/// <summary>
///     Represents an OBIS (Object Identification System) code per IEC 62056-61.
///     Format: A-B:C.D.E*F where each field is a byte value.
/// </summary>
/// <param name = "A">Value group A — medium (0=abstract, 1=electricity, 7=gas, 8=water).</param>
/// <param name = "B">Value group B — channel.</param>
/// <param name = "C">Value group C — physical quantity.</param>
/// <param name = "D">Value group D — processing/measurement algorithm.</param>
/// <param name = "E">Value group E — further classification.</param>
/// <param name = "F">Value group F — storage/billing period (255=not used).</param>
public readonly record struct ObisCode(byte A, byte B, byte C, byte D, byte E, byte F = 255)
{
#region Well-Known Codes
    /// <summary>Active energy import total (1.0.1.8.0.255).</summary>
    public static readonly ObisCode ActiveEnergyImportTotal = new(1, 0, 1, 8, 0);
    /// <summary>Active energy export total (1.0.2.8.0.255).</summary>
    public static readonly ObisCode ActiveEnergyExportTotal = new(1, 0, 2, 8, 0);
    /// <summary>Reactive energy import total (1.0.3.8.0.255).</summary>
    public static readonly ObisCode ReactiveEnergyImportTotal = new(1, 0, 3, 8, 0);
    /// <summary>Reactive energy export total (1.0.4.8.0.255).</summary>
    public static readonly ObisCode ReactiveEnergyExportTotal = new(1, 0, 4, 8, 0);
    /// <summary>Instantaneous voltage L1 (1.0.32.7.0.255).</summary>
    public static readonly ObisCode VoltageL1 = new(1, 0, 32, 7, 0);
    /// <summary>Instantaneous voltage L2 (1.0.52.7.0.255).</summary>
    public static readonly ObisCode VoltageL2 = new(1, 0, 52, 7, 0);
    /// <summary>Instantaneous voltage L3 (1.0.72.7.0.255).</summary>
    public static readonly ObisCode VoltageL3 = new(1, 0, 72, 7, 0);
    /// <summary>Instantaneous current L1 (1.0.31.7.0.255).</summary>
    public static readonly ObisCode CurrentL1 = new(1, 0, 31, 7, 0);
    /// <summary>Instantaneous current L2 (1.0.51.7.0.255).</summary>
    public static readonly ObisCode CurrentL2 = new(1, 0, 51, 7, 0);
    /// <summary>Instantaneous current L3 (1.0.71.7.0.255).</summary>
    public static readonly ObisCode CurrentL3 = new(1, 0, 71, 7, 0);
    /// <summary>Instantaneous active power total (1.0.1.7.0.255).</summary>
    public static readonly ObisCode ActivePowerTotal = new(1, 0, 1, 7, 0);
    /// <summary>Frequency (1.0.14.7.0.255).</summary>
    public static readonly ObisCode Frequency = new(1, 0, 14, 7, 0);
    /// <summary>Power factor total (1.0.13.7.0.255).</summary>
    public static readonly ObisCode PowerFactorTotal = new(1, 0, 13, 7, 0);
    /// <summary>Clock object (0.0.1.0.0.255).</summary>
    public static readonly ObisCode Clock = new(0, 0, 1, 0, 0);
    /// <summary>Meter serial number (0.0.96.1.0.255).</summary>
    public static readonly ObisCode SerialNumber = new(0, 0, 96, 1, 0);
    /// <summary>Firmware version (1.0.0.2.0.255).</summary>
    public static readonly ObisCode FirmwareVersion = new(1, 0, 0, 2, 0);
    /// <summary>Association LN (0.0.40.0.0.255).</summary>
    public static readonly ObisCode AssociationLn = new(0, 0, 40, 0, 0);
    /// <summary>Load profile (1.0.99.1.0.255).</summary>
    public static readonly ObisCode LoadProfile = new(1, 0, 99, 1, 0);
    /// <summary>Event log (0.0.99.98.0.255).</summary>
    public static readonly ObisCode EventLog = new(0, 0, 99, 98, 0);
#endregion
#region Methods
    /// <summary>Encodes the OBIS code as a 6-byte array.</summary>
    public byte[] ToBytes() => [A, B, C, D, E, F];
    /// <summary>Decodes an OBIS code from a 6-byte span.</summary>
    public static ObisCode FromBytes(ReadOnlySpan<byte> bytes)
    {
        if (bytes.Length < 6)
            throw new ArgumentException("OBIS code requires 6 bytes", nameof(bytes));
        return new ObisCode(bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]);
    }

    /// <inheritdoc/>
    public override string ToString() => $"{A}-{B}:{C}.{D}.{E}*{F}";
    /// <summary>Parses an OBIS code from string format "A-B:C.D.E*F" or "A.B.C.D.E.F".</summary>
    public static ObisCode Parse(string value)
    {
        ArgumentNullException.ThrowIfNull(value);
        // Try "A-B:C.D.E*F" format
        var parts = value.Replace("-", ".", StringComparison.Ordinal).Replace(":", ".", StringComparison.Ordinal).Replace("*", ".", StringComparison.Ordinal).Split('.');
        if (parts.Length < 5)
            throw new FormatException($"Invalid OBIS code format: {value}");
        return new ObisCode(byte.Parse(parts[0], CultureInfo.InvariantCulture), byte.Parse(parts[1], CultureInfo.InvariantCulture), byte.Parse(parts[2], CultureInfo.InvariantCulture), byte.Parse(parts[3], CultureInfo.InvariantCulture), byte.Parse(parts[4], CultureInfo.InvariantCulture), parts.Length > 5 ? byte.Parse(parts[5], CultureInfo.InvariantCulture) : (byte)255);
    }
#endregion
}