ladybird/Userland/Libraries/LibJS/Runtime/Temporal/Duration.cpp

/*
 * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/StringBuilder.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Completion.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/Temporal/AbstractOperations.h>
#include <LibJS/Runtime/Temporal/Calendar.h>
#include <LibJS/Runtime/Temporal/Duration.h>
#include <LibJS/Runtime/Temporal/DurationConstructor.h>
#include <LibJS/Runtime/Temporal/Instant.h>
#include <LibJS/Runtime/Temporal/PlainDateTime.h>
#include <LibJS/Runtime/Temporal/TimeZone.h>
#include <LibJS/Runtime/Temporal/ZonedDateTime.h>

namespace JS::Temporal {

// 7 Temporal.Duration Objects, https://tc39.es/proposal-temporal/#sec-temporal-duration-objects
Duration::Duration(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, Object& prototype)
    : Object(prototype)
    , m_years(years)
    , m_months(months)
    , m_weeks(weeks)
    , m_days(days)
    , m_hours(hours)
    , m_minutes(minutes)
    , m_seconds(seconds)
    , m_milliseconds(milliseconds)
    , m_microseconds(microseconds)
    , m_nanoseconds(nanoseconds)
{
}

// 7.5.1 ToTemporalDuration ( item ), https://tc39.es/proposal-temporal/#sec-temporal-totemporalduration
ThrowCompletionOr<Duration*> to_temporal_duration(GlobalObject& global_object, Value item)
{
    TemporalDuration result;

    // 1. If Type(item) is Object, then
    if (item.is_object()) {
        // a. If item has an [[InitializedTemporalDuration]] internal slot, then
        if (is<Duration>(item.as_object())) {
            // i. Return item.
            return &static_cast<Duration&>(item.as_object());
        }
        // b. Let result be ? ToTemporalDurationRecord(item).
        result = TRY(to_temporal_duration_record(global_object, item.as_object()));
    }
    // 2. Else,
    else {
        // a. Let string be ? ToString(item).
        auto string = TRY(item.to_string(global_object));

        // b. Let result be ? ParseTemporalDurationString(string).
        result = TRY(parse_temporal_duration_string(global_object, string));
    }

    // 3. Return ? CreateTemporalDuration(result.[[Years]], result.[[Months]], result.[[Weeks]], result.[[Days]], result.[[Hours]], result.[[Minutes]], result.[[Seconds]], result.[[Milliseconds]], result.[[Microseconds]], result.[[Nanoseconds]]).
    return create_temporal_duration(global_object, result.years, result.months, result.weeks, result.days, result.hours, result.minutes, result.seconds, result.milliseconds, result.microseconds, result.nanoseconds);
}

// 7.5.2 ToTemporalDurationRecord ( temporalDurationLike ), https://tc39.es/proposal-temporal/#sec-temporal-totemporaldurationrecord
ThrowCompletionOr<TemporalDuration> to_temporal_duration_record(GlobalObject& global_object, Object const& temporal_duration_like)
{
    auto& vm = global_object.vm();

    // 1. Assert: Type(temporalDurationLike) is Object.

    // 2. If temporalDurationLike has an [[InitializedTemporalDuration]] internal slot, then
    if (is<Duration>(temporal_duration_like)) {
        auto& duration = static_cast<Duration const&>(temporal_duration_like);

        // a. Return the Record { [[Years]]: temporalDurationLike.[[Years]], [[Months]]: temporalDurationLike.[[Months]], [[Weeks]]: temporalDurationLike.[[Weeks]], [[Days]]: temporalDurationLike.[[Days]], [[Hours]]: temporalDurationLike.[[Hours]], [[Minutes]]: temporalDurationLike.[[Minutes]], [[Seconds]]: temporalDurationLike.[[Seconds]], [[Milliseconds]]: temporalDurationLike.[[Milliseconds]], [[Microseconds]]: temporalDurationLike.[[Microseconds]], [[Nanoseconds]]: temporalDurationLike.[[Nanoseconds]] }.
        return TemporalDuration { .years = duration.years(), .months = duration.months(), .weeks = duration.weeks(), .days = duration.days(), .hours = duration.hours(), .minutes = duration.minutes(), .seconds = duration.seconds(), .milliseconds = duration.milliseconds(), .microseconds = duration.microseconds(), .nanoseconds = duration.nanoseconds() };
    }

    // 3. Let result be a new Record with all the internal slots given in the Internal Slot column in Table 7.
    auto result = TemporalDuration {};

    // 4. Let any be false.
    auto any = false;

    // 5. For each row of Table 7, except the header row, in table order, do
    for (auto& [internal_slot, property] : temporal_duration_like_properties<TemporalDuration, double>(vm)) {
        // a. Let prop be the Property value of the current row.

        // b. Let val be ? Get(temporalDurationLike, prop).
        auto value = TRY(temporal_duration_like.get(property));

        // c. If val is undefined, then
        if (value.is_undefined()) {
            // i. Set result's internal slot whose name is the Internal Slot value of the current row to 0.
            result.*internal_slot = 0;
        }
        // d. Else,
        else {
            // i. Set any to true.
            any = true;

            // ii. Let val be ? ToNumber(val).
            value = TRY(value.to_number(global_object));

            // iii. If ! IsIntegralNumber(val) is false, then
            if (!value.is_integral_number()) {
                // 1. Throw a RangeError exception.
                return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidDurationPropertyValueNonIntegral, property.as_string(), value.to_string_without_side_effects());
            }

            // iv. Set result's internal slot whose name is the Internal Slot value of the current row to val.
            result.*internal_slot = value.as_double();
        }
    }

    // 6. If any is false, then
    if (!any) {
        // a. Throw a TypeError exception.
        return vm.throw_completion<TypeError>(global_object, ErrorType::TemporalInvalidDurationLikeObject);
    }

    // 7. Return result.
    return result;
}

// 7.5.3 DurationSign ( years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-durationsign
i8 duration_sign(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds)
{
    // 1. For each value v of « years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds », do
    for (auto& v : { years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds }) {
        // a. If v < 0, return −1.
        if (v < 0)
            return -1;

        // b. If v > 0, return 1.
        if (v > 0)
            return 1;
    }

    // 2. Return 0.
    return 0;
}

// 7.5.4 IsValidDuration ( years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-isvalidduration
bool is_valid_duration(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds)
{
    // 1. Let sign be ! DurationSign(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds).
    auto sign = duration_sign(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);

    // 2. For each value v of « years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds », do
    for (auto& v : { years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds }) {
        // a. If v is not finite, return false.
        if (!isfinite(v))
            return false;

        // b. If v < 0 and sign > 0, return false.
        if (v < 0 && sign > 0)
            return false;

        // c. If v > 0 and sign < 0, return false.
        if (v > 0 && sign < 0)
            return false;
    }

    // 3. Return true.
    return true;
}

// 7.5.6 ToPartialDuration ( temporalDurationLike ), https://tc39.es/proposal-temporal/#sec-temporal-topartialduration
ThrowCompletionOr<PartialDuration> to_partial_duration(GlobalObject& global_object, Value temporal_duration_like)
{
    auto& vm = global_object.vm();

    // 1. If Type(temporalDurationLike) is not Object, then
    if (!temporal_duration_like.is_object()) {
        // a. Throw a TypeError exception.
        return vm.throw_completion<TypeError>(global_object, ErrorType::NotAnObject, temporal_duration_like.to_string_without_side_effects());
    }

    // 2. Let result be the Record { [[Years]]: undefined, [[Months]]: undefined, [[Weeks]]: undefined, [[Days]]: undefined, [[Hours]]: undefined, [[Minutes]]: undefined, [[Seconds]]: undefined, [[Milliseconds]]: undefined, [[Microseconds]]: undefined, [[Nanoseconds]]: undefined }.
    auto result = PartialDuration {};

    // 3. Let any be false.
    auto any = false;

    // 4. For each row of Table 7, except the header row, in table order, do
    for (auto& [internal_slot, property] : temporal_duration_like_properties<PartialDuration, Optional<double>>(vm)) {
        // a. Let property be the Property value of the current row.

