using Sick.SafetyScanners.DataStructures;
using Sick.SafetyScanners.Helpers;
using System.Text;

namespace Sick.SafetyScanners.DataProcessing;

/// <summary>
/// Parser for FieldSetsData response from COLA2 variable command
/// Thread-safe implementation
/// </summary>
public sealed class ParseFieldSetsData
{
    /// <summary>
    /// Parses the field sets data from a TCP sequence (COLA2 response)
    /// Matches: ParseFieldSetsData::parseTCPSequence in C++
    /// </summary>
    public FieldSets ParseTcpSequence(PacketBuffer buffer)
    {
        var span = buffer.GetBufferSpan();
        uint arrayLength = ReadArrayLength(span);
        
        var nameLengths = new List<uint>((int)arrayLength);
        var fieldNames = new List<string>((int)arrayLength);
        var isDefined = new List<bool>((int)arrayLength);
        
        for (uint i = 0; i < arrayLength; i++)
        {
            uint nameLength = ReadWriteHelper.ReadUint32LittleEndian(span, 8 + (int)(i * 104));
            nameLengths.Add(nameLength);
            
            var nameBuilder = new StringBuilder((int)nameLength);
            for (uint j = 0; j < nameLength; j++)
            {
                byte ch = ReadWriteHelper.ReadUint8(span, 12 + (int)(i * 104) + (int)j);
                nameBuilder.Append((char)ch);
            }
            fieldNames.Add(nameBuilder.ToString());
            
            byte byteValue = ReadWriteHelper.ReadUint8(span, 44 + (int)(i * 104));
            isDefined.Add((byteValue & (0x01 << 0)) != 0);
        }
        
        return new FieldSets
        {
            VersionCVersion = ReadVersionIndicator(span),
            VersionMajorVersionNumber = ReadMajorNumber(span),
            VersionMinorVersionNumber = ReadMinorNumber(span),
            VersionReleaseNumber = ReadReleaseNumber(span),
            NameLengths = nameLengths,
            FieldNames = fieldNames,
            IsDefined = isDefined
        };
    }
    
    /// <summary>
    /// Matches: ParseFieldSetsData::readVersionIndicator in C++
    /// </summary>
    private string ReadVersionIndicator(ReadOnlySpan<byte> span)
    {
        byte ch = ReadWriteHelper.ReadUint8(span, 0);
        return ((char)ch).ToString();
    }
    
    /// <summary>
    /// Matches: ParseFieldSetsData::readMajorNumber in C++
    /// </summary>
    private byte ReadMajorNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 1);
    }
    
    /// <summary>
    /// Matches: ParseFieldSetsData::readMinorNumber in C++
    /// </summary>
    private byte ReadMinorNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 2);
    }
    
    /// <summary>
    /// Matches: ParseFieldSetsData::readReleaseNumber in C++
    /// </summary>
    private byte ReadReleaseNumber(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint8(span, 3);
    }
    
    private uint ReadArrayLength(ReadOnlySpan<byte> span)
    {
        return ReadWriteHelper.ReadUint32LittleEndian(span, 4);
    }
}