shoc-backend/SeaHaven.Services/Helpers/VendorPhoneNormalizer.cs

using System.Text.RegularExpressions;

namespace SeaHaven.Services.Helpers
{
    public static class VendorPhoneNormalizer
    {
        public static readonly Regex NorthAmericanPhoneRegex = new(
            @"^\(\d{3}\) \d{3}-\d{4}$",
            RegexOptions.Compiled);

        public static string? NormalizeToCanonical(string? value)
        {
            if (string.IsNullOrWhiteSpace(value))
                return null;

            var digits = new string(value.Where(char.IsDigit).ToArray());
            if (digits.Length == 11 && digits.StartsWith('1'))
                digits = digits[1..];

            return digits.Length == 10
                ? $"({digits[..3]}) {digits[3..6]}-{digits[6..]}"
                : value;
        }
    }
}