        // b. Let value be ? Get(temporalDurationLike, property).
        auto value = TRY(temporal_duration_like.as_object().get(property));

        // c. If value is not undefined, then
        if (!value.is_undefined()) {
            // i. Set any to true.
            any = true;

            // ii. Set value to ? ToNumber(value).
            value = TRY(value.to_number(global_object));

            // iii. If ! IsIntegralNumber(value) is false, then
            if (!value.is_integral_number()) {
                // 1. Throw a RangeError exception.
                return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidDurationPropertyValueNonIntegral, property.as_string(), value.to_string_without_side_effects());
            }

            // iv. Set result's internal slot whose name is the Internal Slot value of the current row to value.
            result.*internal_slot = value.as_double();
        }
    }

    // 5. If any is false, then
    if (!any) {
        // a. Throw a TypeError exception.
        return vm.throw_completion<TypeError>(global_object, ErrorType::TemporalInvalidDurationLikeObject);
    }

    // 6. Return result.
    return result;
}

// 7.5.7 CreateTemporalDuration ( years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds [ , newTarget ] ), https://tc39.es/proposal-temporal/#sec-temporal-createtemporalduration
ThrowCompletionOr<Duration*> create_temporal_duration(GlobalObject& global_object, double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, FunctionObject const* new_target)
{
    auto& vm = global_object.vm();

    // 1. If ! IsValidDuration(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds) is false, throw a RangeError exception.
    if (!is_valid_duration(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds))
        return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidDuration);

    // 2. If newTarget is not present, set it to %Temporal.Duration%.
    if (!new_target)
        new_target = global_object.temporal_duration_constructor();

    // 3. Let object be ? OrdinaryCreateFromConstructor(newTarget, "%Temporal.Duration.prototype%", « [[InitializedTemporalDuration]], [[Years]], [[Months]], [[Weeks]], [[Days]], [[Hours]], [[Minutes]], [[Seconds]], [[Milliseconds]], [[Microseconds]], [[Nanoseconds]] »).
    // 4. Set object.[[Years]] to years.
    // 5. Set object.[[Months]] to months.
    // 6. Set object.[[Weeks]] to weeks.
    // 7. Set object.[[Days]] to days.
    // 8. Set object.[[Hours]] to hours.
    // 9. Set object.[[Minutes]] to minutes.
    // 10. Set object.[[Seconds]] to seconds.
    // 11. Set object.[[Milliseconds]] to milliseconds.
    // 12. Set object.[[Microseconds]] to microseconds.
    // 13. Set object.[[Nanoseconds]] to nanoseconds.
    auto* object = TRY(ordinary_create_from_constructor<Duration>(global_object, *new_target, &GlobalObject::temporal_duration_prototype, years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds));

    // 14. Return object.
    return object;
}

// 7.5.8 CreateNegatedTemporalDuration ( duration ), https://tc39.es/proposal-temporal/#sec-temporal-createnegatedtemporalduration
Duration* create_negated_temporal_duration(GlobalObject& global_object, Duration const& duration)
{
    // 1. Assert: Type(duration) is Object.
    // 2. Assert: duration has an [[InitializedTemporalDuration]] internal slot.

    // 3. Return ! CreateTemporalDuration(−duration.[[Years]], −duration.[[Months]], −duration.[[Weeks]], −duration.[[Days]], −duration.[[Hours]], −duration.[[Minutes]], −duration.[[Seconds]], −duration.[[Milliseconds]], −duration.[[Microseconds]], −duration.[[Nanoseconds]]).
    return MUST(create_temporal_duration(global_object, -duration.years(), -duration.months(), -duration.weeks(), -duration.days(), -duration.hours(), -duration.minutes(), -duration.seconds(), -duration.milliseconds(), -duration.microseconds(), -duration.nanoseconds()));
}

// 7.5.10 TotalDurationNanoseconds ( days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, offsetShift ), https://tc39.es/proposal-temporal/#sec-temporal-totaldurationnanoseconds
BigInt* total_duration_nanoseconds(GlobalObject& global_object, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, BigInt const& nanoseconds, double offset_shift)
{
    auto& vm = global_object.vm();

    // 1. Assert: offsetShift is an integer.
    VERIFY(offset_shift == trunc(offset_shift));

    // 2. Set nanoseconds to ℝ(nanoseconds).
    auto result_nanoseconds = nanoseconds.big_integer();

    // TODO: Add a way to create SignedBigIntegers from doubles with full precision and remove this restriction
    VERIFY(AK::is_within_range<i64>(days) && AK::is_within_range<i64>(hours) && AK::is_within_range<i64>(minutes) && AK::is_within_range<i64>(seconds) && AK::is_within_range<i64>(milliseconds) && AK::is_within_range<i64>(microseconds));

    // 3. If days ≠ 0, then
    if (days != 0) {
        // a. Set nanoseconds to nanoseconds − offsetShift.
        result_nanoseconds = result_nanoseconds.minus(Crypto::SignedBigInteger::create_from(offset_shift));
    }
    // 4. Set hours to ℝ(hours) + ℝ(days) × 24.
    auto total_hours = Crypto::SignedBigInteger::create_from(hours).plus(Crypto::SignedBigInteger::create_from(days).multiplied_by(Crypto::UnsignedBigInteger(24)));
    // 5. Set minutes to ℝ(minutes) + hours × 60.
    auto total_minutes = Crypto::SignedBigInteger::create_from(minutes).plus(total_hours.multiplied_by(Crypto::UnsignedBigInteger(60)));
    // 6. Set seconds to ℝ(seconds) + minutes × 60.
    auto total_seconds = Crypto::SignedBigInteger::create_from(seconds).plus(total_minutes.multiplied_by(Crypto::UnsignedBigInteger(60)));
    // 7. Set milliseconds to ℝ(milliseconds) + seconds × 1000.
    auto total_milliseconds = Crypto::SignedBigInteger::create_from(milliseconds).plus(total_seconds.multiplied_by(Crypto::UnsignedBigInteger(1000)));
    // 8. Set microseconds to ℝ(microseconds) + milliseconds × 1000.
    auto total_microseconds = Crypto::SignedBigInteger::create_from(microseconds).plus(total_milliseconds.multiplied_by(Crypto::UnsignedBigInteger(1000)));
    // 9. Return nanoseconds + microseconds × 1000.
    return js_bigint(vm, result_nanoseconds.plus(total_microseconds.multiplied_by(Crypto::UnsignedBigInteger(1000))));
}

// 7.5.11 BalanceDuration ( days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, largestUnit [ , relativeTo ] ), https://tc39.es/proposal-temporal/#sec-temporal-balanceduration
ThrowCompletionOr<BalancedDuration> balance_duration(GlobalObject& global_object, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, BigInt const& nanoseconds, String const& largest_unit, Object* relative_to)
{
    auto& vm = global_object.vm();

    // 1. If relativeTo is not present, set relativeTo to undefined.

