/*
    * 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.io.monitor;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.nio.file.attribute.FileTime;
  import java.time.Instant;
  import java.util.Objects;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.io.file.attribute.FileTimes;
  
  /**
   * Wraps a {@link FileTime} and allows it to be Serializable.
   *
   * <h2>Deprecating Serialization</h2>
   * <p>
   * <em>Serialization is deprecated and will be removed in 3.0.</em>
   * </p>
   */
  final class SerializableFileTime implements Serializable {
  
      static final SerializableFileTime EPOCH = new SerializableFileTime(FileTimes.EPOCH);
  
      private static final long serialVersionUID = 1L;
  
      private FileTime fileTime;
  
      SerializableFileTime(final FileTime fileTime) {
          this.fileTime = Objects.requireNonNull(fileTime);
      }
  
      public int compareTo(final FileTime other) {
          return fileTime.compareTo(other);
      }
  
      @Override
      public boolean equals(final Object obj) {
          if (this == obj) {
              return true;
          }
          if (!(obj instanceof SerializableFileTime)) {
              return false;
          }
          final SerializableFileTime other = (SerializableFileTime) obj;
          return Objects.equals(fileTime, other.fileTime);
      }
  
      @Override
      public int hashCode() {
          return fileTime.hashCode();
      }
  
      /**
       * Deserializes an instance from an ObjectInputStream.
       *
       * @param in The source ObjectInputStream.
       * @throws IOException            Any of the usual Input/Output related exceptions.
       * @throws ClassNotFoundException A class of a serialized object cannot be found.
       */
      private void readObject(final ObjectInputStream in) throws ClassNotFoundException, IOException {
          this.fileTime = FileTime.from((Instant) in.readObject());
      }
  
      long to(final TimeUnit unit) {
          return fileTime.to(unit);
      }
  
      Instant toInstant() {
          return fileTime.toInstant();
      }
  
      long toMillis() {
          return fileTime.toMillis();
      }
  
      @Override
      public String toString() {
          return fileTime.toString();
      }
  
      FileTime unwrap() {
         return fileTime;
     }
 
     private void writeObject(final ObjectOutputStream oos) throws IOException {
         oos.writeObject(fileTime.toInstant());
     }
 }