// This file contains material supporting section 6.13 of the textbook:
// "Object Oriented Software Engineering" and is issued under the open-source
// license found at www.lloseng.com 

package ocsf.client;

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

/**
 * This class acts as a subclass of <code>AbstractClient</code>
 * and is also an <code>Observable</code> class.
 * Each time a new message is received, observers are notified.
 *
 * @author Dr Robert Lagani&egrave;re
 * @author Dr Timothy C. Lethbridge
 * @author Fran&ccedil;ois B&eacute;lange
 * @version Febuary 2001
 */
public class ObservableClient extends Observable
{
  // Class variables ***************************************************
  
  /**
   * Indicates occurence of a connection exception.
   */
  public static final String CONNECTION_EXCEPTION = "#OC:Connection error.";
  
  /**
   * Indicates a close of the connection to server.
   */
  public static final String CONNECTION_CLOSED = "#OC:Connection closed.";
  
  /**
   * Indicates establishment of a connection to server.
   */
  public static final String CONNECTION_ESTABLISHED = "#OC:Connection established.";

  //Instance variables **********************************************

  /**
   * The service instance used to simulate multiple class inheritance.
   */
  private AdaptableClient service;

  //Constructor *****************************************************

  public ObservableClient(String host, int port)
  {
    service = new AdaptableClient(host, port, this);
  }

  //Instance methods ************************************************

  /**
   * Opens the connections with the server.
   */
  final public void openConnection() throws IOException
  {
    service.openConnection();
  }

  /**
   * Closes the connection to the server.
   */
  final public void closeConnection() throws IOException
  {
    service.closeConnection();
  }

  /**
   * Sends an object to the server. This is the only way that
   * methods should communicate with the server.
   *
   *  @param msg   The message to be sent.
   */
  final public void sendToServer(Object msg) throws IOException
  {
    service.sendToServer(msg);
  }

// ACCESSING METHODS ------------------------------------------------

  /**
   * @used to find out if the client is connnected.
   */
  final public boolean isConnected()
  {
    return service.isConnected();
  }

  /**
   * @return the port number.
   */
  final public int getPort()
  {
    return service.getPort();
  }

  /**
   * Sets the server port number for the next connection.
   * Only has effect if the client is not currently connected.
   *
   * @param port the port number.
   */
  final public void setPort(int port)
  {
    service.setPort(port);
  }

  /**
   * @return the host name.
   */
  final public String getHost()
  {
    return service.getHost();
  }

  /**
   * Sets the server host for the next connection.
   * Only has effect if the client is not currently connected.
   *
   * @param host the host name.
   */
  final public void setHost(String host)
  {
    service.setHost(host);
  }

  /**
   * @return the client's Inet address.
   */
  final public InetAddress getInetAddress()
  {
    return service.getInetAddress();
  }


  /**
   * This method is used to handle messages from the server.  This method
   * can be overriden but should always call notifyObservers().
   *
   * @param message The message received from the client.
   */
  protected void handleMessageFromServer(Object message)
  {
    setChanged();
    notifyObservers(message);
  }

  /**
   * Hook method called after the connection has been closed.
   */
  protected void connectionClosed() 
  {
    setChanged();
    notifyObservers(CONNECTION_CLOSED);
  }

  /**
   * Hook method called each time an exception
   * is raised by the client listening thread.
   *
   * @param exception the exception raised.
   */
  protected void connectionException(Exception exception) 
  {
    setChanged();
    notifyObservers(CONNECTION_EXCEPTION);
  }

  /**
   * Hook method called after a connection has been established.
   */
  protected void connectionEstablished() 
  {
    setChanged();
    notifyObservers(CONNECTION_ESTABLISHED);
  }
}