/**
 * Copyright 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.bitcoin.core;

import java.util.List;

/**
 * <p>Implementors can listen to events like blocks being downloaded/transactions being broadcast/connect/disconnects,
 * they can pre-filter messages before they are procesesed by a {@link Peer} or {@link PeerGroup}, and they can
 * provide transactions to remote peers when they ask for them.</p>
 */
public interface PeerEventListener {
    /**
     * Called on a Peer thread when a block is received.<p>
     *
     * The block may have transactions or may be a header only once getheaders is implemented.
     *
     * @param peer       the peer receiving the block
     * @param block      the downloaded block
     * @param blocksLeft the number of blocks left to download
     */
    public void onBlocksDownloaded(Peer peer, Block block, int blocksLeft);

    /**
     * Called when a download is started with the initial number of blocks to be downloaded.
     *
     * @param peer       the peer receiving the block
     * @param blocksLeft the number of blocks left to download
     */
    public void onChainDownloadStarted(Peer peer, int blocksLeft);

    /**
     * Called when a peer is connected
     *
     * @param peer
     * @param peerCount the total number of connected peers
     */
    public void onPeerConnected(Peer peer, int peerCount);

    /**
     * Called when a peer is disconnected. Note that this won't be called if the listener is registered on a
     * {@link PeerGroup} and the group is in the process of shutting down.
     *
     * @param peer
     * @param peerCount the total number of connected peers
     */
    public void onPeerDisconnected(Peer peer, int peerCount);

    /**
     * Called when a message is received by a peer, before the message is processed. The returned message is
     * processed instead. Returning null will cause the message to be ignored by the Peer returning the same message
     * object allows you to see the messages received but not change them. The result from one event listeners
     * callback is passed as "m" to the next, forming a chain.
     */
    public Message onPreMessageReceived(Peer peer, Message m);

    /**
     * Called when a new transaction is broadcast over the network.
     */
    public void onTransaction(Peer peer, Transaction t);

    /**
     * Called when a peer receives a getdata message, usually in response to an "inv" being broadcast. Return as many
     * items as possible which appear in the {@link GetDataMessage}, or null if you're not interested in responding.
     */
    public List<Message> getData(Peer peer, GetDataMessage m);
}

@@ -1763,17 +1763,133 @@
 onnected
+. If this listener is registered to a %7B@link Peer%7D instead of a %7B@link PeerGroup%7D,%0A     * this will never be called.
 %0A
-
      *%0A 
@@ -2225,16 +2225,131 @@
 ng down.
+ If this listener is registered to a%0A     * %7B@link Peer%7D instead of a %7B@link PeerGroup%7D, this will never be called.
 %0A     *%0A
@@ -2505,32 +2505,35 @@
 %0A    /**%0A     * 
+%3Cp%3E
 Called when a me
@@ -2842,24 +2842,24 @@
 t listeners%0A
-
      * callb
@@ -2908,16 +2908,182 @@
 a chain.
+%3C/p%3E%0A     *%0A     * %3Cp%3ENote that this will never be called if registered with any executor other than%0A     * %7B@link com.google.bitcoin.utils.Threading#SAME_THREAD%7D%3C/p%3E
 %0A     */

Clarify PeerEventListener JavaDocs a bit