/*
 * 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.OffsetDateTime;

import hunt.time.temporal.ChronoField;
import hunt.time.temporal.ChronoUnit;
import hunt.time.chrono.ChronoLocalDateTime;
import hunt.time.chrono.ChronoLocalDate;

import hunt.Exceptions;
import hunt.stream.ObjectInput;
import hunt.stream.ObjectOutput;

//import hunt.io.ObjectInputStream;
import hunt.stream.Common;
import hunt.time.chrono.IsoChronology;
// 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.Exceptions;
import hunt.time.temporal.ValueRange;
import hunt.time.zone.ZoneRules;
import hunt.util.Comparator;
import hunt.Functions;
import hunt.time.ZoneId;
import hunt.time.Clock;
import hunt.time.LocalDate;
import hunt.time.LocalTime;
import hunt.time.ZoneOffset;
import hunt.time.LocalDateTime;
import hunt.time.Month;
import hunt.time.DayOfWeek;
import hunt.time.ZonedDateTime;
import hunt.time.Instant;
import hunt.time.OffsetTime;
import hunt.time.Exceptions;
import hunt.time.Ser;
import hunt.time.util.QueryHelper;
import hunt.time.util.Common;
import hunt.Long;
import hunt.util.Common;
import hunt.util.Comparator;
import std.conv;
/**
 * A date-time with an offset from UTC/Greenwich _in the ISO-8601 calendar system,
 * such as {@code 2007-12-03T10:15:30+01:00}.
 * !(p)
 * {@code OffsetDateTime} is an immutable representation of a date-time with an offset.
 * This class stores all date and time fields, to a precision of nanoseconds,
 * as well as the offset from UTC/Greenwich. For example, the value
 * "2nd October 2007 at 13:45:30.123456789 +02:00" can be stored _in an {@code OffsetDateTime}.
 * !(p)
 * {@code OffsetDateTime}, {@link hunt.time.ZonedDateTime} and {@link hunt.time.Instant} all store an instant
 * on the time-line to nanosecond precision.
 * {@code Instant} is the simplest, simply representing the instant.
 * {@code OffsetDateTime} adds to the instant the offset from UTC/Greenwich, which allows
 * the local date-time to be obtained.
 * {@code ZonedDateTime} adds full time-zone rules.
 * !(p)
 * It is intended that {@code ZonedDateTime} or {@code Instant} is used to model data
 * _in simpler applications. This class may be used when modeling date-time concepts _in
 * more detail, or when communicating to a database or _in a network protocol.
 *
 * !(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 OffsetDateTime} 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
 */
public final class OffsetDateTime
        : Temporal, TemporalAdjuster, Comparable!(OffsetDateTime) { // , Serializable

    /**
     * The minimum supported {@code OffsetDateTime}, '-999999999-01-01T00:00:00+18:00'.
     * This is the local date-time of midnight at the start of the minimum date
     * _in the maximum offset (larger offsets are earlier on the time-line).
     * This combines {@link LocalDateTime#MIN} and {@link ZoneOffset#MAX}.
     * This could be used by an application as a "far past" date-time.
     */
    // public __gshared OffsetDateTime MIN ;
    /**
     * The maximum supported {@code OffsetDateTime}, '+999999999-12-31T23:59:59.999999999-18:00'.
     * This is the local date-time just before midnight at the end of the maximum date
     * _in the minimum offset (larger negative offsets are later on the time-line).
     * This combines {@link LocalDateTime#MAX} and {@link ZoneOffset#MIN}.
     * This could be used by an application as a "far future" date-time.
     */
    // public __gshared OffsetDateTime MAX ;


    // shared static this()
    // {
        // MIN = LocalDateTime.MIN.atOffset(ZoneOffset.MAX);
        // mixin(MakeGlobalVar!(OffsetDateTime)("MIN",`LocalDateTime.MIN.atOffset(ZoneOffset.MAX)`));
        // MAX = LocalDateTime.MAX.atOffset(ZoneOffset.MIN);
        // mixin(MakeGlobalVar!(OffsetDateTime)("MAX",`LocalDateTime.MAX.atOffset(ZoneOffset.MIN)`));

    // }
    /**
     * Gets a comparator that compares two {@code OffsetDateTime} instances
     * based solely on the instant.
     * !(p)
     * This method differs from the comparison _in {@link #compareTo} _in that it
     * only compares the underlying instant.
     *
     * @return a comparator that compares _in time-line order
     *
     * @see #isAfter
     * @see #isBefore
     * @see #isEqual
     */
    public static Comparator!(OffsetDateTime) timeLineOrder() {
        return new class Comparator!(OffsetDateTime) {
            int compare(OffsetDateTime datetime1, OffsetDateTime datetime2) nothrow
            {
                try {
                    if (datetime1.getOffset() == (datetime2.getOffset())) {
                        return datetime1.toLocalDateTime().compareTo(cast(ChronoLocalDateTime!(ChronoLocalDate))(datetime2.toLocalDateTime()));
                    }
                    int cmp = hunt.util.Comparator.compare(datetime1.toEpochSecond(), datetime2.toEpochSecond());
                    if (cmp == 0) {
                        cmp = datetime1.toLocalTime().getNano() - datetime2.toLocalTime().getNano();
                    }
                    return cmp;
                } catch(Exception) {
                    // FIXME: Needing refactor or cleanup -@zxp at 12/29/2018, 11:26:48 PM
                    // 
                    return 0;
                }
            }
        };
    }

