Split out common calendar package

.gitignore

@@ -1,5 +1,5 @@
 # dependencies
-/node_modules
+node_modules
 /.pnp
 .pnp.js
 

README.md

@@ -1,61 +1,7 @@
-# French Republican Calendar
+# qcal
 
-![demo](demo.png)
+This is **@quantum5**'s collection of calendar webapps, intend to cover all
+calendars from major cultures.
 
-## What is this?
+Currently, the following calendars are supported:
-
+* [French Republican Calendar](frcal/README.md)
-The [French Republican calendar][0] was a calendar created and implemented
-during the French Revolution.
-
-It was also frequently known as the *French Revolutionary Calendar*, but this
-was a misnomer: year 1 of the calendar started on 22 September 1792, the day
-after the [abolition of the monarchy][1] and the founding of the [French
-First Republic][2].
-
-## How does it work?
-
-A year consists of 12 months of 30 days each, divided into three *décades* of
-10 days each, followed by 5 complementary days (6 in leap years).
-
-The year starts on the day of the autumnal equinox at the Paris Observatory
-(longitude 2°20′14.03″ E). A leap year follow directly from this definition:
-a year is a leap year when the next autumnal equinox happens 366 days later
-instead of the normal 365. By this definition, the year will **never** drift
-with respect to the seasons.
-
-The 12 months are: *Vendémiaire*, *Brumaire*, *Frimaire*, *Nivôse*,
-*Pluviôse*, *Ventôse*, *Germinal*, *Floréal*, *Prairial*, *Messidor*,
-*Thermidor*, *Fructidor.*
-
-The complementary days are: *la Fête de la Vertu*, *la Fête du Génie*,
-*la Fête du Travail*, *la Fête de l'Opinion*, *la Fête des Récompenses,*
-and *la Fête de la Révolution* (leap years only).
-
-## What's so special about this version?
-
-Most versions of the calendar floating around doesn't use the original
-definition above.
-
-Most versions uses the so-called *Romme* method for leap years, using the
-same leap year rules as the Gregorian calendar, i.e. every year divisible
-by four, except century years not divisible by 400. This method might make
-sense, except years 3, 7, and 11 were leap years under the original rules
-and were observed as such in real life, but the *Romme* method instead makes
-years 4, 8, 12 leap years instead.
-
-This version uses the original rules. The [JPL's DE440 and DE441
-ephemerides][3] were used to calculate the exact timings of the autumnal
-equinoxes between the Gregorian years 13201 BCE and 17191 CE (corresponding
-to the French Republican years -14991 to 15399). The times were then converted
-to UT1+00:09:21, the exact local time at the Paris Observatory. UT1 was chosen
-to keep track of the Earth's rotation without having to worry about the issues
-posed by leap seconds in UTC. Note that due to the uncertainty over [ΔT][4] —
-the difference between UT1 and Terrestrial Time (TT) used in the ephemerides —
-it is theoretically possible for there to be inaccuracies when the equinox
-occurs very close to midnight.
-
-[0]: https://en.wikipedia.org/wiki/French_Republican_calendar
-[1]: https://en.wikipedia.org/wiki/Proclamation_of_the_abolition_of_the_monarchy
-[2]: https://en.wikipedia.org/wiki/French_First_Republic
-[3]: https://ssd.jpl.nasa.gov/planets/eph_export.html
-[4]: https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)

common/gen_french.py

@@ -83,7 +83,7 @@ def main():
         'start_year': fr_year(int(equinoxes[0].ut1_calendar()[0])),
         'leap': [int(paris_jdn(b) - paris_jdn(a) == 366) for a, b in zip(equinoxes, equinoxes[1:])]
     }
-    with open('src/cal.json', 'w') as f:
+    with open('src/french/cal.json', 'w') as f:
         json.dump(result, f, separators=(',', ':'))
 
 

common/jest.config.js

@@ -0,0 +1,5 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+};

common/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "qcal_common",
+  "version": "0.1.0",
+  "private": true,
+  "dependencies": {
+    "@testing-library/jest-dom": "^5.16.2",
+    "@testing-library/react": "^12.1.2",
+    "@testing-library/user-event": "^13.5.0",
+    "@types/jest": "^27.4.0",
+    "@types/node": "^16.11.24",
+    "@types/react": "^17.0.39",
+    "@types/react-dom": "^17.0.11",
+    "bootstrap": "^5.1.3",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2",
+    "typescript": "^4.5.5",
+    "web-vitals": "^2.1.4"
+  },
+  "scripts": {
+    "test": "jest"
+  },
+  "eslintConfig": {
+    "extends": [
+      "react-app",
+      "react-app/jest"
+    ]
+  },
+  "devDependencies": {
+    "jest": "^29.5.0",
+    "ts-jest": "^29.1.0"
+  }
+}

