using Sick.SafetyScanners.DataStructures;
using Sick.SafetyScanners.Helpers;

namespace Sick.SafetyScanners.DataProcessing;

/// <summary>
/// Parser for ConfigMetadata response from COLA2 variable command
/// Thread-safe implementation
/// </summary>
public sealed class ParseConfigMetadata
{
    /// <summary>
    /// Parses the config metadata from a TCP sequence (COLA2 response)
    /// Matches: ParseConfigMetadata::parseTCPSequence in C++
    /// </summary>
    public ConfigMetadata ParseTcpSequence(PacketBuffer buffer)
    {
        var span = buffer.GetBufferSpan();
        return new ConfigMetadata
        {
            VersionCVersion = ReadVersionIndicator(span),
            VersionMajorVersionNumber = ReadMajorNumber(span),
            VersionMinorVersionNumber = ReadMinorNumber(span),
            VersionReleaseNumber = ReadReleaseNumber(span),
            ModificationTimeDate = ReadModificationTimeDate(span),
            ModificationTimeTime = ReadModificationTimeTime(span),
            TransferTimeDate = ReadTransferTimeDate(span),
            TransferTimeTime = ReadTransferTimeTime(span),
            AppChecksum = ReadAppChecksum(span),
            OverallChecksum = ReadOverallChecksum(span),
            IntegrityHash = ReadIntegrityHash(span)
        };
    }
    
    /// <summary>
    /// Matches: ParseConfigMetadata::readVersionIndicator in C++
    /// </summary>
    private string ReadVersionIndicator(ReadOnlySpan<byte> span)
    {
        byte ch = ReadWriteHelper.ReadUint8(span, 0);
        return ((char)ch).ToString();
    }
    
    /// <summary>
    /// Matches: ParseConfigMetadata::readMajorNumber in C++
    /// </summary>
    private byte ReadMajorNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 1);
    }
    
    /// <summary>
    /// Matches: ParseConfigMetadata::readMinorNumber in C++
    /// </summary>
    private byte ReadMinorNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 2);
    }
    
    /// <summary>
    /// Matches: ParseConfigMetadata::readReleaseNumber in C++
    /// </summary>
    private byte ReadReleaseNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 3);
    }
    
    private ushort ReadModificationTimeDate(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint16LittleEndian(span, 4);
    }
    
    private uint ReadModificationTimeTime(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint32LittleEndian(span, 8);
    }
    
    private ushort ReadTransferTimeDate(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint16LittleEndian(span, 12);
    }
    
    private uint ReadTransferTimeTime(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint32LittleEndian(span, 16);
    }
    
    private uint ReadAppChecksum(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint32BigEndian(span, 36);
    }
    
    private uint ReadOverallChecksum(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint32BigEndian(span, 52);
    }
    
    private IReadOnlyList<uint> ReadIntegrityHash(ReadOnlySpan<byte> span)
    {
        var result = new List<uint>(4);
        for (int i = 0; i < 4; i++)
        {
            uint value = ReadWriteHelper.ReadUint32LittleEndian(span, 68 + (i * 4));
            result.Add(value);
        }
        return result;
    }
}