/*
 * hunt-time: A time library for D programming language.
 *
 * Copyright (C) 2015-2018 HuntLabs
 *
 * Website: https://www.huntlabs.net/
 *
 * Licensed under the Apache-2.0 License.
 *
 */

module hunt.time.LocalDateTime;

import hunt.time.LocalTime;
import hunt.time.temporal.ChronoField;


import hunt.time.Exceptions;
//import hunt.io.ObjectInputStream;
import hunt.time.chrono.ChronoLocalDateTime;
import hunt.time.chrono.ChronoLocalDate;
import hunt.time.chrono.Chronology;
// import hunt.time.format.DateTimeFormatter;
import hunt.time.format.DateTimeParseException;
import hunt.time.temporal.ChronoField;
import hunt.time.temporal.ChronoUnit;
import hunt.time.temporal.Temporal;
import hunt.time.temporal.TemporalAccessor;
import hunt.time.temporal.TemporalAdjuster;
import hunt.time.temporal.TemporalAmount;
import hunt.time.temporal.TemporalField;
import hunt.time.temporal.TemporalQueries;
import hunt.time.temporal.TemporalQuery;
import hunt.time.temporal.TemporalUnit;
import hunt.time.temporal.ValueRange;
import hunt.time.LocalDate;
import hunt.time.ZoneId;
import hunt.time.Clock;
import hunt.time.Month;
import hunt.time.ZoneOffset;
import hunt.time.Instant;
import hunt.time.DayOfWeek;
import hunt.time.OffsetDateTime;
import hunt.time.ZonedDateTime;
import hunt.time.Period;
import hunt.time.Ser;
import hunt.time.ZoneRegion;
import hunt.time.zone.ZoneRules;

import hunt.Exceptions;
import hunt.stream.DataInput;
import hunt.stream.DataOutput;
import hunt.stream.Common;
import hunt.Long;
import hunt.math.Helper;

import std.conv;

import std.concurrency : initOnce;

// import hunt.time.util.Common;
/**
 * A date-time without a time-zone _in the ISO-8601 calendar system,
 * such as {@code 2007-12-03T10:15:30}.
 * !(p)
 * {@code LocalDateTime} is an immutable date-time object that represents a date-time,
 * often viewed as year-month-day-hour-minute-second. Other date and time fields,
 * such as day-of-year, day-of-week and week-of-year, can also be accessed.
 * Time is represented to nanosecond precision.
 * For example, the value "2nd October 2007 at 13:45.30.123456789" can be
 * stored _in a {@code LocalDateTime}.
 * !(p)
 * This class does not store or represent a time-zone.
 * Instead, it is a description of the date, as used for birthdays, combined with
 * the local time as seen on a wall clock.
 * It cannot represent an instant on the time-line without additional information
 * such as an offset or time-zone.
 * !(p)
 * The ISO-8601 calendar system is the modern civil calendar system used today
 * _in most of the world. It is equivalent to the proleptic Gregorian calendar
 * system, _in which today's rules for leap years are applied for all time.
 * For most applications written today, the ISO-8601 rules are entirely suitable.
 * However, any application that makes use of historical dates, and requires them
 * to be accurate will find the ISO-8601 approach unsuitable.
 *
 * !(p)
 * This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 * class; use of identity-sensitive operations (including reference equality
 * ({@code ==}), identity hash code, or synchronization) on instances of
 * {@code LocalDateTime} may have unpredictable results and should be avoided.
 * The {@code equals} method should be used for comparisons.
 *
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
final class LocalDateTime
        : Temporal, TemporalAdjuster, ChronoLocalDateTime!(LocalDate) { // , Serializable

    /**
     * The minimum supported {@code LocalDateTime}, '-999999999-01-01T00:00:00'.
     * This is the local date-time of midnight at the start of the minimum date.
     * This combines {@link LocalDate#MIN} and {@link LocalTime#MIN}.
     * This could be used by an application as a "far past" date-time.
     */
    static LocalDateTime MIN() {
        __gshared LocalDateTime _MIN;
        return initOnce!(_MIN)(LocalDateTime.of(LocalDate.MIN, LocalTime.MIN));
    }

    /**
     * The maximum supported {@code LocalDateTime}, '+999999999-12-31T23:59:59.999999999'.
     * This is the local date-time just before midnight at the end of the maximum date.
     * This combines {@link LocalDate#MAX} and {@link LocalTime#MAX}.
     * This could be used by an application as a "far future" date-time.
     */
    static LocalDateTime MAX() {
        __gshared LocalDateTime _MAX;
        return initOnce!(_MAX)(LocalDateTime.of(LocalDate.MAX, LocalTime.MAX));
    }    

    /**
     * The date part.
     */
    private  LocalDate date;
    /**
     * The time part.
     */
    private  LocalTime time;

    //-----------------------------------------------------------------------
    /**
     * Obtains the current date-time from the system clock _in the default time-zone.
     * !(p)
     * This will query the {@link Clock#systemDefaultZone() system clock} _in the default
     * time-zone to obtain the current date-time.
     * !(p)
     * Using this method will prevent the ability to use an alternate clock for testing
     * because the clock is hard-coded.
     *
     * @return the current date-time using the system clock and default time-zone, not null
     */
    static LocalDateTime now() {
        return now(Clock.systemDefaultZone());
    }

    /**
     * Obtains the current date-time from the system clock _in the specified time-zone.
     * !(p)
     * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date-time.
     * Specifying the time-zone avoids dependence on the default time-zone.
     * !(p)
     * Using this method will prevent the ability to use an alternate clock for testing
     * because the clock is hard-coded.
     *
     * @param zone  the zone ID to use, not null
     * @return the current date-time using the system clock, not null
     */
    static LocalDateTime now(ZoneId zone) {
        return now(Clock.system(zone));
    }

    /**
     * Obtains the current date-time from the specified clock.
     * !(p)
     * This will query the specified clock to obtain the current date-time.
     * Using this method allows the use of an alternate clock for testing.
     * The alternate clock may be introduced using {@link Clock dependency injection}.
     *
     * @param clock  the clock to use, not null
     * @return the current date-time, not null
     */
    static LocalDateTime now(Clock clock) {
        assert(clock, "clock");
        Instant now = clock.instant();  // called once
        ZoneOffset offset = clock.getZone().getRules().getOffset(now);
        return ofEpochSecond(now.getEpochSecond(), now.getNano(), offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour and minute, setting the second and nanosecond to zero.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour and minute.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * The second and nanosecond fields will be set to zero.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, not null
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, Month month, int dayOfMonth, int hour, int minute) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute);
        return new LocalDateTime(date, time);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour, minute and second, setting the nanosecond to zero.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour, minute and second.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * The nanosecond field will be set to zero.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, not null
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @param second  the second-of-minute to represent, from 0 to 59
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, Month month, int dayOfMonth, int hour, int minute, int second) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute, second);
        return new LocalDateTime(date, time);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour, minute, second and nanosecond.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour, minute, second and nanosecond.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, not null
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @param second  the second-of-minute to represent, from 0 to 59
     * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, Month month, int dayOfMonth, 
        int hour, int minute, int second, int nanoOfSecond) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute, second, nanoOfSecond);
        return new LocalDateTime(date, time);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour and minute, setting the second and nanosecond to zero.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour and minute.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * The second and nanosecond fields will be set to zero.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, int month, int dayOfMonth, int hour, int minute) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute);
        return new LocalDateTime(date, time);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour, minute and second, setting the nanosecond to zero.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour, minute and second.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     * The nanosecond field will be set to zero.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @param second  the second-of-minute to represent, from 0 to 59
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, int month, int dayOfMonth, int hour, int minute, int second) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute, second);
        return new LocalDateTime(date, time);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} from year, month,
     * day, hour, minute, second and nanosecond.
     * !(p)
     * This returns a {@code LocalDateTime} with the specified year, month,
     * day-of-month, hour, minute, second and nanosecond.
     * The day must be valid for the year and month, otherwise an exception will be thrown.
     *
     * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
     * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
     * @param dayOfMonth  the day-of-month to represent, from 1 to 31
     * @param hour  the hour-of-day to represent, from 0 to 23
     * @param minute  the minute-of-hour to represent, from 0 to 59
     * @param second  the second-of-minute to represent, from 0 to 59
     * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999
     * @return the local date-time, not null
     * @throws DateTimeException if the value of any field is _out of range,
     *  or if the day-of-month is invalid for the month-year
     */
    static LocalDateTime of(int year, int month, int dayOfMonth, 
        int hour, int minute, int second, int nanoOfSecond) {
        LocalDate date = LocalDate.of(year, month, dayOfMonth);
        LocalTime time = LocalTime.of(hour, minute, second, nanoOfSecond);
        return new LocalDateTime(date, time);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} from a date and time.
     *
     * @param date  the local date, not null
     * @param time  the local time, not null
     * @return the local date-time, not null
     */
    static LocalDateTime of(LocalDate date, LocalTime time) {
        assert(date, "date");
        assert(time, "time");
        return new LocalDateTime(date, time);
    }

