/*
 * 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
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 * 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.LocalDateTime;
import org.threeten.bp.LocalTime;
import org.threeten.bp.ZoneId;
import org.threeten.bp.ZoneOffset;
import org.threeten.bp.format.DateTimeFormatter;
import org.threeten.bp.zone.ZoneRules;

/**
 * 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.
 *
 * <h4>When to use this interface</h4>
 * 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
 */
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
    @Override
    ChronoLocalDateTime<C> with(TemporalAdjuster adjuster);

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

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

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

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

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

    //-----------------------------------------------------------------------
    /**
     * 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}.
     *
     * @param offset  the offset to use for the conversion, not null
     * @return an {@code Instant} representing the same instant, not null
     */
    Instant toInstant(ZoneOffset offset);

    /**
     * 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.
     *
     * @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
     */
    long toEpochSecond(ZoneOffset offset);

    //-----------------------------------------------------------------------
    /**
     * 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.
     *
     * @param other  the other date-time to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     */
    @Override
    int compareTo(ChronoLocalDateTime<?> other);

    /**
     * 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.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this is after the specified date-time
     */
    boolean isAfter(ChronoLocalDateTime<?> other);

    /**
     * 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.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this is before the specified date-time
     */
    boolean isBefore(ChronoLocalDateTime<?> other);

    /**
     * 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.
     *
     * @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
     */
    boolean isEqual(ChronoLocalDateTime<?> other);

    //-----------------------------------------------------------------------
    /**
     * 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.
     *
     * @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);

}