    Crypto::SignedBigInteger total_nanoseconds;
    // 2. If Type(relativeTo) is Object and relativeTo has an [[InitializedTemporalZonedDateTime]] internal slot, then
    if (relative_to && is<ZonedDateTime>(*relative_to)) {
        auto& relative_to_zoned_date_time = static_cast<ZonedDateTime&>(*relative_to);

        // a. Let endNs be ? AddZonedDateTime(relativeTo.[[Nanoseconds]], relativeTo.[[TimeZone]], relativeTo.[[Calendar]], 0, 0, 0, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds).
        auto* end_ns = TRY(add_zoned_date_time(global_object, relative_to_zoned_date_time.nanoseconds(), &relative_to_zoned_date_time.time_zone(), relative_to_zoned_date_time.calendar(), 0, 0, 0, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds.big_integer().to_double()));

        // b. Set nanoseconds to endNs − relativeTo.[[Nanoseconds]].
        total_nanoseconds = end_ns->big_integer().minus(relative_to_zoned_date_time.nanoseconds().big_integer());
    }
    // 3. Else,
    else {
        // a. Set nanoseconds to ℤ(! TotalDurationNanoseconds(days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, 0)).
        total_nanoseconds = total_duration_nanoseconds(global_object, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, 0)->big_integer();
    }

    // 4. If largestUnit is one of "year", "month", "week", or "day", then
    if (largest_unit.is_one_of("year"sv, "month"sv, "week"sv, "day"sv)) {
        // a. Let result be ? NanosecondsToDays(nanoseconds, relativeTo).
        auto result = TRY(nanoseconds_to_days(global_object, *js_bigint(vm, total_nanoseconds), relative_to ?: js_undefined()));

        // b. Set days to result.[[Days]].
        days = result.days;

        // c. Set nanoseconds to result.[[Nanoseconds]].
        total_nanoseconds = result.nanoseconds.cell()->big_integer();
    }
    // 5. Else,
    else {
        // a. Set days to 0.
        days = 0;
    }
    // 6. Set hours, minutes, seconds, milliseconds, and microseconds to 0.
    hours = 0;
    minutes = 0;
    seconds = 0;
    milliseconds = 0;
    microseconds = 0;

    // 7. Set nanoseconds to ℝ(nanoseconds).
    double result_nanoseconds = total_nanoseconds.to_double();

    // 8. If nanoseconds < 0, let sign be −1; else, let sign be 1.
    i8 sign = total_nanoseconds.is_negative() ? -1 : 1;

    // 9. Set nanoseconds to abs(nanoseconds).
    total_nanoseconds = Crypto::SignedBigInteger(total_nanoseconds.unsigned_value());
    result_nanoseconds = fabs(result_nanoseconds);

    // 10. If largestUnit is "year", "month", "week", "day", or "hour", then
    if (largest_unit.is_one_of("year"sv, "month"sv, "day"sv, "hour"sv)) {
        // a. Set microseconds to floor(nanoseconds / 1000).
        auto nanoseconds_division_result = total_nanoseconds.divided_by(Crypto::UnsignedBigInteger(1000));
        // b. Set nanoseconds to nanoseconds modulo 1000.
        result_nanoseconds = nanoseconds_division_result.remainder.to_double();
        // c. Set milliseconds to floor(microseconds / 1000).
        auto microseconds_division_result = nanoseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        // d. Set microseconds to microseconds modulo 1000.
        microseconds = microseconds_division_result.remainder.to_double();
        // e. Set seconds to floor(milliseconds / 1000).
        auto milliseconds_division_result = microseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        // f. Set milliseconds to milliseconds modulo 1000.
        milliseconds = milliseconds_division_result.remainder.to_double();
        // g. Set minutes to floor(seconds / 60).
        auto seconds_division_result = milliseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(60));
        // h. Set seconds to seconds modulo 60.
        seconds = seconds_division_result.remainder.to_double();
        // i. Set hours to floor(minutes / 60).
        auto minutes_division_result = milliseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(60));
        hours = minutes_division_result.quotient.to_double();
        // j. Set minutes to minutes modulo 60.
        minutes = minutes_division_result.remainder.to_double();
    }
    // 11. Else if largestUnit is "minute", then
    else if (largest_unit == "minute"sv) {
        // a. Set microseconds to floor(nanoseconds / 1000).
        auto nanoseconds_division_result = total_nanoseconds.divided_by(Crypto::UnsignedBigInteger(1000));
        // b. Set nanoseconds to nanoseconds modulo 1000.
        result_nanoseconds = nanoseconds_division_result.remainder.to_double();
        // c. Set milliseconds to floor(microseconds / 1000).
        auto microseconds_division_result = nanoseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        // d. Set microseconds to microseconds modulo 1000.
        microseconds = microseconds_division_result.remainder.to_double();
        // e. Set seconds to floor(milliseconds / 1000).
        auto milliseconds_division_result = microseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        // f. Set milliseconds to milliseconds modulo 1000.
        milliseconds = milliseconds_division_result.remainder.to_double();
        // g. Set minutes to floor(seconds / 60).
        auto seconds_division_result = milliseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(60));
        minutes = seconds_division_result.quotient.to_double();
        // h. Set seconds to seconds modulo 60.
        seconds = seconds_division_result.remainder.to_double();
    }
    // 12. Else if largestUnit is "second", then
    else if (largest_unit == "second"sv) {
        // a. Set microseconds to floor(nanoseconds / 1000).
        auto nanoseconds_division_result = total_nanoseconds.divided_by(Crypto::UnsignedBigInteger(1000));
        // b. Set nanoseconds to nanoseconds modulo 1000.
        result_nanoseconds = nanoseconds_division_result.remainder.to_double();
        // c. Set milliseconds to floor(microseconds / 1000).
        auto microseconds_division_result = nanoseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        // d. Set microseconds to microseconds modulo 1000.
        microseconds = microseconds_division_result.remainder.to_double();
        // e. Set seconds to floor(milliseconds / 1000).
        auto milliseconds_division_result = microseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        seconds = milliseconds_division_result.quotient.to_double();
        // f. Set milliseconds to milliseconds modulo 1000.
        milliseconds = milliseconds_division_result.remainder.to_double();
    }
    // 13. Else if largestUnit is "millisecond", then
    else if (largest_unit == "millisecond"sv) {
        // a. Set microseconds to floor(nanoseconds / 1000).
        auto nanoseconds_division_result = total_nanoseconds.divided_by(Crypto::UnsignedBigInteger(1000));
        // b. Set nanoseconds to nanoseconds modulo 1000.
        result_nanoseconds = nanoseconds_division_result.remainder.to_double();
        // c. Set milliseconds to floor(microseconds / 1000).
        auto microseconds_division_result = nanoseconds_division_result.quotient.divided_by(Crypto::UnsignedBigInteger(1000));
        milliseconds = microseconds_division_result.quotient.to_double();
        // d. Set microseconds to microseconds modulo 1000.
        microseconds = microseconds_division_result.remainder.to_double();
    }
    // 14. Else if largestUnit is "microsecond", then
    else if (largest_unit == "microsecond"sv) {
        // a. Set microseconds to floor(nanoseconds / 1000).
        auto nanoseconds_division_result = total_nanoseconds.divided_by(Crypto::UnsignedBigInteger(1000));
        microseconds = nanoseconds_division_result.quotient.to_double();
        // b. Set nanoseconds to nanoseconds modulo 1000.
        result_nanoseconds = nanoseconds_division_result.remainder.to_double();
    }
    // 15. Else,
    else {
        // a. Assert: largestUnit is "nanosecond".
        VERIFY(largest_unit == "nanosecond"sv);
    }
    // 16. Return the Record { [[Days]]: 𝔽(days), [[Hours]]: 𝔽(hours × sign), [[Minutes]]: 𝔽(minutes × sign), [[Seconds]]: 𝔽(seconds × sign), [[Milliseconds]]: 𝔽(milliseconds × sign), [[Microseconds]]: 𝔽(microseconds × sign), [[Nanoseconds]]: 𝔽(nanoseconds × sign) }.
    return BalancedDuration { .days = days, .hours = hours * sign, .minutes = minutes * sign, .seconds = seconds * sign, .milliseconds = milliseconds * sign, .microseconds = microseconds * sign, .nanoseconds = result_nanoseconds * sign };
}

