/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. 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 Rice  University (RICE) 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 RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
or implied including, but not limited to, representations or
warranties of non-infringement, merchantability or fitness for a
particular purpose. In no event shall RICE 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 rice.pastry.socket;

import java.io.*;
import java.net.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;
import java.util.*;
import java.util.zip.*;

import rice.environment.Environment;
import rice.environment.logging.Logger;
import rice.pastry.*;
import rice.pastry.messaging.*;
import rice.pastry.socket.*;
import rice.pastry.socket.SocketCollectionManager.*;

/**
 * Class which serves as an "reader" for messages sent across the wire via the
 * Pastry socket protocol. This class builds up an object as it is being sent
 * across the wire, and when it has recieved all of an object, it informs the
 * WirePastryNode by using the recieveMessage(msg) method. The
 * SocketChannelReader is designed to be reused, to read objects continiously
 * off of one stream.
 *
 * @version $Id: SocketChannelReader.java,v 1.5 2004/03/08 19:53:57 amislove Exp
 *      $
 * @author Alan Mislove
 */
public class SocketChannelRepeater {

  // the default size of the transfer array
  /**
   * DESCRIBE THE FIELD
   */
  protected int REPEATER_BUFFER_SIZE;

  // whether or not this repeater has been connected to the other side
  private boolean connected;

  // the local node
  private SocketPastryNode spn;

  // the original socket channel
  private SocketChannel original;

  // the source route manager
  private SourceRouteManager manager;

  // for first buffer for socket 1 -> 2
  private ByteBuffer buffer1;

  // for first buffer for socket 2 -> 1
  private ByteBuffer buffer2;

  // for reading from the header information socket
  private ByteBuffer headerBuffer;

  private Logger logger;
  // 4 for the ip, 4 for the port (int), 8 for the epoch (long)
  /**
   * DESCRIBE THE FIELD
   */
  protected static int HEADER_BUFFER_SIZE = 16;

  final static byte[] junk = new byte[0];

  /**
   * Constructor which creates this SocketChannelReader and the WirePastryNode.
   * Once the reader has completely read a message, it deserializes the message
   * and hands it off to the pastry node.
   *
   * @param spn The PastryNode the SocketChannelReader serves.
   * @param manager DESCRIBE THE PARAMETER
   */
  public SocketChannelRepeater(SocketPastryNode spn, SourceRouteManager manager) {
    this.spn = spn;
    logger = spn.getEnvironment().getLogManager().getLogger(SocketChannelRepeater.class, null);
    this.manager = manager;
    REPEATER_BUFFER_SIZE = spn.getEnvironment().getParameters().getInt("pastry_socket_repeater_buffer_size");
    this.headerBuffer = ByteBuffer.allocateDirect(HEADER_BUFFER_SIZE);
    this.buffer1 = ByteBuffer.allocateDirect(REPEATER_BUFFER_SIZE);
    this.buffer2 = ByteBuffer.allocateDirect(REPEATER_BUFFER_SIZE);
  }

  /**
   * Internal method which determines which maps socket channels to buffers -
   * the original socket channel gets buffer 1, and the second channel gets
   * buffer 2.
   *
   * @param reading Whether or not the channel is for reading
   * @param sc DESCRIBE THE PARAMETER
   * @return The buffer for that channel
   */
  private ByteBuffer getBuffer(SocketChannel sc, boolean reading) {
    if (reading == (sc == original)) {
      return buffer1;
    } else {
      return buffer2;
    }
  }

  /**
   * Method which is to be called when there is data available on the specified
   * SocketChannel. The data is read in, and is put into the output buffer.
   *
   * @param sc The channel to read from.
   * @return whether or not we the reading key should be turned off an the
   *      writing key on
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public boolean read(SocketChannel sc) throws IOException {
    if (original == null) {
      original = sc;
    }

    if (!connected) {
      int read = sc.read(headerBuffer);

      // implies that the channel is closed
      if (read == -1) {
        throw new IOException("Error on read - the channel has been closed.");
      }

      if (headerBuffer.remaining() == 0) {
        processHeaderBuffer();
      } else {
        return false;
      }
    }

