/*
 * Copyright (c) 2007-2013, 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.
 *
 *  * 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
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.threeten.bp.temporal;

import java.util.Comparator;

import org.threeten.bp.DateTimeException;
import org.threeten.bp.Instant;
import org.threeten.bp.LocalTime;
import org.threeten.bp.ZoneId;
import org.threeten.bp.ZoneOffset;
import org.threeten.bp.ZonedDateTime;
import org.threeten.bp.format.DateTimeFormatter;

/**
 * A date-time with 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 ZonedDateTime}, not this interface.</b>
 * <p>
 * A {@code ChronoZonedDateTime} is the abstract representation of an offset 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.
 *
 * <h4>When to use this interface</h4>
 * The design of the API encourages the use of {@code ZonedDateTime} 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
 */
public interface ChronoZonedDateTime<C extends Chrono<C>>
        extends Temporal, Comparable<ChronoZonedDateTime<?>> {

    /**
     * Comparator for two {@code ChronoZonedDateTime} 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<ChronoZonedDateTime<?>> INSTANT_COMPARATOR = new Comparator<ChronoZonedDateTime<?>>() {
        @Override
        public int compare(ChronoZonedDateTime<?> datetime1, ChronoZonedDateTime<?> datetime2) {
            int cmp = Long.compare(datetime1.toEpochSecond(), datetime2.toEpochSecond());
            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();

    /**
     * Gets the local date-time part of this date-time.
     * <p>
     * This returns a local date with the same year, month and day
     * as this date-time.
     *
     * @return the local date-time part of this date-time, not null
     */
    ChronoLocalDateTime<C> getDateTime();

    /**
     * Gets the zone offset, such as '+01:00'.
     * <p>
     * This is the offset of the local date-time from UTC/Greenwich.
     *
     * @return the zone offset, not null
     */
    ZoneOffset getOffset();

    /**
     * Gets the zone ID, such as 'Europe/Paris'.
     * <p>
     * This returns the stored time-zone id used to determine the time-zone rules.
     *
     * @return the zone ID, not null
     */
    ZoneId getZone();

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date-time changing the zone offset to the
     * earlier of the two valid offsets at a local time-line overlap.
     * <p>
     * This method only has any effect when the local time-line overlaps, such as
     * at an autumn daylight savings cutover. In this scenario, there are two
     * valid offsets for the local date-time. Calling this method will return
     * a zoned date-time with the earlier of the two selected.
     * <p>
     * If this method is called when it is not an overlap, {@code this}
     * is returned.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @return a {@code ZoneChronoDateTime} based on this date-time with the earlier offset, not null
     * @throws DateTimeException if no rules can be found for the zone
     * @throws DateTimeException if no rules are valid for this date-time
     */
    ChronoZonedDateTime<C> withEarlierOffsetAtOverlap();

    /**
     * Returns a copy of this date-time changing the zone offset to the
     * later of the two valid offsets at a local time-line overlap.
     * <p>
     * This method only has any effect when the local time-line overlaps, such as
     * at an autumn daylight savings cutover. In this scenario, there are two
     * valid offsets for the local date-time. Calling this method will return
     * a zoned date-time with the later of the two selected.
     * <p>
     * If this method is called when it is not an overlap, {@code this}
     * is returned.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @return a {@code ChronoZonedDateTime} based on this date-time with the later offset, not null
     * @throws DateTimeException if no rules can be found for the zone
     * @throws DateTimeException if no rules are valid for this date-time
     */
    ChronoZonedDateTime<C> withLaterOffsetAtOverlap();

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this ZonedDateTime with a different time-zone,
     * retaining the local date-time if possible.
     * <p>
     * This method changes the time-zone and retains the local date-time.
     * The local date-time is only changed if it is invalid for the new zone.
     * <p>
     * To change the zone and adjust the local date-time,
     * use {@link #withZoneSameInstant(ZoneId)}.
     * <p>
     * This instance is immutable and unaffected by this method call.
     *
     * @param zoneId  the time-zone to change to, not null
     * @return a {@code ChronoZonedDateTime} based on this date-time with the requested zone, not null
     */
    ChronoZonedDateTime<C> withZoneSameLocal(ZoneId zoneId);