    /**
     * Compares this {@code OffsetDateTime} to another date-time.
     * The comparison is based on the instant.
     *
     * @param datetime1  the first date-time to compare, not null
     * @param datetime2  the other date-time to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     */
    private static int compareInstant(OffsetDateTime datetime1, OffsetDateTime datetime2) {
        if (datetime1.getOffset() == (datetime2.getOffset())) {
            return datetime1.toLocalDateTime().compareTo(cast(ChronoLocalDateTime!(ChronoLocalDate))(datetime2.toLocalDateTime()));
        }
        int cmp = compare(datetime1.toEpochSecond(), datetime2.toEpochSecond());
        if (cmp == 0) {
            cmp = datetime1.toLocalTime().getNano() - datetime2.toLocalTime().getNano();
        }
        return cmp;
    }

    /**
     * Serialization version.
     */
    private enum long serialVersionUID = 2287754244819255394L;

    /**
     * The local date-time.
     */
    private  LocalDateTime dateTime;
    /**
     * The offset from UTC/Greenwich.
     */
    private  ZoneOffset offset;

    //-----------------------------------------------------------------------
    /**
     * 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.
     * The offset will be calculated from the time-zone _in the clock.
     * !(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, not null
     */
    public static OffsetDateTime 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.
     * The offset will be calculated from the specified 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
     */
    public static OffsetDateTime 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.
     * The offset will be calculated from the time-zone _in the clock.
     * !(p)
     * 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
     */
    public static OffsetDateTime now(Clock clock) {
        assert(clock, "clock");
        Instant now = clock.instant();  // called once
        return ofInstant(now, clock.getZone().getRules().getOffset(now));
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code OffsetDateTime} from a date, time and offset.
     * !(p)
     * This creates an offset date-time with the specified local date, time and offset.
     *
     * @param date  the local date, not null
     * @param time  the local time, not null
     * @param offset  the zone offset, not null
     * @return the offset date-time, not null
     */
    public static OffsetDateTime of(LocalDate date, LocalTime time, ZoneOffset offset) {
        LocalDateTime dt = LocalDateTime.of(date, time);
        return new OffsetDateTime(dt, offset);
    }

    /**
     * Obtains an instance of {@code OffsetDateTime} from a date-time and offset.
     * !(p)
     * This creates an offset date-time with the specified local date-time and offset.
     *
     * @param dateTime  the local date-time, not null
     * @param offset  the zone offset, not null
     * @return the offset date-time, not null
     */
    public static OffsetDateTime of(LocalDateTime dateTime, ZoneOffset offset) {
        return new OffsetDateTime(dateTime, offset);
    }

    /**
     * Obtains an instance of {@code OffsetDateTime} from a year, month, day,
     * hour, minute, second, nanosecond and offset.
     * !(p)
     * This creates an offset date-time with the seven specified fields.
     * !(p)
     * This method exists primarily for writing test cases.
     * Non test-code will typically use other methods to create an offset time.
     * {@code LocalDateTime} has five additional convenience variants of the
     * equivalent factory method taking fewer arguments.
     * They are not provided here to reduce the footprint of the API.
     *
     * @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
     * @param offset  the zone offset, not null
     * @return the offset 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
     */
    public static OffsetDateTime of(
            int year, int month, int dayOfMonth,
            int hour, int minute, int second, int nanoOfSecond, ZoneOffset offset) {
        LocalDateTime dt = LocalDateTime.of(year, month, dayOfMonth, hour, minute, second, nanoOfSecond);
        return new OffsetDateTime(dt, offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code OffsetDateTime} from an {@code Instant} and zone ID.
     * !(p)
     * This creates an offset date-time with the same instant as that specified.
     * Finding the offset from UTC/Greenwich is simple as there is only one valid
     * offset for each instant.
     *
     * @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 offset date-time, not null
     * @throws DateTimeException if the result exceeds the supported range
     */
    public static OffsetDateTime ofInstant(Instant instant, ZoneId zone) {
        assert(instant, "instant");
        assert(zone, "zone");
        ZoneRules rules = zone.getRules();
        ZoneOffset offset = rules.getOffset(instant);
        LocalDateTime ldt = LocalDateTime.ofEpochSecond(instant.getEpochSecond(), instant.getNano(), offset);
        return new OffsetDateTime(ldt, offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code OffsetDateTime} from a temporal object.
     * !(p)
     * This obtains an offset 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 OffsetDateTime}.
     * !(p)
     * The conversion will first obtain a {@code ZoneOffset} from the temporal object.
     * It will then try to obtain a {@code LocalDateTime}, falling back to an {@code Instant} if necessary.
     * The result will be the combination of {@code ZoneOffset} with either
     * with {@code LocalDateTime} or {@code Instant}.
     * 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 OffsetDateTime.from}.
     *
     * @param temporal  the temporal object to convert, not null
     * @return the offset date-time, not null
     * @throws DateTimeException if unable to convert to an {@code OffsetDateTime}
     */
    public static OffsetDateTime from(TemporalAccessor temporal) {
        if (cast(OffsetDateTime)(temporal) !is null) {
            return cast(OffsetDateTime) temporal;
        }
        try {
            ZoneOffset offset = ZoneOffset.from(temporal);
            LocalDate date = QueryHelper.query!LocalDate(temporal,TemporalQueries.localDate());
            LocalTime time = QueryHelper.query!LocalTime(temporal ,TemporalQueries.localTime());
            if (date !is null && time !is null) {
                return OffsetDateTime.of(date, time, offset);
            } else {
                Instant instant = Instant.from(temporal);
                return OffsetDateTime.ofInstant(instant, offset);
            }
        } catch (DateTimeException ex) {
            throw new DateTimeException("Unable to obtain OffsetDateTime from TemporalAccessor: " ~
                    typeid(temporal).name ~ " of type " ~ typeid(temporal).stringof, ex);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * Obtains an instance of {@code OffsetDateTime} from a text string
     * such as {@code 2007-12-03T10:15:30+01:00}.
     * !(p)
     * The string must represent a valid date-time and is parsed using
     * {@link hunt.time.format.DateTimeFormatter#ISO_OFFSET_DATE_TIME}.
     *
     * @param text  the text to parse such as "2007-12-03T10:15:30+01:00", not null
     * @return the parsed offset date-time, not null
     * @throws DateTimeParseException if the text cannot be parsed
     */
    // public static OffsetDateTime parse(string text) {
    //     return parse(text, DateTimeFormatter.ISO_OFFSET_DATE_TIME);
    // }

