/**
  * Get the hour of am/pm (0-11) field for this chronology.
  *
  * @return DateTimeField or UnsupportedDateTimeField if unsupported
  */
 public DateTimeField hourOfHalfday() {
   return UnsupportedDateTimeField.getInstance(DateTimeFieldType.hourOfHalfday(), hours());
 }
/**
 * A Chronology in which every year has the same number of days. Such calendar systems are used in
 * many climate simulations.
 *
 * <p>In these Chronologies, a millisecond instant of zero corresponds with 1970-01-01T00:00:00.000Z
 * and a year has a fixed number of milliseconds.
 *
 * <p>There is no concept of an era in these Chronologies, so all durations and fields relating to
 * this concept are not supported. Additionally, the concept of a "weekyear" (the year that "owns" a
 * given week) is not implemented.
 *
 * <p>Instances of this class can only be created in {@link DateTimeZone#UTC}. (Support for time
 * zones makes little sense in this chronology).
 *
 * <p>Instances of this class are immutable.
 *
 * <p><i>Note: Much of this code was copied from the package-private BasicChronology.</i>
 *
 * @author Jon Blower
 * @see "http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#calendar"
 */
abstract class FixedYearLengthChronology extends BaseChronology {

  ///// DURATIONS /////

  private static final DurationField millisecondDuration = MillisDurationField.INSTANCE;

  private static final DurationField secondDuration =
      new PreciseDurationField(DurationFieldType.seconds(), DateTimeConstants.MILLIS_PER_SECOND);

  private static final DurationField minuteDuration =
      new PreciseDurationField(DurationFieldType.minutes(), DateTimeConstants.MILLIS_PER_MINUTE);

  private static final DurationField hourDuration =
      new PreciseDurationField(DurationFieldType.hours(), DateTimeConstants.MILLIS_PER_HOUR);

  private static final DurationField halfdayDuration =
      new PreciseDurationField(
          DurationFieldType.halfdays(), 12 * DateTimeConstants.MILLIS_PER_HOUR);

  private static final DurationField dayDuration =
      new PreciseDurationField(DurationFieldType.days(), 2 * halfdayDuration.getUnitMillis());

  private static final DurationField weekDuration =
      new PreciseDurationField(DurationFieldType.weeks(), 7 * dayDuration.getUnitMillis());

  // We don't know the length of the year or century until we know how many
  // days there are in a year
  private final DurationField yearDuration;
  private final DurationField centuryDuration;

  ///// DATE-TIME FIELDS /////

  private static final DateTimeField millisOfSecond =
      new PreciseDateTimeField(
          DateTimeFieldType.millisOfSecond(), millisecondDuration, secondDuration);

  private static final DateTimeField millisOfDay =
      new PreciseDateTimeField(DateTimeFieldType.millisOfDay(), millisecondDuration, dayDuration);

  private static final DateTimeField secondOfMinute =
      new PreciseDateTimeField(DateTimeFieldType.secondOfMinute(), secondDuration, minuteDuration);

  private static final DateTimeField secondOfDay =
      new PreciseDateTimeField(DateTimeFieldType.secondOfDay(), secondDuration, dayDuration);

  private static final DateTimeField minuteOfHour =
      new PreciseDateTimeField(DateTimeFieldType.minuteOfHour(), minuteDuration, hourDuration);

  private static final DateTimeField minuteOfDay =
      new PreciseDateTimeField(DateTimeFieldType.minuteOfDay(), minuteDuration, dayDuration);

  private static final DateTimeField hourOfDay =
      new PreciseDateTimeField(DateTimeFieldType.hourOfDay(), hourDuration, dayDuration);

  private static final DateTimeField hourOfHalfday =
      new PreciseDateTimeField(DateTimeFieldType.hourOfHalfday(), hourDuration, halfdayDuration);

  private static final DateTimeField halfdayOfDay =
      new PreciseDateTimeField(DateTimeFieldType.halfdayOfDay(), halfdayDuration, dayDuration);

  private static final DateTimeField clockhourOfDay =
      new ZeroIsMaxDateTimeField(hourOfDay, DateTimeFieldType.clockhourOfDay());

  private static final DateTimeField clockhourOfHalfday =
      new ZeroIsMaxDateTimeField(hourOfHalfday, DateTimeFieldType.clockhourOfHalfday());

  private static final DateTimeField dayOfWeek =
      new PreciseDateTimeField(DateTimeFieldType.dayOfWeek(), dayDuration, weekDuration);

  // We don't know the length of the year or century until we know how many
  // days there are in a year
  private final DateTimeField dayOfYear;
  private final DateTimeField yearOfCentury;
  private final DateTimeField year;

  private final int daysInYear;

  private static final class YearField extends PreciseDurationDateTimeField {

    public YearField(DurationField yearDuration) {
      super(DateTimeFieldType.year(), yearDuration);
    }

