using System.Net.Sockets;
using InnovEnergy.Lib.Protocols.Modbus.Protocol;

namespace InnovEnergy.Lib.Protocols.Modbus.Connections;

public class ModbusTcpConnection : ModbusConnection
{
    private String Hostname { get; }
    private Int32  Port     { get; }
    
    private Byte[]      Buffer { get; } = new Byte[1024];
    private TcpClient? _TcpClient;

    public ModbusTcpConnection(String hostname, Int32 port = 502)
    {
        Hostname = hostname;
        Port = port;
    }
    
    public override IReadOnlyList<Byte> Receive(UInt16 bytesToRead)
    {
        var bytesReceived = 0;
        var stream = TcpClient().GetStream();
        
        do
        {
            var maxBytes = Math.Min(bytesToRead, Buffer.Length) - bytesReceived;
            var read = stream.Read(Buffer, bytesReceived, maxBytes);
            if (read <= 0)
                throw new NotConnectedException("The TCP Connection was closed");
        
            bytesReceived += read;
        }
        while (bytesReceived < bytesToRead);
        
        return new ArraySegment<Byte>(Buffer, 0, bytesToRead);
    }

    public override void Transmit(IEnumerable<Byte> data)
    {
        var array = data.ToArray();
        TcpClient().GetStream().Write(array, 0, array.Length);
    }

    public override void Open() => TcpClient();

    private TcpClient TcpClient()
    {
        return _TcpClient ??= new TcpClient(Hostname, Port);
    }

    public override void Close()
    {
        try
        {
            _TcpClient?.Dispose();
        }
        catch (Exception)
        {
            // ignored
        }

        _TcpClient = null;
    }
    
}