mxaccess/src/MxNativeCodec/NmxOperationStatusMessage.cs

namespace MxNativeCodec;

public enum NmxOperationStatusFormat
{
    CompletionOnly,
    StatusWord,
}

public sealed record NmxOperationStatusMessage(
    NmxOperationStatusFormat Format,
    byte Command,
    ushort StatusCode,
    byte CompletionCode,
    MxStatus Status)
{
    public bool IsMxAccessWriteComplete => Format == NmxOperationStatusFormat.StatusWord
        && StatusCode == 0x8050
        && CompletionCode == 0x00;

    public static bool TryParseProcessDataReceivedBody(ReadOnlyMemory<byte> body, out NmxOperationStatusMessage message)
    {
        try
        {
            var envelope = NmxObservedEnvelope.ParseProcessDataReceivedBodyFlexible(body);
            return TryParseInner(envelope.InnerBody.Span, out message);
        }
        catch (ArgumentException)
        {
            message = null!;
            return false;
        }
    }

    public static bool TryParseInner(ReadOnlySpan<byte> inner, out NmxOperationStatusMessage message)
    {
        if (inner.Length == 1)
        {
            byte completionCode = inner[0];
            message = new NmxOperationStatusMessage(
                Format: NmxOperationStatusFormat.CompletionOnly,
                Command: 0,
                StatusCode: 0,
                CompletionCode: completionCode,
                Status: CreateUnpromotedCompletionStatus(completionCode));
            return true;
        }

        if (inner.Length == 5 && inner[0] == 0x00 && inner[1] == 0x00)
        {
            ushort statusCode = (ushort)(inner[2] | (inner[3] << 8));
            byte completionCode = inner[4];
            message = new NmxOperationStatusMessage(
                Format: NmxOperationStatusFormat.StatusWord,
                Command: inner[0],
                StatusCode: statusCode,
                CompletionCode: completionCode,
                Status: statusCode == 0x8050 && completionCode == 0x00 ? MxStatus.WriteCompleteOk : new MxStatus(
                    Success: 0,
                    Category: MxStatusCategory.Unknown,
                    DetectedBy: MxStatusSource.Unknown,
                    Detail: completionCode == 0x00 ? unchecked((short)statusCode) : completionCode));
            return true;
        }

        message = null!;
        return false;
    }

    private static MxStatus CreateUnpromotedCompletionStatus(byte completionCode)
    {
        return new MxStatus(
            Success: 0,
            Category: MxStatusCategory.Unknown,
            DetectedBy: MxStatusSource.Unknown,
            Detail: completionCode);
    }
}