/wiki/List_of_lunar_eclipses_in_the_20th_century

            // (CommonDate::new(1990, 2, 9), CommonDate::new(21, 8, 7)), //Incorrect??

            // Pope Gregory corrects the Julian calendar (1582) (See Julian test)

            // Italian philosopher Giordano Bruno burned at the stake for his heliocentric views (1600)

            //1600-02-17 https://en.wikipedia.org/wiki/Giordano_Bruno

            (CommonDate::new(1600, 2, 17), CommonDate::new(-370, 8, 16)),

            // The planet Pluto is discovered by Clyde Tombaught (1930)

            //1930-02-18 https://en.m.wikipedia.org/wiki/Pluto

            (CommonDate::new(1930, 2, 18), CommonDate::new(-40, 8, 17)),

            // John Glenn aboard the Friendship 7, becomes the first American to orbit Earth (1962)

            //1962-02-20 https://en.wikipedia.org/wiki/Mercury-Atlas_6

            (CommonDate::new(1962, 2, 20), CommonDate::new(-8, 8, 19)),

            // Sir James Chadwick of Great Britain announces the discovery of the neutron (1932)

            //1932-02-27 https://web.mit.edu/22.54/resources/Chadwick.pdf

            (CommonDate::new(1932, 2, 27), CommonDate::new(-38, 8, 26)),

            // The launch of Pioneer 10, first known Earth object to leave solar system (1972)

            //1972-03-03 https://en.wikipedia.org/wiki/Pioneer_10

            // (CommonDate::new(1972, 3, 3), CommonDate::new(3, 9, 1)), //Incorrect?

            // Sir William Herschel discovers Uranus (1781)

            // 1781-03-13 wiki:https://en.wikipedia.org/wiki/Uranus

            // (CommonDate::new(1781, 3, 13), CommonDate::new(-189, 9, 5)), //Incorrect?

            // The Ides of March, the day that Julius Caesar died (-44) (See Julian test)

            // Robert Goddard launches the first successful liquid-fuel rocket (1926)

            // ??

            // The US Congress authorizes conversion to standard time zones and daylight saving time (1918)

            // 1918-03-29 https://en.wikipedia.org/wiki/Standard_Time_Act

            // (CommonDate::new(1918, 3, 29), CommonDate::new(-12, 9, 18)), //Incorrect?

            // Vernal equinox. Serpent of light appears on the pyramid at Chichen Itza, Mexico (1990)

            // 1990-03-20 https://aa.usno.navy.mil/calculated/seasons?year=1990&tz=0.00&tz_sign=-1&tz_label=false&dst=false&submit=Get+Data

            (CommonDate::new(1990, 3, 20), CommonDate::new(21, 9, 19)),

            // Accident at Three Mile Island Nuclear Generating Station in Pennsylvania (1979)

            // 1979-03-28 https://en.wikipedia.org/wiki/Three_Mile_Island_accident

            (CommonDate::new(1979, 3, 28), CommonDate::new(10, 9, 27)),

            // Mariner 10 spacecraft approaches Mercury and sends 647 photos back to Earth (1974)

            // 1974-03-29 https://en.wikipedia.org/wiki/Mariner_10

            (CommonDate::new(1974, 3, 29), CommonDate::new(5, 9, 28)),

            // Samuel Morey patents the internal-combustion engine (1826)

            // 1826-04-01 https://www.ancientpages.com/2017/04/01/samuel-morey-patent/

            (CommonDate::new(1826, 4, 1), CommonDate::new(-144, 10, 3)),

            // First commerical communications satellite launched (US) (1965)

            // 1965-04-06 https://en.wikipedia.org/wiki/Communications_satellite

            // (CommonDate::new(1965, 4, 6), CommonDate::new(-5, 10, 6)), //Incorrect?

            // Robert E. Peary claims discovery of the North Pole (1909)

            // 1909-04-06 wiki:https://en.wikipedia.org/wiki/Robert_Peary

            (CommonDate::new(1909, 4, 6), CommonDate::new(-61, 10, 8)),

            // Cosmonaut Yuri Gagarin of the USSR orbits Earth, becoming the first human in space (1961)

            // 1961-04-12 https://en.wikipedia.org/wiki/Vostok_1

            (CommonDate::new(1961, 4, 12), CommonDate::new(-9, 10, 14)),

            // Two giant pandas, gifts from People's Republic of China, arrive at the National Zoo in Washington DC (1972)

            // 1972-04-16 wiki:https://en.wikipedia.org/wiki/Ling-Ling_and_Hsing-Hsing

            (CommonDate::new(1972, 4, 16), CommonDate::new(3, 10, 18)),

            // -284, 10, 19

            // Sir Isaac Newton presents Philosophiae naturalis principia mathematica to the Royal Society (1686)

            // ??