    //-------------------------------------------------------------------------
    /**
     * Obtains an instance of {@code LocalDateTime} from an {@code Instant} and zone ID.
     * !(p)
     * This creates a local date-time based on the specified instant.
     * First, the offset from UTC/Greenwich is obtained using the zone ID and instant,
     * which is simple as there is only one valid offset for each instant.
     * Then, the instant and offset are used to calculate the local date-time.
     *
     * @param instant  the instant to create the date-time from, not null
     * @param zone  the time-zone, which may be an offset, not null
     * @return the local date-time, not null
     * @throws DateTimeException if the result exceeds the supported range
     */
    static LocalDateTime ofInstant(Instant instant, ZoneId zone) {
        assert(instant, "instant");
        assert(zone, "zone");
        ZoneRules rules = zone.getRules();
        ZoneOffset offset = rules.getOffset(instant);
        return ofEpochSecond(instant.getEpochSecond(), instant.getNano(), offset);
    }

    /**
     * Obtains an instance of {@code LocalDateTime} using seconds from the
     * epoch of 1970-01-01T00:00:00Z.
     * !(p)
     * This allows the {@link ChronoField#INSTANT_SECONDS epoch-second} field
     * to be converted to a local date-time. This is primarily intended for
     * low-level conversions rather than general application usage.
     *
     * @param epochSecond  the number of seconds from the epoch of 1970-01-01T00:00:00Z
     * @param nanoOfSecond  the nanosecond within the second, from 0 to 999,999,999
     * @param offset  the zone offset, not null
     * @return the local date-time, not null
     * @throws DateTimeException if the result exceeds the supported range,
     *  or if the nano-of-second is invalid
     */
    static LocalDateTime ofEpochSecond(long epochSecond, int nanoOfSecond, ZoneOffset offset) {
        assert(offset, "offset");
        ChronoField.NANO_OF_SECOND.checkValidValue(nanoOfSecond);
        long localSecond = epochSecond + offset.getTotalSeconds();  // overflow caught later
        long localEpochDay = MathHelper.floorDiv(localSecond, LocalTime.SECONDS_PER_DAY);
        int secsOfDay = MathHelper.floorMod(localSecond, LocalTime.SECONDS_PER_DAY);
        LocalDate date = LocalDate.ofEpochDay(localEpochDay);
        LocalTime time = LocalTime.ofNanoOfDay(secsOfDay * LocalTime.NANOS_PER_SECOND + nanoOfSecond);
        return new LocalDateTime(date, time);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code LocalDateTime} from a temporal object.
     * !(p)
     * This obtains a local date-time based on the specified temporal.
     * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
     * which this factory converts to an instance of {@code LocalDateTime}.
     * !(p)
     * The conversion extracts and combines the {@code LocalDate} and the
     * {@code LocalTime} from the temporal object.
     * Implementations are permitted to perform optimizations such as accessing
     * those fields that are equivalent to the relevant objects.
     * !(p)
     * This method matches the signature of the functional interface {@link TemporalQuery}
     * allowing it to be used as a query via method reference, {@code LocalDateTime.from}.
     *
     * @param temporal  the temporal object to convert, not null
     * @return the local date-time, not null
     * @throws DateTimeException if unable to convert to a {@code LocalDateTime}
     */
    static LocalDateTime from(TemporalAccessor temporal) {
        if (cast(LocalDateTime)(temporal) !is null) {
            return cast(LocalDateTime) temporal;
        } else if (cast(ZonedDateTime)(temporal) !is null) {
            return (cast(ZonedDateTime) temporal).toLocalDateTime();
        } else if (cast(OffsetDateTime)(temporal) !is null) {
            return (cast(OffsetDateTime) temporal).toLocalDateTime();
        }
        try {
            LocalDate date = LocalDate.from(temporal);
            LocalTime time = LocalTime.from(temporal);
            return new LocalDateTime(date, time);
        } catch (DateTimeException ex) {
            throw new DateTimeException("Unable to obtain LocalDateTime from TemporalAccessor: " ~
                    typeid(temporal).stringof ~ " of type " ~ typeid(temporal).stringof, ex);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code LocalDateTime} from a text string such as {@code 2007-12-03T10:15:30}.
     * !(p)
     * The string must represent a valid date-time and is parsed using
     * {@link hunt.time.format.DateTimeFormatter#ISO_LOCAL_DATE_TIME}.
     *
     * @param text  the text to parse such as "2007-12-03T10:15:30", not null
     * @return the parsed local date-time, not null
     * @throws DateTimeParseException if the text cannot be parsed
     */
    // static LocalDateTime parse(string text) {
    //     return parse(text, DateTimeFormatter.ISO_LOCAL_DATE_TIME);
    // }

    /**
     * Obtains an instance of {@code LocalDateTime} from a text string using a specific formatter.
     * !(p)
     * The text is parsed using the formatter, returning a date-time.
     *
     * @param text  the text to parse, not null
     * @param formatter  the formatter to use, not null
     * @return the parsed local date-time, not null
     * @throws DateTimeParseException if the text cannot be parsed
     */
    // static LocalDateTime parse(string text, DateTimeFormatter formatter) {
    //     assert(formatter, "formatter");
    //     return formatter.parse(text, new class TemporalQuery!LocalDateTime{
    //          LocalDateTime queryFrom(TemporalAccessor temporal)
    //          {
    //              if (cast(LocalDateTime)(temporal) !is null) {
    //                 return cast(LocalDateTime) temporal;
    //             } else if (cast(ZonedDateTime)(temporal) !is null) {
    //                 return (cast(ZonedDateTime) temporal).toLocalDateTime();
    //             } else if (cast(OffsetDateTime)(temporal) !is null) {
    //                 return (cast(OffsetDateTime) temporal).toLocalDateTime();
    //             }
    //             try {
    //                 LocalDate date = LocalDate.from(temporal);
    //                 LocalTime time = LocalTime.from(temporal);
    //                 return new LocalDateTime(date, time);
    //             } catch (DateTimeException ex) {
    //                 throw new DateTimeException("Unable to obtain LocalDateTime from TemporalAccessor: " ~
    //                         typeid(temporal).stringof ~ " of type " ~ typeid(temporal).stringof, ex);
    //             }
    //          }
    //     });
    // }

    //-----------------------------------------------------------------------
    /**
     * Constructor.
     *
     * @param date  the date part of the date-time, validated not null
     * @param time  the time part of the date-time, validated not null
     */
    private this(LocalDate date, LocalTime time) {
        this.date = date;
        this.time = time;
    }

    /**
     * Returns a copy of this date-time with the new date and time, checking
     * to see if a new object is _in fact required.
     *
     * @param newDate  the date of the new date-time, not null
     * @param newTime  the time of the new date-time, not null
     * @return the date-time, not null
     */
    private LocalDateTime _with(LocalDate newDate, LocalTime newTime) {
        if (date == newDate && time == newTime) {
            return this;
        }
        return new LocalDateTime(newDate, newTime);
    }

