using System.Text.RegularExpressions;

namespace HikvisionAttendanceService;

/// <summary>
/// Single place for DeviceId trimming and session/fetch lookup keys so config, CLI, and logs stay aligned.
/// </summary>
internal static class DeviceIdentity
{
    private static readonly Regex FMNumericSuffix = new Regex(@"-FM(\d+)$", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);

    /// <summary>Value stored from JSON after load — trim only; never replace user’s chosen id.</summary>
    public static string NormalizeConfigured(string? raw)
    {
        if (string.IsNullOrWhiteSpace(raw))
            return "";
        return raw.Trim();
    }

    /// <summary>
    /// Stable key for FindSession / fetch: same physical device if only the "-FM" serial prefix differs
    /// (e.g. DS-K1T642MFW-FM7378360 vs DS-K1T642MFW-7378360).
    /// </summary>
    public static string CanonicalLookupKey(string? raw)
    {
        var s = NormalizeConfigured(raw);
        if (s.Length == 0)
            return "";

        s = FMNumericSuffix.Replace(s, "-$1");
        return s.ToUpperInvariant();
    }
}