common/src/french/index.test.ts

@@ -0,0 +1,93 @@
+import {
+    dateName,
+    dateRuralName,
+    frIsLeap,
+    frJDN,
+    jdnFrench,
+    monthName
+} from './index';
+
+describe('frJDN', () => {
+    it('works for sample dates', () => {
+        expect(frJDN(1, 1, 1)).toBe(2375840);
+        expect(frJDN(8, 2, 18)).toBe(2378444);
+    });
+
+    it('works in years starting/ending near midnight', () => {
+        expect(frJDN( 111, 1, 1)).toBe(2416017); // equinox 1902-09-23T23:55:19 UT1
+        expect(frJDN( 206, 1, 1)).toBe(2450715); // equinox 1997-09-22T23:55:46 UT1
+        expect(frJDN(2490, 1, 1)).toBe(3284926); // equinox 4281-09-20T23:50:38 UT1
+    });
+});
+
+describe('frIsLeap', () => {
+    it('works for sample dates', () => {
+        expect(frIsLeap(1)).toBeFalsy();
+        expect(frIsLeap(8)).toBeFalsy();
+        expect(frIsLeap(3)).toBeTruthy();
+        expect(frIsLeap(7)).toBeTruthy();
+        expect(frIsLeap(11)).toBeTruthy();
+    });
+
+    it('works in years starting/ending near midnight', () => {
+        expect(frIsLeap(110)).toBeTruthy();
+        expect(frIsLeap(205)).toBeTruthy();
+        expect(frIsLeap(2489)).toBeFalsy();
+        expect(frIsLeap(111)).toBeFalsy();
+        expect(frIsLeap(206)).toBeFalsy();
+        expect(frIsLeap(2490)).toBeTruthy();
+    });
+});
+
+describe('jdnFrench', () => {
+    it('works for sample dates', () => {
+        expect(jdnFrench(2375840)).toEqual({year: 1, month: 1, day: 1});
+        expect(jdnFrench(2378444)).toEqual({year: 8, month: 2, day: 18});
+    });
+
+    it('works in years starting/ending near midnight', () => {
+        expect(jdnFrench(2416017)).toEqual({year:  111, month: 1, day: 1});
+        expect(jdnFrench(2450715)).toEqual({year:  206, month: 1, day: 1});
+        expect(jdnFrench(3284926)).toEqual({year: 2490, month: 1, day: 1});
+        expect(jdnFrench(2416016)).toEqual({year:  110, month: 13, day: 6});
+        expect(jdnFrench(2450714)).toEqual({year:  205, month: 13, day: 6});
+        expect(jdnFrench(3284925)).toEqual({year: 2489, month: 13, day: 5});
+    });
+});
+
+describe('monthName', () => {
+    it('works', () => {
+        expect(monthName(1)).toBe('Vendémiaire');
+        expect(monthName(12)).toBe('Fructidor');
+        expect(monthName(13)).toBe('Jours Complémentaires');
+    });
+});
+
+describe('dateName', () => {
+    it('works', () => {
+        expect(dateName(1, 1)).toBe('1 Vendémiaire');
+        expect(dateName(2, 18)).toBe('18 Brumaire');
+        expect(dateName(3, 11)).toBe('11 Frimaire');
+        expect(dateName(8, 16)).toBe('16 Floréal');
+        expect(dateName(12, 30)).toBe('30 Fructidor');
+        expect(dateName(13, 1)).toBe('La Fête de la Vertu');
+        expect(dateName(13, 6)).toBe('La Fête de la Révolution');
+    });
+
+    it('returns null for non-existent complimentary days', () => {
+        expect(dateName(13, 7)).toBeNull();
+    });
+});
+
+describe('dateRuralName', () => {
+    it('works', () => {
+        expect(dateRuralName(1, 1)).toEqual({name: 'Raisin', title: 'Grape'});
+        expect(dateRuralName(1, 30)).toEqual({name: 'Tonneau', title: 'Barrel'});
+        expect(dateRuralName(12, 1)).toEqual({name: 'Prune', title: 'Plum'});
+        expect(dateRuralName(12, 30)).toEqual({name: 'Panier', title: 'Pack Basket'});
+    });
+
+    it('returns null for complimentary days', () => {
+        expect(dateRuralName(13, 1)).toBeNull();
+    });
+});

common/src/french/index.ts

@@ -1,9 +1,10 @@
 import data from './cal.json';
 import ruralName from './rural-days.json';
+import {jdnGregorian} from '../gregorian';
 
 // Month 13 is for the complementary days
-export type Month = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13;
+export type FrenchMonth = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13;
-export type Day =
+export type FrenchDay =
     1
     | 2
     | 3
@@ -37,12 +38,12 @@ export type Day =
 
 export type FrenchDate = {
     year: number,
-    month: Month,
+    month: FrenchMonth,
-    day: Day,
+    day: FrenchDay,
 };
 
 const monthNames: {
-    [key in Month]: string
+    [key in FrenchMonth]: string
 } = {
     1: 'Vendémiaire',
     2: 'Brumaire',
@@ -75,24 +76,12 @@ data.leap.forEach(leap => {
 });
 
 export const endYear = startYear + leaps.length - 1;
+
 export function frSupportedYear(year: number): boolean {
     return startYear <= year && year <= endYear;
 }
 
-export function gregorianJDN(year: number, month: number, day: number): number {
+export function frJDN(year: number, month: FrenchMonth, day: FrenchDay): number {
-    const g = year + 4716 - (month <= 2 ? 1 : 0);
-    const f = (month + 9) % 12;
-    const e = Math.floor(1461 * g / 4) + day - 1402;
-    const J = e + Math.floor((153 * f + 2) / 5);
-    const dg = 38 - Math.floor(Math.floor((g + 184) / 100) * 3 / 4);
-    return J + dg;
-}
-
-export function dateJDN(date: Date) {
-    return gregorianJDN(date.getFullYear(), date.getMonth() + 1, date.getDate());
-}
-
-export function frJDN(year: number, month: Month, day: Day): number {
     const dy = year - startYear;
     const dd = month * 30 + day - 31;
     return startJD + 365 * dy + leaps[dy] + dd;
@@ -102,18 +91,7 @@ export function frIsLeap(year: number): boolean {
     return !!data.leap[year - startYear];
 }
 
