namespace Sick.SafetyScanners.DataStructures;

/// <summary>
/// Represents a PacketBuffer with a parsed DatagramHeader
/// Used for merging fragmented UDP packets
/// </summary>
public sealed class ParsedPacketBuffer
{
    /// <summary>
    /// Gets the packet buffer
    /// </summary>
    public PacketBuffer PacketBuffer { get; init; }
    
    /// <summary>
    /// Gets the parsed datagram header
    /// </summary>
    public DatagramHeader DatagramHeader { get; init; }
    
    public ParsedPacketBuffer(PacketBuffer packetBuffer, DatagramHeader datagramHeader)
    {
        PacketBuffer = packetBuffer ?? throw new ArgumentNullException(nameof(packetBuffer));
        DatagramHeader = datagramHeader ?? throw new ArgumentNullException(nameof(datagramHeader));
    }
    
    /// <summary>
    /// Compares two ParsedPacketBuffer instances by fragment offset for sorting
    /// </summary>
    public static int CompareByOffset(ParsedPacketBuffer x, ParsedPacketBuffer y)
    {
        if (x == null && y == null) return 0;
        if (x == null) return -1;
        if (y == null) return 1;
        
        return x.DatagramHeader.FragmentOffset.CompareTo(y.DatagramHeader.FragmentOffset);
    }
}