handshake.java

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// Copyright (c) 2005 Sony Ericsson Mobile Communications AB
//
// This software is provided "AS IS," without a warranty of any kind. 
// ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, 
// INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A 
// PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. 
//
// THIS SOFTWARE IS COMPLEMENTARY OF JAYWAY AB (www.jayway.se)

package bluegammon.io;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import bluegammon.Device;
import bluegammon.Bluegammon;
import bluegammon.RmsFacade;
import bluegammon.logic.Rand;
import bluegammon.logic.GameRecord;
import bluegammon.logic.Rules;

/**
 * <p>
 * A <code>Handshake</code> consists of sending and receiving data as specified
 * below, where one player has server role and the other has client role.
 * </p><p>
 * Stores needed data for further setup, and initializes static aspects
 * of the game (rules and random seed).
 * </p><p>
 * <pre>
 * SERVER                              CLIENT
 *                                     SEND random seed (int)
 *                                     SEND client id (int)
 *                                     SEND client name (UTF)
 * SEND has saved game (boolean)
 * IF saved game: SEND saved data (byte[])
 * SEND server id (int)
 * SEND server name (UTF)
 * SEND client color (boolean)
 * IF no saved game: SEND rules(int)
 *                                     IF no remote saved game: SEND has saved game (boolean)
 *                                     IF no remote saved game AND has saved game: SEND saved data (byte[])
 * </pre>
 * </p>
 * @author Peter Andersson
 */
public class Handshake
{
  /** The id of the remote device being handshaked with*/
  protected int m_remoteId;
  /** The name of the remote device being handshaked with*/
  protected char[] m_remoteName;
  /**
   * The saved game data shared between this device and
   * remote device being handshaked with. The server device
   * has preference.
   */
  protected byte[] m_savedGame;
  /**
   * The color of the this device, as decided between this device
   * and the device being handshaked with.
   */
  protected boolean m_white;
  /**
   * Flag indicating if the saved game data comes from the
   * remote device being handshaked with.
   */
  protected boolean m_remoteResume;
  
  /**
   * Performs a handshake as a server. This will
   * exchange data and any shared game with the other device.
   * 
   * @param dis           The input stream from the other device.
   * @param dos			  The output stream to the other device.
   * @param localName     The name of this device.
   * @throws IOException  if the handshake fails.
   */
  public void serverHandshake(
      DataInputStream dis, DataOutputStream dos, String localName)
      throws IOException
  {
    m_savedGame = null;
    
    // Receive client stats
    long randomSeed = dis.readLong();
    Rand.setRandomSeed(randomSeed);    
    m_remoteId = dis.readInt();
    m_remoteName = dis.readUTF().toCharArray();
    
    // Check for saved game here on server
    m_savedGame = GameRecord.getSavedGame(m_remoteId);
    boolean hasSavedGame = m_savedGame != null;
    dos.writeBoolean(hasSavedGame);
    if (hasSavedGame)
    {
      m_remoteResume = false;
      dos.writeInt(m_savedGame.length);
      for (int i = 0; i < m_savedGame.length; i++)
      {
        dos.writeByte(m_savedGame[i]);
      }
    }
    
    // Send server stats
    dos.writeInt(Device.getDeviceId());
    dos.writeUTF(localName);
    m_white = !RmsFacade.getBoolean(Bluegammon.BLACK_PREFERRED);
    dos.writeBoolean(!m_white);
    if (!hasSavedGame) Rules.saveRules(dos);
    dos.flush();
    
    // Get remote saved game, if no saved game here
    if (!hasSavedGame)
    {
      boolean remoteSavedGame = dis.readBoolean();
      if (remoteSavedGame)
      {
        m_remoteResume = true;
        int len = dis.readInt();
        m_savedGame = new byte[len];
        for (int i = 0; i < len; i++)
        {
          m_savedGame[i] = dis.readByte();
        }
      }
    }
  }
  
  /**
   * Performs a handshake as a client. This will
   * exchange data and any shared game with the other device.
   * 
   * @param dis           The input stream from the other device.
   * @param dos			  The output stream to the other device.
   * @param localName     The name of this device.
   * @throws IOException  if the handshake fails.
   */
  public void clientHandshake(
      DataInputStream dis, DataOutputStream dos, String localName)
	  throws IOException
  {
    m_savedGame = null;
    long randomSeed = System.currentTimeMillis();
    Rand.setRandomSeed(randomSeed);
   
    // Send client stats
    dos.writeLong(randomSeed);
    dos.writeInt(Device.getDeviceId());
    dos.writeUTF(localName);
    dos.flush();
    
    // Check for remote saved game on server
    boolean remoteHasSavedGame = dis.readBoolean();
    if (remoteHasSavedGame)
    {
      m_remoteResume = true;
      int len = dis.readInt();
      m_savedGame = new byte[len];
      for (int i = 0; i < len; i++)
      {
        m_savedGame[i] = dis.readByte();
      }
    }
    
    // Receive server stats
    m_remoteId = dis.readInt();
    m_remoteName = dis.readUTF().toCharArray();
    m_white = dis.readBoolean();
    if (!remoteHasSavedGame) Rules.loadRules(dis);
    
    // Check for saved game here on client if no remote saved game
    if (!remoteHasSavedGame)
    {
      m_savedGame = GameRecord.getSavedGame(m_remoteId);
      boolean hasSavedGame = m_savedGame != null;
      dos.writeBoolean(hasSavedGame);
      if (hasSavedGame)
      {
        m_remoteResume = false;
        dos.writeInt(m_savedGame.length);
        for (int i = 0; i < m_savedGame.length; i++)
        {
          dos.writeByte(m_savedGame[i]);
        }
      }
      dos.flush();
    }
  }
  
  /**
   * Returns the id of the other device after a successful handshake.
   * 
   * @return   The id of the remote device.
   */
  public int getRemoteId()
  {
    return m_remoteId;
  }
  
  /**
   * Returns the name of the other device after a successful handshake.
   * 
   * @return   The name of the remote device.
   */
  public char[] getRemoteName()
  {
    return m_remoteName;
  }
  
  /**
   * Returns the data of a shared saved game. If there was no
   * shared saved game betweed these devices, null is returned.
   * 
   * @return   The shared saved game data or null.
   */
  public byte[] getSavedGame()
  {
    return m_savedGame;
  }
  
  /**
   * Returns the color of this device as decided by the handshake.
   * If a saved game exists, this value is arbitrary.
   * 
   * @return   The local device's color, true for white, false for black.
   */
  public boolean isWhite()
  {
    return m_white;
  }
  
  /**
   * Returns whether the saved game data was collected from the
   * remote device or from this device. If there is no saved game
   * data, this method always returns false.
   * 
   * @return  true if saved game data was collected from remote
   *          device, false if it was collected from local device.
   */
  public boolean isRemoteResume()
  {
    return m_remoteResume;
  }
}