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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  /*
   * This file is available under and governed by the GNU General Public
   * License version 2 only, as published by the Free Software Foundation.
   * However, the following notice accompanied the original version of this
   * file:
   *
   * Copyright (c) 2012-2013, Stephen Colebourne & Michael Nascimento Santos
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *  * Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   *
   *  * Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
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   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
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   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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  package java.time.temporal;
  
  import static java.time.temporal.ChronoField.DAY_OF_MONTH;
  import static java.time.temporal.ChronoField.DAY_OF_WEEK;
  import static java.time.temporal.ChronoField.DAY_OF_YEAR;
  import static java.time.temporal.ChronoUnit.DAYS;
  import static java.time.temporal.ChronoUnit.MONTHS;
  import static java.time.temporal.ChronoUnit.YEARS;
  
  import java.time.DayOfWeek;
  import java.time.LocalDate;
  import java.util.Objects;
  import java.util.function.UnaryOperator;
  
  /**
   * Common and useful TemporalAdjusters.
   * <p>
   * Adjusters are a key tool for modifying temporal objects.
   * They exist to externalize the process of adjustment, permitting different
   * approaches, as per the strategy design pattern.
   * Examples might be an adjuster that sets the date avoiding weekends, or one that
   * sets the date to the last day of the month.
   * <p>
   * There are two equivalent ways of using a {@code TemporalAdjuster}.
   * The first is to invoke the method on the interface directly.
   * The second is to use {@link Temporal#with(TemporalAdjuster)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisAdjuster.adjustInto(temporal);
   *   temporal = temporal.with(thisAdjuster);
   * </pre>
   * It is recommended to use the second approach, {@code with(TemporalAdjuster)},
   * as it is a lot clearer to read in code.
   * <p>
   * This class contains a standard set of adjusters, available as static methods.
   * These include:
   * <ul>
   * <li>finding the first or last day of the month
   * <li>finding the first day of next month
   * <li>finding the first or last day of the year
   * <li>finding the first day of next year
   * <li>finding the first or last day-of-week within a month, such as "first Wednesday in June"
   * <li>finding the next or previous day-of-week, such as "next Thursday"
   * </ul>
   *
   * @implSpec
   * All the implementations supplied by the static methods are immutable.
   *
   * @see TemporalAdjuster
   * @since 1.8
   */
  public final class TemporalAdjusters {
  
      /**
       * Private constructor since this is a utility class.
       */
      private TemporalAdjusters() {
      }
  
      //-----------------------------------------------------------------------
      /**
       * Obtains a {@code TemporalAdjuster} that wraps a date adjuster.
       * <p>
       * The {@code TemporalAdjuster} is based on the low level {@code Temporal} interface.
       * This method allows an adjustment from {@code LocalDate} to {@code LocalDate}
       * to be wrapped to match the temporal-based interface.
       * This is provided for convenience to make user-written adjusters simpler.
       * <p>
       * In general, user-written adjusters should be static constants:
       * <pre>{@code
       *  static TemporalAdjuster TWO_DAYS_LATER =
       *       TemporalAdjusters.ofDateAdjuster(date -> date.plusDays(2));
       * }</pre>
       *
       * @param dateBasedAdjuster  the date-based adjuster, not null
       * @return the temporal adjuster wrapping on the date adjuster, not null
       */
      public static TemporalAdjuster ofDateAdjuster(UnaryOperator<LocalDate> dateBasedAdjuster) {
          Objects.requireNonNull(dateBasedAdjuster, "dateBasedAdjuster");
          return (temporal) -> {
              LocalDate input = LocalDate.from(temporal);
              LocalDate output = dateBasedAdjuster.apply(input);
              return temporal.with(output);
          };
      }
  
      //-----------------------------------------------------------------------
      /**
       * Returns the "first day of month" adjuster, which returns a new date set to
       * the first day of the current month.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2011-01-01.<br>
       * The input 2011-02-15 will return 2011-02-01.
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  temporal.with(DAY_OF_MONTH, 1);
       * </pre>
       *
       * @return the first day-of-month adjuster, not null
       */
      public static TemporalAdjuster firstDayOfMonth() {
          return (temporal) -> temporal.with(DAY_OF_MONTH, 1);
      }
  
      /**
       * Returns the "last day of month" adjuster, which returns a new date set to
       * the last day of the current month.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2011-01-31.<br>
       * The input 2011-02-15 will return 2011-02-28.<br>
       * The input 2012-02-15 will return 2012-02-29 (leap year).<br>
       * The input 2011-04-15 will return 2011-04-30.
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  long lastDay = temporal.range(DAY_OF_MONTH).getMaximum();
       *  temporal.with(DAY_OF_MONTH, lastDay);
       * </pre>
       *
       * @return the last day-of-month adjuster, not null
       */
      public static TemporalAdjuster lastDayOfMonth() {
          return (temporal) -> temporal.with(DAY_OF_MONTH, temporal.range(DAY_OF_MONTH).getMaximum());
      }
  
