import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class Main {

	public static void main(String[] args) {
		startServer(Integer.parseInt(args[0]));
        startClient(Integer.parseInt(args[0]), args[1]);
	}




	private static void startServer(final int port) {
		(new Thread() {
            private DatagramSocket serverSocket;
            private String message="";
            byte[] receiveData = new byte[1024];
    		byte[] sendData = new byte[1024];

    		@Override
            public void run() {
            	System.out.println("START SERVER on [" + port + "] port");
            	try {
        		serverSocket = new DatagramSocket(port);
        		while(true) {
                    receiveData = new byte[1024];
            		sendData = new byte[1024];
        			DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
        			serverSocket.receive(receivePacket);
        			message = new String(receivePacket.getData());
        			System.out.println(" [received] " +  message);
        			InetAddress IPAddress = receivePacket.getAddress();
        			int port = receivePacket.getPort();
        			String capitalizedSentence = message.toUpperCase();
        			sendData = capitalizedSentence.getBytes();
        			DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
        			serverSocket.send(sendPacket);
        			}
            	}
            	catch (SocketException se) {
        			se.printStackTrace();
				}
        		catch (UnknownHostException uhe) {
        			uhe.printStackTrace();
				}
        		catch (IOException ioe) {
					ioe.printStackTrace();
				}
            }
        }).start();
	}





	private static void startClient(final int port, final String host) {
		(new Thread() {
			String name;
			String message;
			private DatagramSocket clientSocket;
			byte[] sendData = new byte[1024];
		    byte[] receiveData = new byte[1024];

            @Override
            public void run() {
            	System.out.println("CLIENT CONNECTED on [" + port + "] port [" + host + "] host");
            	boolean run = true;
            	while(run) {
            		sendData = new byte[1024];
        		    receiveData = new byte[1024];
            		try {
            			System.out.print("Enter message: ");
            			BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            		    message = reader.readLine();
            		    if(message.charAt(0) == '@') {
            		    	if(message.equals("@quit"))
            		    		run = false;
            		    	if(message.startsWith("@name"))
            		    		setClientName(message.substring(6, message.length()));
            		    }
            		    if(name!=null) {
            		    	message = name + " say: " + message;
            		    }
            		    clientSocket = new DatagramSocket();
            		    InetAddress	ipAddress = InetAddress.getByName(host);
            		    sendData = message.getBytes();
            		    DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, ipAddress, port);
						clientSocket.send(sendPacket);
            		    DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
						clientSocket.receive(receivePacket);
	            		message = new String(receivePacket.getData());
	            		System.out.println(" [from server] " + message);
	            		clientSocket.close();
					}
            		catch (SocketException se) {
            			se.printStackTrace();
					}
            		catch (UnknownHostException uhe) {
            			uhe.printStackTrace();
					}
            		catch (IOException ioe) {
						ioe.printStackTrace();
					}
            	}
            	System.out.println("CLIENT DISCONNECTED...");
            }

            public void setClientName(String name) {
            	this.name = name;
            }
        }).start();
	}
}