    //-----------------------------------------------------------------------
    /**
     * Checks if the specified field is supported.
     * !(p)
     * This checks if this date-time can be queried for the specified field.
     * If false, then calling the {@link #range(TemporalField) range},
     * {@link #get(TemporalField) get} and {@link #_with(TemporalField, long)}
     * methods will throw an exception.
     * !(p)
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The supported fields are:
     * !(ul)
     * !(li){@code NANO_OF_SECOND}
     * !(li){@code NANO_OF_DAY}
     * !(li){@code MICRO_OF_SECOND}
     * !(li){@code MICRO_OF_DAY}
     * !(li){@code MILLI_OF_SECOND}
     * !(li){@code MILLI_OF_DAY}
     * !(li){@code SECOND_OF_MINUTE}
     * !(li){@code SECOND_OF_DAY}
     * !(li){@code MINUTE_OF_HOUR}
     * !(li){@code MINUTE_OF_DAY}
     * !(li){@code HOUR_OF_AMPM}
     * !(li){@code CLOCK_HOUR_OF_AMPM}
     * !(li){@code HOUR_OF_DAY}
     * !(li){@code CLOCK_HOUR_OF_DAY}
     * !(li){@code AMPM_OF_DAY}
     * !(li){@code DAY_OF_WEEK}
     * !(li){@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
     * !(li){@code ALIGNED_DAY_OF_WEEK_IN_YEAR}
     * !(li){@code DAY_OF_MONTH}
     * !(li){@code DAY_OF_YEAR}
     * !(li){@code EPOCH_DAY}
     * !(li){@code ALIGNED_WEEK_OF_MONTH}
     * !(li){@code ALIGNED_WEEK_OF_YEAR}
     * !(li){@code MONTH_OF_YEAR}
     * !(li){@code PROLEPTIC_MONTH}
     * !(li){@code YEAR_OF_ERA}
     * !(li){@code YEAR}
     * !(li){@code ERA}
     * </ul>
     * All other {@code ChronoField} instances will return false.
     * !(p)
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
     * passing {@code this} as the argument.
     * Whether the field is supported is determined by the field.
     *
     * @param field  the field to check, null returns false
     * @return true if the field is supported on this date-time, false if not
     */
    override
    bool isSupported(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            return f.isDateBased() || f.isTimeBased();
        }
        return field !is null && field.isSupportedBy(this);
    }

    /**
     * Checks if the specified unit is supported.
     * !(p)
     * This checks if the specified unit can be added to, or subtracted from, this date-time.
     * If false, then calling the {@link #plus(long, TemporalUnit)} and
     * {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
     * !(p)
     * If the unit is a {@link ChronoUnit} then the query is implemented here.
     * The supported units are:
     * !(ul)
     * !(li){@code NANOS}
     * !(li){@code MICROS}
     * !(li){@code MILLIS}
     * !(li){@code SECONDS}
     * !(li){@code MINUTES}
     * !(li){@code HOURS}
     * !(li){@code HALF_DAYS}
     * !(li){@code DAYS}
     * !(li){@code WEEKS}
     * !(li){@code MONTHS}
     * !(li){@code YEARS}
     * !(li){@code DECADES}
     * !(li){@code CENTURIES}
     * !(li){@code MILLENNIA}
     * !(li){@code ERAS}
     * </ul>
     * All other {@code ChronoUnit} instances will return false.
     * !(p)
     * If the unit is not a {@code ChronoUnit}, then the result of this method
     * is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
     * passing {@code this} as the argument.
     * Whether the unit is supported is determined by the unit.
     *
     * @param unit  the unit to check, null returns false
     * @return true if the unit can be added/subtracted, false if not
     */
    override  // override for Javadoc
    bool isSupported(TemporalUnit unit) {
        return /* ChronoLocalDateTime. super.*/super_isSupported(unit);
    }
     bool super_isSupported(TemporalUnit unit) {
        if (cast(ChronoUnit)(unit) !is null) {
            return unit != ChronoUnit.FOREVER;
        }
        return unit !is null && unit.isSupportedBy(this);
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the range of valid values for the specified field.
     * !(p)
     * The range object expresses the minimum and maximum valid values for a field.
     * This date-time is used to enhance the accuracy of the returned range.
     * If it is not possible to return the range, because the field is not supported
     * or for some other reason, an exception is thrown.
     * !(p)
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@link #isSupported(TemporalField) supported fields} will return
     * appropriate range instances.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * !(p)
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
     * passing {@code this} as the argument.
     * Whether the range can be obtained is determined by the field.
     *
     * @param field  the field to query the range for, not null
     * @return the range of valid values for the field, not null
     * @throws DateTimeException if the range for the field cannot be obtained
     * @throws UnsupportedTemporalTypeException if the field is not supported
     */
    override
    ValueRange range(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            return (f.isTimeBased() ? time.range(field) : date.range(field));
        }
        return field.rangeRefinedBy(this);
    }

    /**
     * Gets the value of the specified field from this date-time as an {@code int}.
     * !(p)
     * This queries this date-time for the value of the specified field.
     * The returned value will always be within the valid range of values for the field.
     * If it is not possible to return the value, because the field is not supported
     * or for some other reason, an exception is thrown.
     * !(p)
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@link #isSupported(TemporalField) supported fields} will return valid
     * values based on this date-time, except {@code NANO_OF_DAY}, {@code MICRO_OF_DAY},
     * {@code EPOCH_DAY} and {@code PROLEPTIC_MONTH} which are too large to fit _in
     * an {@code int} and throw an {@code UnsupportedTemporalTypeException}.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * !(p)
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     * passing {@code this} as the argument. Whether the value can be obtained,
     * and what the value represents, is determined by the field.
     *
     * @param field  the field to get, not null
     * @return the value for the field
     * @throws DateTimeException if a value for the field cannot be obtained or
     *         the value is outside the range of valid values for the field
     * @throws UnsupportedTemporalTypeException if the field is not supported or
     *         the range of values exceeds an {@code int}
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    int get(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            return (f.isTimeBased() ? time.get(field) : date.get(field));
        }
        return /* ChronoLocalDateTime. super.*/super_get(field);
    }
     int super_get(TemporalField field) {
        ValueRange range = range(field);
        if (range.isIntValue() == false) {
            throw new UnsupportedTemporalTypeException("Invalid field " ~ typeid(field).name ~ " for get() method, use getLong() instead");
        }
        long value = getLong(field);
        if (range.isValidValue(value) == false) {
            throw new DateTimeException("Invalid value for " ~ typeid(field).name ~ " (valid values " ~ range.toString ~ "): " ~ value.to!string);
        }
        return cast(int) value;
    }

    /**
     * Gets the value of the specified field from this date-time as a {@code long}.
     * !(p)
     * This queries this date-time for the value of the specified field.
     * If it is not possible to return the value, because the field is not supported
     * or for some other reason, an exception is thrown.
     * !(p)
     * If the field is a {@link ChronoField} then the query is implemented here.
     * The {@link #isSupported(TemporalField) supported fields} will return valid
     * values based on this date-time.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * !(p)
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     * passing {@code this} as the argument. Whether the value can be obtained,
     * and what the value represents, is determined by the field.
     *
     * @param field  the field to get, not null
     * @return the value for the field
     * @throws DateTimeException if a value for the field cannot be obtained
     * @throws UnsupportedTemporalTypeException if the field is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    long getLong(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            return (f.isTimeBased() ? time.getLong(field) : date.getLong(field));
        }
        return field.getFrom(this);
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the {@code LocalDate} part of this date-time.
     * !(p)
     * This returns a {@code LocalDate} with the same year, month and day
     * as this date-time.
     *
     * @return the date part of this date-time, not null
     */
    override
    LocalDate toLocalDate() {
        return date;
    }

    /**
     * Gets the year field.
     * !(p)
     * This method returns the primitive {@code int} value for the year.
     * !(p)
     * The year returned by this method is proleptic as per {@code get(YEAR)}.
     * To obtain the year-of-era, use {@code get(YEAR_OF_ERA)}.
     *
     * @return the year, from MIN_YEAR to MAX_YEAR
     */
    int getYear() nothrow {
        return date.getYear();
    }

    /**
     * Gets the month-of-year field from 1 to 12.
     * !(p)
     * This method returns the month as an {@code int} from 1 to 12.
     * Application code is frequently clearer if the enum {@link Month}
     * is used by calling {@link #getMonth()}.
     *
     * @return the month-of-year, from 1 to 12
     * @see #getMonth()
     */
    int getMonthValue() nothrow {
        return date.getMonthValue();
    }

    /**
     * Gets the month-of-year field using the {@code Month} enum.
     * !(p)
     * This method returns the enum {@link Month} for the month.
     * This avoids confusion as to what {@code int} values mean.
     * If you need access to the primitive {@code int} value then the enum
     * provides the {@link Month#getValue() int value}.
     *
     * @return the month-of-year, not null
     * @see #getMonthValue()
     */
    Month getMonth() nothrow {
        return date.getMonth();
    }

