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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) 2007-2012, 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.

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package java.time.temporal;

import static java.time.temporal.ChronoField.EPOCH_DAY;

import static java.time.temporal.ChronoField.NANO_OF_DAY;

import static java.time.temporal.ChronoUnit.NANOS;

import java.time.DateTimeException;

import java.time.Instant;

import java.time.LocalDateTime;

import java.time.LocalTime;

import java.time.ZoneId;

import java.time.ZoneOffset;

import java.time.format.DateTimeFormatter;

import java.time.zone.ZoneRules;

import java.util.Comparator;

import java.util.Objects;

/**

 * A date-time without a time-zone in an arbitrary chronology, intended

 * for advanced globalization use cases.

 * <p>

 * <b>Most applications should declare method signatures, fields and variables

 * as {@link LocalDateTime}, not this interface.</b>

 * <p>

 * A {@code ChronoLocalDateTime} is the abstract representation of a local date-time

 * where the {@code Chrono chronology}, or calendar system, is pluggable.

 * The date-time is defined in terms of fields expressed by {@link TemporalField},

 * where most common implementations are defined in {@link ChronoField}.

 * The chronology defines how the calendar system operates and the meaning of

 * the standard fields.

 *

 * <h3>When to use this interface</h3>

 * The design of the API encourages the use of {@code LocalDateTime} rather than this

 * interface, even in the case where the application needs to deal with multiple

 * calendar systems. The rationale for this is explored in detail in {@link ChronoLocalDate}.

 * <p>

 * Ensure that the discussion in {@code ChronoLocalDate} has been read and understood

 * before using this interface.

 *

 * <h3>Specification for implementors</h3>

 * 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.

 *

 * @param <C> the chronology of this date-time

 * @since 1.8

 */

public interface ChronoLocalDateTime<C extends Chrono<C>>

        extends Temporal, TemporalAdjuster, Comparable<ChronoLocalDateTime<?>> {

    /**

     * Comparator for two {@code ChronoLocalDateTime} instances ignoring the chronology.

     * <p>

     * This method differs from the comparison in {@link #compareTo} in that it

     * only compares the underlying date and not the chronology.

     * This allows dates in different calendar systems to be compared based

     * on the time-line position.

     *

     * @see #isAfter

     * @see #isBefore

     * @see #isEqual

     */

    Comparator<ChronoLocalDateTime<?>> DATE_TIME_COMPARATOR =

            new Comparator<ChronoLocalDateTime<?>>() {

        @Override

        public int compare(ChronoLocalDateTime<?> datetime1, ChronoLocalDateTime<?> datetime2) {

            int cmp = Long.compare(datetime1.getDate().toEpochDay(), datetime2.getDate().toEpochDay());

            if (cmp == 0) {

                cmp = Long.compare(datetime1.getTime().toNanoOfDay(), datetime2.getTime().toNanoOfDay());

            }

            return cmp;

        }

    };

    /**

     * Gets the local date part of this date-time.

     * <p>

     * This returns a local date with the same year, month and day

     * as this date-time.

     *

     * @return the date part of this date-time, not null

     */

    ChronoLocalDate<C> getDate() ;

    /**

     * Gets the local time part of this date-time.

     * <p>

     * This returns a local time with the same hour, minute, second and

     * nanosecond as this date-time.

     *

     * @return the time part of this date-time, not null

     */

    LocalTime getTime();

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

    // override for covariant return type

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    public default ChronoLocalDateTime<C> with(TemporalAdjuster adjuster) {

        return getDate().getChrono().ensureChronoLocalDateTime(Temporal.super.with(adjuster));

    }

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    ChronoLocalDateTime<C> with(TemporalField field, long newValue);

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    public default ChronoLocalDateTime<C> plus(TemporalAdder adder) {

        return getDate().getChrono().ensureChronoLocalDateTime(Temporal.super.plus(adder));

    }

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    ChronoLocalDateTime<C> plus(long amountToAdd, TemporalUnit unit);

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    public default ChronoLocalDateTime<C> minus(TemporalSubtractor subtractor) {

        return getDate().getChrono().ensureChronoLocalDateTime(Temporal.super.minus(subtractor));

    }

    /**

     * {@inheritDoc}

     * @throws DateTimeException {@inheritDoc}

     * @throws ArithmeticException {@inheritDoc}

     */

    @Override

    public default ChronoLocalDateTime<C> minus(long amountToSubtract, TemporalUnit unit) {

        return getDate().getChrono().ensureChronoLocalDateTime(Temporal.super.minus(amountToSubtract, unit));

    }

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

    /**

     * Queries this date-time using the specified query.

     * <p>

     * This queries this date-time using the specified query strategy object.

     * The {@code TemporalQuery} object defines the logic to be used to

     * obtain the result. Read the documentation of the query to understand

     * what the result of this method will be.

