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

namespace Sick.SafetyScanners.DataProcessing;

/// <summary>
/// Parser for the data header from UDP packets
/// Thread-safe implementation
/// </summary>
public sealed class ParseDataHeader
{
    /// <summary>
    /// Parses the data header from a UDP sequence
    /// </summary>
    public DataHeader ParseUdpSequence(PacketBuffer buffer)
    {
        if (buffer == null)
            throw new ArgumentNullException(nameof(buffer));
        
        var bufferData = buffer.GetBuffer();
        if (bufferData.Length < 52) // Minimum header size
            throw new ArgumentException($"Buffer too small (got {bufferData.Length}, expected at least 52)", nameof(buffer));
        
        var span = bufferData.Span;
        
        return new DataHeader
        {
            VersionIndicator = ReadWriteHelper.ReadUint8LittleEndian(span, 0),
            VersionMajor = ReadWriteHelper.ReadUint8LittleEndian(span, 1),
            VersionMinor = ReadWriteHelper.ReadUint8LittleEndian(span, 2),
            VersionRelease = ReadWriteHelper.ReadUint8LittleEndian(span, 3),
            SerialNumberOfDevice = ReadWriteHelper.ReadUint32LittleEndian(span, 4),
            SerialNumberOfSystemPlug = ReadWriteHelper.ReadUint32LittleEndian(span, 8),
            ChannelNumber = ReadWriteHelper.ReadUint8LittleEndian(span, 12),
            // Offset 13-15 reserved
            SequenceNumber = ReadWriteHelper.ReadUint32LittleEndian(span, 16),
            ScanNumber = ReadWriteHelper.ReadUint32LittleEndian(span, 20),
            TimestampDate = ReadWriteHelper.ReadUint16LittleEndian(span, 24),
            TimestampTime = ReadWriteHelper.ReadUint32LittleEndian(span, 28),
            GeneralSystemStateBlockOffset = ReadWriteHelper.ReadUint16LittleEndian(span, 32),
            GeneralSystemStateBlockSize = ReadWriteHelper.ReadUint16LittleEndian(span, 34),
            DerivedValuesBlockOffset = ReadWriteHelper.ReadUint16LittleEndian(span, 36),
            DerivedValuesBlockSize = ReadWriteHelper.ReadUint16LittleEndian(span, 38),
            MeasurementDataBlockOffset = ReadWriteHelper.ReadUint16LittleEndian(span, 40),
            MeasurementDataBlockSize = ReadWriteHelper.ReadUint16LittleEndian(span, 42),
            IntrusionDataBlockOffset = ReadWriteHelper.ReadUint16LittleEndian(span, 44),
            IntrusionDataBlockSize = ReadWriteHelper.ReadUint16LittleEndian(span, 46),
            ApplicationDataBlockOffset = ReadWriteHelper.ReadUint16LittleEndian(span, 48),
            ApplicationDataBlockSize = ReadWriteHelper.ReadUint16LittleEndian(span, 50),
            IsEmpty = false
        };
    }
}