/*-
 * ============LICENSE_START=======================================================
 * org.openecomp.aai
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.openecomp.aai.util;

import java.util.*;
import java.io.*;

public abstract class FileWatcher extends TimerTask {
  private long timeStamp;
  private File file;

  /**
   * Instantiates a new file watcher.
   *
   * @param file the file
   */
  public FileWatcher( File file ) {
    this.file = file;
    this.timeStamp = file.lastModified();
  }

  /**
   * runs a timer task
   * @see java.util.TimerTask.run
   */
  public final void run() {
    long timeStamp = file.lastModified();

    if( (timeStamp - this.timeStamp) > 500 ) {
      this.timeStamp = timeStamp;
      onChange(file);
    }
  }
  
  /**
   * On change.
   *
   * @param file the file
   */
  protected abstract void onChange( File file );
}