Assist_Design/packages/domain/toolkit/formatting/phone.ts

/**
 * Toolkit - Phone Number Formatting
 * 
 * Utilities for formatting phone numbers.
 */

/**
 * Format a phone number for display
 * Handles basic international formats
 */
export function formatPhoneNumber(phone: string): string {
  // Remove all non-digit characters
  const digits = phone.replace(/\D/g, "");

  // Handle common formats
  if (digits.length === 10) {
    // US/Canada format: (123) 456-7890
    return `(${digits.slice(0, 3)}) ${digits.slice(3, 6)}-${digits.slice(6)}`;
  } else if (digits.length === 11 && digits.startsWith("1")) {
    // US/Canada with country code: +1 (123) 456-7890
    return `+1 (${digits.slice(1, 4)}) ${digits.slice(4, 7)}-${digits.slice(7)}`;
  } else if (digits.length >= 10) {
    // International format: +XX XXX XXX XXXX
    const countryCode = digits.slice(0, digits.length - 10);
    const areaCode = digits.slice(-10, -7);
    const localPrefix = digits.slice(-7, -4);
    const localNumber = digits.slice(-4);
    return `+${countryCode} ${areaCode} ${localPrefix} ${localNumber}`;
  }

  // Return original if no known format matches
  return phone;
}

/**
 * Normalize a phone number to E.164 format (+XXXXXXXXXXX)
 */
export function normalizePhoneNumber(phone: string, defaultCountryCode = "1"): string {
  const digits = phone.replace(/\D/g, "");
  
  // If already has country code, return with +
  if (digits.length >= 10 && !digits.startsWith(defaultCountryCode)) {
    return `+${digits}`;
  }
  
  // Add default country code
  return `+${defaultCountryCode}${digits}`;
}

/**
 * Format phone number for WHMCS API
 * WHMCS accepts format: +CC.NNNNNNNNNN (country code dot number)
 * Example: +81.335601006 or +1.2125551234
 */
export function formatPhoneForWhmcs(phone: string): string {
  // Remove all non-digit characters except leading +
  const hasPlus = phone.startsWith("+");
  const digits = phone.replace(/\D/g, "");
  
  if (digits.length === 0) {
    return phone;
  }

  // For Japanese numbers (starts with 81), format as +81.XXXXXXXXX
  if (digits.startsWith("81") && digits.length >= 11) {
    return `+81.${digits.slice(2)}`;
  }
  
  // For US/Canada numbers (10 digits or 11 starting with 1)
  if (digits.length === 10) {
    return `+1.${digits}`;
  }
  if (digits.length === 11 && digits.startsWith("1")) {
    return `+1.${digits.slice(1)}`;
  }

  // For other international numbers, assume first 1-3 digits are country code
  // Use dot separator after country code
  if (digits.length >= 10) {
    // Try to detect country code length (most are 1-3 digits)
    const numberWithoutCountry = digits.length - 10;
    const countryCodeLength = Math.min(Math.max(numberWithoutCountry, 1), 3);
    const countryCode = digits.slice(0, countryCodeLength);
    const localNumber = digits.slice(countryCodeLength);
    return `+${countryCode}.${localNumber}`;
  }

  // Return with + prefix if it had one, otherwise as-is
  return hasPlus ? `+${digits}` : digits;
}