/*
    * 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.logging.log4j.core.config;
  
  import java.io.File;
  import java.util.List;
  
  import org.apache.logging.log4j.core.util.AbstractWatcher;
  import org.apache.logging.log4j.core.util.FileWatcher;
  import org.apache.logging.log4j.core.util.Source;
  import org.apache.logging.log4j.core.util.Watcher;
  
  /**
   * Watcher for configuration files. Causes a reconfiguration when a file changes.
   */
  public class ConfigurationFileWatcher extends AbstractWatcher implements FileWatcher {
  
      private File file;
      private long lastModifiedMillis;
  
      public ConfigurationFileWatcher(final Configuration configuration, final Reconfigurable reconfigurable,
              final List<ConfigurationListener> configurationListeners, long lastModifiedMillis) {
          super(configuration, reconfigurable, configurationListeners);
          this.lastModifiedMillis = lastModifiedMillis;
      }
  
      public long getLastModified() {
          return file != null ? file.lastModified() : 0;
      }
  
      @Override
      public void fileModified(final File file) {
          lastModifiedMillis = file.lastModified();
      }
  
      @Override
      public void watching(Source source) {
          file = source.getFile();
          lastModifiedMillis = file.lastModified();
          super.watching(source);
      }
  
      @Override
      public boolean isModified() {
          return lastModifiedMillis != file.lastModified();
      }
  
      @Override
      public Watcher newWatcher(final Reconfigurable reconfigurable, final List<ConfigurationListener> listeners,
          long lastModifiedMillis) {
          ConfigurationFileWatcher watcher = new ConfigurationFileWatcher(getConfiguration(), reconfigurable, listeners,
              lastModifiedMillis);
          if (getSource() != null) {
              watcher.watching(getSource());
          }
          return watcher;
      }
  }