-export function jdnGregorian(jdn: number): Date {
+export const endJD = frJDN(endYear, 13, frIsLeap(endYear) ? 6 : 5);
-    const e = 4 * (jdn + 1401 + Math.floor(Math.floor((4 * jdn + 274277) / 146097) * 3 / 4) - 38) + 3;
-    const h = 5 * Math.floor((e % 1461 + 1461) % 1461 / 4) + 2;
-    const day = Math.floor((h % 153 + 153) % 153 / 5) + 1;
-    const month = (Math.floor(h / 153) + 2) % 12 + 1;
-    const year = Math.floor(e / 1461) - 4716 + Math.floor((14 - month) / 12);
-    return new Date(year, month - 1, day);
-}
-
-export const endJD = frJDN(endYear, 13, frIsLeap(endYear) ? 6: 5);
-export const startGregorian = jdnGregorian(startJD);
-export const endGregorian = jdnGregorian(endJD);
 
 export function jdnFrench(jdn: number): FrenchDate {
     let lo = 0;
@@ -130,35 +108,16 @@ export function jdnFrench(jdn: number): FrenchDate {
     const dd = jdn - (startJD + 365 * lo + leaps[lo]);
     return {
         year: startYear + lo,
-        month: Math.floor(dd / 30) + 1 as Month,
+        month: Math.floor(dd / 30) + 1 as FrenchMonth,
-        day: dd % 30 + 1 as Day,
+        day: dd % 30 + 1 as FrenchDay,
     }
 }
 
-export function jdnLongCount(jdn: number): string | null {
+export function monthName(month: FrenchMonth): string {
-    let z = jdn - 584283;
-    if (z < 0)
-        return null;
-
-    const parts = [z % 20, Math.floor(z / 20) % 18];
-    z = Math.floor(z / 360);
-    while (z > 0) {
-        parts.push(z % 20);
-        z = Math.floor(z / 20);
-    }
-
-    while (parts.length < 5) {
-        parts.push(0);
-    }
-
-    return parts.reverse().join('.');
-}
-
-export function monthName(month: Month): string {
     return monthNames[month];
 }
 
-export function dateName(month: Month, day: Day): string | null {
+export function dateName(month: FrenchMonth, day: FrenchDay): string | null {
     if (month === 13) {
         switch (day) {
             case 1:
@@ -180,10 +139,13 @@ export function dateName(month: Month, day: Day): string | null {
     return `${day} ${monthNames[month]}`;
 }
 
-export function dateRuralName(month: Month, day: Day): {name: string, title: string} | null {
+export function dateRuralName(month: FrenchMonth, day: FrenchDay): { name: string, title: string } | null {
     const rural = ruralName[month * 30 + day - 31];
     if (!rural)
         return null;
     const [name, title] = rural;
     return {name, title};
 }
+
+export const startGregorian = jdnGregorian(startJD);
+export const endGregorian = jdnGregorian(endJD);

common/src/gregorian.test.ts

@@ -0,0 +1,39 @@
+import {gregorianJDN, jdnGregorian} from './gregorian';
+
+describe('gregorianJDN', () => {
+    it('works', () => {
+        expect(gregorianJDN(2000, 1, 1)).toBe(2451545);
+        expect(gregorianJDN(-4713, 11, 24)).toBe(0);
+        expect(gregorianJDN(11917, 9, 18)).toBe(6073915);
+        expect(gregorianJDN(-28565, 6, 17)).toBe(-8711925);
+        expect(gregorianJDN(-26650, 4, 13)).toBe(-8012550);
+        expect(gregorianJDN(17430, 3, 8)).toBe(8087303);
+        expect(gregorianJDN(3395, 7, 18)).toBe(2961257);
+        expect(gregorianJDN(4579, 3, 11)).toBe(3393575);
+        expect(gregorianJDN(-14851, 11, 22)).toBe(-3702831);
+        expect(gregorianJDN(8824, 11, 28)).toBe(4944292);
+        expect(gregorianJDN(19720, 8, 14)).toBe(8923868);
+        expect(gregorianJDN(7504, 7, 22)).toBe(4462042);
+    });
+});
+
+describe('jdnGregorian', () => {
+    it('works', () => {
+        expect(jdnGregorian(0)).toEqual(new Date(-4713, 10, 24));
+        expect(jdnGregorian(2299160)).toEqual(new Date(1582, 9, 14));
+        expect(jdnGregorian(2299161)).toEqual(new Date(1582, 9, 15));
+        expect(jdnGregorian(2361221)).toEqual(new Date(1752, 8, 13));
+        expect(jdnGregorian(2361222)).toEqual(new Date(1752, 8, 14));
+        expect(jdnGregorian(2451545)).toEqual(new Date(2000, 0, 1));
+        expect(jdnGregorian(-8512316)).toEqual(new Date(-28019, 11, 20));
+        expect(jdnGregorian(-8534852)).toEqual(new Date(-28080, 3, 8));
+        expect(jdnGregorian(2653462)).toEqual(new Date(2552, 9, 30));
+        expect(jdnGregorian(3271156)).toEqual(new Date(4244, 0, 8));
+        expect(jdnGregorian(-666477)).toEqual(new Date(-6537, 1, 23));
+        expect(jdnGregorian(2397854)).toEqual(new Date(1852, 11, 31));
+        expect(jdnGregorian(-1211235)).toEqual(new Date(-8029, 7, 26));
+        expect(jdnGregorian(-91680)).toEqual(new Date(-4964, 10, 20));
+        expect(jdnGregorian(-5605876)).toEqual(new Date(-20061, 6, 14));
+        expect(jdnGregorian(-295121)).toEqual(new Date(-5521, 10, 19));
+    });
+});

