import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Consumer;

public class chat {
    private ServerSocket serverSocket; // initialized in ctor
    private Map<String, Consumer<String>> members = new HashMap<>();

    public static void main(String[] args) {
        try {
            new chat().acceptloop();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public chat() throws IOException {
        this.serverSocket = new ServerSocket(5999);
    }

    private void acceptloop() throws IOException {
        while (true) {
            Socket c = serverSocket.accept();
            new Thread(new connection(this, c)).start();
        }
    }

    public synchronized void connect(String user, Consumer<String> callback) {
        for (Map.Entry<String, Consumer<String>> e : members.entrySet()) {
            try { callback.accept(e.getKey() + " arrived"); }
            catch (Exception ex) { disconnect(e.getKey()); }
        }
        members.put(user, callback);
        announce(user + " arrived");
    }

    public synchronized void disconnect(String user) {
        members.remove(user);
        announce(user + " left");
    }

    public synchronized void speak(String user, String text) {
        announce(user + " says '" + text + "'");
    }

    private void announce(String s) {
        for (Map.Entry<String, Consumer<String>> e : members.entrySet()) {
            try { e.getValue().accept(s); }
            catch (Exception ex) { disconnect(e.getKey()); }
        }
    }

    private static class connection implements Runnable {
        private chat room;
        private Socket c;
        private static int userCount = 0;
        private String user = "user" + (userCount++);

        public connection(chat room, Socket c) {
            this.room = room;
            this.c = c;
        }

        @Override
        public void run() {
            try {
                BufferedReader in = new BufferedReader(new InputStreamReader(c.getInputStream()));
                PrintWriter out = new PrintWriter(new OutputStreamWriter(c.getOutputStream()));
                room.connect(user, (String s) -> {
                    out.println(s);
                    out.flush();
                });
                while (true) {
                    String line = in.readLine();
                    if (line == null) break;
                    room.speak(user, line);
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                room.disconnect(user);
            }
        }
    }
}