    ByteBuffer buffer = getBuffer(sc, true);

    int read = sc.read(buffer);

    if (logger.level <= Logger.FINER) {
      logger.log(
        "Read " + read + " bytes of data..." + buffer.remaining());
    }
    spn.broadcastReceivedListeners(junk, (InetSocketAddress) sc.socket().getRemoteSocketAddress(), read, NetworkListener.TYPE_SR_TCP);

    // implies that the channel is closed
    if (read == -1) {
      throw new ClosedChannelException();
    }

    // return true if we've read anything (and can therefore write something)
    if (read > 0) {
      buffer.flip();
      return true;
    } else {
      return false;
    }
  }

  /**
   * Method which is designed to be called when this repeater should write
   * something out.
   *
   * @param sc The SocketChannel to write to
   * @return true if this output stream is done, false otherwise
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public boolean write(SocketChannel sc) throws IOException {
    ByteBuffer buffer = getBuffer(sc, false);

    int j = buffer.limit();
    int i = sc.write(buffer);

    if (logger.level <= Logger.FINER) {
      logger.log(
        "Wrote " + i + " of " + j + " bytes to " + sc.socket().getRemoteSocketAddress());
    }
    spn.broadcastSentListeners(junk, (InetSocketAddress) sc.socket().getRemoteSocketAddress(), i, NetworkListener.TYPE_SR_TCP);

    // if we've written everything in the buffer, clear it, and return true
    if (buffer.remaining() == 0) {
      buffer.flip();
      buffer.clear();

      return true;
    } else {
      return false;
    }
  }

  /**
   * Private method which is designed to read the header of the incoming
   * message, and determine which foriegn address to connect to
   *
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  private void processHeaderBuffer() throws IOException {
    // flip the buffer
    headerBuffer.flip();

    // allocate space for the header
    byte[] headerArray = new byte[HEADER_BUFFER_SIZE];
    headerBuffer.get(headerArray);

    EpochInetSocketAddress address = decodeHeader(headerArray);
    manager.createConnection(address);

    if (logger.level <= Logger.FINER) {
      logger.log(
        "Read address " + address);
    }

    this.connected = true;
  }

  /**
   * Method which can be used to constuct the necessary header for the
   * intermediate hop
   *
   * @param address The final address of the source route
   * @return The entire header
   */
  public static byte[] encodeHeader(EpochInetSocketAddress address) {
    try {
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      DataOutputStream dos = new DataOutputStream(baos);
      dos.write(address.getAddress().getAddress().getAddress());
      dos.writeInt(address.getAddress().getPort());
      dos.writeLong(address.getEpoch());
      dos.flush();

      return baos.toByteArray();
    } catch (IOException canthappen) {
      throw new RuntimeException("PANIC: SHOULDN'T HAPPEN " + canthappen, canthappen);
    }
  }

  /**
   * Method which can be used to decode the necessary header for the
   * intermediate hop
   *
   * @param array The encoded header
   * @return The address
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public static EpochInetSocketAddress decodeHeader(byte[] array) throws IOException {
    return decodeHeader(array, 0);
  }

  /**
   * Method which can be used to decode the necessary header for the
   * intermediate hop
   *
   * @param array The encoded header
   * @param offset DESCRIBE THE PARAMETER
   * @return The address
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public static EpochInetSocketAddress decodeHeader(byte[] array, int offset) throws IOException {
    byte[] ip = new byte[4];
    byte[] skip = new byte[HEADER_BUFFER_SIZE];

    // read the object size
    DataInputStream dis = new DataInputStream(new ByteArrayInputStream(array));

    // skip the stuff
    for (int i = 0; i < offset; i++) {
      dis.readFully(skip);
    }

    // now read our stuff
    dis.readFully(ip);
    int port = dis.readInt();
    long epoch = dis.readLong();

    if ((port <= 0) || (port >= 65536)) {
      throw new IOException("Found inet address with improper port - " + port);
    }

    return new EpochInetSocketAddress(new InetSocketAddress(InetAddress.getByAddress(ip), port), epoch);
  }
}
