content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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.apache.activemq.transport.mqtt.strategy;
  
  import static org.apache.activemq.transport.mqtt.MQTTProtocolSupport.convertActiveMQToMQTT;
  import static org.apache.activemq.transport.mqtt.MQTTProtocolSupport.convertMQTTToActiveMQ;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.StringTokenizer;
  
  import org.apache.activemq.ActiveMQPrefetchPolicy;
  import org.apache.activemq.broker.region.QueueRegion;
  import org.apache.activemq.broker.region.RegionBroker;
  import org.apache.activemq.command.ActiveMQDestination;
  import org.apache.activemq.command.ActiveMQQueue;
  import org.apache.activemq.command.ActiveMQTopic;
  import org.apache.activemq.command.ConsumerInfo;
  import org.apache.activemq.command.DestinationInfo;
  import org.apache.activemq.command.RemoveSubscriptionInfo;
  import org.apache.activemq.command.Response;
  import org.apache.activemq.command.SubscriptionInfo;
  import org.apache.activemq.transport.mqtt.MQTTProtocolConverter;
  import org.apache.activemq.transport.mqtt.MQTTProtocolException;
  import org.apache.activemq.transport.mqtt.MQTTProtocolSupport;
  import org.apache.activemq.transport.mqtt.MQTTSubscription;
  import org.apache.activemq.transport.mqtt.ResponseHandler;
  import org.fusesource.mqtt.client.QoS;
  import org.fusesource.mqtt.codec.CONNECT;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Subscription strategy that converts all MQTT subscribes that would be durable to
   * Virtual Topic Queue subscriptions.  Also maps all publish requests to be prefixed
   * with the VirtualTopic. prefix unless already present.
   */
  public class MQTTVirtualTopicSubscriptionStrategy extends AbstractMQTTSubscriptionStrategy {
  
      private static final String VIRTUALTOPIC_PREFIX = "VirtualTopic.";
      private static final String VIRTUALTOPIC_CONSUMER_PREFIX = "Consumer.";
  
      private static final Logger LOG = LoggerFactory.getLogger(MQTTVirtualTopicSubscriptionStrategy.class);
  
      private final Set<ActiveMQQueue> restoredQueues = Collections.synchronizedSet(new HashSet<ActiveMQQueue>());
  
      @Override
      public void onConnect(CONNECT connect) throws MQTTProtocolException {
          List<ActiveMQQueue> queues = lookupQueues(protocol.getClientId());
          List<SubscriptionInfo> subs = lookupSubscription(protocol.getClientId());
  
          // When clean session is true we must purge all of the client's old Queue subscriptions
          // and any durable subscriptions created on the VirtualTopic instance as well.
  
          if (connect.cleanSession()) {
              deleteDurableQueues(queues);
              deleteDurableSubs(subs);
          } else {
              restoreDurableQueue(queues);
              restoreDurableSubs(subs);
          }
      }
  
      @Override
      public byte onSubscribe(String topicName, QoS requestedQoS) throws MQTTProtocolException {
          ActiveMQDestination destination = null;
          int prefetch = ActiveMQPrefetchPolicy.DEFAULT_QUEUE_PREFETCH;
          ConsumerInfo consumerInfo = new ConsumerInfo(getNextConsumerId());
          String converted = convertMQTTToActiveMQ(topicName);
          if (!protocol.isCleanSession() && protocol.getClientId() != null && requestedQoS.ordinal() >= QoS.AT_LEAST_ONCE.ordinal()) {
  
              if (converted.startsWith(VIRTUALTOPIC_PREFIX)) {
                  destination = new ActiveMQTopic(converted);
                  prefetch = ActiveMQPrefetchPolicy.DEFAULT_DURABLE_TOPIC_PREFETCH;
                  consumerInfo.setSubscriptionName(requestedQoS + ":" + topicName);
              } else {
                  converted = VIRTUALTOPIC_CONSUMER_PREFIX +
                              convertMQTTToActiveMQ(protocol.getClientId()) + ":" + requestedQoS + "." +
                              VIRTUALTOPIC_PREFIX + converted;
                  destination = new ActiveMQQueue(converted);
                  prefetch = ActiveMQPrefetchPolicy.DEFAULT_QUEUE_PREFETCH;
              }
          } else {
              if (!converted.startsWith(VIRTUALTOPIC_PREFIX)) {
                  converted = VIRTUALTOPIC_PREFIX + converted;
              }
              destination = new ActiveMQTopic(converted);
              prefetch = ActiveMQPrefetchPolicy.DEFAULT_TOPIC_PREFETCH;
          }
  