      /**
       * Returns the "first day of next month" adjuster, which returns a new date set to
       * the first day of the next month.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2011-02-01.<br>
       * The input 2011-02-15 will return 2011-03-01.
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  temporal.with(DAY_OF_MONTH, 1).plus(1, MONTHS);
       * </pre>
       *
       * @return the first day of next month adjuster, not null
       */
      public static TemporalAdjuster firstDayOfNextMonth() {
          return (temporal) -> temporal.with(DAY_OF_MONTH, 1).plus(1, MONTHS);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Returns the "first day of year" adjuster, which returns a new date set to
       * the first day of the current year.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2011-01-01.<br>
       * The input 2011-02-15 will return 2011-01-01.<br>
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  temporal.with(DAY_OF_YEAR, 1);
       * </pre>
       *
       * @return the first day-of-year adjuster, not null
       */
      public static TemporalAdjuster firstDayOfYear() {
          return (temporal) -> temporal.with(DAY_OF_YEAR, 1);
      }
  
      /**
       * Returns the "last day of year" adjuster, which returns a new date set to
       * the last day of the current year.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2011-12-31.<br>
       * The input 2011-02-15 will return 2011-12-31.<br>
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  long lastDay = temporal.range(DAY_OF_YEAR).getMaximum();
       *  temporal.with(DAY_OF_YEAR, lastDay);
       * </pre>
       *
       * @return the last day-of-year adjuster, not null
       */
      public static TemporalAdjuster lastDayOfYear() {
          return (temporal) -> temporal.with(DAY_OF_YEAR, temporal.range(DAY_OF_YEAR).getMaximum());
      }
  
      /**
       * Returns the "first day of next year" adjuster, which returns a new date set to
       * the first day of the next year.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 will return 2012-01-01.
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It is equivalent to:
       * <pre>
       *  temporal.with(DAY_OF_YEAR, 1).plus(1, YEARS);
       * </pre>
       *
       * @return the first day of next month adjuster, not null
       */
      public static TemporalAdjuster firstDayOfNextYear() {
          return (temporal) -> temporal.with(DAY_OF_YEAR, 1).plus(1, YEARS);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Returns the first in month adjuster, which returns a new date
       * in the same month with the first matching day-of-week.
       * This is used for expressions like 'first Tuesday in March'.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-12-15 for (MONDAY) will return 2011-12-05.<br>
       * The input 2011-12-15 for (FRIDAY) will return 2011-12-02.<br>
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields
       * and the {@code DAYS} unit, and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week, not null
       * @return the first in month adjuster, not null
       */
      public static TemporalAdjuster firstInMonth(DayOfWeek dayOfWeek) {
          return TemporalAdjusters.dayOfWeekInMonth(1, dayOfWeek);
      }
  
      /**
       * Returns the last in month adjuster, which returns a new date
       * in the same month with the last matching day-of-week.
       * This is used for expressions like 'last Tuesday in March'.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-12-15 for (MONDAY) will return 2011-12-26.<br>
       * The input 2011-12-15 for (FRIDAY) will return 2011-12-30.<br>
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields
       * and the {@code DAYS} unit, and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week, not null
       * @return the first in month adjuster, not null
       */
      public static TemporalAdjuster lastInMonth(DayOfWeek dayOfWeek) {
          return TemporalAdjusters.dayOfWeekInMonth(-1, dayOfWeek);
      }
  
      /**
       * Returns the day-of-week in month adjuster, which returns a new date
       * in the same month with the ordinal day-of-week.
       * This is used for expressions like the 'second Tuesday in March'.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-12-15 for (1,TUESDAY) will return 2011-12-06.<br>
       * The input 2011-12-15 for (2,TUESDAY) will return 2011-12-13.<br>
       * The input 2011-12-15 for (3,TUESDAY) will return 2011-12-20.<br>
       * The input 2011-12-15 for (4,TUESDAY) will return 2011-12-27.<br>
       * The input 2011-12-15 for (5,TUESDAY) will return 2012-01-03.<br>
       * The input 2011-12-15 for (-1,TUESDAY) will return 2011-12-27 (last in month).<br>
       * The input 2011-12-15 for (-4,TUESDAY) will return 2011-12-06 (3 weeks before last in month).<br>
       * The input 2011-12-15 for (-5,TUESDAY) will return 2011-11-29 (4 weeks before last in month).<br>
       * The input 2011-12-15 for (0,TUESDAY) will return 2011-11-29 (last in previous month).<br>
       * <p>
       * For a positive or zero ordinal, the algorithm is equivalent to finding the first
       * day-of-week that matches within the month and then adding a number of weeks to it.
       * For a negative ordinal, the algorithm is equivalent to finding the last
       * day-of-week that matches within the month and then subtracting a number of weeks to it.
       * The ordinal number of weeks is not validated and is interpreted leniently
       * according to this algorithm. This definition means that an ordinal of zero finds
       * the last matching day-of-week in the previous month.
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} and {@code DAY_OF_MONTH} fields
       * and the {@code DAYS} unit, and assumes a seven day week.
       *
       * @param ordinal  the week within the month, unbounded but typically from -5 to 5
       * @param dayOfWeek  the day-of-week, not null
       * @return the day-of-week in month adjuster, not null
       */
      public static TemporalAdjuster dayOfWeekInMonth(int ordinal, DayOfWeek dayOfWeek) {
          Objects.requireNonNull(dayOfWeek, "dayOfWeek");
          int dowValue = dayOfWeek.getValue();
          if (ordinal >= 0) {
              return (temporal) -> {
                  Temporal temp = temporal.with(DAY_OF_MONTH, 1);
                  int curDow = temp.get(DAY_OF_WEEK);
                  int dowDiff = (dowValue - curDow + 7) % 7;
                  dowDiff += (ordinal - 1L) * 7L;  // safe from overflow
                  return temp.plus(dowDiff, DAYS);
              };
          } else {
              return (temporal) -> {
                  Temporal temp = temporal.with(DAY_OF_MONTH, temporal.range(DAY_OF_MONTH).getMaximum());
                  int curDow = temp.get(DAY_OF_WEEK);
                  int daysDiff = dowValue - curDow;
                  daysDiff = (daysDiff == 0 ? 0 : (daysDiff > 0 ? daysDiff - 7 : daysDiff));
                  daysDiff -= (-ordinal - 1L) * 7L;  // safe from overflow
                  return temp.plus(daysDiff, DAYS);
              };
          }
      }
  