    /**
     * Gets the day-of-month field.
     * !(p)
     * This method returns the primitive {@code int} value for the day-of-month.
     *
     * @return the day-of-month, from 1 to 31
     */
    int getDayOfMonth() nothrow {
        return date.getDayOfMonth();
    }

    /**
     * Gets the day-of-year field.
     * !(p)
     * This method returns the primitive {@code int} value for the day-of-year.
     *
     * @return the day-of-year, from 1 to 365, or 366 _in a leap year
     */
    int getDayOfYear() {
        return date.getDayOfYear();
    }

    /**
     * Gets the day-of-week field, which is an enum {@code DayOfWeek}.
     * !(p)
     * This method returns the enum {@link DayOfWeek} for the day-of-week.
     * This avoids confusion as to what {@code int} values mean.
     * If you need access to the primitive {@code int} value then the enum
     * provides the {@link DayOfWeek#getValue() int value}.
     * !(p)
     * Additional information can be obtained from the {@code DayOfWeek}.
     * This includes textual names of the values.
     *
     * @return the day-of-week, not null
     */
    DayOfWeek getDayOfWeek() {
        return date.getDayOfWeek();
    }

    //-----------------------------------------------------------------------
    /**
     * Gets the {@code LocalTime} part of this date-time.
     * !(p)
     * This returns a {@code LocalTime} with the same hour, minute, second and
     * nanosecond as this date-time.
     *
     * @return the time part of this date-time, not null
     */
    override
    LocalTime toLocalTime() {
        return time;
    }

    /**
     * Gets the hour-of-day field.
     *
     * @return the hour-of-day, from 0 to 23
     */
    int getHour() {
        return time.getHour();
    }

    /**
     * Gets the minute-of-hour field.
     *
     * @return the minute-of-hour, from 0 to 59
     */
    int getMinute() {
        return time.getMinute();
    }

    /**
     * Gets the second-of-minute field.
     *
     * @return the second-of-minute, from 0 to 59
     */
    int getSecond() {
        return time.getSecond();
    }

    int getMillisecond() {
        return time.getMillisecond();
    }

    /**
     * Gets the nano-of-second field.
     *
     * @return the nano-of-second, from 0 to 999,999,999
     */
    int getNano() {
        return time.getNano();
    }

    //-----------------------------------------------------------------------
    /**
     * Returns an adjusted copy of this date-time.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the date-time adjusted.
     * The adjustment takes place using the specified adjuster strategy object.
     * Read the documentation of the adjuster to understand what adjustment will be made.
     * !(p)
     * A simple adjuster might simply set the one of the fields, such as the year field.
     * A more complex adjuster might set the date to the last day of the month.
     * !(p)
     * A selection of common adjustments is provided _in
     * {@link hunt.time.temporal.TemporalAdjusters TemporalAdjusters}.
     * These include finding the "last day of the month" and "next Wednesday".
     * Key date-time classes also implement the {@code TemporalAdjuster} interface,
     * such as {@link Month} and {@link hunt.time.MonthDay MonthDay}.
     * The adjuster is responsible for handling special cases, such as the varying
     * lengths of month and leap years.
     * !(p)
     * For example this code returns a date on the last day of July:
     * !(pre)
     *  import hunt.time.Month.*;
     *  import hunt.time.temporal.TemporalAdjusters.*;
     *
     *  result = localDateTime._with(JULY)._with(lastDayOfMonth());
     * </pre>
     * !(p)
     * The classes {@link LocalDate} and {@link LocalTime} implement {@code TemporalAdjuster},
     * thus this method can be used to change the date, time or offset:
     * !(pre)
     *  result = localDateTime._with(date);
     *  result = localDateTime._with(time);
     * </pre>
     * !(p)
     * The result of this method is obtained by invoking the
     * {@link TemporalAdjuster#adjustInto(Temporal)} method on the
     * specified adjuster passing {@code this} as the argument.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param adjuster the adjuster to use, not null
     * @return a {@code LocalDateTime} based on {@code this} with the adjustment made, not null
     * @throws DateTimeException if the adjustment cannot be made
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime _with(TemporalAdjuster adjuster) {
        // optimizations
        if (cast(LocalDate)(adjuster) !is null) {
            return _with(cast(LocalDate) adjuster, time);
        } else if (cast(LocalTime)(adjuster) !is null) {
            return _with(date, cast(LocalTime) adjuster);
        } else if (cast(LocalDateTime)(adjuster) !is null) {
            return cast(LocalDateTime) adjuster;
        }
        return cast(LocalDateTime) adjuster.adjustInto(this);
    }

    /**
     * Returns a copy of this date-time with the specified field set to a new value.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the value
     * for the specified field changed.
     * This can be used to change any supported field, such as the year, month or day-of-month.
     * If it is not possible to set the value, because the field is not supported or for
     * some other reason, an exception is thrown.
     * !(p)
     * In some cases, changing the specified field can cause the resulting date-time to become invalid,
     * such as changing the month from 31st January to February would make the day-of-month invalid.
     * In cases like this, the field is responsible for resolving the date. Typically it will choose
     * the previous valid date, which would be the last valid day of February _in this example.
     * !(p)
     * If the field is a {@link ChronoField} then the adjustment is implemented here.
     * The {@link #isSupported(TemporalField) supported fields} will behave as per
     * the matching method on {@link LocalDate#_with(TemporalField, long) LocalDate}
     * or {@link LocalTime#_with(TemporalField, long) LocalTime}.
     * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     * !(p)
     * If the field is not a {@code ChronoField}, then the result of this method
     * is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
     * passing {@code this} as the argument. In this case, the field determines
     * whether and how to adjust the instant.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param field  the field to set _in the result, not null
     * @param newValue  the new value of the field _in the result
     * @return a {@code LocalDateTime} based on {@code this} with the specified field set, not null
     * @throws DateTimeException if the field cannot be set
     * @throws UnsupportedTemporalTypeException if the field is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime _with(TemporalField field, long newValue) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            if (f.isTimeBased()) {
                return _with(date, time._with(field, newValue));
            } else {
                return _with(date._with(field, newValue), time);
            }
        }
        return cast(LocalDateTime)(field.adjustInto(this, newValue));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the year altered.
     * !(p)
     * The time does not affect the calculation and will be the same _in the result.
     * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param year  the year to set _in the result, from MIN_YEAR to MAX_YEAR
     * @return a {@code LocalDateTime} based on this date-time with the requested year, not null
     * @throws DateTimeException if the year value is invalid
     */
    LocalDateTime withYear(int year) {
        return _with(date.withYear(year), time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the month-of-year altered.
     * !(p)
     * The time does not affect the calculation and will be the same _in the result.
     * If the day-of-month is invalid for the year, it will be changed to the last valid day of the month.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param month  the month-of-year to set _in the result, from 1 (January) to 12 (December)
     * @return a {@code LocalDateTime} based on this date-time with the requested month, not null
     * @throws DateTimeException if the month-of-year value is invalid
     */
    LocalDateTime withMonth(int month) {
        return _with(date.withMonth(month), time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the day-of-month altered.
     * !(p)
     * If the resulting date-time is invalid, an exception is thrown.
     * The time does not affect the calculation and will be the same _in the result.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param dayOfMonth  the day-of-month to set _in the result, from 1 to 28-31
     * @return a {@code LocalDateTime} based on this date-time with the requested day, not null
     * @throws DateTimeException if the day-of-month value is invalid,
     *  or if the day-of-month is invalid for the month-year
     */
    LocalDateTime withDayOfMonth(int dayOfMonth) {
        return _with(date.withDayOfMonth(dayOfMonth), time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the day-of-year altered.
     * !(p)
     * If the resulting date-time is invalid, an exception is thrown.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param dayOfYear  the day-of-year to set _in the result, from 1 to 365-366
     * @return a {@code LocalDateTime} based on this date with the requested day, not null
     * @throws DateTimeException if the day-of-year value is invalid,
     *  or if the day-of-year is invalid for the year
     */
    LocalDateTime withDayOfYear(int dayOfYear) {
        return _with(date.withDayOfYear(dayOfYear), time);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the hour-of-day altered.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param hour  the hour-of-day to set _in the result, from 0 to 23
     * @return a {@code LocalDateTime} based on this date-time with the requested hour, not null
     * @throws DateTimeException if the hour value is invalid
     */
    LocalDateTime withHour(int hour) {
        LocalTime newTime = time.withHour(hour);
        return _with(date, newTime);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the minute-of-hour altered.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param minute  the minute-of-hour to set _in the result, from 0 to 59
     * @return a {@code LocalDateTime} based on this date-time with the requested minute, not null
     * @throws DateTimeException if the minute value is invalid
     */
    LocalDateTime withMinute(int minute) {
        LocalTime newTime = time.withMinute(minute);
        return _with(date, newTime);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the second-of-minute altered.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param second  the second-of-minute to set _in the result, from 0 to 59
     * @return a {@code LocalDateTime} based on this date-time with the requested second, not null
     * @throws DateTimeException if the second value is invalid
     */
    LocalDateTime withSecond(int second) {
        LocalTime newTime = time.withSecond(second);
        return _with(date, newTime);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the nano-of-second altered.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param nanoOfSecond  the nano-of-second to set _in the result, from 0 to 999,999,999
     * @return a {@code LocalDateTime} based on this date-time with the requested nanosecond, not null
     * @throws DateTimeException if the nano value is invalid
     */
    LocalDateTime withNano(int nanoOfSecond) {
        LocalTime newTime = time.withNano(nanoOfSecond);
        return _with(date, newTime);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the time truncated.
     * !(p)
     * Truncation returns a copy of the original date-time with fields
     * smaller than the specified unit set to zero.
     * For example, truncating with the {@link ChronoUnit#MINUTES minutes} unit
     * will set the second-of-minute and nano-of-second field to zero.
     * !(p)
     * The unit must have a {@linkplain TemporalUnit#getDuration() duration}
     * that divides into the length of a standard day without remainder.
     * This includes all supplied time units on {@link ChronoUnit} and
     * {@link ChronoUnit#DAYS DAYS}. Other units throw an exception.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param unit  the unit to truncate to, not null
     * @return a {@code LocalDateTime} based on this date-time with the time truncated, not null
     * @throws DateTimeException if unable to truncate
     * @throws UnsupportedTemporalTypeException if the unit is not supported
     */
    LocalDateTime truncatedTo(TemporalUnit unit) {
        return _with(date, time.truncatedTo(unit));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date-time with the specified amount added.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the specified amount added.
     * The amount is typically {@link Period} or {@link Duration} but may be
     * any other type implementing the {@link TemporalAmount} interface.
     * !(p)
     * The calculation is delegated to the amount object by calling
     * {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
     * to implement the addition _in any way it wishes, however it typically
     * calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
     * of the amount implementation to determine if it can be successfully added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param amountToAdd  the amount to add, not null
     * @return a {@code LocalDateTime} based on this date-time with the addition made, not null
     * @throws DateTimeException if the addition cannot be made
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime plus(TemporalAmount amountToAdd) {
        if (cast(Period)(amountToAdd) !is null) {
            Period periodToAdd = cast(Period) amountToAdd;
            return _with(date.plus(periodToAdd), time);
        }
        assert(amountToAdd, "amountToAdd");
        return cast(LocalDateTime) amountToAdd.addTo(this);
    }