     * <p>

     * The result of this method is obtained by invoking the

     * {@link java.time.temporal.TemporalQuery#queryFrom(TemporalAccessor)} method on the

     * specified query passing {@code this} as the argument.

     *

     * @param <R> the type of the result

     * @param query  the query to invoke, not null

     * @return the query result, null may be returned (defined by the query)

     * @throws DateTimeException if unable to query (defined by the query)

     * @throws ArithmeticException if numeric overflow occurs (defined by the query)

     */

    @SuppressWarnings("unchecked")

    @Override

    public default <R> R query(TemporalQuery<R> query) {

        if (query == Queries.chrono()) {

            return (R) getDate().getChrono();

        }

        if (query == Queries.precision()) {

            return (R) NANOS;

        }

        // inline TemporalAccessor.super.query(query) as an optimization

        if (query == Queries.zoneId() || query == Queries.zone() || query == Queries.offset()) {

            return null;

        }

        return query.queryFrom(this);

    }

    /**

     * Adjusts the specified temporal object to have the same date and time as this object.

     * <p>

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

     * with the date and time changed to be the same as this.

     * <p>

     * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}

     * twice, passing {@link ChronoField#EPOCH_DAY} and

     * {@link ChronoField#NANO_OF_DAY} as the fields.

     * <p>

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

     * {@link Temporal#with(TemporalAdjuster)}:

     * <pre>

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

     *   temporal = thisLocalDateTime.adjustInto(temporal);

     *   temporal = temporal.with(thisLocalDateTime);

     * </pre>

     * <p>

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

     *

     * @param temporal  the target object to be adjusted, not null

     * @return the adjusted object, not null

     * @throws DateTimeException if unable to make the adjustment

     * @throws ArithmeticException if numeric overflow occurs

     */

    @Override

    public default Temporal adjustInto(Temporal temporal) {

        return temporal

                .with(EPOCH_DAY, getDate().toEpochDay())

                .with(NANO_OF_DAY, getTime().toNanoOfDay());

    }

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

    /**

     * Returns a zoned date-time formed from this date-time and the specified time-zone.

     * <p>

     * This creates a zoned date-time matching the input date-time as closely as possible.

     * Time-zone rules, such as daylight savings, mean that not every local date-time

     * is valid for the specified zone, thus the local date-time may be adjusted.

     * <p>

     * The local date-time is resolved to a single instant on the time-line.

     * This is achieved by finding a valid offset from UTC/Greenwich for the local

     * date-time as defined by the {@link ZoneRules rules} of the zone ID.

     *<p>

     * In most cases, there is only one valid offset for a local date-time.

     * In the case of an overlap, where clocks are set back, there are two valid offsets.

     * This method uses the earlier offset typically corresponding to "summer".

     * <p>

     * In the case of a gap, where clocks jump forward, there is no valid offset.

     * Instead, the local date-time is adjusted to be later by the length of the gap.

     * For a typical one hour daylight savings change, the local date-time will be

     * moved one hour later into the offset typically corresponding to "summer".

     * <p>

     * To obtain the later offset during an overlap, call

     * {@link ChronoZonedDateTime#withLaterOffsetAtOverlap()} on the result of this method.

     * <p>

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

     *

     * @param zone  the time-zone to use, not null

     * @return the zoned date-time formed from this date-time, not null

     */

    ChronoZonedDateTime<C> atZone(ZoneId zone);

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

    /**

     * Converts this date-time to an {@code Instant}.

     * <p>

     * This combines this local date-time and the specified offset to form

     * an {@code Instant}.

     * <p>

     * This default implementation calculates from the epoch-day of the date and the

     * second-of-day of the time.

     *

     * @param offset  the offset to use for the conversion, not null

     * @return an {@code Instant} representing the same instant, not null

     */

    public default Instant toInstant(ZoneOffset offset) {

        return Instant.ofEpochSecond(toEpochSecond(offset), getTime().getNano());

    }

    /**

     * Converts this date-time to the number of seconds from the epoch

     * of 1970-01-01T00:00:00Z.

     * <p>

     * This combines this local date-time and the specified offset to calculate the

     * epoch-second value, which is the number of elapsed seconds from 1970-01-01T00:00:00Z.

     * Instants on the time-line after the epoch are positive, earlier are negative.

     * <p>

     * This default implementation calculates from the epoch-day of the date and the

     * second-of-day of the time.

     *

     * @param offset  the offset to use for the conversion, not null

     * @return the number of seconds from the epoch of 1970-01-01T00:00:00Z

     */

    public default long toEpochSecond(ZoneOffset offset) {

        Objects.requireNonNull(offset, "offset");

        long epochDay = getDate().toEpochDay();

        long secs = epochDay * 86400 + getTime().toSecondOfDay();

        secs -= offset.getTotalSeconds();

        return secs;

    }

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

    /**

     * Compares this date-time to another date-time, including the chronology.

     * <p>

     * The comparison is based first on the underlying time-line date-time, then

     * on the chronology.

