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

namespace InnovEnergy.Lib.Protocols.Modbus.Channels;

public class TcpChannel : ConnectionChannel<TcpClient>
{
    private const Int32 TimeoutMs = 500; // TODO: parametrize 

    public TcpChannel(Ip4Address ip4Address,
                         Boolean closeAfterSuccessfulRead  = false,
                         Boolean closeAfterSuccessfulWrite = false) : 
        this(ip4Address.Host ?? "null",
             ip4Address.Port.HasValue ? (Int32)ip4Address.Port.Value : 0, 
             closeAfterSuccessfulRead, 
             closeAfterSuccessfulWrite)
    {
        
    }
    
    public TcpChannel(String hostname, 
                       Int32 port, 
                     Boolean closeAfterSuccessfulRead  = false,
                     Boolean closeAfterSuccessfulWrite = false) : base(closeAfterSuccessfulRead, closeAfterSuccessfulWrite)
    {
        TcpClient Open()
        {
            var tcpClient = new TcpClient
            {
                LingerState    = new LingerOption(false, 0),
                NoDelay        = true,
                ReceiveTimeout = TimeoutMs, 
                SendTimeout    = TimeoutMs  
            };

            var cts = new CancellationTokenSource();

            var connected = tcpClient
                           .ConnectAsync(hostname, port, cts.Token)
                           .AsTask()
                           .Wait(TimeoutMs);

            if (connected)
                return tcpClient;
            
            cts.Cancel();
            throw new Exception($"Failed to connect to {hostname}:{port}");
        }

        _Open = Open;
    }
    
    private readonly Func<TcpClient> _Open;

    protected override TcpClient Open() => _Open();
    protected override void Close(TcpClient tcpClient) => tcpClient.Close();

    protected override IReadOnlyList<Byte> Read(TcpClient tcpClient, Int32 nToRead)
    {
        var buffer = new Byte[nToRead];

        var stream = tcpClient.GetStream();
        var nReceived = 0;
        
        do
        {
            var nRemaining = nToRead - nReceived;
            var read = stream.Read(buffer, nReceived, nRemaining);
            if (read <= 0)
                throw new NotConnectedException("The TCP Connection was closed");
        
            nReceived += read;
        }
        while (nReceived < nToRead);

        return buffer;
    }

    protected override void Write(TcpClient tcpClient, IReadOnlyList<Byte> data)
    {
        var array = data.ToArray();
        tcpClient.GetStream().Write(array, 0, array.Length);
    }
}