          consumerInfo.setDestination(destination);
          if (protocol.getActiveMQSubscriptionPrefetch() > 0) {
              consumerInfo.setPrefetchSize(protocol.getActiveMQSubscriptionPrefetch());
          } else {
              consumerInfo.setPrefetchSize(prefetch);
          }
          consumerInfo.setRetroactive(true);
          consumerInfo.setDispatchAsync(true);
  
          return doSubscribe(consumerInfo, topicName, requestedQoS);
      }
  
      @Override
      public void onReSubscribe(MQTTSubscription mqttSubscription) throws MQTTProtocolException {
  
          ActiveMQDestination destination = mqttSubscription.getDestination();
  
          // check whether the Queue has been recovered in restoreDurableQueue
          // mark subscription available for recovery for duplicate subscription
          if (destination.isQueue() && restoredQueues.remove(destination)) {
              return;
          }
  
          // check whether the Topic has been recovered in restoreDurableSubs
          // mark subscription available for recovery for duplicate subscription
          if (destination.isTopic() && restoredDurableSubs.remove(destination.getPhysicalName())) {
              return;
          }
  
          if (mqttSubscription.getDestination().isTopic()) {
              super.onReSubscribe(mqttSubscription);
          } else {
              doUnSubscribe(mqttSubscription);
              ConsumerInfo consumerInfo = mqttSubscription.getConsumerInfo();
              consumerInfo.setConsumerId(getNextConsumerId());
              doSubscribe(consumerInfo, mqttSubscription.getTopicName(), mqttSubscription.getQoS());
          }
      }
  
      @Override
      public void onUnSubscribe(String topicName) throws MQTTProtocolException {
          MQTTSubscription subscription = mqttSubscriptionByTopic.remove(topicName);
          if (subscription != null) {
              doUnSubscribe(subscription);
              if (subscription.getDestination().isQueue()) {
                  DestinationInfo remove = new DestinationInfo();
                  remove.setConnectionId(protocol.getConnectionId());
                  remove.setDestination(subscription.getDestination());
                  remove.setOperationType(DestinationInfo.REMOVE_OPERATION_TYPE);
  
                  protocol.sendToActiveMQ(remove, new ResponseHandler() {
                      @Override
                      public void onResponse(MQTTProtocolConverter converter, Response response) throws IOException {
                          // ignore failures..
                      }
                  });
              } else if (subscription.getConsumerInfo().getSubscriptionName() != null) {
                  // also remove it from restored durable subscriptions set
                  restoredDurableSubs.remove(MQTTProtocolSupport.convertMQTTToActiveMQ(subscription.getTopicName()));
  
                  RemoveSubscriptionInfo rsi = new RemoveSubscriptionInfo();
                  rsi.setConnectionId(protocol.getConnectionId());
                  rsi.setSubscriptionName(subscription.getConsumerInfo().getSubscriptionName());
                  rsi.setClientId(protocol.getClientId());
                  protocol.sendToActiveMQ(rsi, new ResponseHandler() {
                      @Override
                      public void onResponse(MQTTProtocolConverter converter, Response response) throws IOException {
                          // ignore failures..
                      }
                  });
              }
          }
      }
  
      @Override
      public ActiveMQDestination onSend(String topicName) {
          ActiveMQTopic topic = new ActiveMQTopic(topicName);
          if (topic.isComposite()) {
             ActiveMQDestination[] composites = topic.getCompositeDestinations();
             for (ActiveMQDestination composite : composites) {
                  composite.setPhysicalName(prefix(composite.getPhysicalName()));
             }
             ActiveMQTopic result = new ActiveMQTopic();
             result.setCompositeDestinations(composites);
             return result;
          } else {
            return new ActiveMQTopic(prefix(topicName));
          }
      }
  
      private String prefix(String topicName) {
          if (!topicName.startsWith(VIRTUALTOPIC_PREFIX)) {
              return VIRTUALTOPIC_PREFIX + topicName;
          } else {
              return topicName;
          }
      }
  