    /**
     * Obtains an instance of {@code OffsetDateTime} 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 offset date-time, not null
     * @throws DateTimeParseException if the text cannot be parsed
     */
    // public static OffsetDateTime parse(string text, DateTimeFormatter formatter) {
    //     assert(formatter, "formatter");
    //     return formatter.parse(text, new class TemporalQuery!OffsetDateTime{
    //         OffsetDateTime queryFrom(TemporalAccessor temporal)
    //         {
    //             if (cast(OffsetDateTime)(temporal) !is null) {
    //                     return cast(OffsetDateTime) temporal;
    //                 }
    //                 try {
    //                     ZoneOffset offset = ZoneOffset.from(temporal);
    //                     LocalDate date = QueryHelper.query!LocalDate(temporal ,TemporalQueries.localDate());
    //                     LocalTime time = QueryHelper.query!LocalTime(temporal ,TemporalQueries.localTime());
    //                     if (date !is null && time !is null) {
    //                         return OffsetDateTime.of(date, time, offset);
    //                     } else {
    //                         Instant instant = Instant.from(temporal);
    //                         return OffsetDateTime.ofInstant(instant, offset);
    //                     }
    //                 } catch (DateTimeException ex) {
    //                     throw new DateTimeException("Unable to obtain OffsetDateTime from TemporalAccessor: " ~
    //                             typeid(temporal).name ~ " of type " ~ typeid(temporal).stringof, ex);
    //                 }
    //         }
    //     });
    // }

    //-----------------------------------------------------------------------
    /**
     * Constructor.
     *
     * @param dateTime  the local date-time, not null
     * @param offset  the zone offset, not null
     */
    private this(LocalDateTime dateTime, ZoneOffset offset) {
        this.dateTime = dateTime;
        this.offset = offset;
    }

    /**
     * Returns a new date-time based on this one, returning {@code this} where possible.
     *
     * @param dateTime  the date-time to create with, not null
     * @param offset  the zone offset to create with, not null
     */
    private OffsetDateTime _with(LocalDateTime dateTime, ZoneOffset offset) {
        if (this.dateTime == dateTime && this.offset == (offset)) {
            return this;
        }
        return new OffsetDateTime(dateTime, offset);
    }

    //-----------------------------------------------------------------------
    /**
     * 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}
     * !(li){@code INSTANT_SECONDS}
     * !(li){@code OFFSET_SECONDS}
     * </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
    public bool isSupported(TemporalField field) {
        return cast(ChronoField)(field) !is null || (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
    public bool 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
    public ValueRange range(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            if (field == ChronoField.INSTANT_SECONDS || field == ChronoField.OFFSET_SECONDS) {
                return field.range();
            }
            return dateTime.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}, {@code PROLEPTIC_MONTH} and {@code INSTANT_SECONDS} 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
    public int get(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            auto f = cast(ChronoField) field;
            {
                if( f ==  ChronoField.INSTANT_SECONDS)
                    throw new UnsupportedTemporalTypeException("Invalid field 'InstantSeconds' for get() method, use getLong() instead");
                if( f ==  ChronoField.OFFSET_SECONDS)
                    return getOffset().getTotalSeconds();
            }
            return dateTime.get(field);
        }
        return /* Temporal. 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
    public long getLong(TemporalField field) {
        if (cast(ChronoField)(field) !is null) {
            auto f =cast(ChronoField) field;
            {
                if( f== ChronoField.INSTANT_SECONDS) return toEpochSecond();
                if( f== ChronoField.OFFSET_SECONDS) return getOffset().getTotalSeconds();
            }
            return dateTime.getLong(field);
        }
        return field.getFrom(this);
    }

