package jutil;

import java.util.*;
import java.io.*;
import java.net.*;
import jutil.*;

/**
 * Base class for all objects that want to communicate
 * using a socket.
 */
 public class Correspondent {
	/**
	 * The socket for this correspondent
	 */
	protected Socket sock;
	/**
	 * Connected to sock's output stream
	 */
	protected BufferedReader sockIn;
	/**
	 * Connected to sock's input stream
	 */
	protected PrintWriter sockOut;
	/**
	 * This constructor does not initialize any fields. Users
	 * must subsequently call initStreams. We need this so the
	 * server can call newInstance.
	 */
	public Correspondent() { }
	/**
	 * Initializes all fields.
	 * @param s the socket to use
	 */
	public Correspondent(Socket s) {
		sock = s;
		initStreams();
	}
	/**
	 * initializes the reader and writer fields.
	 */
	public void initStreams() {
		try {
			sockIn = new BufferedReader(
						new InputStreamReader(
							sock.getInputStream()));
			sockOut = new PrintWriter(
						sock.getOutputStream(), true);
		} catch(IOException e) {
			System.err.println(e.getMessage());
		}
	}
	/**
	 * Closes sock without throwing an exception.
	 */
	public void close() {
		try {
			sock.close();
		} catch(IOException e) {
			System.err.println(e.getMessage());
		}
	}
	/**
	 * Initializes sock and other fields by requesting
	 * a connection to a server.
	 *
	 * @param host  Internet address of the machine hosting the server
	 * @param port  Port of server socket.
	 */
	public void requestConnection(String host, int port) {
		try {
			sock = new Socket(host, port);
			initStreams();
		} catch(UnknownHostException uhe) {
			System.err.println("unknown host " + uhe);
			System.exit(1);
		} catch(IOException ioe) {
			System.err.println("failed to create streams " + ioe);
			System.exit(1);
		}
	}

	/**
	 * Sends a message to the server. This is a non-blocking send.
	 * @param msg the message to be sent
	 */
	public void send(String msg) {
		sockOut.println(msg);
	}

	/**
	 * Receives a message from server. This is a blocking receive.
	 * @return the message received.
	 */
	public String receive() {
		String msg = null;
		try {
			msg = sockIn.readLine();
		} catch(Exception e) {

		}
		return msg;
	}
}