      @Override
      public String onSend(ActiveMQDestination destination) {
          String destinationName = destination.getPhysicalName();
          int position = destinationName.indexOf(VIRTUALTOPIC_PREFIX);
          if (position >= 0) {
              destinationName = destinationName.substring(position + VIRTUALTOPIC_PREFIX.length()).substring(0);
          }
          return destinationName;
      }
  
      @Override
      public boolean isControlTopic(ActiveMQDestination destination) {
          String destinationName = destination.getPhysicalName();
          if (destinationName.startsWith("$") || destinationName.startsWith(VIRTUALTOPIC_PREFIX + "$")) {
              return true;
          }
          return false;
      }
  
      private void deleteDurableQueues(List<ActiveMQQueue> queues) {
          try {
              for (ActiveMQQueue queue : queues) {
                  LOG.debug("Removing queue subscription for {} ",queue.getPhysicalName());
                  DestinationInfo removeAction = new DestinationInfo();
                  removeAction.setConnectionId(protocol.getConnectionId());
                  removeAction.setDestination(queue);
                  removeAction.setOperationType(DestinationInfo.REMOVE_OPERATION_TYPE);
  
                  protocol.sendToActiveMQ(removeAction, new ResponseHandler() {
                      @Override
                      public void onResponse(MQTTProtocolConverter converter, Response response) throws IOException {
                          // ignore failures..
                      }
                  });
              }
          } catch (Throwable e) {
              LOG.warn("Could not delete the MQTT queue subscriptions.", e);
          }
      }
  
      private void restoreDurableQueue(List<ActiveMQQueue> queues) {
          try {
              for (ActiveMQQueue queue : queues) {
                  String name = queue.getPhysicalName().substring(VIRTUALTOPIC_CONSUMER_PREFIX.length());
                  StringTokenizer tokenizer = new StringTokenizer(name);
                  tokenizer.nextToken(":.");
                  String qosString = tokenizer.nextToken();
                  tokenizer.nextToken();
                  String topicName = convertActiveMQToMQTT(tokenizer.nextToken("").substring(1));
                  QoS qoS = QoS.valueOf(qosString);
                  LOG.trace("Restoring queue subscription: {}:{}", topicName, qoS);
  
                  ConsumerInfo consumerInfo = new ConsumerInfo(getNextConsumerId());
                  consumerInfo.setDestination(queue);
                  consumerInfo.setPrefetchSize(ActiveMQPrefetchPolicy.DEFAULT_QUEUE_PREFETCH);
                  if (protocol.getActiveMQSubscriptionPrefetch() > 0) {
                      consumerInfo.setPrefetchSize(protocol.getActiveMQSubscriptionPrefetch());
                  }
                  consumerInfo.setRetroactive(true);
                  consumerInfo.setDispatchAsync(true);
  
                  doSubscribe(consumerInfo, topicName, qoS);
  
                  // mark this durable subscription as restored by Broker
                  restoredQueues.add(queue);
              }
          } catch (IOException e) {
              LOG.warn("Could not restore the MQTT queue subscriptions.", e);
          }
      }
  
      List<ActiveMQQueue> lookupQueues(String clientId) throws MQTTProtocolException {
          List<ActiveMQQueue> result = new ArrayList<ActiveMQQueue>();
          RegionBroker regionBroker;
  
          try {
              regionBroker = (RegionBroker) brokerService.getBroker().getAdaptor(RegionBroker.class);
          } catch (Exception e) {
              throw new MQTTProtocolException("Error recovering queues: " + e.getMessage(), false, e);
          }
  
          final QueueRegion queueRegion = (QueueRegion) regionBroker.getQueueRegion();
          for (ActiveMQDestination destination : queueRegion.getDestinationMap().keySet()) {
              if (destination.isQueue() && !destination.isTemporary()) {
                  if (destination.getPhysicalName().startsWith("Consumer." + clientId + ":")) {
                      LOG.debug("Recovered client sub: {} on connect", destination.getPhysicalName());
                      result.add((ActiveMQQueue) destination);
                  }
              }
          }
  
          return result;
      }
  }
  