Provide a HistoryList mechanism down here in the basic service.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6194 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/crowd/chat/client/ChatDirector.java

@@ -154,21 +154,6 @@ public class ChatDirector extends BasicDirector
         registerCommandHandlers();
     }
 
-    /**
-     * Registers all the chat-command handlers.
-     */
-    protected void registerCommandHandlers ()
-    {
-        MessageBundle msg = _ctx.getMessageManager().getBundle(_bundle);
-        registerCommandHandler(msg, "help", new HelpHandler());
-        registerCommandHandler(msg, "clear", new ClearHandler());
-        registerCommandHandler(msg, "speak", new SpeakHandler());
-        registerCommandHandler(msg, "emote", new EmoteHandler());
-        registerCommandHandler(msg, "think", new ThinkHandler());
-        registerCommandHandler(msg, "tell", new TellHandler());
-        registerCommandHandler(msg, "broadcast", new BroadcastHandler());
-    }
-
     /**
      * Adds the supplied chat display to the front of the chat display list. It will subsequently
      * be notified of incoming chat messages as well as tell responses.
@@ -599,6 +584,21 @@ public class ChatDirector extends BasicDirector
         _auxes.remove(source.getOid());
     }
 
+    /**
+     * Returns the history list containing a trailing window of messages that have passed through
+     * this chat director. The history list is created on demand so that systems which don't make
+     * use of chat history need not incur the overhead of tracking historical chat messages. Thus
+     * messages will only be added to the history <em>after</em> this method has been called at
+     * least once.
+     */
+    public HistoryList getHistory ()
+    {
+        if (_hlist == null) {
+            addChatDisplay(_hlist = new HistoryList());
+        }
+        return _hlist;
+    }
+
     /**
      * Run a message through all the currently registered filters.
      */
@@ -702,6 +702,21 @@ public class ChatDirector extends BasicDirector
         _cservice = null;
     }
 
+    /**
+     * Registers all the chat-command handlers.
+     */
+    protected void registerCommandHandlers ()
+    {
+        MessageBundle msg = _ctx.getMessageManager().getBundle(_bundle);
+        registerCommandHandler(msg, "help", new HelpHandler());
+        registerCommandHandler(msg, "clear", new ClearHandler());
+        registerCommandHandler(msg, "speak", new SpeakHandler());
+        registerCommandHandler(msg, "emote", new EmoteHandler());
+        registerCommandHandler(msg, "think", new ThinkHandler());
+        registerCommandHandler(msg, "tell", new TellHandler());
+        registerCommandHandler(msg, "broadcast", new BroadcastHandler());
+    }
+
     /**
      * Processes and dispatches the specified chat message.
      */
@@ -1443,6 +1458,9 @@ public class ChatDirector extends BasicDirector
     /** Operation used to display chat messages. */
     protected DisplayMessageOp _displayMessageOp = new DisplayMessageOp();
 
+    /** A rolling chat history, or null if {@link #getHistory} is never called. */
+    protected HistoryList _hlist;
+
     /** Registered chat command handlers. */
     protected static HashMap<String, CommandHandler> _handlers = Maps.newHashMap();
 

src/java/com/threerings/crowd/chat/client/HistoryList.java

@@ -0,0 +1,127 @@
+//
+// $Id$
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2010 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.crowd.chat.client;
+
+import java.util.ArrayList;
+
+import com.samskivert.util.ObserverList;
+
+import com.threerings.crowd.chat.data.ChatMessage;
+
+/**
+ * Stores chat history.
+ */
+public class HistoryList extends ArrayList<ChatMessage>
+    implements ChatDisplay
+{
+    /** An interface for chat history observers. */
+    public interface Observer {
+        /** Called when messages have been added or removed from the chat history.
+         * @param adjustment the number of messages that have been added (+) or removed (-). */
+        void historyUpdated (int adjustment);
+    }
+
+    // documentation inherited from interface
+    public boolean displayMessage (ChatMessage msg, boolean alreadyDisplayed)
+    {
+        // see if we're full, and if so, clear out a bunch of old stuff
+        int adjusted;
+        if (size() == MAX_HISTORY) {
+            removeRange(0, PRUNE_HISTORY);
+            adjusted = PRUNE_HISTORY;
+
+        } else {
+            adjusted = 0;
+        }
+
+        // add the message to the history
+        add(msg);
+
+        // notify observers that something changed
+        notify(adjusted);
+
+        return true;
+    }
+
+    @Override
+    public void clear ()
+    {
+        // see how many entries we're clearing out..
+        int adjusted = size();
+        super.clear();
+
+        // and notify the chat displays of that fact
+        notify(adjusted);
+    }
+
+    /**
+     * Adds an {@link Observer} that wants to know about changes to the history.
+     */
+    public void addObserver (Observer obs)
+    {
+        _obs.add(obs);
+    }
+
+    /**
+     * Removes a {@link Observer} from hearing about changes to the history.
+     */
+    public void removeObserver (Observer obs)
+    {
+        _obs.remove(obs);
+    }
+
+    /**
+     * Notifies listening {@link Observer}s that there has been a change to this history.
+     */
+    protected void notify (int adjustment)
+    {
+        _historyUpdatedOp.setAdjustment(adjustment);
+        _obs.apply(_historyUpdatedOp);
+    }
+
+    protected static class HistoryUpdatedOp
+        implements ObserverList.ObserverOp<Observer>
+    {
+        public void setAdjustment (int adjustment) {
+            _adjustment = adjustment;
+        }
+
+        public boolean apply (Observer obs) {
+            obs.historyUpdated(_adjustment);
+            return true;
+        }
+
+        protected int _adjustment;
+    }
+
+    /** A list of {@link Observer}s interested in history changes. */
+    protected ObserverList<Observer> _obs = ObserverList.newFastUnsafe();
+
+    /** An operation used to notify observers of history updates. */
+    protected HistoryList.HistoryUpdatedOp _historyUpdatedOp = new HistoryUpdatedOp();
+
+    /** The maximum number of history entries we'll keep. */
+    protected static final int MAX_HISTORY = 2000;
+
+    /** The number of history entries we'll prune when we hit the max. */
+    protected static final int PRUNE_HISTORY = 200;
+}