     * It is "consistent with equals", as defined by {@link Comparable}.

     * <p>

     * For example, the following is the comparator order:

     * <ol>

     * <li>{@code 2012-12-03T12:00 (ISO)}</li>

     * <li>{@code 2012-12-04T12:00 (ISO)}</li>

     * <li>{@code 2555-12-04T12:00 (ThaiBuddhist)}</li>

     * <li>{@code 2012-12-05T12:00 (ISO)}</li>

     * </ol>

     * Values #2 and #3 represent the same date-time on the time-line.

     * When two values represent the same date-time, the chronology ID is compared to distinguish them.

     * This step is needed to make the ordering "consistent with equals".

     * <p>

     * If all the date-time objects being compared are in the same chronology, then the

     * additional chronology stage is not required and only the local date-time is used.

     * <p>

     * This default implementation performs the comparison defined above.

     *

     * @param other  the other date-time to compare to, not null

     * @return the comparator value, negative if less, positive if greater

     */

    @Override

    public default int compareTo(ChronoLocalDateTime<?> other) {

        int cmp = getDate().compareTo(other.getDate());

        if (cmp == 0) {

            cmp = getTime().compareTo(other.getTime());

            if (cmp == 0) {

                cmp = getDate().getChrono().compareTo(other.getDate().getChrono());

            }

        }

        return cmp;

    }

    /**

     * Checks if this date-time is after the specified date-time ignoring the chronology.

     * <p>

     * This method differs from the comparison in {@link #compareTo} in that it

     * only compares the underlying date-time and not the chronology.

     * This allows dates in different calendar systems to be compared based

     * on the time-line position.

     * <p>

     * This default implementation performs the comparison based on the epoch-day

     * and nano-of-day.

     *

     * @param other  the other date-time to compare to, not null

     * @return true if this is after the specified date-time

     */

    public default boolean isAfter(ChronoLocalDateTime<?> other) {

        long thisEpDay = this.getDate().toEpochDay();

        long otherEpDay = other.getDate().toEpochDay();

        return thisEpDay > otherEpDay ||

            (thisEpDay == otherEpDay && this.getTime().toNanoOfDay() > other.getTime().toNanoOfDay());

    }

    /**

     * Checks if this date-time is before the specified date-time ignoring the chronology.

     * <p>

     * This method differs from the comparison in {@link #compareTo} in that it

     * only compares the underlying date-time and not the chronology.

     * This allows dates in different calendar systems to be compared based

     * on the time-line position.

     * <p>

     * This default implementation performs the comparison based on the epoch-day

     * and nano-of-day.

     *

     * @param other  the other date-time to compare to, not null

     * @return true if this is before the specified date-time

     */

    public default boolean isBefore(ChronoLocalDateTime<?> other) {

        long thisEpDay = this.getDate().toEpochDay();

        long otherEpDay = other.getDate().toEpochDay();

        return thisEpDay < otherEpDay ||

            (thisEpDay == otherEpDay && this.getTime().toNanoOfDay() < other.getTime().toNanoOfDay());

    }

    /**

     * Checks if this date-time is equal to the specified date-time ignoring the chronology.

     * <p>

     * This method differs from the comparison in {@link #compareTo} in that it

     * only compares the underlying date and time and not the chronology.

     * This allows date-times in different calendar systems to be compared based

     * on the time-line position.

     * <p>

     * This default implementation performs the comparison based on the epoch-day

     * and nano-of-day.

     *

     * @param other  the other date-time to compare to, not null

     * @return true if the underlying date-time is equal to the specified date-time on the timeline

     */

    public default boolean isEqual(ChronoLocalDateTime<?> other) {

        // Do the time check first, it is cheaper than computing EPOCH day.

        return this.getTime().toNanoOfDay() == other.getTime().toNanoOfDay() &&

               this.getDate().toEpochDay() == other.getDate().toEpochDay();

    }

    /**

     * Checks if this date-time is equal to another date-time, including the chronology.

     * <p>

     * Compares this date-time with another ensuring that the date-time and chronology are the same.

     *

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

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

     */

    @Override

    boolean equals(Object obj);

    /**

     * A hash code for this date-time.

     *

     * @return a suitable hash code

     */

    @Override

    int hashCode();

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

    /**

     * Outputs this date-time as a {@code String}.

     * <p>

     * The output will include the full local date-time and the chronology ID.

     *

     * @return a string representation of this date-time, not null

     */

    @Override

    String toString();

    /**

     * Outputs this date-time as a {@code String} using the formatter.

     * <p>

     * The default implementation must behave as follows:

     * <pre>

     *  return formatter.print(this);

     * </pre>

     *

     * @param formatter  the formatter to use, not null

     * @return the formatted date-time string, not null

     * @throws DateTimeException if an error occurs during printing

     */

    public default String toString(DateTimeFormatter formatter) {

        Objects.requireNonNull(formatter, "formatter");

        return formatter.print(this);

    }

}