// 7.5.16 MoveRelativeDate ( calendar, relativeTo, duration ), https://tc39.es/proposal-temporal/#sec-temporal-moverelativedate
ThrowCompletionOr<MoveRelativeDateResult> move_relative_date(GlobalObject& global_object, Object& calendar, PlainDateTime& relative_to, Duration& duration)
{
    // 1. Assert: Type(relativeTo) is Object.
    // 2. Assert: relativeTo has an [[InitializedTemporalDateTime]] internal slot.

    // 3. Let options be ! OrdinaryObjectCreate(null).
    auto* options = Object::create(global_object, nullptr);

    // 4. Let later be ? CalendarDateAdd(calendar, relativeTo, duration, options).
    auto* later = TRY(calendar_date_add(global_object, calendar, &relative_to, duration, options));

    // FIXME: This cannot return an abrupt completion (spec issue, see https://github.com/tc39/proposal-temporal/pull/1909)
    // 5. Let days be ? DaysUntil(relativeTo, later).
    auto days = days_until(global_object, relative_to, *later);

    // 6. Let dateTime be ? CreateTemporalDateTime(later.[[ISOYear]], later.[[ISOMonth]], later.[[ISODay]], relativeTo.[[ISOHour]], relativeTo.[[ISOMinute]], relativeTo.[[ISOSecond]], relativeTo.[[ISOMillisecond]], relativeTo.[[ISOMicrosecond]], relativeTo.[[ISONanosecond]], relativeTo.[[Calendar]]).
    auto* date_time = TRY(create_temporal_date_time(global_object, later->iso_year(), later->iso_month(), later->iso_day(), relative_to.iso_hour(), relative_to.iso_minute(), relative_to.iso_second(), relative_to.iso_millisecond(), relative_to.iso_microsecond(), relative_to.iso_nanosecond(), relative_to.calendar()));

    // 7. Return the Record { [[RelativeTo]]: dateTime, [[Days]]: days }.
    return MoveRelativeDateResult { .relative_to = make_handle(date_time), .days = days };
}

// 7.5.17 MoveRelativeZonedDateTime ( zonedDateTime, years, months, weeks, days ), https://tc39.es/proposal-temporal/#sec-temporal-moverelativezoneddatetime
ThrowCompletionOr<ZonedDateTime*> move_relative_zoned_date_time(GlobalObject& global_object, ZonedDateTime& zoned_date_time, double years, double months, double weeks, double days)
{
    // 1. Let intermediateNs be ? AddZonedDateTime(zonedDateTime.[[Nanoseconds]], zonedDateTime.[[TimeZone]], zonedDateTime.[[Calendar]], years, months, weeks, days, 0, 0, 0, 0, 0, 0).
    auto* intermediate_ns = TRY(add_zoned_date_time(global_object, zoned_date_time.nanoseconds(), &zoned_date_time.time_zone(), zoned_date_time.calendar(), years, months, weeks, days, 0, 0, 0, 0, 0, 0));

    // 2. Return ! CreateTemporalZonedDateTime(intermediateNs, zonedDateTime.[[TimeZone]], zonedDateTime.[[Calendar]]).
    return MUST(create_temporal_zoned_date_time(global_object, *intermediate_ns, zoned_date_time.time_zone(), zoned_date_time.calendar()));
}

// 7.5.18 RoundDuration ( years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, increment, unit, roundingMode [ , relativeTo ] ), https://tc39.es/proposal-temporal/#sec-temporal-roundduration
ThrowCompletionOr<RoundedDuration> round_duration(GlobalObject& global_object, double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, u32 increment, StringView unit, StringView rounding_mode, Object* relative_to_object)
{
    auto& vm = global_object.vm();

    Object* calendar = nullptr;
    double fractional_seconds = 0;

    // 1. If relativeTo is not present, set relativeTo to undefined.
    // NOTE: `relative_to_object`, `relative_to_date`, and `relative_to` in the various code paths below
    // are all the same as far as the spec is concerned, but the latter two are more strictly typed for convenience.
    // The `_date` suffix is used as relativeTo is guaranteed to be a PlainDateTime object or undefined after step 5
    // (i.e. PlainDateTime*), but a PlainDate object is assigned in a couple of cases.
    PlainDateTime* relative_to = nullptr;

    // 2. Let years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, and increment each be the mathematical values of themselves.

    // 3. If unit is "year", "month", or "week", and relativeTo is undefined, then
    if (unit.is_one_of("year"sv, "month"sv, "week"sv) && !relative_to_object) {
        // a. Throw a RangeError exception.
        return vm.throw_completion<RangeError>(global_object, ErrorType::OptionIsNotValidValue, unit, "smallestUnit"sv);
    }

    // 4. Let zonedRelativeTo be undefined.
    ZonedDateTime* zoned_relative_to = nullptr;

    // 5. If relativeTo is not undefined, then
    if (relative_to_object) {
        // a. If relativeTo has an [[InitializedTemporalZonedDateTime]] internal slot, then
        if (is<ZonedDateTime>(relative_to_object)) {
            auto* relative_to_zoned_date_time = static_cast<ZonedDateTime*>(relative_to_object);

            // i. Let instant be ! CreateTemporalInstant(relativeTo.[[Nanoseconds]]).
            auto* instant = MUST(create_temporal_instant(global_object, relative_to_zoned_date_time->nanoseconds()));

            // ii. Set zonedRelativeTo to relativeTo.
            zoned_relative_to = relative_to_zoned_date_time;