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

    /**
     * Returns a copy of this {@code OffsetDateTime} with the specified offset ensuring
     * that the result has the same local date-time.
     * !(p)
     * This method returns an object with the same {@code LocalDateTime} and the specified {@code ZoneOffset}.
     * No calculation is needed or performed.
     * For example, if this time represents {@code 2007-12-03T10:30+02:00} and the offset specified is
     * {@code +03:00}, then this method will return {@code 2007-12-03T10:30+03:00}.
     * !(p)
     * To take into account the difference between the offsets, and adjust the time fields,
     * use {@link #withOffsetSameInstant}.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param offset  the zone offset to change to, not null
     * @return an {@code OffsetDateTime} based on this date-time with the requested offset, not null
     */
    public OffsetDateTime withOffsetSameLocal(ZoneOffset offset) {
        return _with(dateTime, offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the specified offset ensuring
     * that the result is at the same instant.
     * !(p)
     * This method returns an object with the specified {@code ZoneOffset} and a {@code LocalDateTime}
     * adjusted by the difference between the two offsets.
     * This will result _in the old and new objects representing the same instant.
     * This is useful for finding the local time _in a different offset.
     * For example, if this time represents {@code 2007-12-03T10:30+02:00} and the offset specified is
     * {@code +03:00}, then this method will return {@code 2007-12-03T11:30+03:00}.
     * !(p)
     * To change the offset without adjusting the local time use {@link #withOffsetSameLocal}.
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param offset  the zone offset to change to, not null
     * @return an {@code OffsetDateTime} based on this date-time with the requested offset, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime withOffsetSameInstant(ZoneOffset offset) {
        if (offset == (this.offset)) {
            return this;
        }
        int difference = offset.getTotalSeconds() - this.offset.getTotalSeconds();
        LocalDateTime adjusted = dateTime.plusSeconds(difference);
        return new OffsetDateTime(adjusted, offset);
    }

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

    //-----------------------------------------------------------------------
    /**
     * 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
     */
    public LocalDate toLocalDate() {
        return dateTime.toLocalDate();
    }

    /**
     * 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
     */
    public int getYear() {
        return dateTime.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()
     */
    public int getMonthValue() {
        return dateTime.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()
     */
    public Month getMonth() {
        return dateTime.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
     */
    public int getDayOfMonth() {
        return dateTime.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
     */
    public int getDayOfYear() {
        return dateTime.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
     */
    public DayOfWeek getDayOfWeek() {
        return dateTime.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
     */
    public LocalTime toLocalTime() {
        return dateTime.toLocalTime();
    }

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

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

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

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

    //-----------------------------------------------------------------------
    /**
     * Returns an adjusted copy of this date-time.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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.
     * 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 = offsetDateTime._with(JULY)._with(lastDayOfMonth());
     * </pre>
     * !(p)
     * The classes {@link LocalDate}, {@link LocalTime} and {@link ZoneOffset} implement
     * {@code TemporalAdjuster}, thus this method can be used to change the date, time or offset:
     * !(pre)
     *  result = offsetDateTime._with(date);
     *  result = offsetDateTime._with(time);
     *  result = offsetDateTime._with(offset);
     * </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 an {@code OffsetDateTime} 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
    public OffsetDateTime _with(TemporalAdjuster adjuster) {
        // optimizations
        if (cast(LocalDate)(adjuster) !is null || cast(LocalTime)(adjuster) !is null || cast(LocalDateTime)(adjuster) !is null) {
            return _with(dateTime._with(adjuster), offset);
        } else if (cast(Instant)(adjuster) !is null) {
            return ofInstant(cast(Instant) adjuster, offset);
        } else if (cast(ZoneOffset)(adjuster) !is null) {
            return _with(dateTime, cast(ZoneOffset) adjuster);
        } else if (cast(OffsetDateTime)(adjuster) !is null) {
            return cast(OffsetDateTime) adjuster;
        }
        return cast(OffsetDateTime) adjuster.adjustInto(this);
    }