    /**
     * Returns a copy of this date-time with the specified amount added.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the amount
     * _in terms of the unit added. If it is not possible to add the amount, because the
     * unit is not supported or for some other reason, an exception is thrown.
     * !(p)
     * If the field is a {@link ChronoUnit} then the addition is implemented here.
     * Date units are added as per {@link LocalDate#plus(long, TemporalUnit)}.
     * Time units are added as per {@link LocalTime#plus(long, TemporalUnit)} with
     * any overflow _in days added equivalent to using {@link #plusDays(long)}.
     * !(p)
     * If the field is not a {@code ChronoUnit}, then the result of this method
     * is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
     * passing {@code this} as the argument. In this case, the unit determines
     * whether and how to perform the addition.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param amountToAdd  the amount of the unit to add to the result, may be negative
     * @param unit  the unit of the amount to add, not null
     * @return a {@code LocalDateTime} based on this date-time with the specified amount added, not null
     * @throws DateTimeException if the addition cannot be made
     * @throws UnsupportedTemporalTypeException if the unit is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime plus(long amountToAdd, TemporalUnit unit) {
        if (cast(ChronoUnit)(unit) !is null) {
            ChronoUnit f = cast(ChronoUnit) unit;
            {
                if( f == ChronoUnit.NANOS) return plusNanos(amountToAdd);
                if( f == ChronoUnit.MICROS) return plusDays(amountToAdd / LocalTime.MICROS_PER_DAY).plusNanos((amountToAdd % LocalTime.MICROS_PER_DAY) * 1000);
                if( f == ChronoUnit.MILLIS) return plusDays(amountToAdd / LocalTime.MILLIS_PER_DAY).plusNanos((amountToAdd % LocalTime.MILLIS_PER_DAY) * 1000_000);
                if( f == ChronoUnit.SECONDS) return plusSeconds(amountToAdd);
                if( f == ChronoUnit.MINUTES) return plusMinutes(amountToAdd);
                if( f == ChronoUnit.HOURS) return plusHours(amountToAdd);
                if( f == ChronoUnit.HALF_DAYS) return plusDays(amountToAdd / 256).plusHours((amountToAdd % 256) * 12);  // no overflow (256 is multiple of 2)
            }
            return _with(date.plus(amountToAdd, unit), time);
        }
        return cast(LocalDateTime)(unit.addTo(this, amountToAdd));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of years added.
     * !(p)
     * This method adds the specified amount to the years field _in three steps:
     * !(ol)
     * !(li)Add the input years to the year field</li>
     * !(li)Check if the resulting date would be invalid</li>
     * !(li)Adjust the day-of-month to the last valid day if necessary</li>
     * </ol>
     * !(p)
     * For example, 2008-02-29 (leap year) plus one year would result _in the
     * invalid date 2009-02-29 (standard year). Instead of returning an invalid
     * result, the last valid day of the month, 2009-02-28, is selected instead.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param years  the years to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the years added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusYears(long years) {
        LocalDate newDate = date.plusYears(years);
        return _with(newDate, time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of months added.
     * !(p)
     * This method adds the specified amount to the months field _in three steps:
     * !(ol)
     * !(li)Add the input months to the month-of-year field</li>
     * !(li)Check if the resulting date would be invalid</li>
     * !(li)Adjust the day-of-month to the last valid day if necessary</li>
     * </ol>
     * !(p)
     * For example, 2007-03-31 plus one month would result _in the invalid date
     * 2007-04-31. Instead of returning an invalid result, the last valid day
     * of the month, 2007-04-30, is selected instead.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param months  the months to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the months added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusMonths(long months) {
        LocalDate newDate = date.plusMonths(months);
        return _with(newDate, time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of weeks added.
     * !(p)
     * This method adds the specified amount _in weeks to the days field incrementing
     * the month and year fields as necessary to ensure the result remains valid.
     * The result is only invalid if the maximum/minimum year is exceeded.
     * !(p)
     * For example, 2008-12-31 plus one week would result _in 2009-01-07.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param weeks  the weeks to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the weeks added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusWeeks(long weeks) {
        LocalDate newDate = date.plusWeeks(weeks);
        return _with(newDate, time);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of days added.
     * !(p)
     * This method adds the specified amount to the days field incrementing the
     * month and year fields as necessary to ensure the result remains valid.
     * The result is only invalid if the maximum/minimum year is exceeded.
     * !(p)
     * For example, 2008-12-31 plus one day would result _in 2009-01-01.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the days to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the days added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusDays(long days) {
        LocalDate newDate = date.plusDays(days);
        return _with(newDate, time);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of hours added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param hours  the hours to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the hours added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusHours(long hours) {
        return plusWithOverflow(date, hours, 0, 0, 0, 1);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of minutes added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param minutes  the minutes to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the minutes added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusMinutes(long minutes) {
        return plusWithOverflow(date, 0, minutes, 0, 0, 1);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of seconds added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param seconds  the seconds to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the seconds added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusSeconds(long seconds) {
        return plusWithOverflow(date, 0, 0, seconds, 0, 1);
    }

