let phoneUtil: any = null;

export const getPhoneUtil = async () => {
  if (!phoneUtil) {
    const result = await import(/* webpackChunkName: "phone-util" */ 'google-libphonenumber');
    const PhoneNumberUtil = (result.default || result)?.PhoneNumberUtil;
    if (!PhoneNumberUtil) {
      throw new Error('PhoneNumberUtil not found');
    }
    phoneUtil = PhoneNumberUtil.getInstance();
  }
  return phoneUtil;
};

export const validatePhoneNumber = async (phoneNumber: string) => {
  if (!phoneNumber) return true;
  try {
    let util: any = null;
    try {
      util = await getPhoneUtil();
    } catch (err) {
      const pattern = /^[+]?[(]?[0-9]{3}[)]?[-\s.]?[0-9]{3}[-\s.]?[0-9]{4,6}$/im;
      return pattern.test(phoneNumber);
    }

    const parsed = util.parseAndKeepRawInput(phoneNumber);
    return util.isValidNumber(parsed);
  } catch (err) {
    console.error('Phone validation error:', err);
    return false;
  }
};

/**
 * Format a phone number to international format
 * @param phoneNumber The original phone number
 * @param defaultCountry Default country code (ISO 3166-1 alpha-2)
 * @returns Formatted phone number
 */
export const formatPhone = (phoneNumber: string | undefined, defaultCountry = 'US') => {
  if (!phoneNumber || phoneNumber.trim() === '') {
    return '';
  }

  // Remove all non-digit characters (preserve plus sign)
  const cleanedNumber = phoneNumber.replace(/[^\d+]/g, '');

  // If already in international format (starting with +), return cleaned number
  if (cleanedNumber.startsWith('+')) {
    return cleanedNumber;
  }

  // Country code mapping
  const COUNTRY_CODES: Record<string, string> = {
    US: '1', // United States
    CA: '1', // Canada
    CN: '86', // China
    HK: '852', // Hong Kong
    IN: '91', // India
    UK: '44', // United Kingdom
    GB: '44', // United Kingdom
    JP: '81', // Japan
    KR: '82', // South Korea
    AU: '61', // Australia
    DE: '49', // Germany
    FR: '33', // France
    IT: '39', // Italy
    ES: '34', // Spain
    BR: '55', // Brazil
    RU: '7', // Russia
    MX: '52', // Mexico
    SG: '65', // Singapore
    AE: '971', // UAE
  };

  // Country-specific patterns
  const COUNTRY_PATTERNS: [RegExp, string][] = [
    [/^1[3-9]\d{9}$/, '86'], // China mobile: 11 digits, starts with 1
    [/^\d{10}$/, '1'], // US/Canada: 10 digits
    [/^[6-9]\d{9}$/, '91'], // India: 10 digits, starts with 6-9
    [/^0[1-9]\d{8,9}$/, '81'], // Japan: 10-11 digits, starts with 0
    [/^07\d{9}$/, '44'], // UK mobile: 11 digits, starts with 07
    [/^04\d{8}$/, '61'], // Australia mobile: 10 digits, starts with 04
    [/^01[0-9]\d{7,8}$/, '82'], // Korea mobile: 10-11 digits, starts with 01
    [/^[0-9]\d{8}$/, '86'], // China landline: 9 digits
  ];

  // Remove leading zero (common in many countries)
  let numberToFormat = cleanedNumber;
  if (numberToFormat.startsWith('0')) {
    numberToFormat = numberToFormat.substring(1);
  }

  // Try to match with country-specific patterns
  for (const [pattern, countryCode] of COUNTRY_PATTERNS) {
    if (pattern.test(cleanedNumber)) {
      // For numbers starting with 0 that need the zero removed
      if (cleanedNumber.startsWith('0') && !['1', '86'].includes(countryCode)) {
        return `+${countryCode}${cleanedNumber.substring(1)}`;
      }
      return `+${countryCode}${cleanedNumber}`;
    }
  }

  // If no pattern matched, use default country code
  const countryCode = COUNTRY_CODES[defaultCountry.toUpperCase()] || defaultCountry;
  return `+${countryCode}${numberToFormat}`;
};