common/src/gregorian.ts

@@ -0,0 +1,21 @@
+export function gregorianJDN(year: number, month: number, day: number): number {
+    const g = year + 4716 - (month <= 2 ? 1 : 0);
+    const f = (month + 9) % 12;
+    const e = Math.floor(1461 * g / 4) + day - 1402;
+    const J = e + Math.floor((153 * f + 2) / 5);
+    const dg = 38 - Math.floor(Math.floor((g + 184) / 100) * 3 / 4);
+    return J + dg;
+}
+
+export function dateJDN(date: Date) {
+    return gregorianJDN(date.getFullYear(), date.getMonth() + 1, date.getDate());
+}
+
+export function jdnGregorian(jdn: number): Date {
+    const e = 4 * (jdn + 1401 + Math.floor(Math.floor((4 * jdn + 274277) / 146097) * 3 / 4) - 38) + 3;
+    const h = 5 * Math.floor((e % 1461 + 1461) % 1461 / 4) + 2;
+    const day = Math.floor((h % 153 + 153) % 153 / 5) + 1;
+    const month = (Math.floor(h / 153) + 2) % 12 + 1;
+    const year = Math.floor(e / 1461) - 4716 + Math.floor((14 - month) / 12);
+    return new Date(year, month - 1, day);
+}

common/src/longCount.test.ts

@@ -0,0 +1,62 @@
+import {jdnLongCount} from './longCount';
+
+describe('jdnLongCount', () => {
+    it('works for normal dates', () => {
+        expect(jdnLongCount(2456282)).toEqual('12.19.19.17.19');
+        expect(jdnLongCount(2459413)).toEqual('13.0.8.12.10');
+        expect(jdnLongCount(1708616)).toEqual('7.16.3.2.13');
+        expect(jdnLongCount(1787816)).toEqual('8.7.3.2.13');
+        expect(jdnLongCount(1709981)).toEqual('7.16.6.16.18');
+        expect(jdnLongCount(1725275)).toEqual('7.18.9.7.12');
+        expect(jdnLongCount(1727095)).toEqual('7.18.14.8.12');
+        expect(jdnLongCount(1731775)).toEqual('7.19.7.8.12');
+        expect(jdnLongCount(1734635)).toEqual('7.19.15.7.12');
+        expect(jdnLongCount(1751618)).toEqual('8.2.2.10.15');
+        expect(jdnLongCount(1758818)).toEqual('8.3.2.10.15');
+        expect(jdnLongCount(1767234)).toEqual('8.4.5.17.11');
+        expect(jdnLongCount(1773428)).toEqual('8.5.3.3.5');
+        expect(jdnLongCount(1778230)).toEqual('8.5.16.9.7');
+        expect(jdnLongCount(1780300)).toEqual('8.6.2.4.17');
+        expect(jdnLongCount(2283483)).toEqual('11.16.0.0.0');
+        expect(jdnLongCount(584283)).toEqual('0.0.0.0.0');
+        expect(jdnLongCount(728283)).toEqual('1.0.0.0.0');
+        expect(jdnLongCount(872283)).toEqual('2.0.0.0.0');
+        expect(jdnLongCount(1016283)).toEqual('3.0.0.0.0');
+        expect(jdnLongCount(1160283)).toEqual('4.0.0.0.0');
+        expect(jdnLongCount(1304283)).toEqual('5.0.0.0.0');
+        expect(jdnLongCount(1448283)).toEqual('6.0.0.0.0');
+        expect(jdnLongCount(1592283)).toEqual('7.0.0.0.0');
+        expect(jdnLongCount(1736283)).toEqual('8.0.0.0.0');
+        expect(jdnLongCount(1880283)).toEqual('9.0.0.0.0');
+        expect(jdnLongCount(2024283)).toEqual('10.0.0.0.0');
+        expect(jdnLongCount(2168283)).toEqual('11.0.0.0.0');
+        expect(jdnLongCount(2312283)).toEqual('12.0.0.0.0');
+        expect(jdnLongCount(2456283)).toEqual('13.0.0.0.0');
+        expect(jdnLongCount(2600283)).toEqual('14.0.0.0.0');
+        expect(jdnLongCount(2744283)).toEqual('15.0.0.0.0');
+        expect(jdnLongCount(2888283)).toEqual('16.0.0.0.0');
+        expect(jdnLongCount(3032283)).toEqual('17.0.0.0.0');
+        expect(jdnLongCount(3176283)).toEqual('18.0.0.0.0');
+        expect(jdnLongCount(3320283)).toEqual('19.0.0.0.0');
+        expect(jdnLongCount(3464283)).toEqual('1.0.0.0.0.0');
+        expect(jdnLongCount(1941383)).toEqual('9.8.9.13.0');
+    });
+
+    it('works for insane dates in the future', () => {
+        expect(jdnLongCount(591279564516)).toEqual('1.5.13.5.5.4.0.11.13.13');
+        expect(jdnLongCount(570988471138)).toEqual('1.4.15.12.19.13.13.3.8.15');
+        expect(jdnLongCount(166410754861)).toEqual('7.4.9.1.6.3.13.14.18');
+        expect(jdnLongCount(176632006419)).toEqual('7.13.6.10.7.1.19.4.16');
+        expect(jdnLongCount(652557304645)).toEqual('1.8.6.9.2.3.17.16.10.2');
+        expect(jdnLongCount(140305417242)).toEqual('6.1.15.16.19.2.7.1.19');
+        expect(jdnLongCount(805888002058)).toEqual('1.14.19.11.2.0.8.0.8.15');
+        expect(jdnLongCount(176433890202)).toEqual('7.13.3.1.11.5.16.7.19');
+        expect(jdnLongCount(331888546361)).toEqual('14.8.1.18.17.10.5.13.18');
+        expect(jdnLongCount(657363764536)).toEqual('1.8.10.12.11.2.1.14.0.13');
+    });
+
+    it('returns null for dates before inception of calendar', () => {
+        expect(jdnLongCount(0)).toBeNull();
+        expect(jdnLongCount(584282)).toBeNull();
+    });
+})