    /**
     * Returns a copy of this date-time with the specified field set to a new value.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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.
     * !(p)
     * The {@code INSTANT_SECONDS} field will return a date-time with the specified instant.
     * The offset and nano-of-second are unchanged.
     * If the new instant value is outside the valid range then a {@code DateTimeException} will be thrown.
     * !(p)
     * The {@code OFFSET_SECONDS} field will return a date-time with the specified offset.
     * The local date-time is unaltered. If the new offset value is outside the valid range
     * then a {@code DateTimeException} will be thrown.
     * !(p)
     * The other {@link #isSupported(TemporalField) supported fields} will behave as per
     * the matching method on {@link LocalDateTime#_with(TemporalField, long) LocalDateTime}.
     * In this case, the offset is not part of the calculation and will be unchanged.
     * !(p)
     * 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 an {@code OffsetDateTime} 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
    public OffsetDateTime _with(TemporalField field, long newValue) {
        if (cast(ChronoField)(field) !is null) {
            ChronoField f = cast(ChronoField) field;
            {
                 if( f == ChronoField.INSTANT_SECONDS) return ofInstant(Instant.ofEpochSecond(newValue, getNano()), offset);
                 if( f == ChronoField.OFFSET_SECONDS) {
                    return _with(dateTime, ZoneOffset.ofTotalSeconds(f.checkValidIntValue(newValue)));
                }
            }
            return _with(dateTime._with(field, newValue), offset);
        }
        return cast(OffsetDateTime)(field.adjustInto(this, newValue));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code OffsetDateTime} with the year altered.
     * !(p)
     * The time and offset do 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 an {@code OffsetDateTime} based on this date-time with the requested year, not null
     * @throws DateTimeException if the year value is invalid
     */
    public OffsetDateTime withYear(int year) {
        return _with(dateTime.withYear(year), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the month-of-year altered.
     * !(p)
     * The time and offset do 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 an {@code OffsetDateTime} based on this date-time with the requested month, not null
     * @throws DateTimeException if the month-of-year value is invalid
     */
    public OffsetDateTime withMonth(int month) {
        return _with(dateTime.withMonth(month), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the day-of-month altered.
     * !(p)
     * If the resulting {@code OffsetDateTime} is invalid, an exception is thrown.
     * The time and offset do 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 an {@code OffsetDateTime} 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
     */
    public OffsetDateTime withDayOfMonth(int dayOfMonth) {
        return _with(dateTime.withDayOfMonth(dayOfMonth), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the day-of-year altered.
     * !(p)
     * The time and offset do not affect the calculation and will be the same _in the result.
     * If the resulting {@code OffsetDateTime} 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 an {@code OffsetDateTime} 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
     */
    public OffsetDateTime withDayOfYear(int dayOfYear) {
        return _with(dateTime.withDayOfYear(dayOfYear), offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code OffsetDateTime} with the hour-of-day altered.
     * !(p)
     * The date and offset do not affect the calculation and will be the same _in the result.
     * !(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 an {@code OffsetDateTime} based on this date-time with the requested hour, not null
     * @throws DateTimeException if the hour value is invalid
     */
    public OffsetDateTime withHour(int hour) {
        return _with(dateTime.withHour(hour), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the minute-of-hour altered.
     * !(p)
     * The date and offset do not affect the calculation and will be the same _in the result.
     * !(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 an {@code OffsetDateTime} based on this date-time with the requested minute, not null
     * @throws DateTimeException if the minute value is invalid
     */
    public OffsetDateTime withMinute(int minute) {
        return _with(dateTime.withMinute(minute), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the second-of-minute altered.
     * !(p)
     * The date and offset do not affect the calculation and will be the same _in the result.
     * !(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 an {@code OffsetDateTime} based on this date-time with the requested second, not null
     * @throws DateTimeException if the second value is invalid
     */
    public OffsetDateTime withSecond(int second) {
        return _with(dateTime.withSecond(second), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} with the nano-of-second altered.
     * !(p)
     * The date and offset do not affect the calculation and will be the same _in the result.
     * !(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 an {@code OffsetDateTime} based on this date-time with the requested nanosecond, not null
     * @throws DateTimeException if the nano value is invalid
     */
    public OffsetDateTime withNano(int nanoOfSecond) {
        return _with(dateTime.withNano(nanoOfSecond), offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code OffsetDateTime} 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)
     * The offset 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 unit  the unit to truncate to, not null
     * @return an {@code OffsetDateTime} 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
     */
    public OffsetDateTime truncatedTo(TemporalUnit unit) {
        return _with(dateTime.truncatedTo(unit), offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date-time with the specified amount added.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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 an {@code OffsetDateTime} 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
    public OffsetDateTime plus(TemporalAmount amountToAdd) {
        return cast(OffsetDateTime) amountToAdd.addTo(this);
    }

    /**
     * Returns a copy of this date-time with the specified amount added.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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 by
     * {@link LocalDateTime#plus(long, TemporalUnit)}.
     * The offset is not part of the calculation and will be unchanged _in the result.
     * !(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 an {@code OffsetDateTime} 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
    public OffsetDateTime plus(long amountToAdd, TemporalUnit unit) {
        if (cast(ChronoUnit)(unit) !is null) {
            return _with(dateTime.plus(amountToAdd, unit), offset);
        }
        return cast(OffsetDateTime)(unit.addTo(this, amountToAdd));
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the years added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusYears(long years) {
        return _with(dateTime.plusYears(years), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the months added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusMonths(long months) {
        return _with(dateTime.plusMonths(months), offset);
    }

    /**
     * Returns a copy of this OffsetDateTime 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 an {@code OffsetDateTime} based on this date-time with the weeks added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusWeeks(long weeks) {
        return _with(dateTime.plusWeeks(weeks), offset);
    }

    /**
     * Returns a copy of this OffsetDateTime 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 an {@code OffsetDateTime} based on this date-time with the days added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusDays(long days) {
        return _with(dateTime.plusDays(days), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the hours added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusHours(long hours) {
        return _with(dateTime.plusHours(hours), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the minutes added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusMinutes(long minutes) {
        return _with(dateTime.plusMinutes(minutes), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the seconds added, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime plusSeconds(long seconds) {
        return _with(dateTime.plusSeconds(seconds), offset);
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the nanoseconds added, not null
     * @throws DateTimeException if the unit cannot be added to this type
     */
    public OffsetDateTime plusNanos(long nanos) {
        return _with(dateTime.plusNanos(nanos), offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a copy of this date-time with the specified amount subtracted.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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 an {@code OffsetDateTime} 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
    public OffsetDateTime minus(TemporalAmount amountToSubtract) {
        return cast(OffsetDateTime) amountToSubtract.subtractFrom(this);
    }