    LocalDateTime plusMilliseconds(long milliseconds) {
        return plusWithOverflow(date, 0, 0, 0, milliseconds * LocalTime.NANOS_PER_MILLI, 1);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of nanoseconds added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param nanos  the nanos to add, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the nanoseconds added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime plusNanos(long nanos) {
        return plusWithOverflow(date, 0, 0, 0, nanos, 1);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date-time with the specified amount subtracted.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the specified amount subtracted.
     * The amount is typically {@link Period} or {@link Duration} but may be
     * any other type implementing the {@link TemporalAmount} interface.
     * !(p)
     * The calculation is delegated to the amount object by calling
     * {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
     * to implement the subtraction _in any way it wishes, however it typically
     * calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
     * of the amount implementation to determine if it can be successfully subtracted.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param amountToSubtract  the amount to subtract, not null
     * @return a {@code LocalDateTime} based on this date-time with the subtraction made, not null
     * @throws DateTimeException if the subtraction cannot be made
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime minus(TemporalAmount amountToSubtract) {
        if (cast(Period)(amountToSubtract) !is null) {
            Period periodToSubtract = cast(Period) amountToSubtract;
            return _with(date.minus(periodToSubtract), time);
        }
        assert(amountToSubtract, "amountToSubtract");
        return cast(LocalDateTime) amountToSubtract.subtractFrom(this);
    }

    /**
     * Returns a copy of this date-time with the specified amount subtracted.
     * !(p)
     * This returns a {@code LocalDateTime}, based on this one, with the amount
     * _in terms of the unit subtracted. If it is not possible to subtract the amount,
     * because the unit is not supported or for some other reason, an exception is thrown.
     * !(p)
     * This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
     * See that method for a full description of how addition, and thus subtraction, works.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param amountToSubtract  the amount of the unit to subtract from the result, may be negative
     * @param unit  the unit of the amount to subtract, not null
     * @return a {@code LocalDateTime} based on this date-time with the specified amount subtracted, not null
     * @throws DateTimeException if the subtraction cannot be made
     * @throws UnsupportedTemporalTypeException if the unit is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    LocalDateTime minus(long amountToSubtract, TemporalUnit unit) {
        return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of years subtracted.
     * !(p)
     * This method subtracts the specified amount from the years field _in three steps:
     * !(ol)
     * !(li)Subtract the input years from the year field</li>
     * !(li)Check if the resulting date would be invalid</li>
     * !(li)Adjust the day-of-month to the last valid day if necessary</li>
     * </ol>
     * !(p)
     * For example, 2008-02-29 (leap year) minus one year would result _in the
     * invalid date 2007-02-29 (standard year). Instead of returning an invalid
     * result, the last valid day of the month, 2007-02-28, is selected instead.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param years  the years to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the years subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusYears(long years) {
        return (years == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-years));
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of months subtracted.
     * !(p)
     * This method subtracts the specified amount from the months field _in three steps:
     * !(ol)
     * !(li)Subtract the input months from the month-of-year field</li>
     * !(li)Check if the resulting date would be invalid</li>
     * !(li)Adjust the day-of-month to the last valid day if necessary</li>
     * </ol>
     * !(p)
     * For example, 2007-03-31 minus one month would result _in the invalid date
     * 2007-02-31. Instead of returning an invalid result, the last valid day
     * of the month, 2007-02-28, is selected instead.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param months  the months to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the months subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusMonths(long months) {
        return (months == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-months));
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of weeks subtracted.
     * !(p)
     * This method subtracts the specified amount _in weeks from the days field decrementing
     * the month and year fields as necessary to ensure the result remains valid.
     * The result is only invalid if the maximum/minimum year is exceeded.
     * !(p)
     * For example, 2009-01-07 minus one week would result _in 2008-12-31.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param weeks  the weeks to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the weeks subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusWeeks(long weeks) {
        return (weeks == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeks));
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of days subtracted.
     * !(p)
     * This method subtracts the specified amount from the days field decrementing the
     * month and year fields as necessary to ensure the result remains valid.
     * The result is only invalid if the maximum/minimum year is exceeded.
     * !(p)
     * For example, 2009-01-01 minus one day would result _in 2008-12-31.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param days  the days to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the days subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusDays(long days) {
        return (days == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-days));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of hours subtracted.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param hours  the hours to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the hours subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusHours(long hours) {
        return plusWithOverflow(date, hours, 0, 0, 0, -1);
   }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of minutes subtracted.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param minutes  the minutes to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the minutes subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusMinutes(long minutes) {
        return plusWithOverflow(date, 0, minutes, 0, 0, -1);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of seconds subtracted.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param seconds  the seconds to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the seconds subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusSeconds(long seconds) {
        return plusWithOverflow(date, 0, 0, seconds, 0, -1);
    }

    LocalDateTime minusMilliseconds(long milliseconds) {
        return plusWithOverflow(date, 0, 0, 0, milliseconds * LocalTime.NANOS_PER_MILLI, -1);
    }

    /**
     * Returns a copy of this {@code LocalDateTime} with the specified number of nanoseconds subtracted.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param nanos  the nanos to subtract, may be negative
     * @return a {@code LocalDateTime} based on this date-time with the nanoseconds subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    LocalDateTime minusNanos(long nanos) {
        return plusWithOverflow(date, 0, 0, 0, nanos, -1);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code LocalDateTime} with the specified period added.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param newDate  the new date to base the calculation on, not null
     * @param hours  the hours to add, may be negative
     * @param minutes the minutes to add, may be negative
     * @param seconds the seconds to add, may be negative
     * @param nanos the nanos to add, may be negative
     * @param sign  the sign to determine add or subtract
     * @return the combined result, not null
     */
    private LocalDateTime plusWithOverflow(LocalDate newDate, long hours, long minutes, long seconds, long nanos, int sign) {
        // 9223372036854775808 long, 2147483648 int
        if ((hours | minutes | seconds | nanos) == 0) {
            return _with(newDate, time);
        }
        long totDays = nanos / LocalTime.NANOS_PER_DAY +             //   max/24*60*60*1B
                seconds / LocalTime.SECONDS_PER_DAY +                //   max/24*60*60
                minutes / LocalTime.MINUTES_PER_DAY +                //   max/24*60
                hours / LocalTime.HOURS_PER_DAY;                     //   max/24
        totDays *= sign;                                   // total max*0.4237...
        long totNanos = nanos % LocalTime.NANOS_PER_DAY +                    //   max  86400000000000
                (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND +   //   max  86400000000000
                (minutes % LocalTime.MINUTES_PER_DAY) * LocalTime.NANOS_PER_MINUTE +   //   max  86400000000000
                (hours % LocalTime.HOURS_PER_DAY) * LocalTime.NANOS_PER_HOUR;          //   max  86400000000000
        long curNoD = time.toNanoOfDay();                       //   max  86400000000000
        totNanos = totNanos * sign + curNoD;                    // total 432000000000000
        totDays += MathHelper.floorDiv(totNanos, LocalTime.NANOS_PER_DAY);
        long newNoD = MathHelper.floorMod(totNanos, LocalTime.NANOS_PER_DAY);
        LocalTime newTime = (newNoD == curNoD ? time : LocalTime.ofNanoOfDay(newNoD));
        return _with(newDate.plusDays(totDays), newTime);
    }

    //-----------------------------------------------------------------------
    /**
     * 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 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  // override for Javadoc
    R query(R)(TemporalQuery!(R) query) {
        if (query == TemporalQueries.localDate()) {
            return cast(R) date;
        }
        return /* ChronoLocalDateTime. */super_query(query);
    }

