/*
    * 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.commons.jci.examples.configuration;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Properties;
  
  import org.apache.commons.jci.listeners.FileChangeListener;
  import org.apache.commons.jci.monitor.FilesystemAlterationListener;
  import org.apache.commons.jci.monitor.FilesystemAlterationMonitor;
  import org.apache.commons.jci.monitor.FilesystemAlterationObserver;
  
  /**
   * 
   * @author tcurdt
   */
  public final class ConfigurationReloading {
  
      private final FilesystemAlterationMonitor fam = new FilesystemAlterationMonitor();
  
      private void run(String[] args) {
  
          final File configFile = new File("some.properties");
  
          System.out.println("Watching " + configFile.getAbsolutePath());
  
          final Collection<Configurable> configurables = new ArrayList<Configurable>();
  
          final FilesystemAlterationListener listener = new FileChangeListener() {
              public void onStop(FilesystemAlterationObserver pObserver) {
                  super.onStop(pObserver);
  
                  if (hasChanged()) {
                      System.out.println("Configuration change detected " + configFile);
  
                      final Properties props = new Properties();
                      InputStream is = null; 
                      try {
                      	is = new FileInputStream(configFile);
                          props.load(is);
  
                          System.out.println("Notifying about configuration change " + configFile);
  
                          for (Configurable configurable : configurables) {
                              configurable.configure(props);
                          }
  
                      } catch (Exception e) {
                          System.err.println("Failed to load configuration " + configFile);
                      } finally {
                      	try {
  							is.close();
  						} catch (IOException e) {
  						}
                      }
  
                  }
              }
          };
  
          fam.addListener(configFile, listener);
  		fam.start();
  
  		configurables.add(new Something());
  
          while(true) {
              try {
                  Thread.sleep(1000);
              } catch (InterruptedException e) {
              }
          }
      }
  
      public static void main(String[] args) {
          new ConfigurationReloading().run(args);
      }
  }