feat: add function that returns holidays of the year

src/index.test.ts

@@ -30,6 +30,7 @@ describe('Public API', () => {
     'capitalize',
     'formatCurrency',
     'parseCurrency',
+    'getAllNationalHolidays',
   ];
 
   Object.keys(API).forEach((method) => {

src/utilities/holidays/index.test.ts

@@ -0,0 +1,61 @@
+import { getAllNationalHolidays } from '.';
+
+describe('getAllNationalHolidays', () => {
+  test('should return fixed holidays for the given year', () => {
+    const year = 2024;
+    const holidays = getAllNationalHolidays(year);
+
+    const fixedHolidays = [
+      { name: 'Ano novo', date: new Date(year, 0, 1) },
+      { name: 'Tiradentes', date: new Date(year, 3, 21) },
+      { name: 'Dia do trabalhador', date: new Date(year, 4, 1) },
+      { name: 'Independência do Brasil', date: new Date(year, 8, 7) },
+      { name: 'Nossa Senhora Aparecida', date: new Date(year, 9, 12) },
+      { name: 'Finados', date: new Date(year, 10, 2) },
+      { name: 'Proclamação da República', date: new Date(year, 10, 15) },
+      { name: 'Dia da Consciência Negra', date: new Date(year, 10, 20) },
+      { name: 'Natal', date: new Date(year, 11, 25) },
+    ];
+
+    fixedHolidays.forEach(({ name, date }) => {
+      expect(holidays).toContainEqual({ name, date });
+    });
+  });
+
+  test('should calculate Easter-related holidays correctly', () => {
+    const year = 2024;
+    const holidays = getAllNationalHolidays(year);
+
+    const easterDate = new Date(2024, 2, 31); // Easter Sunday 2024
+    const expectedHolidays = [
+      { name: 'Páscoa', date: easterDate },
+      { name: 'Carnaval (terça-feira)', date: new Date(2024, 1, 13) },
+      { name: 'Sexta-feira Santa', date: new Date(2024, 2, 29) },
+      { name: 'Corpus Christi', date: new Date(2024, 5, 9) },
+    ];
+
+    expectedHolidays.forEach(({ name, date }) => {
+      expect(holidays).toContainEqual({ name, date });
+    });
+  });
+
+  test('should return the correct number of holidays', () => {
+    const year = 2024;
+    const holidays = getAllNationalHolidays(year);
+
+    expect(holidays.length).toBe(13); // 9 fixed + 4 Easter-related holidays
+  });
+
+  test('should work for leap years', () => {
+    const year = 2020;
+    const holidays = getAllNationalHolidays(year);
+
+    expect(holidays).toContainEqual({
+      name: 'Ano novo',
+      date: new Date(year, 0, 1),
+    });
+
+    const easterDate = new Date(2020, 3, 12); // Easter Sunday 2020
+    expect(holidays).toContainEqual({ name: 'Páscoa', date: easterDate });
+  });
+});

src/utilities/holidays/index.ts

@@ -0,0 +1,88 @@
+const FIXED_HOLIDAYS = {
+  'Ano novo': { day: 1, month: 1 },
+  Tiradentes: { day: 21, month: 4 },
+  'Dia do trabalhador': { day: 1, month: 5 },
+  'Independência do Brasil': { day: 7, month: 9 },
+  'Nossa Senhora Aparecida': { day: 12, month: 10 },
+  Finados: { day: 2, month: 11 },
+  'Proclamação da República': { day: 15, month: 11 },
+  'Dia da Consciência Negra': { day: 20, month: 11 },
+  Natal: { day: 25, month: 12 },
+};
+
+function calculateEaster(year: number): Date {
+  // Calculation based on the computus algorithm
+  const a = year % 19;
+  const b = Math.floor(year / 100);
+  const c = year % 100;
+  const d = Math.floor(b / 4);
+  const e = b % 4;
+  const f = Math.floor((b + 8) / 25);
+  const g = Math.floor((b - f + 1) / 3);
+  const h = (19 * a + b - d - g + 15) % 30;
+  const i = Math.floor(c / 4);
+  const k = c % 4;
+  const l = (32 + 2 * e + 2 * i - h - k) % 7;
+  const m = Math.floor((a + 11 * h + 22 * l) / 451);
+
+  const month = Math.floor((h + l - 7 * m + 114) / 31) - 1; // 0-based month
+  const day = ((h + l - 7 * m + 114) % 31) + 1;
+
+  return new Date(year, month, day);
+}
+
+function calculateHolidayFromEaster(year: number, offset: number): Date {
+  // Calculates the date of Easter
+  const easterDate = calculateEaster(year);
+
+  // Creates a new Date object for the holiday
+  const holidayDate = new Date(easterDate);
+
+  // Adds or subtracts the offset to get the holiday date
+  holidayDate.setDate(easterDate.getDate() + offset);
+
+  return holidayDate;
+}
+
+export function getAllNationalHolidays(year: number): Object[] {
+  const allHolidays: Object[] = [];
+
+  // Add fixed holidays
+  for (const [key, { day, month }] of Object.entries(FIXED_HOLIDAYS)) {
+    const holiday = {
+      name: key,
+      date: new Date(year, month - 1, day),
+    };
+    allHolidays.push(holiday);
+  }
+
+  // Calculate and add Easter
+  const easterHoliday = {
+    name: 'Páscoa',
+    date: calculateEaster(year),
+  };
+  allHolidays.push(easterHoliday);
+
+  // Calculate Gras
+  const mardiGrasHoliday = {
+    name: 'Carnaval (terça-feira)',
+    date: calculateHolidayFromEaster(year, -47),
+  };
+  allHolidays.push(mardiGrasHoliday);
+
+  // Calculate Good Friday
+  const goodFridayHoliday = {
+    name: 'Sexta-feira Santa',
+    date: calculateHolidayFromEaster(year, -2),
+  };
+  allHolidays.push(goodFridayHoliday);
+
+  // Calculate and add Corpus Christi
+  const corpusChristiHoliday = {
+    name: 'Corpus Christi',
+    date: calculateHolidayFromEaster(year, 70),
+  };
+  allHolidays.push(corpusChristiHoliday);
+
+  return allHolidays;
+}

src/utilities/index.ts

@@ -11,3 +11,4 @@ export { format as formatCNPJ, generate as generateCNPJ, isValid as isValidCNPJ
 export { capitalize } from './capitalize';
 export { getStates } from './states';
 export { getCities } from './cities';
+export { getAllNationalHolidays } from './holidays';