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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   * This code is free software; you can redistribute it and/or modify it
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   * This code is distributed in the hope that it will be useful, but WITHOUT
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   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
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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, 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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   *  * Neither the name of JSR-310 nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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   */
  package java.time.temporal;
  
  import static java.time.temporal.ChronoField.EPOCH_DAY;
  import static java.time.temporal.ChronoUnit.DAYS;
  import static java.time.temporal.ChronoUnit.FOREVER;
  
  import java.time.DateTimeException;
  import java.time.chrono.ChronoLocalDate;
  import java.time.chrono.Chronology;
  import java.time.format.ResolverStyle;
  import java.util.Map;
  
  /**
   * A set of date fields that provide access to Julian Days.
   * <p>
   * The Julian Day is a standard way of expressing date and time commonly used in the scientific community.
   * It is expressed as a decimal number of whole days where days start at midday.
   * This class represents variations on Julian Days that count whole days from midnight.
   * <p>
   * The fields are implemented relative to {@link ChronoField#EPOCH_DAY EPOCH_DAY}.
   * The fields are supported, and can be queried and set if {@code EPOCH_DAY} is available.
   * The fields work with all chronologies.
   *
   * @implSpec
   * This is an immutable and thread-safe class.
   *
   * @since 1.8
   */
  public final class JulianFields {
  
      /**
       * The offset from Julian to EPOCH DAY.
       */
      private static final long JULIAN_DAY_OFFSET = 2440588L;
  
      /**
       * Julian Day field.
       * <p>
       * This is an integer-based version of the Julian Day Number.
       * Julian Day is a well-known system that represents the count of whole days since day 0,
       * which is defined to be January 1, 4713 BCE in the Julian calendar, and -4713-11-24 Gregorian.
       * The field  has "JulianDay" as 'name', and 'DAYS' as 'baseUnit'.
       * The field always refers to the local date-time, ignoring the offset or zone.
       * <p>
       * For date-times, 'JULIAN_DAY.getFrom()' assumes the same value from
       * midnight until just before the next midnight.
       * When 'JULIAN_DAY.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
       * 'JULIAN_DAY.adjustInto()' and 'JULIAN_DAY.getFrom()' only apply to {@code Temporal} objects that
       * can be converted into {@link ChronoField#EPOCH_DAY}.
       * An {@link UnsupportedTemporalTypeException} is thrown for any other type of object.
       * <p>
       * In the resolving phase of parsing, a date can be created from a Julian Day field.
       * In {@linkplain ResolverStyle#STRICT strict mode} and {@linkplain ResolverStyle#SMART smart mode}
       * the Julian Day value is validated against the range of valid values.
       * In {@linkplain ResolverStyle#LENIENT lenient mode} no validation occurs.
       *
       * <h3>Astronomical and Scientific Notes</h3>
       * The standard astronomical definition uses a fraction to indicate the time-of-day,
       * thus 3.25 would represent the time 18:00, since days start at midday.
       * This implementation uses an integer and days starting at midnight.
       * The integer value for the Julian Day Number is the astronomical Julian Day value at midday
       * of the date in question.
       * This amounts to the astronomical Julian Day, rounded to an integer {@code JDN = floor(JD + 0.5)}.
       *
       * <pre>
       *  | ISO date          |  Julian Day Number | Astronomical Julian Day |
       *  | 1970-01-01T00:00  |         2,440,588  |         2,440,587.5     |
       *  | 1970-01-01T06:00  |         2,440,588  |         2,440,587.75    |
       *  | 1970-01-01T12:00  |         2,440,588  |         2,440,588.0     |
       *  | 1970-01-01T18:00  |         2,440,588  |         2,440,588.25    |
       *  | 1970-01-02T00:00  |         2,440,589  |         2,440,588.5     |
       *  | 1970-01-02T06:00  |         2,440,589  |         2,440,588.75    |
       *  | 1970-01-02T12:00  |         2,440,589  |         2,440,589.0     |
       * </pre>
       * <p>
       * Julian Days are sometimes taken to imply Universal Time or UTC, but this
       * implementation always uses the Julian Day number for the local date,
       * regardless of the offset or time-zone.
       */
      public static final TemporalField JULIAN_DAY = Field.JULIAN_DAY;
  
      /**
       * Modified Julian Day field.
       * <p>
       * This is an integer-based version of the Modified Julian Day Number.
       * Modified Julian Day (MJD) is a well-known system that counts days continuously.
       * It is defined relative to astronomical Julian Day as  {@code MJD = JD - 2400000.5}.
       * Each Modified Julian Day runs from midnight to midnight.
       * The field always refers to the local date-time, ignoring the offset or zone.
       * <p>
       * For date-times, 'MODIFIED_JULIAN_DAY.getFrom()' assumes the same value from
       * midnight until just before the next midnight.
       * When 'MODIFIED_JULIAN_DAY.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
       * 'MODIFIED_JULIAN_DAY.adjustInto()' and 'MODIFIED_JULIAN_DAY.getFrom()' only apply to {@code Temporal} objects
       * that can be converted into {@link ChronoField#EPOCH_DAY}.
       * An {@link UnsupportedTemporalTypeException} is thrown for any other type of object.
       * <p>
       * This implementation is an integer version of MJD with the decimal part rounded to floor.
       * <p>
       * In the resolving phase of parsing, a date can be created from a Modified Julian Day field.
       * In {@linkplain ResolverStyle#STRICT strict mode} and {@linkplain ResolverStyle#SMART smart mode}
       * the Modified Julian Day value is validated against the range of valid values.
       * In {@linkplain ResolverStyle#LENIENT lenient mode} no validation occurs.
       *
       * <h3>Astronomical and Scientific Notes</h3>
       * <pre>
       *  | ISO date          | Modified Julian Day |      Decimal MJD |
       *  | 1970-01-01T00:00  |             40,587  |       40,587.0   |
       *  | 1970-01-01T06:00  |             40,587  |       40,587.25  |
       *  | 1970-01-01T12:00  |             40,587  |       40,587.5   |
       *  | 1970-01-01T18:00  |             40,587  |       40,587.75  |
       *  | 1970-01-02T00:00  |             40,588  |       40,588.0   |
       *  | 1970-01-02T06:00  |             40,588  |       40,588.25  |
       *  | 1970-01-02T12:00  |             40,588  |       40,588.5   |
       * </pre>
       *
       * Modified Julian Days are sometimes taken to imply Universal Time or UTC, but this
       * implementation always uses the Modified Julian Day for the local date,
       * regardless of the offset or time-zone.
       */
      public static final TemporalField MODIFIED_JULIAN_DAY = Field.MODIFIED_JULIAN_DAY;
  