    /**
     * Returns a copy of this date-time with the specified amount subtracted.
     * !(p)
     * This returns an {@code OffsetDateTime}, 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 an {@code OffsetDateTime} 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
    public OffsetDateTime 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 OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the years subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusYears(long years) {
        return (years == Long.MIN_VALUE ? plusYears(Long.MAX_VALUE).plusYears(1) : plusYears(-years));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the months subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusMonths(long months) {
        return (months == Long.MIN_VALUE ? plusMonths(Long.MAX_VALUE).plusMonths(1) : plusMonths(-months));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the weeks subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusWeeks(long weeks) {
        return (weeks == Long.MIN_VALUE ? plusWeeks(Long.MAX_VALUE).plusWeeks(1) : plusWeeks(-weeks));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the days subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusDays(long days) {
        return (days == Long.MIN_VALUE ? plusDays(Long.MAX_VALUE).plusDays(1) : plusDays(-days));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the hours subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusHours(long hours) {
        return (hours == Long.MIN_VALUE ? plusHours(Long.MAX_VALUE).plusHours(1) : plusHours(-hours));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the minutes subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusMinutes(long minutes) {
        return (minutes == Long.MIN_VALUE ? plusMinutes(Long.MAX_VALUE).plusMinutes(1) : plusMinutes(-minutes));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the seconds subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusSeconds(long seconds) {
        return (seconds == Long.MIN_VALUE ? plusSeconds(Long.MAX_VALUE).plusSeconds(1) : plusSeconds(-seconds));
    }

    /**
     * Returns a copy of this {@code OffsetDateTime} 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 an {@code OffsetDateTime} based on this date-time with the nanoseconds subtracted, not null
     * @throws DateTimeException if the result exceeds the supported date range
     */
    public OffsetDateTime minusNanos(long nanos) {
        return (nanos == Long.MIN_VALUE ? plusNanos(Long.MAX_VALUE).plusNanos(1) : plusNanos(-nanos));
    }

    //-----------------------------------------------------------------------
    /**
     * 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
    public R query(R)(TemporalQuery!(R) query) {
        if (query == TemporalQueries.offset() || query == TemporalQueries.zone()) {
            return cast(R) getOffset();
        } else if (query == TemporalQueries.zoneId()) {
            return null;
        } else if (query == TemporalQueries.localDate()) {
            return cast(R) toLocalDate();
        } else if (query == TemporalQueries.localTime()) {
            return cast(R) toLocalTime();
        } else if (query == TemporalQueries.chronology()) {
            return cast(R) IsoChronology.INSTANCE;
        } else if (query == TemporalQueries.precision()) {
            return cast(R) (ChronoUnit.NANOS);
        }
        // inline TemporalAccessor.super.query(query) as an optimization
        // non-JDK classes are not permitted to make this optimization
        return query.queryFrom(this);
    }

    /**
     * Adjusts the specified temporal object to have the same offset, date
     * and time as this object.
     * !(p)
     * This returns a temporal object of the same observable type as the input
     * with the offset, date and time changed to be the same as this.
     * !(p)
     * The adjustment is equivalent to using {@link Temporal#_with(TemporalField, long)}
     * three times, passing {@link ChronoField#EPOCH_DAY},
     * {@link ChronoField#NANO_OF_DAY} and {@link ChronoField#OFFSET_SECONDS} 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 = thisOffsetDateTime.adjustInto(temporal);
     *   temporal = temporal._with(thisOffsetDateTime);
     * </pre>
     * !(p)
     * This instance is immutable and unaffected by this method call.
     *
     * @param temporal  the target object to be adjusted, not null
     * @return the adjusted object, not null
     * @throws DateTimeException if unable to make the adjustment
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    public Temporal adjustInto(Temporal temporal) {
        // OffsetDateTime is treated as three separate fields, not an instant
        // this produces the most consistent set of results overall
        // the offset is set after the date and time, as it is typically a small
        // tweak to the result, with ZonedDateTime frequently ignoring the offset
        return temporal
                ._with(ChronoField.EPOCH_DAY, toLocalDate().toEpochDay())
                ._with(ChronoField.NANO_OF_DAY, toLocalTime().toNanoOfDay())
                ._with(ChronoField.OFFSET_SECONDS, getOffset().getTotalSeconds());
    }

    /**
     * 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 OffsetDateTime}
     * 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.
     * For example, the amount _in days between two date-times can be calculated
     * using {@code startDateTime.until(endDateTime, DAYS)}.
     * !(p)
     * The {@code Temporal} passed to this method is converted to a
     * {@code OffsetDateTime} using {@link #from(TemporalAccessor)}.
     * If the offset differs between the two date-times, the specified
     * end date-time is normalized to have the same offset as this date-time.
     * !(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 2012-06-15T00:00Z and 2012-08-14T23:59Z
     * 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 an {@code OffsetDateTime}, 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 an {@code OffsetDateTime}
     * @throws UnsupportedTemporalTypeException if the unit is not supported
     * @throws ArithmeticException if numeric overflow occurs
     */
    override
    public long until(Temporal endExclusive, TemporalUnit unit) {
        OffsetDateTime end = OffsetDateTime.from(endExclusive);
        if (cast(ChronoUnit)(unit) !is null) {
            end = end.withOffsetSameInstant(offset);
            return dateTime.until(end.dateTime, unit);
        }
        return unit.between(this, end);
    }

