Innovenergy_trunk/csharp/Lib/Protocols/Modbus/Channels/ConnectionChannel.cs

namespace InnovEnergy.Lib.Protocols.Modbus.Channels;

public abstract class ConnectionChannel<T> : Channel, IDisposable
{
    private readonly Func<Exception, Boolean> _CloseAfterException ;
    private readonly Boolean                  _CloseAfterSuccessfulRead  ;
    private readonly Boolean                  _CloseAfterSuccessfulWrite ;

    protected abstract T    Open();
    protected abstract void Close(T connection);
    
    protected abstract IReadOnlyList<Byte> Read (T connection, Int32 nBytes);
    protected abstract void                Write(T connection, IReadOnlyList<Byte> data);
    
    private T? _Connection;

    protected ConnectionChannel(Boolean closeAfterSuccessfulRead  = false,
                                Boolean closeAfterSuccessfulWrite = false, 
              Func<Exception, Boolean>? closeAfterException       = null)
    {
        _CloseAfterSuccessfulRead  = closeAfterSuccessfulRead;
        _CloseAfterSuccessfulWrite = closeAfterSuccessfulWrite;
        _CloseAfterException       = closeAfterException ?? (_ => true);
    }

    public override IReadOnlyList<Byte> Read(Int32 nBytes)
    {
        try
        {
            return Read(Connection, nBytes);
        }
        catch (Exception e)
        {
            if (_CloseAfterException(e))
                Close();
            
            throw;
        }
        finally
        {
            if (_CloseAfterSuccessfulRead)
                Close();
        }
    }

 
    public override void Write(IReadOnlyList<Byte> data)
    {
        try
        {
            Write(Connection, data);
        }
        catch (Exception e)
        {
            if (_CloseAfterException(e))
                Close();
            
            throw;
        }
        finally
        {
            if (_CloseAfterSuccessfulWrite)
                Close();
        }
    }
    

    private T Connection => _Connection ??= Open();

    
    private void Close()
    {
        if (_Connection is null)
            return;
        
        Close(_Connection);
        _Connection = default;
    }

    
    public void Dispose() => Close();
}