            // iii. Set relativeTo to ? BuiltinTimeZoneGetPlainDateTimeFor(relativeTo.[[TimeZone]], instant, relativeTo.[[Calendar]]).
            relative_to = TRY(builtin_time_zone_get_plain_date_time_for(global_object, &relative_to_zoned_date_time->time_zone(), *instant, relative_to_zoned_date_time->calendar()));
        }
        // b. Else,
        else {
            // i. Assert: relativeTo has an [[InitializedTemporalDateTime]] internal slot.
            VERIFY(is<PlainDateTime>(relative_to_object));

            relative_to = static_cast<PlainDateTime*>(relative_to_object);
        }

        // c. Let calendar be relativeTo.[[Calendar]].
        calendar = &relative_to->calendar();
    }

    // 6. If unit is one of "year", "month", "week", or "day", then
    if (unit.is_one_of("year"sv, "month"sv, "week"sv, "day"sv)) {
        auto* nanoseconds_bigint = js_bigint(vm, Crypto::SignedBigInteger::create_from((i64)nanoseconds));

        // a. Let nanoseconds be ! TotalDurationNanoseconds(0, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, 0).
        nanoseconds_bigint = total_duration_nanoseconds(global_object, 0, hours, minutes, seconds, milliseconds, microseconds, *nanoseconds_bigint, 0);

        // b. Let intermediate be undefined.
        ZonedDateTime* intermediate = nullptr;

        // c. If zonedRelativeTo is not undefined, then
        if (zoned_relative_to) {
            // i. Let intermediate be ? MoveRelativeZonedDateTime(zonedRelativeTo, years, months, weeks, days).
            intermediate = TRY(move_relative_zoned_date_time(global_object, *zoned_relative_to, years, months, weeks, days));
        }

        // d. Let result be ? NanosecondsToDays(nanoseconds, intermediate).
        auto result = TRY(nanoseconds_to_days(global_object, *nanoseconds_bigint, intermediate));

        // e. Set days to days + result.[[Days]] + result.[[Nanoseconds]] / result.[[DayLength]].
        days += result.days + result.nanoseconds.cell()->big_integer().divided_by(Crypto::UnsignedBigInteger::create_from((u64)result.day_length)).quotient.to_double();

        // f. Set hours, minutes, seconds, milliseconds, microseconds, and nanoseconds to 0.
        hours = 0;
        minutes = 0;
        seconds = 0;
        milliseconds = 0;
        microseconds = 0;
        nanoseconds = 0;
    }
    // 7. Else,
    else {
        // a. Let fractionalSeconds be nanoseconds × 10^−9 + microseconds × 10^−6 + milliseconds × 10^−3 + seconds.
        fractional_seconds = nanoseconds * 0.000000001 + microseconds * 0.000001 + milliseconds * 0.001 + seconds;
    }

    // 8. Let remainder be undefined.
    double remainder = 0;

    // 9. If unit is "year", then
    if (unit == "year"sv) {
        VERIFY(relative_to);

        // a. Let yearsDuration be ? CreateTemporalDuration(years, 0, 0, 0, 0, 0, 0, 0, 0, 0).
        auto* years_duration = TRY(create_temporal_duration(global_object, years, 0, 0, 0, 0, 0, 0, 0, 0, 0));

        // b. Let dateAdd be ? GetMethod(calendar, "dateAdd").
        auto* date_add = TRY(Value(calendar).get_method(global_object, vm.names.dateAdd));

        // c. Let firstAddOptions be ! OrdinaryObjectCreate(null).
        auto* first_add_options = Object::create(global_object, nullptr);

        // d. Let yearsLater be ? CalendarDateAdd(calendar, relativeTo, yearsDuration, firstAddOptions, dateAdd).
        auto* years_later = TRY(calendar_date_add(global_object, *calendar, relative_to, *years_duration, first_add_options, date_add));

        // e. Let yearsMonthsWeeks be ? CreateTemporalDuration(years, months, weeks, 0, 0, 0, 0, 0, 0, 0).
        auto* years_months_weeks = TRY(create_temporal_duration(global_object, years, months, weeks, 0, 0, 0, 0, 0, 0, 0));

        // f. Let secondAddOptions be ! OrdinaryObjectCreate(null).
        auto* second_add_options = Object::create(global_object, nullptr);

        // g. Let yearsMonthsWeeksLater be ? CalendarDateAdd(calendar, relativeTo, yearsMonthsWeeks, secondAddOptions, dateAdd).
        auto* years_months_weeks_later = TRY(calendar_date_add(global_object, *calendar, relative_to, *years_months_weeks, second_add_options, date_add));

        // FIXME: This cannot return an abrupt completion (spec issue, see https://github.com/tc39/proposal-temporal/pull/1909)
        // h. Let monthsWeeksInDays be ? DaysUntil(yearsLater, yearsMonthsWeeksLater).
        auto months_weeks_in_days = days_until(global_object, *years_later, *years_months_weeks_later);

        // i. Set relativeTo to yearsLater.
        auto* relative_to_date = years_later;

        // j. Let days be days + monthsWeeksInDays.
        days += months_weeks_in_days;

        // k. Let daysDuration be ? CreateTemporalDuration(0, 0, 0, days, 0, 0, 0, 0, 0, 0).
        auto* days_duration = TRY(create_temporal_duration(global_object, 0, 0, 0, days, 0, 0, 0, 0, 0, 0));

        // l. Let thirdAddOptions be ! OrdinaryObjectCreate(null).
        auto* third_add_options = Object::create(global_object, nullptr);

        // m. Let daysLater be ? CalendarDateAdd(calendar, relativeTo, daysDuration, thirdAddOptions, dateAdd).
        auto* days_later = TRY(calendar_date_add(global_object, *calendar, relative_to_date, *days_duration, third_add_options, date_add));

        // n. Let untilOptions be ! OrdinaryObjectCreate(null).
        auto* until_options = Object::create(global_object, nullptr);

        // o. Perform ! CreateDataPropertyOrThrow(untilOptions, "largestUnit", "year").
        MUST(until_options->create_data_property_or_throw(vm.names.largestUnit, js_string(vm, "year"sv)));

        // p. Let timePassed be ? CalendarDateUntil(calendar, relativeTo, daysLater, untilOptions).
        auto* time_passed = TRY(calendar_date_until(global_object, *calendar, *relative_to_date, *days_later, *until_options));

        // q. Let yearsPassed be timePassed.[[Years]].
        auto years_passed = time_passed->years();

        // r. Set years to years + yearsPassed.
        years += years_passed;

        // s. Let oldRelativeTo be relativeTo.
        auto* old_relative_to_date = relative_to_date;

        // t. Let yearsDuration be ? CreateTemporalDuration(yearsPassed, 0, 0, 0, 0, 0, 0, 0, 0, 0).
        years_duration = TRY(create_temporal_duration(global_object, years_passed, 0, 0, 0, 0, 0, 0, 0, 0, 0));

        // u. Let fourthAddOptions be ! OrdinaryObjectCreate(null).
        auto* fourth_add_options = Object::create(global_object, nullptr);

        // v. Set relativeTo to ? CalendarDateAdd(calendar, relativeTo, yearsDuration, fourthAddOptions, dateAdd).
        relative_to_date = TRY(calendar_date_add(global_object, *calendar, relative_to_date, *years_duration, fourth_add_options, date_add));

