using Sick.SafetyScanners.Helpers;

namespace Sick.SafetyScanners.Cola2.Commands;

/// <summary>
/// Command to create a new COLA2 session
/// </summary>
public sealed class CreateSessionCommand : CommandBase
{
    private const byte HeartbeatTimeoutSeconds = 60;
    private const uint ClientId = 1;
    
    public CreateSessionCommand() 
        : base(0x4F, 0x58) // 'O' and 'X' in ASCII
    {
    }
    
    public override bool CanBeExecutedWithoutSessionId => true;
    
    protected override ReadOnlyMemory<byte> AddTelegramData()
    {
        var data = new byte[5];
        var span = data.AsSpan();
        
        // Heartbeat timeout (1 byte)
        ReadWriteHelper.WriteUint8BigEndian(span, 0, HeartbeatTimeoutSeconds);
        
        // Client ID (4 bytes)
        ReadWriteHelper.WriteUint32BigEndian(span, 1, ClientId);
        
        return data;
    }
    
    protected override bool ProcessReplyInternal(ReadOnlyMemory<byte> replyData, 
        byte replyCommandType, byte replyCommandMode)
    {
        // Reply should be 'O' (0x4F) and 'A' (0x41) for Acknowledge
        // Note: Session ID is NOT in reply data, it's in the packet header (offset 10)
        // In C++ reference, ParseTCPPacket reads session ID from header and sets it to Command
        // In C# implementation, Cola2Session extracts it from parseResult.SessionId
        if ((replyCommandType == 0x4F && replyCommandMode == 0x41) ||
            (replyCommandType == 'O' && replyCommandMode == 'A'))
        {
            return true;
        }
        
        return false;
    }
}