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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) 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.

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package java.time.chrono;

import java.time.DateTimeException;

import java.time.temporal.ChronoUnit;

import java.time.temporal.Temporal;

import java.time.temporal.TemporalAmount;

import java.time.temporal.TemporalUnit;

import java.time.temporal.UnsupportedTemporalTypeException;

import java.util.List;

import java.util.Objects;

/**

 * A date-based amount of time, such as '3 years, 4 months and 5 days' in an

 * arbitrary chronology, intended for advanced globalization use cases.

 * <p>

 * This interface models a date-based amount of time in a calendar system.

 * While most calendar systems use years, months and days, some do not.

 * Therefore, this interface operates solely in terms of a set of supported

 * units that are defined by the {@code Chronology}.

 * The set of supported units is fixed for a given chronology.

 * The amount of a supported unit may be set to zero.

 * <p>

 * The period is modeled as a directed amount of time, meaning that individual

 * parts of the period may be negative.

 *

 * @implSpec

 * This interface must be implemented with care to ensure other classes operate correctly.

 * All implementations that can be instantiated must be final, immutable and thread-safe.

 * Subclasses should be Serializable wherever possible.

 *

 * @since 1.8

 */

public interface ChronoPeriod

        extends TemporalAmount {

    /**

     * Obtains a {@code ChronoPeriod} consisting of amount of time between two dates.

     * <p>

     * The start date is included, but the end date is not.

     * The period is calculated using {@link ChronoLocalDate#until(ChronoLocalDate)}.

     * As such, the calculation is chronology specific.

     * <p>

     * The chronology of the first date is used.

     * The chronology of the second date is ignored, with the date being converted

     * to the target chronology system before the calculation starts.

     * <p>

     * The result of this method can be a negative period if the end is before the start.

     * In most cases, the positive/negative sign will be the same in each of the supported fields.

     *

     * @param startDateInclusive  the start date, inclusive, specifying the chronology of the calculation, not null

     * @param endDateExclusive  the end date, exclusive, in any chronology, not null

     * @return the period between this date and the end date, not null

     * @see ChronoLocalDate#until(ChronoLocalDate)

     */

    public static ChronoPeriod between(ChronoLocalDate startDateInclusive, ChronoLocalDate endDateExclusive) {

        Objects.requireNonNull(startDateInclusive, "startDateInclusive");

        Objects.requireNonNull(endDateExclusive, "endDateExclusive");

        return startDateInclusive.until(endDateExclusive);

    }

    //-----------------------------------------------------------------------

    /**

     * Gets the value of the requested unit.

     * <p>

     * The supported units are chronology specific.

     * They will typically be {@link ChronoUnit#YEARS YEARS},

     * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.

     * Requesting an unsupported unit will throw an exception.

     *

     * @param unit the {@code TemporalUnit} for which to return the value

     * @return the long value of the unit

     * @throws DateTimeException if the unit is not supported

     * @throws UnsupportedTemporalTypeException if the unit is not supported

     */

    @Override

    long get(TemporalUnit unit);

    /**

     * Gets the set of units supported by this period.

     * <p>

     * The supported units are chronology specific.

     * They will typically be {@link ChronoUnit#YEARS YEARS},

     * {@link ChronoUnit#MONTHS MONTHS} and {@link ChronoUnit#DAYS DAYS}.

     * They are returned in order from largest to smallest.

     * <p>

     * This set can be used in conjunction with {@link #get(TemporalUnit)}

     * to access the entire state of the period.

     *

     * @return a list containing the supported units, not null

     */

    @Override

    List<TemporalUnit> getUnits();

    /**

     * Gets the chronology that defines the meaning of the supported units.

     * <p>

     * The period is defined by the chronology.

     * It controls the supported units and restricts addition/subtraction

     * to {@code ChronoLocalDate} instances of the same chronology.

     *

     * @return the chronology defining the period, not null

     */

    Chronology getChronology();

    //-----------------------------------------------------------------------

    /**

     * Checks if all the supported units of this period are zero.

     *

     * @return true if this period is zero-length

     */

    default boolean isZero() {

        for (TemporalUnit unit : getUnits()) {

            if (get(unit) != 0) {

                return false;

            }

        }

        return true;

    }

    /**

     * Checks if any of the supported units of this period are negative.

     *

     * @return true if any unit of this period is negative

     */

    default boolean isNegative() {

        for (TemporalUnit unit : getUnits()) {

            if (get(unit) < 0) {

                return true;

            }

        }

        return false;

    }

    //-----------------------------------------------------------------------

    /**

     * Returns a copy of this period with the specified period added.

     * <p>

     * If the specified amount is a {@code ChronoPeriod} then it must have

     * the same chronology as this period. Implementations may choose to

     * accept or reject other {@code TemporalAmount} implementations.

     * <p>

     * This instance is immutable and unaffected by this method call.

     *

     * @param amountToAdd  the period to add, not null

     * @return a {@code ChronoPeriod} based on this period with the requested period added, not null

     * @throws ArithmeticException if numeric overflow occurs

     */

    ChronoPeriod plus(TemporalAmount amountToAdd);

    /**

     * Returns a copy of this period with the specified period subtracted.

