/*
 * Copyright (c) 2006, The JAP-Team
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   - Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of the University of Technology Dresden, Germany nor
 *     the names of its contributors may be used to endorse or promote
 *     products derived from this software without specific prior written
 *     permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package anon.client.replay;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;


/** 
 * @author Stefan Lieske
 */
public class ReplayTimestamp {

  private static final long SECONDS_PER_INTERVAL = 600;
  
  
  private String m_mixId;
  
  /**
   * Stores the time in ms (see System.currentTimeMillis()) the mix has chosen
   * as reference time for replay detection. This value is synchronized with
   * the local clock.
   */
  private long m_replayReferenceTime;
  

  public ReplayTimestamp(String a_mixId, int a_interval, int a_offset) {
    m_mixId = a_mixId;
    m_replayReferenceTime = System.currentTimeMillis() - ((long)a_interval * SECONDS_PER_INTERVAL + (long)a_offset) * 1000;
  }
  
  
  public String getMixId() {
    return m_mixId;
  }
  
  /**
   * 
   * @return The current interval.
   */
  public byte[] getCurrentTimestamp() {
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
    try {
      dataOutputStream.writeShort((int)(((System.currentTimeMillis() - m_replayReferenceTime) / (SECONDS_PER_INTERVAL * (long)1000))));
      dataOutputStream.flush();
    }
    catch (IOException e) {
      /* cannot occur */
    }
    return outputStream.toByteArray(); 
  }
  
}
