// ChatClient.java
// Code Example: A Simple Socket Client and Server
//
// Written by Alex Thornton for Informatics 45 Spring 2010
// Minor revisions by Norman Jacobson for ICS 45J Spring 2012 
//
// This is the server program.  It differs slightly from
// the client, though a lot of the same ideas are here, e
// specially once the two sides are connected.
//
// (If you haven't read the code and comments for the client 
// yet, you should do that now: some things are explained
// in the client code that are not explained here, to avoid 
// explaining it twice.)

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;


public class ChatServer
{
	public static void main(String[] args)
	throws IOException
	{
		Scanner consoleIn = new Scanner(System.in);

		// We don't ask the user what address they'd like to connect to; we
		// only ask them for a port.  In particular, we're asking the user to
		// tell us the port that they'd like to listen on.  Listening just 
		// means waiting for someone to connect to the server's address on the
		// same port.  When someone connects on that port, a socket is created
		// and the conversation can proceed.
		System.out.print("Listen port: ");
		int port = Integer.parseInt(consoleIn.nextLine());

		// A ServerSocket implements "listening."  We tell it
		// what port to listen on when we create it.
		ServerSocket serverSocket = new ServerSocket(port);
		System.out.println("Waiting for connection...");

		// We call accept() when we want the program to suspend until 
		// a connection is made.  So, at this point, the server just 
		/  waits until a client connects.
		Socket socket = serverSocket.accept();

		// Once accept() returns a Socket, there is a connection and the
		// conversation can proceed.  The remaining code in this program is
		// very similar to the client: the difference is that the server
		// doesn't speak first.
		System.out.println("Connection accepted!");
		
		Scanner socketIn = new Scanner(socket.getInputStream());
		PrintWriter socketOut = new PrintWriter(socket.getOutputStream(), true);
		
		boolean done = false;
		do
		{
			// Get a message from the client; if it's empty; we're done
			String message = socketIn.nextLine();
			if (message.length() == 0)
			{
				System.out.println("Client ended conversation");
				done = true;
			}
			else
			{
				System.out.println("Message: " + message);
			}
			// Message received; send a response. If the 
			// response is empty, we're done
			if (!done)
			{
				System.out.print("Response: ");
				String response = consoleIn.nextLine();

				if (response.length() != 0)
					socketOut.println(response);
				else
				{
					System.out.println("Ending conversation");
					socketOut.println("");
					done = true;
				}
			}
		} while (!done);

		System.out.println("Closing connection");
		socket.close();
	}
}