     * <p>

     * If the specified amount is a {@code ChronoPeriod} then it must have

     * the same chronology as this period. Implementations may choose to

     * accept or reject other {@code TemporalAmount} implementations.

     * <p>

     * This instance is immutable and unaffected by this method call.

     *

     * @param amountToSubtract  the period to subtract, not null

     * @return a {@code ChronoPeriod} based on this period with the requested period subtracted, not null

     * @throws ArithmeticException if numeric overflow occurs

     */

    ChronoPeriod minus(TemporalAmount amountToSubtract);

    //-----------------------------------------------------------------------

    /**

     * Returns a new instance with each amount in this period in this period

     * multiplied by the specified scalar.

     * <p>

     * This returns a period with each supported unit individually multiplied.

     * For example, a period of "2 years, -3 months and 4 days" multiplied by

     * 3 will return "6 years, -9 months and 12 days".

     * No normalization is performed.

     *

     * @param scalar  the scalar to multiply by, not null

     * @return a {@code ChronoPeriod} based on this period with the amounts multiplied

     *  by the scalar, not null

     * @throws ArithmeticException if numeric overflow occurs

     */

    ChronoPeriod multipliedBy(int scalar);

    /**

     * Returns a new instance with each amount in this period negated.

     * <p>

     * This returns a period with each supported unit individually negated.

     * For example, a period of "2 years, -3 months and 4 days" will be

     * negated to "-2 years, 3 months and -4 days".

     * No normalization is performed.

     *

     * @return a {@code ChronoPeriod} based on this period with the amounts negated, not null

     * @throws ArithmeticException if numeric overflow occurs, which only happens if

     *  one of the units has the value {@code Long.MIN_VALUE}

     */

    default ChronoPeriod negated() {

        return multipliedBy(-1);

    }

    //-----------------------------------------------------------------------

    /**

     * Returns a copy of this period with the amounts of each unit normalized.

     * <p>

     * The process of normalization is specific to each calendar system.

     * For example, in the ISO calendar system, the years and months are

     * normalized but the days are not, such that "15 months" would be

     * normalized to "1 year and 3 months".

     * <p>

     * This instance is immutable and unaffected by this method call.

     *

     * @return a {@code ChronoPeriod} based on this period with the amounts of each

     *  unit normalized, not null

     * @throws ArithmeticException if numeric overflow occurs

     */

    ChronoPeriod normalized();

    //-------------------------------------------------------------------------

    /**

     * Adds this period to the specified temporal object.

     * <p>

     * This returns a temporal object of the same observable type as the input

     * with this period added.

     * <p>

     * In most cases, it is clearer to reverse the calling pattern by using

     * {@link Temporal#plus(TemporalAmount)}.

     * <pre>

     *   // these two lines are equivalent, but the second approach is recommended

     *   dateTime = thisPeriod.addTo(dateTime);

     *   dateTime = dateTime.plus(thisPeriod);

     * </pre>

     * <p>

     * The specified temporal must have the same chronology as this period.

     * This returns a temporal with the non-zero supported units added.

     * <p>

     * This instance is immutable and unaffected by this method call.

     *

     * @param temporal  the temporal object to adjust, not null

     * @return an object of the same type with the adjustment made, not null

     * @throws DateTimeException if unable to add

     * @throws ArithmeticException if numeric overflow occurs

     */

    @Override

    Temporal addTo(Temporal temporal);

    /**

     * Subtracts this period from the specified temporal object.

     * <p>

     * This returns a temporal object of the same observable type as the input

     * with this period subtracted.

     * <p>

     * In most cases, it is clearer to reverse the calling pattern by using

     * {@link Temporal#minus(TemporalAmount)}.

     * <pre>

     *   // these two lines are equivalent, but the second approach is recommended

     *   dateTime = thisPeriod.subtractFrom(dateTime);

     *   dateTime = dateTime.minus(thisPeriod);

     * </pre>

     * <p>

     * The specified temporal must have the same chronology as this period.

     * This returns a temporal with the non-zero supported units subtracted.

     * <p>

     * This instance is immutable and unaffected by this method call.

     *

     * @param temporal  the temporal object to adjust, not null

     * @return an object of the same type with the adjustment made, not null

     * @throws DateTimeException if unable to subtract

     * @throws ArithmeticException if numeric overflow occurs

     */

    @Override

    Temporal subtractFrom(Temporal temporal);

    //-----------------------------------------------------------------------

    /**

     * Checks if this period is equal to another period, including the chronology.

     * <p>

     * Compares this period with another ensuring that the type, each amount and

     * the chronology are the same.

     * Note that this means that a period of "15 Months" is not equal to a period

     * of "1 Year and 3 Months".

     *

     * @param obj  the object to check, null returns false

     * @return true if this is equal to the other period

     */

    @Override

    boolean equals(Object obj);

    /**

     * A hash code for this period.

     *

     * @return a suitable hash code

     */

    @Override

    int hashCode();

    //-----------------------------------------------------------------------

    /**

     * Outputs this period as a {@code String}.

     * <p>

     * The output will include the period amounts and chronology.

     *

     * @return a string representation of this period, not null

     */

    @Override

    String toString();

}