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

"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.p2p.splitstream;

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

import rice.environment.Environment;
import rice.environment.params.Parameters;
import rice.p2p.commonapi.*;
import rice.p2p.commonapi.rawserialization.InputBuffer;
import rice.p2p.scribe.*;
import rice.p2p.scribe.rawserialization.ScribeContentDeserializer;

/**
 * This is the implementing class of the ISplitStream interface. It provides the
 * functionality of creating and attaching to channels. This class is
 * responsible for handling all channels that a local node is part of. @(#)
 * SplitStreamImpl.java
 *
 * @version $Id: SplitStreamImpl.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Ansley Post
 * @author Alan Mislove
 */
public class SplitStreamImpl implements SplitStream {

  /**
   * The scribe instance for this SplitStream Object
   */
  protected Scribe scribe;

  /**
   * The node that this application is running on
   */
  protected Node node;

  /**
   * Hashtable of all the channels currently created on this node implicitly or
   * explicitly.
   */
  protected Hashtable channels;

  /**
   * DESCRIBE THE FIELD
   */
  protected final int stripeBaseBitLength;
  /**
   * DESCRIBE THE FIELD
   */
  protected final int maxFailedSubscriptions;
  /**
   * DESCRIBE THE FIELD
   */
  protected final int defaultMaxChildren;

  /**
   * DESCRIBE THE FIELD
   */
  protected String instance;

  /**
   * Convienience constructor which uses the default SplitStreamScribePolicy.
   *
   * @param node
   * @param instance
   */
  public SplitStreamImpl(Node node, String instance) {
    this(node, instance,
      new SplitStreamScribePolicyFactory() {
        public ScribePolicy getSplitStreamScribePolicy(Scribe scribe,
                                                       SplitStream splitstream) {
          return new SplitStreamScribePolicy(scribe, splitstream);
        }
      });
  }

  /**
   * The constructor for building the splitStream object which internally
   * creates it's own Scribe.
   *
   * @param node the pastry node that we will use
   * @param instance The instance name for this splitstream
   * @param factory DESCRIBE THE PARAMETER
   */
  public SplitStreamImpl(Node node, String instance, SplitStreamScribePolicyFactory factory) {
    this.instance = instance;
    Environment environment = node.getEnvironment();
    Parameters p = environment.getParameters();
    defaultMaxChildren = p.getInt("p2p_splitStream_policy_default_maximum_children");
    maxFailedSubscriptions = p.getInt("p2p_splitStream_stripe_max_failed_subscription");
    stripeBaseBitLength = p.getInt("p2p_splitStream_stripeBaseBitLength");
    this.scribe = new ScribeImpl(node, instance);
    scribe.setContentDeserializer(
      new ScribeContentDeserializer() {
        public ScribeContent deserializeScribeContent(InputBuffer buf,
                                                      Endpoint endpoint, short contentType) throws IOException {
          switch (contentType) {
            case SplitStreamContent.TYPE:
              return new SplitStreamContent(buf);
            case SplitStreamSubscribeContent.TYPE:
              return new SplitStreamSubscribeContent(buf);
          }
          throw new IllegalArgumentException("Invalid type:" + contentType);
        }
      });

    this.node = node;
    this.channels = new Hashtable();
    scribe.setPolicy(factory.getSplitStreamScribePolicy(scribe, this));
  }


  /**
   * Returns all of the channels on this local splitstream
   *
   * @return All of the channels currently being received by this splitstream
   */
  public Channel[] getChannels() {
    return (Channel[]) channels.values().toArray(new Channel[0]);
  }

  /**
   * Returns the policy used to control Scribe
   *
   * @return The Scribe policy
   */
  public SplitStreamScribePolicy getPolicy() {
    return (SplitStreamScribePolicy) (scribe.getPolicy());
  }

  /**
   * Gets the StripeBaseBitLength attribute of the SplitStreamImpl object
   *
   * @return The StripeBaseBitLength value
   */
  public int getStripeBaseBitLength() {
    return stripeBaseBitLength;
  }

  /**
   * Gets the Environment attribute of the SplitStreamImpl object
   *
   * @return The Environment value
   */
  public Environment getEnvironment() {
    return scribe.getEnvironment();
  }

  /**
   * This method is used by a peer who wishes to distribute the content using
   * SplitStream. It creates a Channel Object consisting of numStripes number of
   * Stripes, one for each stripe's content. A Channel object is responsible for
   * implementing SplitStream functionality, like maintaining multiple multicast
   * trees, bandwidth management and discovering parents having spare capacity.
   * One Channel object should be created for each content distribution which
   * wishes to use SplitStream.
   *
   * @param id The id of the channel to create
   * @return an instance of a Channel class.
   */
  public Channel createChannel(ChannelId id) {
    return attachChannel(id);
  }

  /**
   * This method is used by peers who wish to listen to content distributed by
   * some other peer using SplitStream. It attaches the local node to the
   * Channel which is being used by the source peer to distribute the content.
   * Essentially, this method finds out the different parameters of Channel
   * object which is created by the source, (the peer distributing the content)
   * , and then creates a local Channel object with these parameters and returns
   * it. This is a non-blocking call so the returned Channel object may not be
   * initialized with all the parameters, so applications should wait for
   * channelIsReady() notification made by channels when they are ready.
   *
   * @param id The id of the channel to create
   * @return An instance of Channel object.
   */
  public Channel attachChannel(ChannelId id) {
    Channel channel = (Channel) channels.get(id);

    if (channel == null) {
      channel = new Channel(id, scribe, instance, node.getIdFactory(), this.node.getId(),
        stripeBaseBitLength, maxFailedSubscriptions);
      channels.put(id, channel);
    }

    ((SplitStreamScribePolicy) scribe.getPolicy()).setMaxChildren(id,
      defaultMaxChildren);
    return channel;
  }

  /**
   * DESCRIBE THE METHOD
   */
  public void destroy() {
    scribe.destroy();
  }
}