    R super_query(R)(TemporalQuery!(R) query) {
         if (query == TemporalQueries.zoneId()
                 || query == TemporalQueries.chronology()
                 || query == TemporalQueries.precision()) {
             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  // override for Javadoc
    Temporal adjustInto(Temporal temporal) {
        return/*  ChronoLocalDateTime. super.*/super_adjustInto(temporal);
    }
     Temporal super_adjustInto(Temporal temporal) {
        return temporal
                ._with(ChronoField.EPOCH_DAY, toLocalDate().toEpochDay())
                ._with(ChronoField.NANO_OF_DAY, toLocalTime().toNanoOfDay());
    }
    /**
     * Calculates the amount of time until another date-time _in terms of the specified unit.
     * !(p)
     * This calculates the amount of time between two {@code LocalDateTime}
     * objects _in terms of a single {@code TemporalUnit}.
     * The start and end points are {@code this} and the specified date-time.
     * The result will be negative if the end is before the start.
     * The {@code Temporal} passed to this method is converted to a
     * {@code LocalDateTime} using {@link #from(TemporalAccessor)}.
     * For example, the amount _in days between two date-times can be calculated
     * using {@code startDateTime.until(endDateTime, DAYS)}.
     * !(p)
     * The calculation returns a whole number, representing the number of
     * complete units between the two date-times.
     * For example, the amount _in months between 2012-06-15T00:00 and 2012-08-14T23:59
     * will only be one month as it is one minute short of two months.
     * !(p)
     * There are two equivalent ways of using this method.
     * The first is to invoke this method.
     * The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
     * !(pre)
     *   // these two lines are equivalent
     *   amount = start.until(end, MONTHS);
     *   amount = MONTHS.between(start, end);
     * </pre>
     * The choice should be made based on which makes the code more readable.
     * !(p)
     * The calculation is implemented _in this method for {@link ChronoUnit}.
     * The units {@code NANOS}, {@code MICROS}, {@code MILLIS}, {@code SECONDS},
     * {@code MINUTES}, {@code HOURS} and {@code HALF_DAYS}, {@code DAYS},
     * {@code WEEKS}, {@code MONTHS}, {@code YEARS}, {@code DECADES},
     * {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS} are supported.
     * Other {@code ChronoUnit} values will throw an exception.
     * !(p)
     * If the unit is not a {@code ChronoUnit}, then the result of this method
     * is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
     * passing {@code this} as the first argument and the converted input temporal
     * as the second argument.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param endExclusive  the end date, exclusive, which is converted to a {@code LocalDateTime}, not null
     * @param unit  the unit to measure the amount _in, not null
     * @return the amount of time between this date-time and the end date-time
     * @throws DateTimeException if the amount cannot be calculated, or the end
     *  temporal cannot be converted to a {@code LocalDateTime}
     * @throws UnsupportedTemporalTypeException if the unit is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    long until(Temporal endExclusive, TemporalUnit unit) {
        LocalDateTime end = LocalDateTime.from(endExclusive);
        ChronoUnit f = cast(ChronoUnit) unit;

        if (f is null)
            return unit.between(this, end);

        if (unit.isTimeBased()) {
            
            long amount = date.daysUntil(end.date);
            if (amount == 0) {
                return time.until(end.time, unit);
            }
            long timePart = end.time.toNanoOfDay() - time.toNanoOfDay();
            if (amount > 0) {
                amount--; // safe
                timePart += LocalTime.NANOS_PER_DAY; // safe
            } else {
                amount++; // safe
                timePart -= LocalTime.NANOS_PER_DAY; // safe
            }

            if (f == ChronoUnit.NANOS) {
                amount = MathHelper.multiplyExact(amount, LocalTime.NANOS_PER_DAY);
            } else if (f == ChronoUnit.MICROS) {
                amount = MathHelper.multiplyExact(amount, LocalTime.MICROS_PER_DAY);
                timePart = timePart / 1000;
            } else if (f == ChronoUnit.MILLIS) {
                amount = MathHelper.multiplyExact(amount, LocalTime.MILLIS_PER_DAY);
                timePart = timePart / 1_000_000;
            } else if (f == ChronoUnit.SECONDS) {
                amount = MathHelper.multiplyExact(amount, LocalTime.SECONDS_PER_DAY);
                timePart = timePart / LocalTime.NANOS_PER_SECOND;
            } else if (f == ChronoUnit.MINUTES) {
                amount = MathHelper.multiplyExact(amount, LocalTime.MINUTES_PER_DAY);
                timePart = timePart / LocalTime.NANOS_PER_MINUTE;
            } else if (f == ChronoUnit.HOURS) {
                amount = MathHelper.multiplyExact(amount, LocalTime.HOURS_PER_DAY);
                timePart = timePart / LocalTime.NANOS_PER_HOUR;
            } else if (f == ChronoUnit.HALF_DAYS) {
                amount = MathHelper.multiplyExact(amount, 2);
                timePart = timePart / (LocalTime.NANOS_PER_HOUR * 12);
            }

            return MathHelper.addExact(amount, timePart);
        }
        
        LocalDate endDate = end.date;
        if (endDate.isAfter(date) && end.time.isBefore(time)) {
            endDate = endDate.minusDays(1);
        } else if (endDate.isBefore(date) && end.time.isAfter(time)) {
            endDate = endDate.plusDays(1);
        }
        return date.until(endDate, unit);
    }

    /**
     * Formats this date-time using the specified formatter.
     * !(p)
     * This date-time will be passed to the formatter to produce a string.
     *
     * @param formatter  the formatter to use, not null
     * @return the formatted date-time string, not null
     * @throws DateTimeException if an error occurs during printing
     */
    // override  // override for Javadoc and performance
    // string format(DateTimeFormatter formatter) {
    //     assert(formatter, "formatter");
    //     return formatter.format(this);
    // }

    //-----------------------------------------------------------------------
    /**
     * Combines this date-time with an offset to create an {@code OffsetDateTime}.
     * !(p)
     * This returns an {@code OffsetDateTime} formed from this date-time at the specified offset.
     * All possible combinations of date-time and offset are valid.
     *
     * @param offset  the offset to combine with, not null
     * @return the offset date-time formed from this date-time and the specified offset, not null
     */
    OffsetDateTime atOffset(ZoneOffset offset) {
        return OffsetDateTime.of(this, offset);
    }

    /**
     * Combines this date-time with a time-zone to create a {@code ZonedDateTime}.
     * !(p)
     * This returns a {@code ZonedDateTime} formed from this date-time at the
     * specified time-zone. The result will match this 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 ZonedDateTime#withLaterOffsetAtOverlap()} on the result of this method.
     * To throw an exception when there is a gap or overlap, use
     * {@link ZonedDateTime#ofStrict(LocalDateTime, ZoneOffset, ZoneId)}.
     *
     * @param zone  the time-zone to use, not null
     * @return the zoned date-time formed from this date-time, not null
     */
    // override
    ZonedDateTime atZone(ZoneId zone) {
        return ZonedDateTime.of(this, zone);
    }

    //-----------------------------------------------------------------------
    /**
     * Compares this date-time to another date-time.
     * !(p)
     * The comparison is primarily based on the date-time, from earliest to latest.
     * It is "consistent with equals", as defined by {@link Comparable}.
     * !(p)
     * If all the date-times being compared are instances of {@code LocalDateTime},
     * then the comparison will be entirely based on the date-time.
     * If some dates being compared are _in different chronologies, then the
     * chronology is also considered, see {@link ChronoLocalDateTime#compareTo}.
     *
     * @param other  the other date-time to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     */
    // override  // override for Javadoc and performance
    int compareTo(ChronoLocalDateTime!(ChronoLocalDate) other) {
        if (cast(LocalDateTime)(other) !is null) {
            return opCmp(cast(LocalDateTime) other);
        }
        return /* ChronoLocalDateTime. super.*/super_compareTo(other);
    }

     int super_compareTo(ChronoLocalDateTime!(ChronoLocalDate) other) {
        int cmp = toLocalDate().compareTo(other.toLocalDate());
        if (cmp == 0) {
            cmp = toLocalTime().compareTo(other.toLocalTime());
            if (cmp == 0) {
                cmp = getChronology().compareTo(other.getChronology());
            }
        }
        return cmp;
    }

    int opCmp(LocalDateTime other) {
        int cmp = date.compareTo0(other.toLocalDate());
        if (cmp == 0) {
            cmp = time.compareTo(other.toLocalTime());
        }
        return cmp;
    }

    override 
    int opCmp(ChronoLocalDateTime!(ChronoLocalDate) other) {
        if (cast(LocalDateTime)(other) !is null) {
            return opCmp(cast(LocalDateTime) other);
        }
        return /* ChronoLocalDateTime. super.*/super_compareTo(other);
    }

