// ============================================================
// ابزار تقویم شمسی — پورت jalali.js به TypeScript
// تبدیل‌ها با الگوریتم استاندارد Kazimierz M. Borkowski
// ============================================================

const FA_DIGITS = ["۰", "۱", "۲", "۳", "۴", "۵", "۶", "۷", "۸", "۹"];

export function div(a: number, b: number): number {
  return Math.floor(a / b);
}

export function jalaliToGregorian(jy: number, jm: number, jd: number): [number, number, number] {
  jy = +jy;
  jm = +jm;
  jd = +jd;
  let gy = jy <= 979 ? 621 : 1600;
  jy -= jy <= 979 ? 0 : 979;
  let days =
    365 * jy +
    div(jy, 33) * 8 +
    div((jy % 33) + 3, 4) +
    78 +
    jd +
    (jm < 7 ? (jm - 1) * 31 : (jm - 7) * 30 + 186);
  gy += 400 * div(days, 146097);
  days %= 146097;
  if (days > 36524) {
    gy += 100 * div(--days, 36524);
    if (days === 36524) days = 0;
    days++;
  }
  gy += 4 * div(days, 1461);
  days %= 1461;
  if (days > 365) {
    gy += div(days - 1, 365);
    days = (days - 1) % 365;
  }
  let gd = days + 1;
  const sal_a = [0, 31, (gy % 4 === 0 && gy % 100 !== 0) || gy % 400 === 0 ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
  let gm = 0;
  for (; gm < 13 && gd > sal_a[gm]; gm++) gd -= sal_a[gm];
  return [gy, gm, gd];
}

export function gregorianToJalali(gy: number, gm: number, gd: number): [number, number, number] {
  gy = +gy;
  gm = +gm;
  gd = +gd;
  const g_d_m = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
  let jy = gy <= 1600 ? 0 : 979;
  gy -= gy <= 1600 ? 621 : 1600;
  let days =
    365 * gy +
    div(gy + 3, 4) -
    div(gy + 99, 100) +
    div(gy + 399, 400) -
    80 +
    gd +
    g_d_m[gm - 1];
  jy += 33 * div(days, 12053);
  days %= 12053;
  jy += 4 * div(days, 1461);
  days %= 1461;
  if (days > 365) {
    jy += div(days - 1, 365);
    days = (days - 1) % 365;
  }
  const jm = days < 186 ? 1 + div(days, 31) : 7 + div(days - 186, 30);
  const jd = 1 + (days < 186 ? days % 31 : (days - 186) % 30);
  return [jy, jm, jd];
}

export function isLeapJalali(jy: number): boolean {
  const breaks = [-61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210, 1635, 2060, 2097, 2192, 2262, 2324, 2394, 2456, 3178];
  const jp = breaks[0];
  const jm = breaks[1];
  let jump = 0;
  let jp2 = jp;
  for (const jl of breaks) {
    jump = jl - jp2;
    if (jy <= jl) break;
    jp2 = jl;
  }
  let n = jy - jm;
  if (n < jump) n = n + jump + 1;
  return (n % 33) % 4 === 1;
}

// ---------- formatting (Persian digits) ----------
export function toFa(s: string | number): string {
  return String(s).replace(/[0-9]/g, (d) => FA_DIGITS[Number(d)]);
}

// ماه‌های شمسی (نسخه‌ی درست‌شده — «مهر» به‌جای «آذر» تکراری)
export const MONTHS = [
  "فروردین", "اردیبهشت", "خرداد", "تیر", "مرداد", "شهریور",
  "مهر", "آبان", "آذر", "دی", "بهمن", "اسفند",
];

export const WEEKDAYS = ["ش", "ی", "د", "س", "چ", "پ", "ج"];

export function toAsciiDigits(s: string | number | null | undefined): string {
  if (s == null) return "";
  return String(s)
    .replace(/[۰-۹]/g, (d) => String("۰۱۲۳۴۵۶۷۸۹".indexOf(d)))
    .replace(/[٠-٩]/g, (d) => String("٠١٢٣٤٥٦٧٨٩".indexOf(d)));
}

// format an ISO (gregorian) string to "۱۴۰۳/۰۵/۱۲"
export function isoToJalaliStr(iso: string | null | undefined): string {
  if (!iso) return "";
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return "";
  const [jy, jm, jd] = gregorianToJalali(d.getFullYear(), d.getMonth() + 1, d.getDate());
  return `${toFa(jy)}/${toFa(String(jm).padStart(2, "0"))}/${toFa(String(jd).padStart(2, "0"))}`;
}

// format with month name: "۱۸ مرداد ۱۴۰۴"
export function isoToJalaliLong(iso: string | null | undefined): string {
  if (!iso) return "";
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return "";
  const [jy, jm, jd] = gregorianToJalali(d.getFullYear(), d.getMonth() + 1, d.getDate());
  return `${toFa(jd)} ${MONTHS[jm - 1]} ${toFa(jy)}`;
}

// parse a jalali "yyyy/m/d" or "yyyy/m/d h:m" string to a JS Date (gregorian) ISO string
export function jalaliStrToIso(str: string | null | undefined): string | null {
  if (!str) return null;
  const s = toAsciiDigits(str).trim();
  const m = s.match(/^(1[34]\d{2})[/\-.](\d{1,2})[/\-.](\d{1,2})(?:[ T](\d{1,2}):(\d{1,2})(?::(\d{1,2}))?)?/);
  if (!m) {
    const nums = s
      .split(/[/\-.]/)
      .map((x) => parseInt(x, 10));
    if (nums.length < 3 || nums.some((n) => Number.isNaN(n))) return null;
    const [jy, jm, jd] = nums;
    const [gy, gm, gd] = jalaliToGregorian(jy, jm, jd);
    const dt = new Date(gy, gm - 1, gd);
    return Number.isNaN(dt.getTime()) ? null : dt.toISOString();
  }
  const jy = parseInt(m[1], 10);
  const jm = parseInt(m[2], 10);
  const jd = parseInt(m[3], 10);
  const h = m[4] != null ? parseInt(m[4], 10) : 0;
  const min = m[5] != null ? parseInt(m[5], 10) : 0;
  const sec = m[6] != null ? parseInt(m[6], 10) : 0;
  const [gy, gm, gd] = jalaliToGregorian(jy, jm, jd);
  const dt = new Date(gy, gm - 1, gd, h, min, sec);
  return Number.isNaN(dt.getTime()) ? null : dt.toISOString();
}

export function daysInMonth(jy: number, jm: number): number {
  if (jm <= 6) return 31;
  if (jm <= 11) return 30;
  return isLeapJalali(jy) ? 30 : 29;
}