// Copyright 1997, <a href=http://www.MageLang.com>MageLang Institute</a>.

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

public class Server {
  public static final int DEFAULT_PORT = 8002;
  protected ServerSocket server;

  public static void main(String[] args) {
    // first determine the port to use
    int port = DEFAULT_PORT;
    if (args.length > 1) {
      System.err.println("Usage: java Server [port]");
      System.exit(0);
    }
    else if (args.length == 1) {
      try { port = Integer.parseInt(args[0]); }
      catch (NumberFormatException e) {
        System.err.println("Invalid port number" + port);
        System.exit(0);
      }
    }
    // create a new server on that port, and wait for a connection
    Server s = new Server(port);
    s.accept();
   }

  public Server(int port) {
    // create a server listening at port, max 15 pending connections
    try {
      server = new ServerSocket(port, 15);
    }
    catch (IOException e) {
      System.err.println("cannot listen at "+port+" ("+e.getMessage()+")");
    }
  }

  public void accept() {
    ObjectOutput out = null;
    ObjectInput in = null;
    Socket socket = null;
    while (true) {
      try {
        socket = server.accept();
        System.out.println("socket opened");
        out = new ObjectOutputStream(socket.getOutputStream());
        in = new ObjectInputStream(socket.getInputStream());

        // read in a tree, add a node, and send it back
        TreeNode n = (TreeNode)in.readObject();
        n.addChild(new TreeNode("server node"));
        out.writeObject(n);
        out.flush();
      }

      catch (IOException e) {
        System.err.println("Error creating socket connection");
        System.exit(1);
      }
      catch (Exception e) {
	System.err.println(e);
      }
    }
  }
}