common/src/longCount.ts

@@ -0,0 +1,18 @@
+export function jdnLongCount(jdn: number): string | null {
+    let z = jdn - 584283;
+    if (z < 0)
+        return null;
+
+    const parts = [z % 20, Math.floor(z / 20) % 18];
+    z = Math.floor(z / 360);
+    while (z > 0) {
+        parts.push(z % 20);
+        z = Math.floor(z / 20);
+    }
+
+    while (parts.length < 5) {
+        parts.push(0);
+    }
+
+    return parts.reverse().join('.');
+}

frcal/README.md

@@ -0,0 +1,61 @@
+# French Republican Calendar
+
+![demo](demo.png)
+
+## What is this?
+
+The [French Republican calendar][0] was a calendar created and implemented
+during the French Revolution.
+
+It was also frequently known as the *French Revolutionary Calendar*, but this
+was a misnomer: year 1 of the calendar started on 22 September 1792, the day
+after the [abolition of the monarchy][1] and the founding of the [French
+First Republic][2].
+
+## How does it work?
+
+A year consists of 12 months of 30 days each, divided into three *décades* of
+10 days each, followed by 5 complementary days (6 in leap years).
+
+The year starts on the day of the autumnal equinox at the Paris Observatory
+(longitude 2°20′14.03″ E). A leap year follow directly from this definition:
+a year is a leap year when the next autumnal equinox happens 366 days later
+instead of the normal 365. By this definition, the year will **never** drift
+with respect to the seasons.
+
+The 12 months are: *Vendémiaire*, *Brumaire*, *Frimaire*, *Nivôse*,
+*Pluviôse*, *Ventôse*, *Germinal*, *Floréal*, *Prairial*, *Messidor*,
+*Thermidor*, *Fructidor.*
+
+The complementary days are: *la Fête de la Vertu*, *la Fête du Génie*,
+*la Fête du Travail*, *la Fête de l'Opinion*, *la Fête des Récompenses,*
+and *la Fête de la Révolution* (leap years only).
+
+## What's so special about this version?
+
+Most versions of the calendar floating around doesn't use the original
+definition above.
+
+Most versions uses the so-called *Romme* method for leap years, using the
+same leap year rules as the Gregorian calendar, i.e. every year divisible
+by four, except century years not divisible by 400. This method might make
+sense, except years 3, 7, and 11 were leap years under the original rules
+and were observed as such in real life, but the *Romme* method instead makes
+years 4, 8, 12 leap years instead.
+
+This version uses the original rules. The [JPL's DE440 and DE441
+ephemerides][3] were used to calculate the exact timings of the autumnal
+equinoxes between the Gregorian years 13201 BCE and 17191 CE (corresponding
+to the French Republican years -14991 to 15399). The times were then converted
+to UT1+00:09:21, the exact local time at the Paris Observatory. UT1 was chosen
+to keep track of the Earth's rotation without having to worry about the issues
+posed by leap seconds in UTC. Note that due to the uncertainty over [ΔT][4] —
+the difference between UT1 and Terrestrial Time (TT) used in the ephemerides —
+it is theoretically possible for there to be inaccuracies when the equinox
+occurs very close to midnight.
+
+[0]: https://en.wikipedia.org/wiki/French_Republican_calendar
+[1]: https://en.wikipedia.org/wiki/Proclamation_of_the_abolition_of_the_monarchy
+[2]: https://en.wikipedia.org/wiki/French_First_Republic
+[3]: https://ssd.jpl.nasa.gov/planets/eph_export.html
+[4]: https://en.wikipedia.org/wiki/%CE%94T_(timekeeping)

frcal/config-overrides.js

@@ -0,0 +1,5 @@
+const {aliasWebpack, aliasJest} = require('react-app-alias-ex');
+
+const options = {};
+module.exports = aliasWebpack(options);
+module.exports.jest = aliasJest(options);

frcal/package.json

@@ -20,9 +20,9 @@
     "web-vitals": "^2.1.4"
   },
   "scripts": {
-    "start": "react-scripts start",
+    "start": "react-app-rewired start",
-    "build": "react-scripts build",
+    "build": "react-app-rewired build",
-    "test": "react-scripts test",
+    "test": "react-app-rewired test",
     "eject": "react-scripts eject"
   },
   "eslintConfig": {
@@ -44,6 +44,8 @@
     ]
   },
   "devDependencies": {
-    "@types/bootstrap": "^5.1.9"
+    "@types/bootstrap": "^5.1.9",
+    "react-app-alias-ex": "^2.1.0",
+    "react-app-rewired": "^2.2.1"
   }
 }

frcal/src/App.tsx

@@ -1,21 +1,20 @@
 import React, {FormEvent} from 'react';
 import {Calendar} from './Calendar';
 import {
-    dateJDN,
     endGregorian,
     endJD,
+    FrenchMonth,
     frSupportedYear,
-    gregorianJDN,
     jdnFrench,
-    Month,
     startGregorian,
-    startJD
+    startJD,
-} from './dates';
+} from '@common/french';
+import {dateJDN, gregorianJDN} from '@common/gregorian';
 import {TimeOfDay} from './TimeOfDay';
 
