[muc] Introduce MucMessageInterceptor

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MucMessageInterceptor.java

@@ -0,0 +1,25 @@
+/**
+ *
+ * Copyright 2021 Florian Schmaus
+ *
+ * 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 org.jivesoftware.smackx.muc;
+
+import org.jivesoftware.smack.packet.MessageBuilder;
+
+public interface MucMessageInterceptor {
+
+    void intercept(MessageBuilder messageBuilder, MultiUserChat multiUserChat);
+
+}

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MultiUserChat.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -156,10 +157,13 @@ public class MultiUserChat {
      */
     private volatile boolean processedReflectedSelfPresence;
 
+    private CopyOnWriteArrayList<MucMessageInterceptor> messageInterceptors;
+
     MultiUserChat(XMPPConnection connection, EntityBareJid room, MultiUserChatManager multiUserChatManager) {
         this.connection = connection;
         this.room = room;
         this.multiUserChatManager = multiUserChatManager;
+        this.messageInterceptors = MultiUserChatManager.getMessageInterceptors();
 
         fromRoomFilter = FromMatchesFilter.create(room);
         fromRoomGroupchatFilter = new AndFilter(fromRoomFilter, MessageTypeFilter.GROUPCHAT);
@@ -778,8 +782,7 @@ public class MultiUserChat {
                                         MUCUserStatusCodeFilter.STATUS_110_PRESENCE_TO_SELF),
                         new AndFilter(fromRoomFilter, PresenceTypeFilter.ERROR)));
 
-        boolean supportsStableId = mucServiceDiscoInfo.containsFeature(MultiUserChatConstants.STABLE_ID_FEATURE);
-        if (supportsStableId) {
+        if (serviceSupportsStableIds()) {
             reflectedLeavePresenceFilters.add(new StanzaIdFilter(leavePresence));
         }
 
@@ -2035,6 +2038,10 @@ public class MultiUserChat {
      * @throws InterruptedException if the calling thread was interrupted.
      */
     public void sendMessage(MessageBuilder messageBuilder) throws NotConnectedException, InterruptedException {
+        for (MucMessageInterceptor interceptor : messageInterceptors) {
+            interceptor.intercept(messageBuilder, this);
+        }
+
         Message message = messageBuilder.to(room).ofType(Message.Type.groupchat).build();
         connection.sendStanza(message);
     }
@@ -2118,6 +2125,14 @@ public class MultiUserChat {
         return messageListeners.remove(listener);
     }
 
+    public boolean addMessageInterceptor(MucMessageInterceptor interceptor) {
+        return messageInterceptors.add(interceptor);
+    }
+
+    public boolean removeMessageInterceptor(MucMessageInterceptor interceptor) {
+        return messageInterceptors.remove(interceptor);
+    }
+
     /**
      * Changes the subject within the room. As a default, only users with a role of "moderator"
      * are allowed to change the subject in a room. Although some rooms may be configured to
@@ -2539,6 +2554,10 @@ public class MultiUserChat {
         return connection;
     }
 
+    public boolean serviceSupportsStableIds() {
+        return mucServiceDiscoInfo.containsFeature(MultiUserChatConstants.STABLE_ID_FEATURE);
+    }
+
     @Override
     public String toString() {
         return "MUC: " + room + "(" + connection.getUser() + ")";

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MultiUserChatManager.java

@@ -20,10 +20,12 @@ import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.WeakHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -140,6 +142,8 @@ public final class MultiUserChatManager extends Manager {
     private static final ExpirationCache<DomainBareJid, DiscoverInfo> KNOWN_MUC_SERVICES = new ExpirationCache<>(
         100, 1000 * 60 * 60 * 24);
 
+    private static final Set<MucMessageInterceptor> DEFAULT_MESSAGE_INTERCEPTORS = new HashSet<>();
+
     private final Set<InvitationListener> invitationsListeners = new CopyOnWriteArraySet<InvitationListener>();
 
     /**
@@ -275,6 +279,18 @@ public final class MultiUserChatManager extends Manager {
         return multiUserChat;
     }
 
+    public static boolean addDefaultMessageInterceptor(MucMessageInterceptor messageInterceptor) {
+        synchronized (DEFAULT_MESSAGE_INTERCEPTORS) {
+            return DEFAULT_MESSAGE_INTERCEPTORS.add(messageInterceptor);
+        }
+    }
+
+    public static boolean removeDefaultMessageInterceptor(MucMessageInterceptor messageInterceptor) {
+        synchronized (DEFAULT_MESSAGE_INTERCEPTORS) {
+            return DEFAULT_MESSAGE_INTERCEPTORS.remove(messageInterceptor);
+        }
+    }
+
     private MultiUserChat createNewMucAndAddToMap(EntityBareJid jid) {
         MultiUserChat multiUserChat = new MultiUserChat(connection(), jid, this);
         multiUserChats.put(jid, new WeakReference<MultiUserChat>(multiUserChat));
@@ -535,4 +551,10 @@ public final class MultiUserChatManager extends Manager {
     void removeJoinedRoom(EntityBareJid room) {
         joinedRooms.remove(room);
     }
+
+    static CopyOnWriteArrayList<MucMessageInterceptor> getMessageInterceptors() {
+        synchronized (DEFAULT_MESSAGE_INTERCEPTORS) {
+            return new CopyOnWriteArrayList<>(DEFAULT_MESSAGE_INTERCEPTORS);
+        }
+    }
 }