        // FIXME: This cannot return an abrupt completion (spec issue, see https://github.com/tc39/proposal-temporal/pull/1909)
        // w. Let daysPassed be ? DaysUntil(oldRelativeTo, relativeTo).
        auto days_passed = days_until(global_object, *old_relative_to_date, *relative_to_date);

        // x. Set days to days - daysPassed.
        days -= days_passed;

        // y. Let sign be ! Sign(days).
        auto sign = JS::Temporal::sign(days);

        // z. If sign is 0, set sign to 1.
        if (sign == 0)
            sign = 1;

        // aa. Let oneYear be ? CreateTemporalDuration(sign, 0, 0, 0, 0, 0, 0, 0, 0, 0).
        auto* one_year = TRY(create_temporal_duration(global_object, sign, 0, 0, 0, 0, 0, 0, 0, 0, 0));

        // ab. Set relativeTo to ! CreateTemporalDateTime(relativeTo.[[ISOYear]], relativeTo.[[ISOMonth]], relativeTo.[[ISODay]], 0, 0, 0, 0, 0, 0, relativeTo.[[Calendar]]).
        relative_to = MUST(create_temporal_date_time(global_object, relative_to_date->iso_year(), relative_to_date->iso_month(), relative_to_date->iso_day(), 0, 0, 0, 0, 0, 0, relative_to->calendar()));

        // ac. Let moveResult be ? MoveRelativeDate(calendar, relativeTo, oneYear).
        auto move_result = TRY(move_relative_date(global_object, *calendar, *relative_to, *one_year));

        // ad. Let oneYearDays be moveResult.[[Days]].
        auto one_year_days = move_result.days;

        // ae. Let fractionalYears be years + days / abs(oneYearDays).
        auto fractional_years = years + days / fabs(one_year_days);

        // af. Set years to ! RoundNumberToIncrement(fractionalYears, increment, roundingMode).
        years = (double)round_number_to_increment(fractional_years, increment, rounding_mode);

        // ag. Set remainder to fractionalYears - years.
        remainder = fractional_years - years;

        // ah. Set months, weeks, and days to 0.
        months = 0;
        weeks = 0;
        days = 0;
    }
    // 10. Else if unit is "month", then
    else if (unit == "month"sv) {
        VERIFY(relative_to);

        // a. Let yearsMonths be ? CreateTemporalDuration(years, months, 0, 0, 0, 0, 0, 0, 0, 0).
        auto* years_months = TRY(create_temporal_duration(global_object, years, months, 0, 0, 0, 0, 0, 0, 0, 0));

        // b. Let dateAdd be ? GetMethod(calendar, "dateAdd").
        auto* date_add = TRY(Value(calendar).get_method(global_object, vm.names.dateAdd));

        // c. Let firstAddOptions be ! OrdinaryObjectCreate(null).
        auto* first_add_options = Object::create(global_object, nullptr);

        // d. Let yearsMonthsLater be ? CalendarDateAdd(calendar, relativeTo, yearsMonths, firstAddOptions, dateAdd).
        auto* years_months_later = TRY(calendar_date_add(global_object, *calendar, relative_to, *years_months, first_add_options, date_add));

        // e. Let yearsMonthsWeeks be ? CreateTemporalDuration(years, months, weeks, 0, 0, 0, 0, 0, 0, 0).
        auto* years_months_weeks = TRY(create_temporal_duration(global_object, years, months, weeks, 0, 0, 0, 0, 0, 0, 0));

        // f. Let secondAddOptions be ! OrdinaryObjectCreate(null).
        auto* seconds_add_options = Object::create(global_object, nullptr);

        // g. Let yearsMonthsWeeksLater be ? CalendarDateAdd(calendar, relativeTo, yearsMonthsWeeks, secondAddOptions, dateAdd).
        auto* years_months_weeks_later = TRY(calendar_date_add(global_object, *calendar, relative_to, *years_months_weeks, seconds_add_options, date_add));

        // FIXME: This cannot return an abrupt completion (spec issue, see https://github.com/tc39/proposal-temporal/pull/1909)
        // h. Let weeksInDays be ? DaysUntil(yearsMonthsLater, yearsMonthsWeeksLater).
        auto weeks_in_days = days_until(global_object, *years_months_later, *years_months_weeks_later);

        // i. Set relativeTo to yearsMonthsLater.
        auto* relative_to_date = years_months_later;

        // j. Let days be days + weeksInDays.
        days += weeks_in_days;

        // k. Let sign be ! Sign(days).
        auto sign = JS::Temporal::sign(days);

        // l. If sign is 0, set sign to 1.
        if (sign == 0)
            sign = 1;

        // m. Let oneMonth be ? CreateTemporalDuration(0, sign, 0, 0, 0, 0, 0, 0, 0, 0).
        auto* one_month = TRY(create_temporal_duration(global_object, 0, sign, 0, 0, 0, 0, 0, 0, 0, 0));

        // n. Set relativeTo to ! CreateTemporalDateTime(relativeTo.[[ISOYear]], relativeTo.[[ISOMonth]], relativeTo.[[ISODay]], 0, 0, 0, 0, 0, 0, relativeTo.[[Calendar]]).
        relative_to = MUST(create_temporal_date_time(global_object, relative_to_date->iso_year(), relative_to_date->iso_month(), relative_to_date->iso_day(), 0, 0, 0, 0, 0, 0, relative_to_date->calendar()));

        // o. Let moveResult be ? MoveRelativeDate(calendar, relativeTo, oneMonth).
        auto move_result = TRY(move_relative_date(global_object, *calendar, *relative_to, *one_month));

        // p. Set relativeTo to moveResult.[[RelativeTo]].
        relative_to = move_result.relative_to.cell();

        // q. Let oneMonthDays be moveResult.[[Days]].
        auto one_month_days = move_result.days;

        // r. Repeat, while abs(days) ≥ abs(oneMonthDays),
        while (fabs(days) >= fabs(one_month_days)) {
            // i. Set months to months + sign.
            months += sign;

            // ii. Set days to days − oneMonthDays.
            days -= one_month_days;

            // iii. Set moveResult to ? MoveRelativeDate(calendar, relativeTo, oneMonth).
            move_result = TRY(move_relative_date(global_object, *calendar, *relative_to, *one_month));

            // iv. Set relativeTo to moveResult.[[RelativeTo]].
            relative_to = move_result.relative_to.cell();

            // v. Set oneMonthDays to moveResult.[[Days]].
            one_month_days = move_result.days;
        }

        // s. Let fractionalMonths be months + days / abs(oneMonthDays).
        auto fractional_months = months + days / fabs(one_month_days);

        // t. Set months to ! RoundNumberToIncrement(fractionalMonths, increment, roundingMode).
        months = (double)round_number_to_increment(fractional_months, increment, rounding_mode);

        // u. Set remainder to fractionalMonths - months.
        remainder = fractional_months - months;

        // v. Set weeks and days to 0.
        weeks = 0;
        days = 0;
    }
    // 11. Else if unit is "week", then
    else if (unit == "week"sv) {
        VERIFY(relative_to);

        // a. Let sign be ! Sign(days).
        auto sign = JS::Temporal::sign(days);