      /**
       * Rata Die field.
       * <p>
       * Rata Die counts whole days continuously starting day 1 at midnight at the beginning of 0001-01-01 (ISO).
       * The field always refers to the local date-time, ignoring the offset or zone.
       * <p>
       * For date-times, 'RATA_DIE.getFrom()' assumes the same value from
       * midnight until just before the next midnight.
       * When 'RATA_DIE.adjustInto()' is applied to a date-time, the time of day portion remains unaltered.
       * 'RATA_DIE.adjustInto()' and 'RATA_DIE.getFrom()' only apply to {@code Temporal} objects
       * that can be converted into {@link ChronoField#EPOCH_DAY}.
       * An {@link UnsupportedTemporalTypeException} is thrown for any other type of object.
       * <p>
       * In the resolving phase of parsing, a date can be created from a Rata Die field.
       * In {@linkplain ResolverStyle#STRICT strict mode} and {@linkplain ResolverStyle#SMART smart mode}
       * the Rata Die value is validated against the range of valid values.
       * In {@linkplain ResolverStyle#LENIENT lenient mode} no validation occurs.
       */
      public static final TemporalField RATA_DIE = Field.RATA_DIE;
  
      /**
       * Restricted constructor.
       */
      private JulianFields() {
          throw new AssertionError("Not instantiable");
      }
  
      /**
       * Implementation of JulianFields.  Each instance is a singleton.
       */
      private static enum Field implements TemporalField {
          JULIAN_DAY("JulianDay", DAYS, FOREVER, JULIAN_DAY_OFFSET),
          MODIFIED_JULIAN_DAY("ModifiedJulianDay", DAYS, FOREVER, 40587L),
          RATA_DIE("RataDie", DAYS, FOREVER, 719163L);
  
          private static final long serialVersionUID = -7501623920830201812L;
  
          private final transient String name;
          private final transient TemporalUnit baseUnit;
          private final transient TemporalUnit rangeUnit;
          private final transient ValueRange range;
          private final transient long offset;
  
          private Field(String name, TemporalUnit baseUnit, TemporalUnit rangeUnit, long offset) {
              this.name = name;
              this.baseUnit = baseUnit;
              this.rangeUnit = rangeUnit;
              this.range = ValueRange.of(-365243219162L + offset, 365241780471L + offset);
              this.offset = offset;
          }
  
          //-----------------------------------------------------------------------
          @Override
          public TemporalUnit getBaseUnit() {
              return baseUnit;
          }
  
          @Override
          public TemporalUnit getRangeUnit() {
              return rangeUnit;
          }
  
          @Override
          public boolean isDateBased() {
              return true;
          }
  
          @Override
          public boolean isTimeBased() {
              return false;
          }
  
          @Override
          public ValueRange range() {
              return range;
          }
  
          //-----------------------------------------------------------------------
          @Override
          public boolean isSupportedBy(TemporalAccessor temporal) {
              return temporal.isSupported(EPOCH_DAY);
          }
  
          @Override
          public ValueRange rangeRefinedBy(TemporalAccessor temporal) {
              if (isSupportedBy(temporal) == false) {
                  throw new DateTimeException("Unsupported field: " + this);
              }
              return range();
          }
  
          @Override
          public long getFrom(TemporalAccessor temporal) {
              return temporal.getLong(EPOCH_DAY) + offset;
          }
  
          @SuppressWarnings("unchecked")
          @Override
          public <R extends Temporal> R adjustInto(R temporal, long newValue) {
              if (range().isValidValue(newValue) == false) {
                  throw new DateTimeException("Invalid value: " + name + " " + newValue);
              }
              return (R) temporal.with(EPOCH_DAY, Math.subtractExact(newValue, offset));
          }
  
          //-----------------------------------------------------------------------
          @Override
          public ChronoLocalDate resolve(
                  Map<TemporalField, Long> fieldValues, TemporalAccessor partialTemporal, ResolverStyle resolverStyle) {
              long value = fieldValues.remove(this);
              Chronology chrono = Chronology.from(partialTemporal);
              if (resolverStyle == ResolverStyle.LENIENT) {
                  return chrono.dateEpochDay(Math.subtractExact(value, offset));
              }
              range().checkValidValue(value, this);
              return chrono.dateEpochDay(value - offset);
          }
  
          //-----------------------------------------------------------------------
          @Override
          public String toString() {
              return name;
          }
      }
  }
  