using System.Buffers.Binary;
using RPG.Network.Proto;

namespace RPG.Services.Core.Network.Command;
public static class ServiceCommandEncoder
{
    public static ServiceCommand DecodeCommand(ReadOnlyMemory<byte> buffer)
    {
        ReadOnlySpan<byte> span = buffer.Span;

        RPGServiceType senderType = (RPGServiceType)span[0];
        ServiceCommandType commandType = (ServiceCommandType)BinaryPrimitives.ReadUInt16BigEndian(span[1..3]);
        ReadOnlyMemory<byte> body = buffer.Slice(7, BinaryPrimitives.ReadInt32BigEndian(span[3..7]));

        return new(senderType, commandType, body);
    }

    public static void EncodeCommand(ServiceCommand command, Memory<byte> buffer)
    {
        Span<byte> span = buffer.Span;

        span[0] = (byte)command.SenderType;
        BinaryPrimitives.WriteUInt16BigEndian(span[1..3], (ushort)command.CommandType);
        BinaryPrimitives.WriteInt32BigEndian(span[3..7], command.Body.Length);
        command.Body.CopyTo(buffer[7..]);
    }
}