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.artemis.jms.client;
  
  import javax.jms.JMSException;
  import javax.jms.Queue;
  import javax.jms.QueueBrowser;
  import java.util.Enumeration;
  import java.util.NoSuchElementException;
  import java.util.Objects;
  
  import org.apache.activemq.artemis.api.core.ActiveMQException;
  import org.apache.activemq.artemis.api.core.SimpleString;
  import org.apache.activemq.artemis.api.core.client.ClientConsumer;
  import org.apache.activemq.artemis.api.core.client.ClientMessage;
  import org.apache.activemq.artemis.api.core.client.ClientSession;
  import org.apache.activemq.artemis.jms.client.compatible1X.ActiveMQCompatibleMessage;
  import org.apache.activemq.artemis.utils.SelectorTranslator;
  
  /**
   * ActiveMQ Artemis implementation of a JMS QueueBrowser.
   */
  public final class ActiveMQQueueBrowser implements QueueBrowser {
  
  
     private final ConnectionFactoryOptions options;
  
     private final ClientSession session;
  
     private ClientConsumer consumer;
  
     private final ActiveMQQueue queue;
  
     private SimpleString filterString;
  
     private final boolean enable1xPrefixes;
  
  
  
     protected ActiveMQQueueBrowser(final ConnectionFactoryOptions options,
                                    final ActiveMQQueue queue,
                                    final String messageSelector,
                                    final ClientSession session,
                                    final boolean enable1xPrefixes) throws JMSException {
        this.options = options;
        this.session = session;
        this.queue = queue;
        if (messageSelector != null) {
           filterString = SimpleString.of(SelectorTranslator.convertToActiveMQFilterString(messageSelector));
        }
        this.enable1xPrefixes = enable1xPrefixes;
     }
  
     // QueueBrowser implementation -------------------------------------------------------------------
  
     @Override
     public void close() throws JMSException {
        if (consumer != null) {
           try {
              consumer.close();
           } catch (ActiveMQException e) {
              throw JMSExceptionHelper.convertFromActiveMQException(e);
           }
        }
     }
  
     @Override
     public Enumeration getEnumeration() throws JMSException {
        try {
           close();
  
           consumer = session.createConsumer(queue.getSimpleAddress(), filterString, true);
  
           return new BrowserEnumeration();
        } catch (ActiveMQException e) {
           throw JMSExceptionHelper.convertFromActiveMQException(e);
        }
  
     }
  
     @Override
     public String getMessageSelector() throws JMSException {
        return Objects.toString(filterString, null);
     }
  
     @Override
     public Queue getQueue() throws JMSException {
        return queue;
     }
  
  
     @Override
     public String toString() {
        return "ActiveMQQueueBrowser->" + consumer;
     }
  
     private final class BrowserEnumeration implements Enumeration<ActiveMQMessage> {
  
        ClientMessage current = null;
  
        @Override
        public boolean hasMoreElements() {
           if (current == null) {
              try {
                 current = consumer.receiveImmediate();
              } catch (ActiveMQException e) {
                 return false;
              }
           }
           return current != null;
        }
  
        @Override
        public ActiveMQMessage nextElement() {
           ActiveMQMessage msg;
           if (hasMoreElements()) {
              ClientMessage next = current;
              current = null;
              if (enable1xPrefixes) {
                 msg = ActiveMQCompatibleMessage.createMessage(next, session, options);
              } else {
                 msg = ActiveMQMessage.createMessage(next, session, options);
              }
  
              try {
                 msg.doBeforeReceive();
              } catch (Exception e) {
                 ActiveMQJMSClientLogger.LOGGER.errorCreatingMessage(msg.getCoreMessage().toString(), e);
  
                 return null;
              }
              return msg;
           } else {
              throw new NoSuchElementException();
           }
        }
     }
  }
  