 type YearMonth = {
     year: number;
-    month: Month;
+    month: FrenchMonth;
 }
 
 function parseURL(): YearMonth | null {
@@ -27,7 +26,7 @@ function parseURL(): YearMonth | null {
     const year = +match[1];
     if (!frSupportedYear(year) || month < 1 || month > 13)
         return null;
-    return {year: year, month: month as Month};
+    return {year: year, month: month as FrenchMonth};
 }
 
 type AppState = YearMonth & {

frcal/src/Calendar.tsx

@@ -3,26 +3,26 @@ import './Calendar.scss';
 import {
     dateName,
     dateRuralName,
-    Day,
     decadeNames,
     endYear,
+    FrenchDay,
+    FrenchMonth,
     frIsLeap,
     frJDN,
     jdnFrench,
-    jdnGregorian,
-    jdnLongCount,
-    Month,
     monthName,
-    startYear
+    startYear,
-} from './dates';
+} from '@common/french';
+import {jdnGregorian} from '@common/gregorian';
+import {jdnLongCount} from '@common/longCount';
 
 type MonthProps = {
     year: number;
-    month: Month;
+    month: FrenchMonth;
 };
 
 type DateProps = MonthProps & {
-    day: Day;
+    day: FrenchDay;
 };
 
 function DecadeName({name}: { name: string }): JSX.Element {
@@ -54,7 +54,7 @@ function NormalMonth({year, month, todayJDN}: MonthProps & { todayJDN: number })
         <div className="Month-decades">{
             Array.from(Array(3).keys()).map(i => <div key={i} className="Month-decade">{
                 Array.from(Array(10).keys()).map(j => <React.Fragment key={j}>
-                    <NormalDay year={year} month={month} day={i * 10 + j + 1 as Day} todayJDN={todayJDN}/>
+                    <NormalDay year={year} month={month} day={i * 10 + j + 1 as FrenchDay} todayJDN={todayJDN}/>
                     {j % 2 === 1 && <div className="Month-decadeSplitter-small"/>}
                     {j === 4 && <div className="Month-decadeSplitter-medium"/>}
                 </React.Fragment>)
@@ -75,7 +75,7 @@ function ComplementaryDays({year, todayJDN}: { year: number, todayJDN: number })
     const leap = frIsLeap(year);
     return <div className="ComplementaryDays">{
         Array.from(Array(6).keys()).map(i => <React.Fragment key={i}>
-            {(i < 5 || leap) && <ComplementaryDay year={year} month={13} day={i + 1 as Day} todayJDN={todayJDN}/>}
+            {(i < 5 || leap) && <ComplementaryDay year={year} month={13} day={i + 1 as FrenchDay} todayJDN={todayJDN}/>}
             {i === 5 && !leap && <div className="ComplementaryDay-fake"/>}
             {i % 2 === 1 && <div className="ComplementaryDays-splitter"/>}
         </React.Fragment>)
@@ -84,7 +84,7 @@ function ComplementaryDays({year, todayJDN}: { year: number, todayJDN: number })
 
 export type CalendarProps = MonthProps & {
     todayJDN: number;
-    onSwitch?: (year: number, month: Month) => void,
+    onSwitch?: (year: number, month: FrenchMonth) => void,
 };
 
 type CalendarState = {
@@ -131,7 +131,7 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
             month = 13;
         }
 
-        this.props.onSwitch && this.props.onSwitch(year, month as Month);
+        this.props.onSwitch && this.props.onSwitch(year, month as FrenchMonth);
     }
 
     prevYear = () => {
@@ -165,7 +165,7 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
     }
 
     monthChange = (event: any) => {
-        this.goToNormalized(this.props.year, +event.target.value as Month);
+        this.goToNormalized(this.props.year, +event.target.value as FrenchMonth);
     }
 
     yearChange = (event: any) => {
@@ -210,7 +210,7 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
                   <select className="Calendar-month-input form-control" onChange={this.monthChange}
                           value={this.props.month}>{
                       Array.from(Array(13).keys()).map(i => {
-                          const month = i + 1 as Month;
+                          const month = i + 1 as FrenchMonth;
                           return <option key={i} value={month}>{monthName(month)}</option>;
                       })
                   }</select>

frcal/src/TimeOfDay.tsx

@@ -1,6 +1,6 @@
 import React from 'react';
 import './TimeOfDay.scss';
-import {dateJDN, gregorianJDN} from './dates';
+import {dateJDN, gregorianJDN} from '@common/gregorian';
 
 type TimeStamp = {
     hour: number,

frcal/tsconfig.json

@@ -0,0 +1,27 @@
+{
+  "extends": "./tsconfig.paths.json",
+  "compilerOptions": {
+    "target": "es5",
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "forceConsistentCasingInFileNames": true,
+    "noFallthroughCasesInSwitch": true,
+    "module": "esnext",
+    "moduleResolution": "node",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx"
+  },
+  "include": [
+    "src"
+  ]
+}

frcal/tsconfig.paths.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "baseUrl": ".",
+    "paths": {
+      "@common/*": ["../common/src/*"]
+    }
+  }
+}