        // b. If sign is 0, set sign to 1.
        if (sign == 0)
            sign = 1;

        // c. Let oneWeek be ? CreateTemporalDuration(0, 0, sign, 0, 0, 0, 0, 0, 0, 0).
        auto* one_week = TRY(create_temporal_duration(global_object, 0, 0, sign, 0, 0, 0, 0, 0, 0, 0));

        // d. Let moveResult be ? MoveRelativeDate(calendar, relativeTo, oneWeek).
        auto move_result = TRY(move_relative_date(global_object, *calendar, *relative_to, *one_week));

        // e. Set relativeTo to moveResult.[[RelativeTo]].
        relative_to = move_result.relative_to.cell();

        // f. Let oneWeekDays be moveResult.[[Days]].
        auto one_week_days = move_result.days;

        // g. Repeat, while abs(days) ≥ abs(oneWeekDays),
        while (fabs(days) >= fabs(one_week_days)) {
            // i. Set weeks to weeks + sign.
            weeks += sign;

            // ii. Set days to days − oneWeekDays.
            days -= one_week_days;

            // iii. Set moveResult to ? MoveRelativeDate(calendar, relativeTo, oneWeek).
            move_result = TRY(move_relative_date(global_object, *calendar, *relative_to, *one_week));

            // iv. Set relativeTo to moveResult.[[RelativeTo]].
            relative_to = move_result.relative_to.cell();

            // v. Set oneWeekDays to moveResult.[[Days]].
            one_week_days = move_result.days;
        }

        // h. Let fractionalWeeks be weeks + days / abs(oneWeekDays).
        auto fractional_weeks = weeks + days / fabs(one_week_days);

        // i. Set weeks to ! RoundNumberToIncrement(fractionalWeeks, increment, roundingMode).
        weeks = (double)round_number_to_increment(fractional_weeks, increment, rounding_mode);

        // j. Set remainder to fractionalWeeks - weeks.
        remainder = fractional_weeks - weeks;

        // k. Set days to 0.
        days = 0;
    }
    // 12. Else if unit is "day", then
    else if (unit == "day"sv) {
        // a. Let fractionalDays be days.
        auto fractional_days = days;

        // b. Set days to ! RoundNumberToIncrement(days, increment, roundingMode).
        days = (double)round_number_to_increment(days, increment, rounding_mode);

        // c. Set remainder to fractionalDays - days.
        remainder = fractional_days - days;
    }
    // 13. Else if unit is "hour", then
    else if (unit == "hour"sv) {
        // a. Let fractionalHours be (fractionalSeconds / 60 + minutes) / 60 + hours.
        auto fractional_hours = (fractional_seconds / 60 + minutes) / 60 + hours;

        // b. Set hours to ! RoundNumberToIncrement(fractionalHours, increment, roundingMode).
        hours = (double)round_number_to_increment(fractional_hours, increment, rounding_mode);

        // c. Set remainder to fractionalHours - hours.
        remainder = fractional_hours - days;

        // d. Set minutes, seconds, milliseconds, microseconds, and nanoseconds to 0.
        minutes = 0;
        seconds = 0;
        milliseconds = 0;
        microseconds = 0;
        nanoseconds = 0;
    }
    // 14. Else if unit is "minute", then
    else if (unit == "minute"sv) {
        // a. Let fractionalMinutes be fractionalSeconds / 60 + minutes.
        auto fractional_minutes = fractional_seconds / 60 + minutes;

        // b. Set minutes to ! RoundNumberToIncrement(fractionalMinutes, increment, roundingMode).
        minutes = (double)round_number_to_increment(fractional_minutes, increment, rounding_mode);

        // c. Set remainder to fractionalMinutes - minutes.
        remainder = fractional_minutes - minutes;

        // d. Set seconds, milliseconds, microseconds, and nanoseconds to 0.
        seconds = 0;
        milliseconds = 0;
        microseconds = 0;
        nanoseconds = 0;
    }
    // 15. Else if unit is "second", then
    else if (unit == "second"sv) {
        // a. Set seconds to ! RoundNumberToIncrement(fractionalSeconds, increment, roundingMode).
        seconds = (double)round_number_to_increment(fractional_seconds, increment, rounding_mode);

        // b. Set remainder to fractionalSeconds - seconds.
        remainder = fractional_seconds - seconds;

        // c. Set milliseconds, microseconds, and nanoseconds to 0.
        milliseconds = 0;
        microseconds = 0;
        nanoseconds = 0;
    }
    // 16. Else if unit is "millisecond", then
    else if (unit == "millisecond"sv) {
        // a. Let fractionalMilliseconds be nanoseconds × 10^−6 + microseconds × 10^−3 + milliseconds.
        auto fractional_milliseconds = nanoseconds * 0.000001 + microseconds * 0.001 + milliseconds;

        // b. Set milliseconds to ! RoundNumberToIncrement(fractionalMilliseconds, increment, roundingMode).
        milliseconds = (double)round_number_to_increment(fractional_milliseconds, increment, rounding_mode);

        // c. Set remainder to fractionalMilliseconds - milliseconds.
        remainder = fractional_milliseconds - milliseconds;

        // d. Set microseconds and nanoseconds to 0.
        microseconds = 0;
        nanoseconds = 0;
    }
    // 17. Else if unit is "microsecond", then
    else if (unit == "microsecond"sv) {
        // a. Let fractionalMicroseconds be nanoseconds × 10^−3 + microseconds.
        auto fractional_microseconds = nanoseconds * 0.001 + microseconds;

        // b. Set microseconds to ! RoundNumberToIncrement(fractionalMicroseconds, increment, roundingMode).
        microseconds = (double)round_number_to_increment(fractional_microseconds, increment, rounding_mode);

        // c. Set remainder to fractionalMicroseconds - microseconds.
        remainder = fractional_microseconds - microseconds;

        // d. Set nanoseconds to 0.
        nanoseconds = 0;
    }
    // 18. Else,
    else {
        // a. Assert: unit is "nanosecond".
        VERIFY(unit == "nanosecond"sv);

        // b. Set remainder to nanoseconds.
        remainder = nanoseconds;

        // c. Set nanoseconds to ! RoundNumberToIncrement(nanoseconds, increment, roundingMode).
        nanoseconds = (double)round_number_to_increment(nanoseconds, increment, rounding_mode);

        // d. Set remainder to remainder − nanoseconds.
        remainder -= nanoseconds;
    }

    // Return the Record { [[Years]]: years, [[Months]]: months, [[Weeks]]: weeks, [[Days]]: days, [[Hours]]: hours, [[Minutes]]: minutes, [[Seconds]]: seconds, [[Milliseconds]]: milliseconds, [[Microseconds]]: microseconds, [[Nanoseconds]]: nanoseconds, [[Remainder]]: remainder }.
    return RoundedDuration { .years = years, .months = months, .weeks = weeks, .days = days, .hours = hours, .minutes = minutes, .seconds = seconds, .milliseconds = milliseconds, .microseconds = microseconds, .nanoseconds = nanoseconds, .remainder = remainder };
}

