Server

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace serverDoWielu
{
    public partial class MainWindow : Window
    {

        private List<TcpClient> listaClientow = new List<TcpClient>();
        private List<StreamReader> listaSTR = new List<StreamReader>();
        private List<StreamWriter> listaSTW = new List<StreamWriter>();

        private string received;
        private String text_to_send;
        public BackgroundWorker worker1;
        public BackgroundWorker worker2;
        public BackgroundWorker worker3;

        public MainWindow()
        {
            InitializeComponent();
            worker1 = new BackgroundWorker();
            worker1.DoWork += backgroundWorker1_DoWork;
            worker2 = new BackgroundWorker();
            worker2.DoWork += backgroundWorker2_DoWork;
            worker3 = new BackgroundWorker();
            worker3.DoWork += backgroundWorker3_DoWork;
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
            worker3.RunWorkerAsync(); // po odpaleniu serwera nasluchuje nowych klientow
        }
        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            while (true)
            {
                try
                {
                    foreach (var item in listaSTR)
                    {
                        received = item.ReadLine();
                        text_to_send = received;
                    }
                    worker2.RunWorkerAsync();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }
        }
        private void backgroundWorker2_DoWork(object sender, DoWorkEventArgs e)//wysyl wiadomosci
        {
            if (true)
            {

                foreach (var item in listaSTW)      //wysyłamy do kazdego klienta
                {
                    item.WriteLine(text_to_send);
                }
            }
            else
            {
                MessageBox.Show("send failed !");
            }
            worker2.CancelAsync();
        }
        private void backgroundWorker3_DoWork(object sender, DoWorkEventArgs e)
        {
            TcpListener listener = new TcpListener(IPAddress.Any, 13000);
            //listaTcpListener.Add(new TcpListener(IPAddress.Any, 13000)); czy wystarczy 1 listener?
            bool NieMaZadnegoKlienta = true;

            int licznikClientow = 0;
            while (true)
            {
                listener.Start(); // nasluchujemy
                listaClientow.Add(new TcpClient()); // dodajemy nowego

                listaClientow[licznikClientow] = listener.AcceptTcpClient(); //przypisujemy
                listaSTR.Add(new StreamReader(  listaClientow[licznikClientow].GetStream() ) );  // do czytania
                listaSTW.Add(new StreamWriter(  listaClientow[licznikClientow].GetStream() ) );   // do wysylania wiadomosci
                listaSTW[licznikClientow].AutoFlush = true; //czysci bufor
                if(listaClientow[0].Connected && NieMaZadnegoKlienta) // start watku nasluchiwania przez serwer
                {
                    NieMaZadnegoKlienta = false;
                    worker1.RunWorkerAsync();  // ten nasluchuje
                    worker2.WorkerSupportsCancellation = true; //ten wysla
                }
                licznikClientow++;

            }
        }

    }
}