    /**
     * 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
     */
    // public string format(DateTimeFormatter formatter) {
    //     assert(formatter, "formatter");
    //     return formatter.format(this);
    // }

    //-----------------------------------------------------------------------
    /**
     * Combines this date-time with a time-zone to create a {@code ZonedDateTime}
     * ensuring that the result has the same instant.
     * !(p)
     * This returns a {@code ZonedDateTime} formed from this date-time and the specified time-zone.
     * This conversion will ignore the visible local date-time and use the underlying instant instead.
     * This avoids any problems with local time-line gaps or overlaps.
     * The result might have different values for fields such as hour, minute an even day.
     * !(p)
     * To attempt to retain the values of the fields, use {@link #atZoneSimilarLocal(ZoneId)}.
     * To use the offset as the zone ID, use {@link #toZonedDateTime()}.
     *
     * @param zone  the time-zone to use, not null
     * @return the zoned date-time formed from this date-time, not null
     */
    public ZonedDateTime atZoneSameInstant(ZoneId zone) {
        return ZonedDateTime.ofInstant(dateTime, offset, zone);
    }

    /**
     * Combines this date-time with a time-zone to create a {@code ZonedDateTime}
     * trying to keep the same local date and time.
     * !(p)
     * This returns a {@code ZonedDateTime} formed from this date-time and the specified time-zone.
     * Where possible, the result will have the same local date-time as this object.
     * !(p)
     * Time-zone rules, such as daylight savings, mean that not every time on the
     * local time-line exists. If the local date-time is _in a gap or overlap according to
     * the rules then a resolver is used to determine the resultant local time and offset.
     * This method uses {@link ZonedDateTime#ofLocal(LocalDateTime, ZoneId, ZoneOffset)}
     * to retain the offset from this instance if possible.
     * !(p)
     * Finer control over gaps and overlaps is available _in two ways.
     * If you simply want to use the later offset at overlaps then call
     * {@link ZonedDateTime#withLaterOffsetAtOverlap()} immediately after this method.
     * !(p)
     * To create a zoned date-time at the same instant irrespective of the local time-line,
     * use {@link #atZoneSameInstant(ZoneId)}.
     * To use the offset as the zone ID, use {@link #toZonedDateTime()}.
     *
     * @param zone  the time-zone to use, not null
     * @return the zoned date-time formed from this date and the earliest valid time for the zone, not null
     */
    public ZonedDateTime atZoneSimilarLocal(ZoneId zone) {
        return ZonedDateTime.ofLocal(dateTime, zone, offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Converts this date-time to an {@code OffsetTime}.
     * !(p)
     * This returns an offset time with the same local time and offset.
     *
     * @return an OffsetTime representing the time and offset, not null
     */
    public OffsetTime toOffsetTime() {
        return OffsetTime.of(dateTime.toLocalTime(), offset);
    }

    /**
     * Converts this date-time to a {@code ZonedDateTime} using the offset as the zone ID.
     * !(p)
     * This creates the simplest possible {@code ZonedDateTime} using the offset
     * as the zone ID.
     * !(p)
     * To control the time-zone used, see {@link #atZoneSameInstant(ZoneId)} and
     * {@link #atZoneSimilarLocal(ZoneId)}.
     *
     * @return a zoned date-time representing the same local date-time and offset, not null
     */
    public ZonedDateTime toZonedDateTime() {
        return ZonedDateTime.of(dateTime, offset);
    }

    /**
     * Converts this date-time to an {@code Instant}.
     * !(p)
     * This returns an {@code Instant} representing the same point on the
     * time-line as this date-time.
     *
     * @return an {@code Instant} representing the same instant, not null
     */
    public Instant toInstant() {
        return dateTime.toInstant(offset);
    }

    /**
     * Converts this date-time to the number of seconds from the epoch of 1970-01-01T00:00:00Z.
     * !(p)
     * This allows this date-time to be converted to a value of the
     * {@link ChronoField#INSTANT_SECONDS epoch-seconds} field. This is primarily
     * intended for low-level conversions rather than general application usage.
     *
     * @return the number of seconds from the epoch of 1970-01-01T00:00:00Z
     */
    public long toEpochSecond() {
        return dateTime.toEpochSecond(offset);
    }

