/*
    *  Copyright 2010 Felix Roethenbacher
    *
    *  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 ch.syabru.nagios.broker.impl;
  
  import java.io.PrintStream;
  import java.util.List;
  
  import javax.annotation.PreDestroy;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.annotation.Required;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.ApplicationContextAware;
  import org.springframework.context.support.AbstractApplicationContext;
  
  import ch.syabru.nagios.broker.MessageListener;
  import ch.syabru.nagios.broker.MessageListenerException;
  import ch.syabru.nagios.broker.NagiosMessageBroker;
  
  /**
   * Nagios message broker main class.
   *
   * @author Felix Roethenbacher
   *
   */
  public class NagiosMessageBrokerImpl
  implements Runnable, NagiosMessageBroker, ApplicationContextAware
  {
      private final Logger logger =
          LoggerFactory.getLogger(NagiosMessageBrokerImpl.class);
  
      private List<MessageListener> messageListeners;
      private AbstractApplicationContext applicationContext;
  
      private boolean isDaemon = false;
      private boolean stopping = false;
  
      @Override
      public void run() {
          if (!isDaemon)
              outputApplicationInfo();
          startMessageListeners();
          while (!stopping) {
              try {
                  Thread.sleep(1000);
              } catch (InterruptedException e) {
                  logger.error("Thread interrupted", e);
              }
          }
          logger.info("Shutting down ...");
          applicationContext.destroy();
          logger.info("Shutdown completed.");
      }
  
      /**
       * Start message listeners.
       */
      private void startMessageListeners() {
          for (MessageListener listener : messageListeners) {
              listener.registerListener();
          }
      }
  
      /**
       * Stop message listeners.
       */
      private void stopMessageListeners() {
          for (MessageListener listener : messageListeners) {
              try {
                  listener.unregisterListener();
              } catch (MessageListenerException e) {
                  logger.error("Error unregistering message listener", e);
              }
          }
      }
  
      /**
       * Shut-down method.
       */
      @PreDestroy
      public void destroy() {
          stopMessageListeners();
      }
  
      @Override
     public void start() {
         Thread t = new Thread(this);
         t.start();
     }
 
     @Override
     public void stop() {
         stopping = true;
     }
 
     /**
      * Output application info.
      */
     private void outputApplicationInfo() {
         PrintStream out = System.out;
         out.println("Syabru Nagios Message Broker");
         out.println();
         out.println("Hit 'Enter' to terminate application.");
     }
 
     @Required
     public void setMessageListeners(List<MessageListener> messageListeners) {
         this.messageListeners = messageListeners;
     }
 
     public void setIsDaemon(boolean isDaemon) {
         this.isDaemon = isDaemon;
     }
 
     @Override
     public void setApplicationContext(ApplicationContext applicationContext)
     {
         this.applicationContext =
             (AbstractApplicationContext) applicationContext;
     }
 }