Add month and date functions

src/Calendar.ts

@@ -1,26 +0,0 @@
-import data from '../cal.json';
-
-const startJD = data.start_jd;
-const startYear = data.start_year;
-const leaps: Array<number> = [0];
-
-let leapFromStart = 0;
-data.leap.forEach(leap => {
-    leapFromStart += leap;
-    leaps.push(leapFromStart);
-});
-
-export function gregorianJDN(year: number, month: number, day: 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 frJDN(year: number, month: number, day: number) {
-    const dy = year - startYear;
-    const dd = month * 30 + day - 31;
-    return startJD + 365 * dy + leaps[dy] + dd;
-}

src/dates.test.ts

@@ -1,4 +1,4 @@
-import {frJDN, gregorianJDN} from './Calendar';
+import {dateName, frJDN, gregorianJDN, monthName} from './dates';
 
 describe('gregorianJDN', () => {
     it('works', () => {
@@ -29,3 +29,27 @@ describe('frJDN', () => {
         expect(frJDN(2490, 1, 1)).toBe(3284926); // equinox 4281-09-20T23:50:38 UT1
     });
 });
+
+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();
+    });
+});

src/dates.ts

@@ -0,0 +1,97 @@
+import data from '../cal.json';
+
+// 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 Day =
+    1
+    | 2
+    | 3
+    | 4
+    | 5
+    | 6
+    | 7
+    | 8
+    | 9
+    | 10
+    | 11
+    | 12
+    | 13
+    | 14
+    | 15
+    | 16
+    | 17
+    | 18
+    | 19
+    | 20
+    | 21
+    | 22
+    | 23
+    | 24
+    | 25
+    | 26
+    | 27
+    | 28
+    | 29
+    | 30;
+
+const monthNames: {
+    [key in Month]: string
+} = {
+    1: 'Vendémiaire',
+    2: 'Brumaire',
+    3: 'Frimaire',
+    4: 'Nivôse',
+    5: 'Pluviôse',
+    6: 'Ventôse',
+    7: 'Germinal',
+    8: 'Floréal',
+    9: 'Prairial',
+    10: 'Messidor',
+    11: 'Thermidor',
+    12: 'Fructidor',
+    13: 'Jours Complémentaires',
+};
+
+const startJD = data.start_jd;
+const startYear = data.start_year;
+const leaps: Array<number> = [0];
+
+let leapFromStart = 0;
+data.leap.forEach(leap => {
+    leapFromStart += leap;
+    leaps.push(leapFromStart);
+});
+
+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 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;
+}
+
+export function monthName(month: Month): string {
+    return monthNames[month];
+}
+
+export function dateName(month: Month, day: Day): string | null {
+    if (month === 13) {
+        switch (day) {
+            case 1: return 'La Fête de la Vertu';
+            case 2: return 'La Fête du Génie';
+            case 3: return 'La Fête du Travail';
+            case 4: return "La Fête de l'Opinion";
+            case 5: return 'La Fête des Récompenses';
+            case 6: return 'La Fête de la Révolution';
+            default: return null;
+        }
+    }
+    return `${day} ${monthNames[month]}`;
+}