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.amqp;
  
  import java.io.IOException;
  import java.util.ArrayList;
  
  import org.apache.activemq.broker.BrokerService;
  import org.apache.activemq.command.Command;
  import org.apache.activemq.transport.amqp.protocol.AmqpConnection;
  
  /**
   * Used to assign the best implementation of a AmqpProtocolConverter to the
   * AmqpTransport based on the AmqpHeader that the client sends us.
   */
  public class AmqpProtocolDiscriminator implements AmqpProtocolConverter {
  
      public static final int DEFAULT_PREFETCH = 1000;
  
      private final AmqpTransport transport;
      private final BrokerService brokerService;
  
      interface Discriminator {
          boolean matches(AmqpHeader header);
  
          AmqpProtocolConverter create(AmqpTransport transport, BrokerService brokerService);
      }
  
      static final private ArrayList<Discriminator> DISCRIMINATORS = new ArrayList<Discriminator>();
      static {
          DISCRIMINATORS.add(new Discriminator() {
  
              @Override
              public AmqpProtocolConverter create(AmqpTransport transport, BrokerService brokerService) {
                  return new AmqpConnection(transport, brokerService);
              }
  
              @Override
              public boolean matches(AmqpHeader header) {
                  switch (header.getProtocolId()) {
                      case 0:
                      case 3:
                          if (header.getMajor() == 1 && header.getMinor() == 0 && header.getRevision() == 0) {
                              return true;
                          }
                  }
                  return false;
              }
          });
      }
  
      final private ArrayList<Command> pendingCommands = new ArrayList<Command>();
  
      public AmqpProtocolDiscriminator(AmqpTransport transport, BrokerService brokerService) {
          this.transport = transport;
          this.brokerService = brokerService;
      }
  
      @Override
      public void onAMQPData(Object command) throws Exception {
          if (command.getClass() == AmqpHeader.class) {
              AmqpHeader header = (AmqpHeader) command;
  
              Discriminator match = null;
              for (Discriminator discriminator : DISCRIMINATORS) {
                  if (discriminator.matches(header)) {
                      match = discriminator;
                  }
              }
  
              // Lets use first in the list if none are a good match.
              if (match == null) {
                  match = DISCRIMINATORS.get(0);
              }
  
              AmqpProtocolConverter next = match.create(transport, brokerService);
              transport.setProtocolConverter(next);
              for (Command send : pendingCommands) {
                  next.onActiveMQCommand(send);
              }
              pendingCommands.clear();
              next.onAMQPData(command);
          } else {
              throw new IllegalStateException();
          }
      }
  
      @Override
      public void onAMQPException(IOException error) {
          transport.sendToActiveMQ(error);
      }
  
      @Override
      public void onActiveMQCommand(Command command) throws Exception {
          pendingCommands.add(command);
      }
  
      @Override
      public void updateTracer() {
      }
  
      @Override
      public long keepAlive() {
          return 0;
      }
  }
  