src/dates.test.ts

@@ -1,195 +0,0 @@
-import {
-    dateName,
-    dateRuralName,
-    frIsLeap,
-    frJDN,
-    gregorianJDN,
-    jdnFrench,
-    jdnGregorian,
-    jdnLongCount,
-    monthName
-} from './dates';
-
-describe('gregorianJDN', () => {
-    it('works', () => {
-        expect(gregorianJDN(2000, 1, 1)).toBe(2451545);
-        expect(gregorianJDN(-4713, 11, 24)).toBe(0);
-        expect(gregorianJDN(11917, 9, 18)).toBe(6073915);
-        expect(gregorianJDN(-28565, 6, 17)).toBe(-8711925);
-        expect(gregorianJDN(-26650, 4, 13)).toBe(-8012550);
-        expect(gregorianJDN(17430, 3, 8)).toBe(8087303);
-        expect(gregorianJDN(3395, 7, 18)).toBe(2961257);
-        expect(gregorianJDN(4579, 3, 11)).toBe(3393575);
-        expect(gregorianJDN(-14851, 11, 22)).toBe(-3702831);
-        expect(gregorianJDN(8824, 11, 28)).toBe(4944292);
-        expect(gregorianJDN(19720, 8, 14)).toBe(8923868);
-        expect(gregorianJDN(7504, 7, 22)).toBe(4462042);
-    });
-});
-
-describe('frJDN', () => {
-    it('works for sample dates', () => {
-        expect(frJDN(1, 1, 1)).toBe(2375840);
-        expect(frJDN(8, 2, 18)).toBe(2378444);
-    });
-
-    it('works in years starting/ending near midnight', () => {
-        expect(frJDN( 111, 1, 1)).toBe(2416017); // equinox 1902-09-23T23:55:19 UT1
-        expect(frJDN( 206, 1, 1)).toBe(2450715); // equinox 1997-09-22T23:55:46 UT1
-        expect(frJDN(2490, 1, 1)).toBe(3284926); // equinox 4281-09-20T23:50:38 UT1
-    });
-});
-
-describe('frIsLeap', () => {
-    it('works for sample dates', () => {
-        expect(frIsLeap(1)).toBeFalsy();
-        expect(frIsLeap(8)).toBeFalsy();
-        expect(frIsLeap(3)).toBeTruthy();
-        expect(frIsLeap(7)).toBeTruthy();
-        expect(frIsLeap(11)).toBeTruthy();
-    });
-
-    it('works in years starting/ending near midnight', () => {
-        expect(frIsLeap(110)).toBeTruthy();
-        expect(frIsLeap(205)).toBeTruthy();
-        expect(frIsLeap(2489)).toBeFalsy();
-        expect(frIsLeap(111)).toBeFalsy();
-        expect(frIsLeap(206)).toBeFalsy();
-        expect(frIsLeap(2490)).toBeTruthy();
-    });
-});
-
-describe('jdnFrench', () => {
-    it('works for sample dates', () => {
-        expect(jdnFrench(2375840)).toEqual({year: 1, month: 1, day: 1});
-        expect(jdnFrench(2378444)).toEqual({year: 8, month: 2, day: 18});
-    });
-
-    it('works in years starting/ending near midnight', () => {
-        expect(jdnFrench(2416017)).toEqual({year:  111, month: 1, day: 1});
-        expect(jdnFrench(2450715)).toEqual({year:  206, month: 1, day: 1});
-        expect(jdnFrench(3284926)).toEqual({year: 2490, month: 1, day: 1});
-        expect(jdnFrench(2416016)).toEqual({year:  110, month: 13, day: 6});
-        expect(jdnFrench(2450714)).toEqual({year:  205, month: 13, day: 6});
-        expect(jdnFrench(3284925)).toEqual({year: 2489, month: 13, day: 5});
-    });
-});
-
-describe('jdnGregorian', () => {
-    it('works', () => {
-        expect(jdnGregorian(0)).toEqual(new Date(-4713, 10, 24));
-        expect(jdnGregorian(2299160)).toEqual(new Date(1582, 9, 14));
-        expect(jdnGregorian(2299161)).toEqual(new Date(1582, 9, 15));
-        expect(jdnGregorian(2361221)).toEqual(new Date(1752, 8, 13));
-        expect(jdnGregorian(2361222)).toEqual(new Date(1752, 8, 14));
-        expect(jdnGregorian(2451545)).toEqual(new Date(2000, 0, 1));
-        expect(jdnGregorian(-8512316)).toEqual(new Date(-28019, 11, 20));
-        expect(jdnGregorian(-8534852)).toEqual(new Date(-28080, 3, 8));
-        expect(jdnGregorian(2653462)).toEqual(new Date(2552, 9, 30));
-        expect(jdnGregorian(3271156)).toEqual(new Date(4244, 0, 8));
-        expect(jdnGregorian(-666477)).toEqual(new Date(-6537, 1, 23));
-        expect(jdnGregorian(2397854)).toEqual(new Date(1852, 11, 31));
-        expect(jdnGregorian(-1211235)).toEqual(new Date(-8029, 7, 26));
-        expect(jdnGregorian(-91680)).toEqual(new Date(-4964, 10, 20));
-        expect(jdnGregorian(-5605876)).toEqual(new Date(-20061, 6, 14));
-        expect(jdnGregorian(-295121)).toEqual(new Date(-5521, 10, 19));
-    });
-});
-
-describe('jdnLongCount', () => {
-    it('works for normal dates', () => {
-        expect(jdnLongCount(2456282)).toEqual('12.19.19.17.19');
-        expect(jdnLongCount(2459413)).toEqual('13.0.8.12.10');
-        expect(jdnLongCount(1708616)).toEqual('7.16.3.2.13');
-        expect(jdnLongCount(1787816)).toEqual('8.7.3.2.13');