    @Override
    public int get(long instant) {
      // We need to use Math.floor() to deal with negative instants
      return (int) Math.floor(instant * 1.0 / this.getDurationField().getUnitMillis()) + 1970;
    }

    /** Returns null: the field has no range */
    @Override
    public DurationField getRangeDurationField() {
      return null;
    }

    @Override
    public int getMinimumValue() {
      return this.get(Long.MIN_VALUE);
    }

    @Override
    // We subtract one to ensure that the whole of this year can be
    // encoded
    public int getMaximumValue() {
      return this.get(Long.MAX_VALUE) - 1;
    }
  };

  ///// CONSTRUCTORS AND FACTORIES /////

  /** @param daysInYear The number of days in each year */
  protected FixedYearLengthChronology(int daysInYear) {
    this.daysInYear = daysInYear;

    this.yearDuration =
        new PreciseDurationField(
            DurationFieldType.years(), daysInYear * dayDuration.getUnitMillis());
    this.centuryDuration =
        new PreciseDurationField(DurationFieldType.centuries(), 100 * yearDuration.getUnitMillis());

    this.dayOfYear =
        new OneBasedPreciseDateTimeField(
            DateTimeFieldType.dayOfYear(), dayDuration, this.yearDuration);
    this.yearOfCentury =
        new PreciseDateTimeField(
            DateTimeFieldType.yearOfCentury(), this.yearDuration, this.centuryDuration);
    this.year = new YearField(this.yearDuration);
  }

  ///// DURATION ACCESSORS /////

  @Override
  public final DurationField millis() {
    return millisecondDuration;
  }

  @Override
  public final DurationField seconds() {
    return secondDuration;
  }

  @Override
  public final DurationField minutes() {
    return minuteDuration;
  }

  @Override
  public final DurationField hours() {
    return hourDuration;
  }

  @Override
  public final DurationField halfdays() {
    return halfdayDuration;
  }

  /** Each day has exactly the same length: there is no daylight saving */
  @Override
  public final DurationField days() {
    return dayDuration;
  }

  /** Each week has 7 days */
  @Override
  public final DurationField weeks() {
    return weekDuration;
  }

  @Override
  public abstract DurationField months();

  @Override
  public final DurationField years() {
    return this.yearDuration;
  }

  @Override
  public final DurationField centuries() {
    return this.centuryDuration;
  }

  ///// DATE-TIME FIELD ACCESSORS /////

  @Override
  public final DateTimeField millisOfSecond() {
    return millisOfSecond;
  }

  @Override
  public final DateTimeField millisOfDay() {
    return millisOfDay;
  }

  @Override
  public final DateTimeField secondOfMinute() {
    return secondOfMinute;
  }

  @Override
  public final DateTimeField secondOfDay() {
    return secondOfDay;
  }

  @Override
  public final DateTimeField minuteOfHour() {
    return minuteOfHour;
  }

  @Override
  public final DateTimeField minuteOfDay() {
    return minuteOfDay;
  }

  @Override
  public final DateTimeField hourOfDay() {
    return hourOfDay;
  }

  @Override
  public final DateTimeField hourOfHalfday() {
    return hourOfHalfday;
  }

  @Override
  public final DateTimeField halfdayOfDay() {
    return halfdayOfDay;
  }

  @Override
  public final DateTimeField clockhourOfDay() {
    return clockhourOfDay;
  }

  @Override
  public final DateTimeField clockhourOfHalfday() {
    return clockhourOfHalfday;
  }

  @Override
  public final DateTimeField dayOfWeek() {
    return dayOfWeek;
  }

  @Override
  public abstract DateTimeField dayOfMonth();

  @Override
  public final DateTimeField dayOfYear() {
    return dayOfYear;
  }

  @Override
  public abstract DateTimeField monthOfYear();

  @Override
  public final DateTimeField year() {
    return year;
  }

  @Override
  public final DateTimeField yearOfCentury() {
    return yearOfCentury;
  }

  /** Returns the number of days in the year */
  final int getDaysInYear() {
    return this.daysInYear;
  }

  /** Always returns UTC */
  @Override
  public final DateTimeZone getZone() {
    return DateTimeZone.UTC;
  }

  /** Throws UnsupportedOperationException unless the time zone is UTC */
  @Override
  public final Chronology withZone(DateTimeZone zone) {
    if (zone.equals(DateTimeZone.UTC)) return this.withUTC();
    throw new UnsupportedOperationException("Not supported yet.");
  }

  /** Returns this object */
  @Override
  public final Chronology withUTC() {
    return this;
  }
}