            // Francis Crick and James Watson report their discovery of the DNA double helix (1953)

            //1953-04-25 wiki:https://www.nature.com/articles/171737a0

            (CommonDate::new(1953, 04, 25), CommonDate::new(-17, 10, 27)),

            // Alan Shepard becomes the first American in space (1961)

            //1961-05-05 wiki:https://en.wikipedia.org/wiki/Mercury-Redstone_3

            (CommonDate::new(1961, 05, 05), CommonDate::new(-9, 11, 9)),

            // -174, 11, 18

            // Dr Edward Jenner conducts his first experiment with cow-pox vaccination (1796)

            // ??

            // Charles Lindbergh lands in Paris, becoming the first person to fly an airplane solo, nonstop across the Atlantic Ocean (1927)

            //1927-05-21 wiki:https://en.wikipedia.org/wiki/Spirit_of_St._Louis

            (CommonDate::new(1927, 05, 21), CommonDate::new(-43, 11, 25)),

            // The Concorde supersonic transport makes its first transatlantic flight to USA (1976)

            //1976-05-24 wiki:https://en.wikipedia.org/wiki/Concorde_operational_history

            (CommonDate::new(1976, 05, 24), CommonDate::new(7, 11, 28)),

            // Most famous ancient solar eclipse occurs during a battle between Lydians and Medes (585 BC) (see Julian test)

            // -585-05-28 wiki:https://en.wikipedia.org/wiki/Eclipse_of_Thales

            // You would think this is a Julian date but no, this is a Gregorian date without year 0

            (CommonDate::new(-584, 5, 28), CommonDate::new(-2554, 12, 4)),

            // US launches the Mariner 9, first spacecraft to orbit another planet (1971)

            // 1971-05-30 https://en.wikipedia.org/wiki/Mariner_9

            (CommonDate::new(1971, 5, 30), CommonDate::new(2, 12, 6)),

            // Guglielmo Marconi is granted patent for the radio in Great Britain (1896)

            // 1896-06-02 https://en.wikipedia.org/wiki/Guglielmo_Marconi

            (CommonDate::new(1896, 6, 2), CommonDate::new(-74, 12, 9)),

            // Byron Allen pedals Gossamer Albatross aircraft across the English Channel (1979)

            // 1979-06-12 https://en.wikipedia.org/wiki/MacCready_Gossamer_Albatross

            (CommonDate::new(1979, 6, 12), CommonDate::new(10, 12, 19)),

            // Pioneer 10 exits solar system (1983)

            // 1983-06-13 https://en.wikipedia.org/wiki/Pioneer_10

            (CommonDate::new(1983, 6, 13), CommonDate::new(14, 12, 20)),

            // Ben Franklin flies kite during a lightning storm and discovers electricity (1752)

            //1752-06-15 https://en.wikipedia.org/wiki/Benjamin_Franklin

            (CommonDate::new(1752, 6, 15), CommonDate::new(-218, 12, 22)),

            // Sally Ride becomes first US woman in space (1983)

            //1983-06-18 https://en.wikipedia.org/wiki/STS-7

            (CommonDate::new(1983, 6, 18), CommonDate::new(14, 12, 25)),

            // Summer solstice, longest day of year, Northern Hemisphere (1990)

            //1990-06-21 https://aa.usno.navy.mil/calculated/seasons?year=1990&tz=0.00&tz_sign=-1&tz_label=false&dst=false&submit=Get+Data

            (CommonDate::new(1990, 6, 21), CommonDate::new(21, 12, 28)),

            // First reported UFO sighting using the term flying saucers (1947)

            //1947-06-24 https://en.wikipedia.org/wiki/Kenneth_Arnold_UFO_sighting

            (CommonDate::new(1947, 6, 24), CommonDate::new(-23, 13, 3)),

            // -13, 13, 4

            // CBS broadcasts first commercial color TV program (1957)

            // ???

            // Mysterious explosion devastates a huge forest in Tunguska, Siberia (1908)

            // 1908-06-30 https://en.wikipedia.org/wiki/Tunguska_event

            (CommonDate::new(1908, 6, 30), CommonDate::new(-62, 13, 9)),

            // -83, 13, 15

            // Louis Pasteur inoculates a boy with antirabies serum (1887)

            // ???

            // Skylab falls to Earth (1979)

            // 1979-07-11 https://en.wikipedia.org/wiki/Skylab

            (CommonDate::new(1979, 7, 11), CommonDate::new(10, 13, 20)),

            // -8, 13, 22

            // First transatlantic conversation using communications satellite (1962)

            // 1962-07-23 wiki:https://en.wikipedia.org/wiki/Telstar

            // (CommonDate::new(1962, 7, 23), CommonDate::new(-8, 13, 22)), //Incorrect?

            // First atomic bomb is detonated, Trinity Site, New Mexico (1945)

            // 1945-07-16 https://en.wikipedia.org/wiki/Trinity_(nuclear_test)

            (CommonDate::new(1945, 7, 16), CommonDate::new(-25, 13, 25)),

        ];

        for 
pair58
 in d_list {

            let dg = Gregorian::try_from_common_date(pair.0).unwrap().to_fixed();

            let dq = TranquilityMoment::try_from_common_date(pair.1)

                .unwrap()

                .to_fixed();

            assert_eq!(dg.get_day_i(), dq.get_day_i(), 
"{:?}"0
, pair);

        }

    }