/**
 * 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.usecases;

import javax.jms.Connection;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.TextMessage;
import java.util.LinkedList;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.broker.BrokerRegistry;
import org.apache.activemq.broker.region.DestinationStatistics;
import org.apache.activemq.broker.region.RegionBroker;
import org.apache.activemq.util.Wait;
import org.apache.activemq.util.Wait.Condition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 */
public class ConsumeTopicPrefetchTest extends ProducerConsumerTestSupport {

   private static final Logger LOG = LoggerFactory.getLogger(ConsumeTopicPrefetchTest.class);

   protected int prefetchSize = 100;
   protected String[] messageTexts;
   protected long consumerTimeout = 10000L;

   public void testSendPrefetchSize() throws JMSException {
      testWithMessageCount(prefetchSize);
   }

   public void testSendDoublePrefetchSize() throws JMSException {
      testWithMessageCount(prefetchSize * 2);
   }

   public void testSendPrefetchSizePlusOne() throws JMSException {
      testWithMessageCount(prefetchSize + 1);
   }

   protected void testWithMessageCount(int messageCount) throws JMSException {
      makeMessages(messageCount);

      LOG.info("About to send and receive: " + messageCount + " on destination: " + destination + " of type: " + destination.getClass().getName());

      for (int i = 0; i < messageCount; i++) {
         Message message = session.createTextMessage(messageTexts[i]);
         producer.send(message);
      }

      validateConsumerPrefetch(this.getSubject(), prefetchSize);

      LinkedList<TextMessage> consumed = new LinkedList<>();
      // lets consume them in two fetch batches
      int batchSize = messageCount / 2;
      for (int i = 0; i < batchSize; i++) {
         consumed.add(consumeMessge(i));
      }

      // delayed delivered ack a .5 prefetch
      validateConsumerPrefetchGreaterOrEqual(this.getSubject(), (long) Math.min(messageCount, 1.5 * prefetchSize));

      for (int i = 0; i < batchSize; i++) {
         consumed.remove().acknowledge();
      }

      // second batch to consume the rest
      for (int i = batchSize; i < messageCount; i++) {
         consumeMessge(i).acknowledge();
      }
      validateConsumerPrefetch(this.getSubject(), 0);
   }

   @Override
   protected Connection createConnection() throws Exception {
      ActiveMQConnection connection = (ActiveMQConnection) super.createConnection();
      connection.getPrefetchPolicy().setQueuePrefetch(prefetchSize);
      connection.getPrefetchPolicy().setTopicPrefetch(prefetchSize);
      return connection;
   }

   protected TextMessage consumeMessge(int i) throws JMSException {
      Message message = consumer.receive(consumerTimeout);
      assertTrue("Should have received a message by now for message: " + i, message != null);
      assertTrue("Should be a TextMessage: " + message, message instanceof TextMessage);
      TextMessage textMessage = (TextMessage) message;
      assertEquals("Message content", messageTexts[i], textMessage.getText());
      return textMessage;
   }

   protected void makeMessages(int messageCount) {
      messageTexts = new String[messageCount];
      for (int i = 0; i < messageCount; i++) {
         messageTexts[i] = "Message for test: + " + getName() + " = " + i;
      }
   }

   private void validateConsumerPrefetchGreaterOrEqual(String subject, long min) throws JMSException {
      doValidateConsumerPrefetch(subject, min, true);
   }

   protected void validateConsumerPrefetch(String subject, final long expectedCount) throws JMSException {
      doValidateConsumerPrefetch(subject, expectedCount, false);
   }

   protected void doValidateConsumerPrefetch(String destination,
                                             final long expectedCount,
                                             final boolean greaterOrEqual) throws JMSException {
      RegionBroker regionBroker = (RegionBroker) BrokerRegistry.getInstance().lookup("localhost").getRegionBroker();
      for (org.apache.activemq.broker.region.Destination dest : regionBroker.getTopicRegion().getDestinationMap().values()) {
         final org.apache.activemq.broker.region.Destination target = dest;
         if (dest.getName().equals(destination)) {
            try {
               Wait.waitFor(new Condition() {
                  @Override
                  public boolean isSatisified() throws Exception {
                     DestinationStatistics stats = target.getDestinationStatistics();
                     LOG.info("inflight for : " + target.getName() + ": " + stats.getInflight().getCount());
                     if (greaterOrEqual) {
                        return stats.getInflight().getCount() >= expectedCount;
                     } else {
                        return stats.getInflight().getCount() == expectedCount;
                     }
                  }
               });
            } catch (Exception e) {
               throw new JMSException(e.toString());
            }
            DestinationStatistics stats = dest.getDestinationStatistics();
            LOG.info("inflight for : " + dest.getName() + ": " + stats.getInflight().getCount());
            if (greaterOrEqual) {
               assertTrue("inflight for: " + dest.getName() + ": " + stats.getInflight().getCount() + " > " + stats.getInflight().getCount(), stats.getInflight().getCount() >= expectedCount);
            } else {
               assertEquals("inflight for: " + dest.getName() + ": " + stats.getInflight().getCount() + " matches", expectedCount, stats.getInflight().getCount());
            }
         }
      }
   }
}
