/*
    *  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.compress.utils;
  
  import java.nio.file.attribute.FileTime;
  import java.time.Instant;
  import java.util.Date;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.io.file.attribute.FileTimes;
  
  /**
   * Utility class for handling time-related types and conversions.
   * <p>
   * Understanding Unix vs NTFS timestamps:
   * </p>
   * <ul>
   * <li>A <a href="https://en.wikipedia.org/wiki/Unix_time">Unix timestamp</a> is a primitive long starting at the Unix Epoch on January 1st, 1970 at Coordinated
   * Universal Time (UTC)</li>
   * <li>An <a href="https://learn.microsoft.com/en-us/windows/win32/sysinfo/file-times">NTFS timestamp</a> is a file time is a 64-bit value that represents the
   * number of 100-nanosecond intervals that have elapsed since 12:00 A.M. January 1, 1601 Coordinated Universal Time (UTC).</li>
   * </ul>
   *
   * @since 1.23
   */
  public final class TimeUtils {
  
      /** The amount of 100-nanosecond intervals in one millisecond. */
      static final long HUNDRED_NANOS_PER_MILLISECOND = TimeUnit.MILLISECONDS.toNanos(1) / 100;
  
      /**
       * <a href="https://msdn.microsoft.com/en-us/library/windows/desktop/ms724290%28v=vs.85%29.aspx">Windows File Times</a>
       * <p>
       * A file time is a 64-bit value that represents the number of 100-nanosecond intervals that have elapsed since 12:00 A.M. January 1, 1601 Coordinated
       * Universal Time (UTC). This is the offset of Windows time 0 to Unix epoch in 100-nanosecond intervals.
       * </p>
       */
      static final long WINDOWS_EPOCH_OFFSET = -116444736000000000L;
  
      /**
       * Tests whether a FileTime can be safely represented in the standard UNIX time.
       *
       * <p>
       * TODO ? If the FileTime is null, this method always returns true.
       * </p>
       *
       * @param time the FileTime to evaluate, can be null.
       * @return true if the time exceeds the minimum or maximum UNIX time, false otherwise.
       */
      public static boolean isUnixTime(final FileTime time) {
          // TODO Apache Commons IO 2.16.0
          return isUnixTime(toUnixTime(time));
      }
  
      /**
       * Tests whether a given number of seconds (since Epoch) can be safely represented in the standard UNIX time.
       *
       * @param seconds the number of seconds (since Epoch) to evaluate.
       * @return true if the time can be represented in the standard UNIX time, false otherwise.
       */
      public static boolean isUnixTime(final long seconds) {
          // TODO Apache Commons IO 2.16.0
          return Integer.MIN_VALUE <= seconds && seconds <= Integer.MAX_VALUE;
      }
  
      /**
       * Converts NTFS time (100 nanosecond units since 1 January 1601) to Java time.
       *
       * @param ntfsTime the NTFS time in 100 nanosecond units.
       * @return the Date.
       * @deprecated Use {@link FileTimes#ntfsTimeToDate(long)}.
       */
      @Deprecated
      public static Date ntfsTimeToDate(final long ntfsTime) {
          return FileTimes.ntfsTimeToDate(ntfsTime);
      }
  
      /**
       * Converts NTFS time (100-nanosecond units since 1 January 1601) to a FileTime.
       *
       * @param ntfsTime the NTFS time in 100-nanosecond units.
       * @return the FileTime.
       * @see FileTimes#toNtfsTime(FileTime)
       * @deprecated Use {@link FileTimes#ntfsTimeToFileTime(long)}.
       */
     @Deprecated
     public static FileTime ntfsTimeToFileTime(final long ntfsTime) {
         return FileTimes.ntfsTimeToFileTime(ntfsTime);
     }
 
     /**
      * Converts {@link FileTime} to a {@link Date}. If the provided FileTime is {@code null}, the returned Date is also {@code null}.
      *
      * @param fileTime the file time to be converted.
      * @return a {@link Date} which corresponds to the supplied time, or {@code null} if the time is {@code null}.
      * @see FileTimes#toFileTime(Date)
      * @deprecated Use {@link FileTimes#toDate(FileTime)}.
      */
     @Deprecated
     public static Date toDate(final FileTime fileTime) {
         return FileTimes.toDate(fileTime);
     }
 
     /**
      * Converts {@link Date} to a {@link FileTime}. If the provided Date is {@code null}, the returned FileTime is also {@code null}.
      *
      * @param date the date to be converted.
      * @return a {@link FileTime} which corresponds to the supplied date, or {@code null} if the date is {@code null}.
      * @see FileTimes#toDate(FileTime)
      * @deprecated Use {@link FileTimes#toFileTime(Date)}.
      */
     @Deprecated
     public static FileTime toFileTime(final Date date) {
         return FileTimes.toFileTime(date);
     }
 
     /**
      * Converts a {@link Date} to NTFS time.
      *
      * @param date the Date.
      * @return the NTFS time.
      * @deprecated Use {@link FileTimes#toNtfsTime(Date)}.
      */
     @Deprecated
     public static long toNtfsTime(final Date date) {
         return FileTimes.toNtfsTime(date);
     }
 
     /**
      * Converts a {@link FileTime} to NTFS time (100-nanosecond units since 1 January 1601).
      *
      * @param fileTime the FileTime.
      * @return the NTFS time in 100-nanosecond units.
      * @see FileTimes#ntfsTimeToFileTime(long)
      * @deprecated Use {@link FileTimes#toNtfsTime(FileTime)}.
      */
     @Deprecated
     public static long toNtfsTime(final FileTime fileTime) {
         return FileTimes.toNtfsTime(fileTime);
     }
 
     /**
      * Converts Java time (milliseconds since Epoch) to NTFS time.
      *
      * @param javaTime the Java time.
      * @return the NTFS time.
      */
     public static long toNtfsTime(final long javaTime) {
         // TODO Apache Commons IO 2.16.0
         final long javaHundredNanos = javaTime * HUNDRED_NANOS_PER_MILLISECOND;
         return Math.subtractExact(javaHundredNanos, WINDOWS_EPOCH_OFFSET);
     }
 
     /**
      * Converts {@link FileTime} to standard UNIX time.
      *
      * @param fileTime the original FileTime.
      * @return the UNIX timestamp.
      */
     public static long toUnixTime(final FileTime fileTime) {
         // TODO Apache Commons IO 2.16.0
         return fileTime != null ? fileTime.to(TimeUnit.SECONDS) : 0;
     }
 
     /**
      * Truncates a FileTime to 100-nanosecond precision.
      *
      * @param fileTime the FileTime to be truncated.
      * @return the truncated FileTime.
      */
     public static FileTime truncateToHundredNanos(final FileTime fileTime) {
         final Instant instant = fileTime.toInstant();
         return FileTime.from(Instant.ofEpochSecond(instant.getEpochSecond(), instant.getNano() / 100 * 100));
     }
 
     /**
      * Converts standard UNIX time (in seconds, UTC/GMT) to {@link FileTime}.
      *
      * @param time UNIX timestamp (in seconds, UTC/GMT).
      * @return the corresponding FileTime.
      */
     public static FileTime unixTimeToFileTime(final long time) {
         // TODO Apache Commons IO 2.16.0 FileTimes.fromUnixTime(long)
         return FileTime.from(time, TimeUnit.SECONDS);
     }
 
     /** Private constructor to prevent instantiation of this utility class. */
     private TimeUtils() {
     }
 }