package LR1.server;

import javax.xml.crypto.Data;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Map;

public class Server implements Runnable {
    private int port;

    public Server(int port) {
        this.port = port;
    }

    public void handleClient(Socket client) {
        String message = null;
        try {
            DataInputStream input = new DataInputStream(client.getInputStream());
            message = input.readUTF();
            System.out.println("Received client's message: " + message);
        } catch (IOException e) {
            System.out.println("Failed to receive client's message");
            e.printStackTrace();
            return;
        }

        String reversed = new StringBuilder(message).reverse().toString();

        try {
            DataOutputStream outputStream = new DataOutputStream(client.getOutputStream());
            outputStream.writeUTF(reversed);

            System.out.println("Sent response: " + reversed);
            System.out.println("Client disconnected.");
            System.out.println();
        } catch (IOException ex) {
            System.out.println("Couldn't send response: ");
            ex.printStackTrace();
            System.out.println();
        }
    }

    @Override
    public void run() {
        ServerSocket server;
        try {
            server = new ServerSocket(this.port);
            System.out.println("Server is running...");
            System.out.println();
        } catch (IOException e) {
            System.out.println("Couldn't start server: ");
            e.printStackTrace();
            return;
        }

        while (true) {
            Socket client = null;
            try {
                client = server.accept();
                handleClient(client);
                client.close();
            } catch (IOException e) {
                System.out.println("Couldn't wait for client's connection: ");
                e.printStackTrace();
            }
        }
    }
}


package LR1.server;

public class ServerApp {
    private static final int port = 8080;

    public static void main(String[] args) {
        Server server = new Server(port);
        server.run();
    }
}

package LR1.client;

import java.io.*;
import java.net.ConnectException;
import java.net.Socket;

public class Client {
    private static final int port = 8080;

    private static Socket client;
    private static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void handleMessage(String message) throws IOException {
        DataOutputStream output = new DataOutputStream(client.getOutputStream());
        DataInputStream input = new DataInputStream(client.getInputStream());

        output.writeUTF(message);

        String result = input.readUTF();
        System.out.println("Server response: " + result);
    }

    public static void main(String[] args) throws IOException {
        try {
            client = new Socket("localhost", port);
            System.out.println("Connected");
        } catch (ConnectException ex) {
            System.out.println("Couldn't connect to the server");
            return;
        }

        System.out.print("Enter word: ");
        String message = br.readLine();

        try {
            handleMessage(message);
        } catch (IOException ex) {
            System.out.println("Couldn't send message to server.");
        }

        client.close();
        System.out.println("Connection closed.");
    }
}