using System;
using System.Net;
using System.Net.Sockets;

const char DELIM = ' ';
const int DELAY_DURATION_S = 990;

short ReadPort() => args.Length != 0 && short.TryParse(args[0], out var port) ? port : (short)22;

IList<string> ReadBanner() => Console.In.ReadToEnd().Split(DELIM, StringSplitOptions.RemoveEmptyEntries);

async Task SshClientHandler(TcpClient client, IEnumerable<string> banner)
{
    var remote = client.Client.RemoteEndPoint;
    Console.WriteLine($"{remote}: Client connected.");

    try
    {
        using (client)
        {
            var stream = client.GetStream();
            var writer = new StreamWriter(stream) { AutoFlush = true };

            while (true)
            {
                foreach (var word in banner)
                {
                    await writer.WriteAsync($"{word}{DELIM}");
                    await Task.Delay(DELAY_DURATION_S);
                }

                Console.WriteLine($"{remote}: Client read it all!");
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"{remote}: Client handler error: {ex.Message}");
    }
    finally
    {
        Console.WriteLine($"{remote}: Client hung up");
    }
}

// main 
var banner = ReadBanner();
var port = ReadPort();
var listener = new TcpListener(IPAddress.Any, port);

using (listener)
{
    listener.Start();
    Console.WriteLine($"Listening on port {port}...");

    while (true)
    {
        try
        {
            var client = await listener.AcceptTcpClientAsync();

            _ = Task.Run(() => SshClientHandler(client, banner));
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Accept error: {ex.Message}");
        }
    }
}