      //-----------------------------------------------------------------------
      /**
       * Returns the next day-of-week adjuster, which adjusts the date to the
       * first occurrence of the specified day-of-week after the date being adjusted.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).<br>
       * The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).<br>
       * The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-22 (seven days later).
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit,
       * and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week to move the date to, not null
       * @return the next day-of-week adjuster, not null
       */
      public static TemporalAdjuster next(DayOfWeek dayOfWeek) {
          int dowValue = dayOfWeek.getValue();
          return (temporal) -> {
              int calDow = temporal.get(DAY_OF_WEEK);
              int daysDiff = calDow - dowValue;
              return temporal.plus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS);
          };
      }
  
      /**
       * Returns the next-or-same day-of-week adjuster, which adjusts the date to the
       * first occurrence of the specified day-of-week after the date being adjusted
       * unless it is already on that day in which case the same object is returned.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-17 (two days later).<br>
       * The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-19 (four days later).<br>
       * The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit,
       * and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week to check for or move the date to, not null
       * @return the next-or-same day-of-week adjuster, not null
       */
      public static TemporalAdjuster nextOrSame(DayOfWeek dayOfWeek) {
          int dowValue = dayOfWeek.getValue();
          return (temporal) -> {
              int calDow = temporal.get(DAY_OF_WEEK);
              if (calDow == dowValue) {
                  return temporal;
              }
              int daysDiff = calDow - dowValue;
              return temporal.plus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS);
          };
      }
  
      /**
       * Returns the previous day-of-week adjuster, which adjusts the date to the
       * first occurrence of the specified day-of-week before the date being adjusted.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).<br>
       * The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).<br>
       * The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-08 (seven days earlier).
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit,
       * and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week to move the date to, not null
       * @return the previous day-of-week adjuster, not null
       */
      public static TemporalAdjuster previous(DayOfWeek dayOfWeek) {
          int dowValue = dayOfWeek.getValue();
          return (temporal) -> {
              int calDow = temporal.get(DAY_OF_WEEK);
              int daysDiff = dowValue - calDow;
              return temporal.minus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS);
          };
      }
  
      /**
       * Returns the previous-or-same day-of-week adjuster, which adjusts the date to the
       * first occurrence of the specified day-of-week before the date being adjusted
       * unless it is already on that day in which case the same object is returned.
       * <p>
       * The ISO calendar system behaves as follows:<br>
       * The input 2011-01-15 (a Saturday) for parameter (MONDAY) will return 2011-01-10 (five days earlier).<br>
       * The input 2011-01-15 (a Saturday) for parameter (WEDNESDAY) will return 2011-01-12 (three days earlier).<br>
       * The input 2011-01-15 (a Saturday) for parameter (SATURDAY) will return 2011-01-15 (same as input).
       * <p>
       * The behavior is suitable for use with most calendar systems.
       * It uses the {@code DAY_OF_WEEK} field and the {@code DAYS} unit,
       * and assumes a seven day week.
       *
       * @param dayOfWeek  the day-of-week to check for or move the date to, not null
       * @return the previous-or-same day-of-week adjuster, not null
       */
      public static TemporalAdjuster previousOrSame(DayOfWeek dayOfWeek) {
          int dowValue = dayOfWeek.getValue();
          return (temporal) -> {
              int calDow = temporal.get(DAY_OF_WEEK);
              if (calDow == dowValue) {
                  return temporal;
              }
              int daysDiff = dowValue - calDow;
              return temporal.minus(daysDiff >= 0 ? 7 - daysDiff : -daysDiff, DAYS);
          };
      }
  
  }
  