initial commit

src/common/helpers/jalali-date.helper.ts

@@ -0,0 +1,132 @@
+const JALALI_BREAKS = [
+  -61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210, 1635, 2060, 2097,
+  2192, 2262, 2324, 2394, 2456, 3178,
+];
+
+export function jalaliDateToGregorianDate(jalaliDate: string): string {
+  const match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(jalaliDate);
+  if (!match) {
+    throw new Error('birthDate must be a Jalali date in YYYY-MM-DD format');
+  }
+
+  const jy = Number(match[1]);
+  const jm = Number(match[2]);
+  const jd = Number(match[3]);
+
+  if (!isValidJalaliDate(jy, jm, jd)) {
+    throw new Error('birthDate is not a valid Jalali date');
+  }
+
+  const { gy, gm, gd } = jalaliToGregorian(jy, jm, jd);
+  return `${gy}-${pad2(gm)}-${pad2(gd)}`;
+}
+
+function isValidJalaliDate(jy: number, jm: number, jd: number): boolean {
+  if (jm < 1 || jm > 12 || jd < 1) return false;
+  if (jm <= 6) return jd <= 31;
+  if (jm <= 11) return jd <= 30;
+  return jd <= (isJalaliLeapYear(jy) ? 30 : 29);
+}
+
+function isJalaliLeapYear(jy: number): boolean {
+  return jalCal(jy).leap === 0;
+}
+
+function jalaliToGregorian(
+  jy: number,
+  jm: number,
+  jd: number,
+): { gy: number; gm: number; gd: number } {
+  const gy = jalCal(jy).gy;
+  const march = jalCal(jy).march;
+  const daysInGregorianMonth = [
+    31,
+    isGregorianLeapYear(gy) ? 29 : 28,
+    31,
+    30,
+    31,
+    30,
+    31,
+    31,
+    30,
+    31,
+    30,
+    31,
+  ];
+
+  let dayOfYear = jd - 1;
+  if (jm <= 6) {
+    dayOfYear += (jm - 1) * 31;
+  } else {
+    dayOfYear += 186 + (jm - 7) * 30;
+  }
+
+  let gd = march + dayOfYear;
+  let gm = 3;
+  let targetGy = gy;
+
+  while (gd > daysInGregorianMonth[gm - 1]) {
+    gd -= daysInGregorianMonth[gm - 1];
+    gm += 1;
+
+    if (gm > 12) {
+      gm = 1;
+      targetGy += 1;
+      daysInGregorianMonth[1] = isGregorianLeapYear(targetGy) ? 29 : 28;
+    }
+  }
+
+  return { gy: targetGy, gm, gd };
+}
+
+function jalCal(jy: number): { leap: number; gy: number; march: number } {
+  const breaksLength = JALALI_BREAKS.length;
+  const gy = jy + 621;
+  let leapJ = -14;
+  let jp = JALALI_BREAKS[0];
+  let jump = 0;
+
+  if (jy < jp || jy >= JALALI_BREAKS[breaksLength - 1]) {
+    throw new Error('Jalali year is out of supported range');
+  }
+
+  for (let i = 1; i < breaksLength; i += 1) {
+    const jm = JALALI_BREAKS[i];
+    jump = jm - jp;
+    if (jy < jm) break;
+    leapJ += div(jump, 33) * 8 + div(mod(jump, 33), 4);
+    jp = jm;
+  }
+
+  let n = jy - jp;
+  leapJ += div(n, 33) * 8 + div(mod(n, 33) + 3, 4);
+  if (mod(jump, 33) === 4 && jump - n === 4) leapJ += 1;
+
+  const leapG = div(gy, 4) - div((div(gy, 100) + 1) * 3, 4) - 150;
+  const march = 20 + leapJ - leapG;
+
+  if (jump - n < 6) {
+    n = n - jump + div(jump + 4, 33) * 33;
+  }
+
+  let leap = mod(mod(n + 1, 33) - 1, 4);
+  if (leap === -1) leap = 4;
+
+  return { leap, gy, march };
+}
+
+function isGregorianLeapYear(year: number): boolean {
+  return year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0);
+}
+
+function div(a: number, b: number): number {
+  return Math.floor(a / b);
+}
+
+function mod(a: number, b: number): number {
+  return a - Math.floor(a / b) * b;
+}
+
+function pad2(value: number): string {
+  return String(value).padStart(2, '0');
+}