    // override 
    // int opCmp(LocalDateTime other) {
    //         return compareTo(other);
    // }
    /**
     * Checks if this date-time is after the specified date-time.
     * !(p)
     * This checks to see if this date-time represents a point on the
     * local time-line after the other date-time.
     * !(pre)
     *   LocalDate a = LocalDateTime.of(2012, 6, 30, 12, 00);
     *   LocalDate b = LocalDateTime.of(2012, 7, 1, 12, 00);
     *   a.isAfter(b) == false
     *   a.isAfter(a) == false
     *   b.isAfter(a) == true
     * </pre>
     * !(p)
     * This method only considers the position of the two date-times on the local time-line.
     * It does not take into account the chronology, or calendar system.
     * This is different from the comparison _in {@link #compareTo(ChronoLocalDateTime)},
     * but is the same approach as {@link ChronoLocalDateTime#timeLineOrder()}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this date-time is after the specified date-time
     */
    override  // override for Javadoc and performance
    bool isAfter(ChronoLocalDateTime!(ChronoLocalDate) other) {
        if (cast(LocalDateTime)(other) !is null) {
            return opCmp(cast(LocalDateTime) other) > 0;
        }
        return /* ChronoLocalDateTime. super.*/super_isAfter(other);
    }
     bool super_isAfter(ChronoLocalDateTime!(ChronoLocalDate) other) {
        long thisEpDay = this.toLocalDate().toEpochDay();
        long otherEpDay = other.toLocalDate().toEpochDay();
        return thisEpDay > otherEpDay ||
            (thisEpDay == otherEpDay && this.toLocalTime().toNanoOfDay() > other.toLocalTime().toNanoOfDay());
    }

    bool isAfter(LocalDateTime other) {
        if (other !is null) {
            return opCmp(other) > 0;
        }
        return false;
    }
    /**
     * Checks if this date-time is before the specified date-time.
     * !(p)
     * This checks to see if this date-time represents a point on the
     * local time-line before the other date-time.
     * !(pre)
     *   LocalDate a = LocalDateTime.of(2012, 6, 30, 12, 00);
     *   LocalDate b = LocalDateTime.of(2012, 7, 1, 12, 00);
     *   a.isBefore(b) == true
     *   a.isBefore(a) == false
     *   b.isBefore(a) == false
     * </pre>
     * !(p)
     * This method only considers the position of the two date-times on the local time-line.
     * It does not take into account the chronology, or calendar system.
     * This is different from the comparison _in {@link #compareTo(ChronoLocalDateTime)},
     * but is the same approach as {@link ChronoLocalDateTime#timeLineOrder()}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this date-time is before the specified date-time
     */
    override  // override for Javadoc and performance
    bool isBefore(ChronoLocalDateTime!(ChronoLocalDate) other) {
        if (cast(LocalDateTime)(other) !is null) {
            return opCmp(cast(LocalDateTime) other) < 0;
        }
        return /* ChronoLocalDateTime. super.*/super_isBefore(other);
    }

     bool super_isBefore(ChronoLocalDateTime!(ChronoLocalDate) other) {
        long thisEpDay = this.toLocalDate().toEpochDay();
        long otherEpDay = other.toLocalDate().toEpochDay();
        return thisEpDay < otherEpDay ||
            (thisEpDay == otherEpDay && this.toLocalTime().toNanoOfDay() < other.toLocalTime().toNanoOfDay());
    }

    bool isBefore(LocalDateTime other) {
        if (other !is null) {
            return opCmp(other) < 0;
        }
        return false;
    }
    /**
     * Checks if this date-time is equal to the specified date-time.
     * !(p)
     * This checks to see if this date-time represents the same point on the
     * local time-line as the other date-time.
     * !(pre)
     *   LocalDate a = LocalDateTime.of(2012, 6, 30, 12, 00);
     *   LocalDate b = LocalDateTime.of(2012, 7, 1, 12, 00);
     *   a.isEqual(b) == false
     *   a.isEqual(a) == true
     *   b.isEqual(a) == false
     * </pre>
     * !(p)
     * This method only considers the position of the two date-times on the local time-line.
     * It does not take into account the chronology, or calendar system.
     * This is different from the comparison _in {@link #compareTo(ChronoLocalDateTime)},
     * but is the same approach as {@link ChronoLocalDateTime#timeLineOrder()}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this date-time is equal to the specified date-time
     */
    override  // override for Javadoc and performance
    bool isEqual(ChronoLocalDateTime!(ChronoLocalDate) other) {
        if (cast(LocalDateTime)(other) !is null) {
            return opCmp(cast(LocalDateTime) other) == 0;
        }
        return /* ChronoLocalDateTime. super.*/super_isEqual(other);
    }

     bool super_isEqual(ChronoLocalDateTime!(ChronoLocalDate) other) {
        // Do the time check first, it is cheaper than computing EPOCH day.
        return this.toLocalTime().toNanoOfDay() == other.toLocalTime().toNanoOfDay() &&
               this.toLocalDate().toEpochDay() == other.toLocalDate().toEpochDay();
    }

    //-----------------------------------------------------------------------
    /**
     * Checks if this date-time is equal to another date-time.
     * !(p)
     * Compares this {@code LocalDateTime} with another ensuring that the date-time is the same.
     * Only objects of type {@code LocalDateTime} 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
    bool opEquals(Object obj) {
        if (this is obj) {
            return true;
        }
        if (cast(LocalDateTime)(obj) !is null) {
            LocalDateTime other = cast(LocalDateTime) obj;
            return date.opEquals(other.date) && time.opEquals(other.time);
        }
        return false;
    }

    /**
     * A hash code for this date-time.
     *
     * @return a suitable hash code
     */
    override
    size_t toHash() @trusted nothrow {
        return date.toHash() ^ time.toHash();
    }

    //-----------------------------------------------------------------------
    /**
     * Outputs this date-time as a {@code string}, such as {@code 2007-12-03T10:15:30}.
     * !(p)
     * The output will be one of the following ISO-8601 formats:
     * !(ul)
     * !(li){@code uuuu-MM-dd'T'HH:mm}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSS}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSSSSS}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSSSSSSSS}</li>
     * </ul>
     * The format used will be the shortest that outputs the full value of
     * the time where the omitted parts are implied to be zero.
     *
     * @return a string representation of this date-time, not null
     */
    override
    string toString() {
        return date.toString() ~ 'T' ~ time.toString();
    }

    //-----------------------------------------------------------------------
    /**
     * Writes the object using a
     * <a href="{@docRoot}/serialized-form.html#hunt.time.Ser">dedicated serialized form</a>.
     * @serialData
     * !(pre)
     *  _out.writeByte(5);  // identifies a LocalDateTime
     *  // the <a href="{@docRoot}/serialized-form.html#hunt.time.LocalDate">date</a> excluding the one byte header
     *  // the <a href="{@docRoot}/serialized-form.html#hunt.time.LocalTime">time</a> excluding the one byte header
     * </pre>
     *
     * @return the instance of {@code Ser}, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.LOCAL_DATE_TIME_TYPE, this);
    }

    /**
     * Defend against malicious streams.
     *
     * @param s the stream to read
     * @throws InvalidObjectException always
     */
     ///@gxc
    // private void readObject(ObjectInputStream s) /*throws InvalidObjectException*/ {
    //     throw new InvalidObjectException("Deserialization via serialization delegate");
    // }

    void writeExternal(DataOutput _out) /*throws IOException*/ {
        date.writeExternal(_out);
        time.writeExternal(_out);
    }

    static LocalDateTime readExternal(DataInput _in) /*throws IOException*/ {
        LocalDate date = LocalDate.readExternal(_in);
        LocalTime time = LocalTime.readExternal(_in);
        return LocalDateTime.of(date, time);
    }

    override
    Chronology getChronology() {
        return toLocalDate().getChronology();
    }

    override Instant toInstant(ZoneOffset offset) {
        return Instant.ofEpochSecond(toEpochSecond(offset), toLocalTime().getNano());
    }

    override long toEpochSecond(ZoneOffset offset) {
        assert(offset, "offset");
        long epochDay = toLocalDate().toEpochDay();
        long secs = epochDay * 86400 + toLocalTime().toSecondOfDay();
        secs -= offset.getTotalSeconds();
        return secs;
    }

    long toEpochMilli() {
        return this.atZone(ZoneRegion.systemDefault())
			.toInstant()
			.toEpochMilli();
    }
    
    static LocalDateTime ofEpochMilli(long v) {
        return LocalDateTime.now(Clock.fixed(Instant.ofEpochMilli(v), ZoneRegion.systemDefault()));
    }
    
    static LocalDateTime ofEpochMilli(long v, ZoneId zoneId) {
        return LocalDateTime.now(Clock.fixed(Instant.ofEpochMilli(v), zoneId));
    }
}