/**
 * Small Windows timezone name -> IANA timezone name mapper.
 *
 * MS_TIMEZONE is documented to accept either IANA names (e.g. "America/New_York")
 * or Windows names (e.g. "Eastern Standard Time"). Intl.DateTimeFormat only
 * understands IANA identifiers, so we normalize Windows names before use.
 */
const WINDOWS_TO_IANA = {
  'dateline standard time': 'Etc/GMT+12',
  'utc-11': 'Etc/GMT+11',
  'aleutian standard time': 'America/Adak',
  'hawaiian standard time': 'Pacific/Honolulu',
  'marquesas standard time': 'Pacific/Marquesas',
  'alaskan standard time': 'America/Anchorage',
  'utc-09': 'Etc/GMT+9',
  'pacific standard time (mexico)': 'America/Tijuana',
  'utc-08': 'Etc/GMT+8',
  'pacific standard time': 'America/Los_Angeles',
  'us mountain standard time': 'America/Phoenix',
  'mountain standard time (mexico)': 'America/Chihuahua',
  'mountain standard time': 'America/Denver',
  'central america standard time': 'America/Guatemala',
  'central standard time': 'America/Chicago',
  'central standard time (mexico)': 'America/Mexico_City',
  'canada central standard time': 'America/Regina',
  'sa pacific standard time': 'America/Bogota',
  'eastern standard time': 'America/New_York',
  'us eastern standard time': 'America/Indianapolis',
  'venezuela standard time': 'America/Caracas',
  'paraguay standard time': 'America/Asuncion',
  'atlantic standard time': 'America/Halifax',
  'central brazilian standard time': 'America/Cuiaba',
  'sa western standard time': 'America/La_Paz',
  'pacific sa standard time': 'America/Santiago',
  'newfoundland standard time': 'America/St_Johns',
  'e. south america standard time': 'America/Sao_Paulo',
  'argentina standard time': 'America/Buenos_Aires',
  'greenland standard time': 'America/Godthab',
  'montevideo standard time': 'America/Montevideo',
  'bahia standard time': 'America/Bahia',
  'utc-02': 'Etc/GMT+2',
  'mid-atlantic standard time': 'Etc/GMT+2',
  'azores standard time': 'Atlantic/Azores',
  'cape verde standard time': 'Atlantic/Cape_Verde',
  'utc': 'UTC',
  'gmt standard time': 'Europe/London',
  'greenwich standard time': 'Etc/GMT',
  'w. europe standard time': 'Europe/Berlin',
  'central europe standard time': 'Europe/Budapest',
  'romance standard time': 'Europe/Paris',
  'w. central africa standard time': 'Africa/Lagos',
  'jordan standard time': 'Asia/Amman',
  'gtb standard time': 'Europe/Athens',
  'middle east standard time': 'Asia/Beirut',
  'egypt standard time': 'Africa/Cairo',
  'e. europe standard time': 'Europe/Chisinau',
  'syria standard time': 'Asia/Damascus',
  'west bank standard time': 'Asia/Hebron',
  'south africa standard time': 'Africa/Johannesburg',
  'fle standard time': 'Europe/Kiev',
  'israel standard time': 'Asia/Jerusalem',
  'kaliningrad standard time': 'Europe/Kaliningrad',
  'libya standard time': 'Africa/Tripoli',
  'arabic standard time': 'Asia/Baghdad',
  'turkey standard time': 'Europe/Istanbul',
  'arab standard time': 'Asia/Riyadh',
  'belarus standard time': 'Europe/Minsk',
  'russian standard time': 'Europe/Moscow',
  'e. africa standard time': 'Africa/Nairobi',
  'iran standard time': 'Asia/Tehran',
  'arabian standard time': 'Asia/Dubai',
  'azerbaijan standard time': 'Asia/Baku',
  'caucasus standard time': 'Asia/Yerevan',
  'mauritius standard time': 'Indian/Mauritius',
  'georgian standard time': 'Asia/Tbilisi',
  'caucasus standard time': 'Asia/Yerevan',
  'afghanistan standard time': 'Asia/Kabul',
  'west asia standard time': 'Asia/Tashkent',
  'ekaterinburg standard time': 'Asia/Yekaterinburg',
  'pakistan standard time': 'Asia/Karachi',
  'india standard time': 'Asia/Kolkata',
  'sri lanka standard time': 'Asia/Colombo',
  'nepal standard time': 'Asia/Kathmandu',
  'central asia standard time': 'Asia/Almaty',
  'bangladesh standard time': 'Asia/Dhaka',
  'myanmar standard time': 'Asia/Yangon',
  'se asia standard time': 'Asia/Bangkok',
  'north asia standard time': 'Asia/Krasnoyarsk',
  'china standard time': 'Asia/Shanghai',
  'north asia east standard time': 'Asia/Irkutsk',
  'singapore standard time': 'Asia/Singapore',
  'w. australia standard time': 'Australia/Perth',
  'taipei standard time': 'Asia/Taipei',
  'ulaanbaatar standard time': 'Asia/Ulaanbaatar',
  'tokyo standard time': 'Asia/Tokyo',
  'korea standard time': 'Asia/Seoul',
  'yakutsk standard time': 'Asia/Yakutsk',
  'cen. australia standard time': 'Australia/Adelaide',
  'aus central standard time': 'Australia/Darwin',
  'e. australia standard time': 'Australia/Brisbane',
  'aus eastern standard time': 'Australia/Sydney',
  'west pacific standard time': 'Pacific/Port_Moresby',
  'tasmania standard time': 'Australia/Hobart',
  'vladivostok standard time': 'Asia/Vladivostok',
  'russia time zone 10': 'Asia/Srednekolymsk',
  'central pacific standard time': 'Pacific/Guadalcanal',
  'russia time zone 11': 'Asia/Kamchatka',
  'new zealand standard time': 'Pacific/Auckland',
  'utc+12': 'Etc/GMT-12',
  'fiji standard time': 'Pacific/Fiji',
  'tonga standard time': 'Pacific/Tongatapu',
  'samoa standard time': 'Pacific/Apia',
  'line islands standard time': 'Pacific/Kiritimati'
};

function windowsToIana(windowsName) {
  if (!windowsName) return windowsName;
  const normalized = String(windowsName).trim().toLowerCase();
  return WINDOWS_TO_IANA[normalized] || windowsName;
}

/**
 * Normalize a configured timezone name for use with Intl.DateTimeFormat.
 * MS_TIMEZONE may be an IANA name (returned as-is) or a Windows name (mapped).
 * @param {string} [timeZone] - Timezone name (defaults to config.DEFAULT_TIMEZONE)
 * @returns {string}
 */
function resolveTimeZone(timeZone = require('../config').DEFAULT_TIMEZONE) {
  return windowsToIana(timeZone);
}

module.exports = {
  WINDOWS_TO_IANA,
  windowsToIana,
  resolveTimeZone
};