    //-----------------------------------------------------------------------
    /**
     * Compares this date-time to another date-time.
     * !(p)
     * The comparison is based on the instant then on the local date-time.
     * It is "consistent with equals", as defined by {@link Comparable}.
     * !(p)
     * For example, the following is the comparator order:
     * !(ol)
     * !(li){@code 2008-12-03T10:30+01:00}</li>
     * !(li){@code 2008-12-03T11:00+01:00}</li>
     * !(li){@code 2008-12-03T12:00+02:00}</li>
     * !(li){@code 2008-12-03T11:30+01:00}</li>
     * !(li){@code 2008-12-03T12:00+01:00}</li>
     * !(li){@code 2008-12-03T12:30+01:00}</li>
     * </ol>
     * Values #2 and #3 represent the same instant on the time-line.
     * When two values represent the same instant, the local date-time is compared
     * to distinguish them. This step is needed to make the ordering
     * consistent with {@code equals()}.
     *
     * @param other  the other date-time to compare to, not null
     * @return the comparator value, negative if less, positive if greater
     */
    // override
    public int compareTo(OffsetDateTime other) {
        int cmp = compareInstant(this, other);
        if (cmp == 0) {
            cmp = toLocalDateTime().compareTo(cast(ChronoLocalDateTime!(ChronoLocalDate))(other.toLocalDateTime()));
        }
        return cmp;
    }
    override
    public int opCmp(OffsetDateTime other) {
        return compareTo(other);
    }
    //-----------------------------------------------------------------------
    /**
     * Checks if the instant of this date-time is after that of the specified date-time.
     * !(p)
     * This method differs from the comparison _in {@link #compareTo} and {@link #equals} _in that it
     * only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().isAfter(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this is after the instant of the specified date-time
     */
    public bool isAfter(OffsetDateTime other) {
        long thisEpochSec = toEpochSecond();
        long otherEpochSec = other.toEpochSecond();
        return thisEpochSec > otherEpochSec ||
            (thisEpochSec == otherEpochSec && toLocalTime().getNano() > other.toLocalTime().getNano());
    }

    /**
     * Checks if the instant of this date-time is before that of the specified date-time.
     * !(p)
     * This method differs from the comparison _in {@link #compareTo} _in that it
     * only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().isBefore(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if this is before the instant of the specified date-time
     */
    public bool isBefore(OffsetDateTime other) {
        long thisEpochSec = toEpochSecond();
        long otherEpochSec = other.toEpochSecond();
        return thisEpochSec < otherEpochSec ||
            (thisEpochSec == otherEpochSec && toLocalTime().getNano() < other.toLocalTime().getNano());
    }

    /**
     * Checks if the instant of this date-time is equal to that of the specified date-time.
     * !(p)
     * This method differs from the comparison _in {@link #compareTo} and {@link #equals}
     * _in that it only compares the instant of the date-time. This is equivalent to using
     * {@code dateTime1.toInstant().equals(dateTime2.toInstant());}.
     *
     * @param other  the other date-time to compare to, not null
     * @return true if the instant equals the instant of the specified date-time
     */
    public bool isEqual(OffsetDateTime other) {
        return toEpochSecond() == other.toEpochSecond() &&
                toLocalTime().getNano() == other.toLocalTime().getNano();
    }

    //-----------------------------------------------------------------------
    /**
     * Checks if this date-time is equal to another date-time.
     * !(p)
     * The comparison is based on the local date-time and the offset.
     * To compare for the same instant on the time-line, use {@link #isEqual}.
     * Only objects of type {@code OffsetDateTime} 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
    public bool opEquals(Object obj) {
        if (this is obj) {
            return true;
        }
        if (cast(OffsetDateTime)(obj) !is null) {
            OffsetDateTime other = cast(OffsetDateTime) obj;
            return dateTime == (other.dateTime) && offset == (other.offset);
        }
        return false;
    }

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

    //-----------------------------------------------------------------------
    /**
     * Outputs this date-time as a {@code string}, such as {@code 2007-12-03T10:15:30+01:00}.
     * !(p)
     * The output will be one of the following ISO-8601 formats:
     * !(ul)
     * !(li){@code uuuu-MM-dd'T'HH:mmXXXXX}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ssXXXXX}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSSXXXXX}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSSSSSXXXXX}</li>
     * !(li){@code uuuu-MM-dd'T'HH:mm:ss.SSSSSSSSSXXXXX}</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
    public string toString() {
        return dateTime.toString() ~ offset.toString();
    }

    //-----------------------------------------------------------------------
    /**
     * Writes the object using a
     * <a href="{@docRoot}/serialized-form.html#hunt.time.Ser">dedicated serialized form</a>.
     * @serialData
     * !(pre)
     *  _out.writeByte(10);  // identifies an OffsetDateTime
     *  // the <a href="{@docRoot}/serialized-form.html#hunt.time.LocalDateTime">datetime</a> excluding the one byte header
     *  // the <a href="{@docRoot}/serialized-form.html#hunt.time.ZoneOffset">offset</a> excluding the one byte header
     * </pre>
     *
     * @return the instance of {@code Ser}, not null
     */
    private Object writeReplace() {
        return new Ser(Ser.OFFSET_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(ObjectOutput _out) /*throws IOException*/ {
    //     dateTime.writeExternal(_out);
    //     offset.writeExternal(_out);
    // }

    // static OffsetDateTime readExternal(ObjectInput _in) /*throws IOException, ClassNotFoundException*/ {
    //     LocalDateTime dateTime = LocalDateTime.readExternal(_in);
    //     ZoneOffset offset = ZoneOffset.readExternal(_in);
    //     return OffsetDateTime.of(dateTime, offset);
    // }

}