-        expect(jdnLongCount(1709981)).toEqual('7.16.6.16.18');
-        expect(jdnLongCount(1725275)).toEqual('7.18.9.7.12');
-        expect(jdnLongCount(1727095)).toEqual('7.18.14.8.12');
-        expect(jdnLongCount(1731775)).toEqual('7.19.7.8.12');
-        expect(jdnLongCount(1734635)).toEqual('7.19.15.7.12');
-        expect(jdnLongCount(1751618)).toEqual('8.2.2.10.15');
-        expect(jdnLongCount(1758818)).toEqual('8.3.2.10.15');
-        expect(jdnLongCount(1767234)).toEqual('8.4.5.17.11');
-        expect(jdnLongCount(1773428)).toEqual('8.5.3.3.5');
-        expect(jdnLongCount(1778230)).toEqual('8.5.16.9.7');
-        expect(jdnLongCount(1780300)).toEqual('8.6.2.4.17');
-        expect(jdnLongCount(2283483)).toEqual('11.16.0.0.0');
-        expect(jdnLongCount(584283)).toEqual('0.0.0.0.0');
-        expect(jdnLongCount(728283)).toEqual('1.0.0.0.0');
-        expect(jdnLongCount(872283)).toEqual('2.0.0.0.0');
-        expect(jdnLongCount(1016283)).toEqual('3.0.0.0.0');
-        expect(jdnLongCount(1160283)).toEqual('4.0.0.0.0');
-        expect(jdnLongCount(1304283)).toEqual('5.0.0.0.0');
-        expect(jdnLongCount(1448283)).toEqual('6.0.0.0.0');
-        expect(jdnLongCount(1592283)).toEqual('7.0.0.0.0');
-        expect(jdnLongCount(1736283)).toEqual('8.0.0.0.0');
-        expect(jdnLongCount(1880283)).toEqual('9.0.0.0.0');
-        expect(jdnLongCount(2024283)).toEqual('10.0.0.0.0');
-        expect(jdnLongCount(2168283)).toEqual('11.0.0.0.0');
-        expect(jdnLongCount(2312283)).toEqual('12.0.0.0.0');
-        expect(jdnLongCount(2456283)).toEqual('13.0.0.0.0');
-        expect(jdnLongCount(2600283)).toEqual('14.0.0.0.0');
-        expect(jdnLongCount(2744283)).toEqual('15.0.0.0.0');
-        expect(jdnLongCount(2888283)).toEqual('16.0.0.0.0');
-        expect(jdnLongCount(3032283)).toEqual('17.0.0.0.0');
-        expect(jdnLongCount(3176283)).toEqual('18.0.0.0.0');
-        expect(jdnLongCount(3320283)).toEqual('19.0.0.0.0');
-        expect(jdnLongCount(3464283)).toEqual('1.0.0.0.0.0');
-        expect(jdnLongCount(1941383)).toEqual('9.8.9.13.0');
-    });
-
-    it('works for insane dates in the future', () => {
-        expect(jdnLongCount(591279564516)).toEqual('1.5.13.5.5.4.0.11.13.13');
-        expect(jdnLongCount(570988471138)).toEqual('1.4.15.12.19.13.13.3.8.15');
-        expect(jdnLongCount(166410754861)).toEqual('7.4.9.1.6.3.13.14.18');
-        expect(jdnLongCount(176632006419)).toEqual('7.13.6.10.7.1.19.4.16');
-        expect(jdnLongCount(652557304645)).toEqual('1.8.6.9.2.3.17.16.10.2');
-        expect(jdnLongCount(140305417242)).toEqual('6.1.15.16.19.2.7.1.19');
-        expect(jdnLongCount(805888002058)).toEqual('1.14.19.11.2.0.8.0.8.15');
-        expect(jdnLongCount(176433890202)).toEqual('7.13.3.1.11.5.16.7.19');
-        expect(jdnLongCount(331888546361)).toEqual('14.8.1.18.17.10.5.13.18');
-        expect(jdnLongCount(657363764536)).toEqual('1.8.10.12.11.2.1.14.0.13');
-    });
-
-    it('returns null for dates before inception of calendar', () => {
-        expect(jdnLongCount(0)).toBeNull();
-        expect(jdnLongCount(584282)).toBeNull();
-    });
-})
-
-describe('monthName', () => {
-    it('works', () => {
-        expect(monthName(1)).toBe('Vendémiaire');
-        expect(monthName(12)).toBe('Fructidor');
-        expect(monthName(13)).toBe('Jours Complémentaires');
-    });
-});
-
-describe('dateName', () => {
-    it('works', () => {
-        expect(dateName(1, 1)).toBe('1 Vendémiaire');
-        expect(dateName(2, 18)).toBe('18 Brumaire');
-        expect(dateName(3, 11)).toBe('11 Frimaire');
-        expect(dateName(8, 16)).toBe('16 Floréal');
-        expect(dateName(12, 30)).toBe('30 Fructidor');
-        expect(dateName(13, 1)).toBe('La Fête de la Vertu');
-        expect(dateName(13, 6)).toBe('La Fête de la Révolution');
-    });
-
-    it('returns null for non-existent complimentary days', () => {
-        expect(dateName(13, 7)).toBeNull();
-    });
-});
-
-describe('dateRuralName', () => {
-    it('works', () => {
-        expect(dateRuralName(1, 1)).toEqual({name: 'Raisin', title: 'Grape'});
-        expect(dateRuralName(1, 30)).toEqual({name: 'Tonneau', title: 'Barrel'});
-        expect(dateRuralName(12, 1)).toEqual({name: 'Prune', title: 'Plum'});
-        expect(dateRuralName(12, 30)).toEqual({name: 'Panier', title: 'Pack Basket'});
-    });
-
-    it('returns null for complimentary days', () => {
-        expect(dateRuralName(13, 1)).toBeNull();
-    });
-});