    /**
     * Returns a copy of this date-time with a different time-zone,
     * retaining the instant.
     * <p>
     * This method changes the time-zone and retains the instant.
     * This normally results in a change to the local date-time.
     * <p>
     * This method is based on retaining the same instant, thus gaps and overlaps
     * in the local time-line have no effect on the result.
     * <p>
     * To change the offset while keeping the local time,
     * use {@link #withZoneSameLocal(ZoneId)}.
     *
     * @param zoneId  the time-zone to change to, not null
     * @return a {@code ChronoZonedDateTime} based on this date-time with the requested zone, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    ChronoZonedDateTime<C> withZoneSameInstant(ZoneId zoneId);

    //-------------------------------------------------------------------------
    // override for covariant return type
    @Override
    ChronoZonedDateTime<C> with(TemporalAdjuster adjuster);

    @Override
    ChronoZonedDateTime<C> with(TemporalField field, long newValue);

    @Override
    ChronoZonedDateTime<C> plus(TemporalAdder adjuster);

    @Override
    ChronoZonedDateTime<C> plus(long amountToAdd, TemporalUnit unit);

    @Override
    ChronoZonedDateTime<C> minus(TemporalSubtractor adjuster);

    @Override
    ChronoZonedDateTime<C> minus(long amountToSubtract, TemporalUnit unit);

    //-----------------------------------------------------------------------
    /**
     * Converts this date-time to an {@code Instant}.
     * <p>
     * This combines the {@link #getDateTime() local date-time} and
     * {@link #getOffset() offset} to form an {@code Instant}.
     *
     * @return an {@code Instant} representing the same instant, not null
     */
    Instant toInstant();

    /**
     * Converts this date-time to the number of seconds from the epoch
     * of 1970-01-01T00:00:00Z.
     * <p>
     * This uses the {@link #getDateTime() local date-time} and
     * {@link #getOffset() 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.
     *
     * @return the number of seconds from the epoch of 1970-01-01T00:00:00Z
     */
    long toEpochSecond();

    //-----------------------------------------------------------------------
    /**
     * Compares this date-time to another date-time, including the chronology.
     * <p>
     * The comparison is based first on the instant, then on the local date-time,
     * then on the zone ID, then on the chronology.
     * It is "consistent with equals", as defined by {@link Comparable}.
     * <p>
     * If all the date-time objects being compared are in the same chronology, then the
     * additional chronology stage is not required.
     *
     * @param other  the other date-time to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     */
    @Override
    int compareTo(ChronoZonedDateTime<?> other);

    //-----------------------------------------------------------------------
    /**
     * Checks if the instant of this date-time is before that of the specified date-time.
     * <p>
     * This method differs from the comparison in {@link #compareTo} in that it
     * only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().isBefore(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this point is before the specified date-time
     */
    boolean isBefore(ChronoZonedDateTime<?> other);

    /**
     * Checks if the instant of this date-time is after that of the specified date-time.
     * <p>
     * This method differs from the comparison in {@link #compareTo} in that it
     * only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().isAfter(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this is after the specified date-time
     */
    boolean isAfter(ChronoZonedDateTime<?> other);

    /**
     * Checks if the instant of this date-time is equal to that of the specified date-time.
     * <p>
     * This method differs from the comparison in {@link #compareTo} and {@link #equals}
     * in that it only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().equals(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if the instant equals the instant of the specified date-time
     */
    boolean isEqual(ChronoZonedDateTime<?> other);

    //-----------------------------------------------------------------------
    /**
     * Checks if this date-time is equal to another date-time.
     * <p>
     * The comparison is based on the offset date-time and the zone.
     * To compare for the same instant on the time-line, use {@link #compareTo}.
     * Only objects of type {@code ChronoZoneDateTime} are compared, other types return false.
     *
     * @param obj  the object to check, null returns false
     * @return true if this is equal to the other date-time
     */
    @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 zoned 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.
     *
     * @param formatter  the formatter to use, not null
     * @return the formatted date-time string, not null
     * @throws DateTimeException if an error occurs during printing
     */
    String toString(DateTimeFormatter formatter) ;

}