'use strict';

const toEnglishDigits = (value) =>
  String(value ?? '')
    .replace(/[۰-۹]/g, (d) => '۰۱۲۳۴۵۶۷۸۹'.indexOf(d))
    .replace(/[٠-٩]/g, (d) => '٠١٢٣٤٥٦٧٨٩'.indexOf(d));

const jalaliToGregorian = (jy, jm, jd) => {
  const gy = jy <= 979 ? 621 : 1600;
  jy -= jy <= 979 ? 0 : 979;
  let days =
    365 * jy +
    Math.floor(jy / 33) * 8 +
    Math.floor(((jy % 33) + 3) / 4) +
    78 +
    jd +
    (jm < 7 ? (jm - 1) * 31 : (jm - 7) * 30 + 186);
  let gyOut = gy + 400 * Math.floor(days / 146097);
  days %= 146097;
  if (days > 36524) {
    gyOut += 100 * Math.floor(--days / 36524);
    days %= 36524;
    if (days >= 365) days += 1;
  }
  gyOut += 4 * Math.floor(days / 1461);
  days %= 1461;
  if (days > 365) {
    gyOut += Math.floor((days - 1) / 365);
    days = (days - 1) % 365;
  }
  let gd = days + 1;
  const sal_a = [
    0,
    31,
    (gyOut % 4 === 0 && gyOut % 100 !== 0) || gyOut % 400 === 0 ? 29 : 28,
    31,
    30,
    31,
    30,
    31,
    31,
    30,
    31,
    30,
    31
  ];
  let gm = 0;
  for (gm = 1; gm <= 12 && gd > sal_a[gm]; gm += 1) gd -= sal_a[gm];
  return `${gyOut}-${String(gm).padStart(2, '0')}-${String(gd).padStart(2, '0')}`;
};

const parseJalaliDate = (raw) => {
  if (!raw) return null;
  const text = toEnglishDigits(raw).replace(/[./\-]/g, '/').trim();
  const match = text.match(/^(\d{3,4})\/(\d{1,2})\/(\d{1,2})$/);
  if (!match) return null;
  const jy = Number(match[1]);
  const jm = Number(match[2]);
  const jd = Number(match[3]);
  if (!jy || !jm || !jd || jm > 12 || jd > 31 || jy < 1200 || jy > 1599) return null;
  try {
    return jalaliToGregorian(jy, jm, jd);
  } catch {
    return null;
  }
};

const parseImportDate = (raw) => {
  if (!raw) return null;
  if (raw instanceof Date) {
    return Number.isNaN(raw.getTime()) ? null : raw;
  }
  const text = String(raw).trim();
  if (!text) return null;
  const gregorian = text.match(/^(\d{4}-\d{2}-\d{2})/);
  if (gregorian) return new Date(`${gregorian[1]}T00:00:00.000Z`);
  const jalali = parseJalaliDate(text);
  if (jalali) return new Date(`${jalali}T00:00:00.000Z`);
  const date = new Date(text);
  return Number.isNaN(date.getTime()) ? null : date;
};

const utcDayRange = (value) => {
  const date = parseImportDate(value);
  if (!date) return null;
  const start = new Date(Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate()));
  const end = new Date(start.getTime() + 24 * 60 * 60 * 1000);
  return { start, end };
};

module.exports = {
  toEnglishDigits,
  jalaliToGregorian,
  parseJalaliDate,
  parseImportDate,
  utcDayRange
};