// 7.5.20 ToLimitedTemporalDuration ( temporalDurationLike, disallowedFields ),https://tc39.es/proposal-temporal/#sec-temporal-tolimitedtemporalduration
ThrowCompletionOr<TemporalDuration> to_limited_temporal_duration(GlobalObject& global_object, Value temporal_duration_like, Vector<StringView> const& disallowed_fields)
{
    auto& vm = global_object.vm();

    TemporalDuration duration;

    // 1. If Type(temporalDurationLike) is not Object, then
    if (!temporal_duration_like.is_object()) {
        // a. Let str be ? ToString(temporalDurationLike).
        auto str = TRY(temporal_duration_like.to_string(global_object));

        // b. Let duration be ? ParseTemporalDurationString(str).
        duration = TRY(parse_temporal_duration_string(global_object, str));
    }
    // 2. Else,
    else {
        // a. Let duration be ? ToTemporalDurationRecord(temporalDurationLike).
        duration = TRY(to_temporal_duration_record(global_object, temporal_duration_like.as_object()));
    }

    // 3. If ! IsValidDuration(duration.[[Years]], duration.[[Months]], duration.[[Weeks]], duration.[[Days]], duration.[[Hours]], duration.[[Minutes]], duration.[[Seconds]], duration.[[Milliseconds]], duration.[[Microseconds]], duration.[[Nanoseconds]]) is false, throw a RangeError exception.
    if (!is_valid_duration(duration.years, duration.months, duration.weeks, duration.days, duration.hours, duration.minutes, duration.seconds, duration.milliseconds, duration.microseconds, duration.nanoseconds))
        return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidDuration);

    // 4. For each row of Table 7, except the header row, in table order, do
    for (auto& [internal_slot, property] : temporal_duration_like_properties<TemporalDuration, double>(vm)) {
        // a. Let prop be the Property value of the current row.

        // b. Let value be duration's internal slot whose name is the Internal Slot value of the current row.
        auto value = duration.*internal_slot;

        // If value is not 0 and disallowedFields contains prop, then
        if (value != 0 && disallowed_fields.contains_slow(property.as_string())) {
            // i. Throw a RangeError exception.
            return vm.throw_completion<RangeError>(global_object, ErrorType::TemporalInvalidDurationPropertyValueNonZero, property.as_string(), value);
        }
    }

    // 5. Return duration.
    return duration;
}

// 7.5.21 TemporalDurationToString ( years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds, precision ), https://tc39.es/proposal-temporal/#sec-temporal-temporaldurationtostring
String temporal_duration_to_string(double years, double months, double weeks, double days, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds, Variant<StringView, u8> const& precision)
{
    // 1. Assert: precision is not "minute".
    if (precision.has<StringView>())
        VERIFY(precision.get<StringView>() != "minute"sv);

    // 2. Set seconds to the mathematical value of seconds.
    // 3. Set milliseconds to the mathematical value of milliseconds.
    // 4. Set microseconds to the mathematical value of microseconds.
    // 5. Set nanoseconds to the mathematical value of nanoseconds.

    // 6. Let sign be ! DurationSign(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds).
    auto sign = duration_sign(years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);

    // 7. Set microseconds to microseconds + the integral part of nanoseconds / 1000.
    microseconds += trunc(nanoseconds / 1000);

    // 8. Set nanoseconds to remainder(nanoseconds, 1000).
    nanoseconds = fmod(nanoseconds, 1000);

    // 9. Set milliseconds to milliseconds + the integral part of microseconds / 1000.
    milliseconds += trunc(microseconds / 1000);

    // 10. Set microseconds to remainder(microseconds, 1000).
    microseconds = fmod(microseconds, 1000);

    // 11. Set seconds to seconds + the integral part of milliseconds / 1000.
    seconds += trunc(milliseconds / 1000);

    // 12. Set milliseconds to remainder(milliseconds, 1000).
    milliseconds = fmod(milliseconds, 1000);

    // 13. Let datePart be "".
    StringBuilder date_part;

    // 14. If years is not 0, then
    if (years != 0) {
        // a. Set datePart to the string concatenation of abs(years) formatted as a decimal number and the code unit 0x0059 (LATIN CAPITAL LETTER Y).
        date_part.appendff("{}", fabs(years));
        date_part.append('Y');
    }

    // 15. If months is not 0, then
    if (months != 0) {
        // a. Set datePart to the string concatenation of datePart, abs(months) formatted as a decimal number, and the code unit 0x004D (LATIN CAPITAL LETTER M).
        date_part.appendff("{}", fabs(months));
        date_part.append('M');
    }

    // 16. If weeks is not 0, then
    if (weeks != 0) {
        // a. Set datePart to the string concatenation of datePart, abs(weeks) formatted as a decimal number, and the code unit 0x0057 (LATIN CAPITAL LETTER W).
        date_part.appendff("{}", fabs(weeks));
        date_part.append('W');
    }

    // 17. If days is not 0, then
    if (days != 0) {
        // a. Set datePart to the string concatenation of datePart, abs(days) formatted as a decimal number, and the code unit 0x0044 (LATIN CAPITAL LETTER D).
        date_part.appendff("{}", fabs(days));
        date_part.append('D');
    }

    // 18. Let timePart be "".
    StringBuilder time_part;

    // 19. If hours is not 0, then
    if (hours != 0) {
        // a. Set timePart to the string concatenation of abs(hours) formatted as a decimal number and the code unit 0x0048 (LATIN CAPITAL LETTER H).
        time_part.appendff("{}", fabs(hours));
        time_part.append('H');
    }

    // 20. If minutes is not 0, then
    if (minutes != 0) {
        // a. Set timePart to the string concatenation of timePart, abs(minutes) formatted as a decimal number, and the code unit 0x004D (LATIN CAPITAL LETTER M).
        time_part.appendff("{}", fabs(minutes));
        time_part.append('M');
    }

    // 21. If any of seconds, milliseconds, microseconds, and nanoseconds are not 0; or years, months, weeks, days, hours, and minutes are all 0, then
    if ((seconds != 0 || milliseconds != 0 || microseconds != 0 || nanoseconds != 0) || (years == 0 && months == 0 && weeks == 0 && days == 0 && hours == 0 && minutes == 0)) {
        // a. Let fraction be abs(milliseconds) × 10^6 + abs(microseconds) × 10^3 + abs(nanoseconds).
        auto fraction = fabs(milliseconds) * 1'000'000 + fabs(microseconds) * 1'000 + fabs(nanoseconds);

        // b. Let decimalPart be fraction formatted as a nine-digit decimal number, padded to the left with zeroes if necessary.
        // NOTE: padding with zeros leads to weird results when applied to a double. Not sure if that's a bug in AK/Format.h or if I'm doing this wrong.
        auto decimal_part = String::formatted("{:09}", (u64)fraction);

        // c. If precision is "auto", then
        if (precision.has<StringView>() && precision.get<StringView>() == "auto"sv) {
            // i. Set decimalPart to the longest possible substring of decimalPart starting at position 0 and not ending with the code unit 0x0030 (DIGIT ZERO).
            // NOTE: trim() would keep the left-most 0.
            while (decimal_part.ends_with('0'))
                decimal_part = decimal_part.substring(0, decimal_part.length() - 1);
        }
        // d. Else if precision = 0, then
        else if (precision.get<u8>() == 0) {
            // i. Set decimalPart to "".
            decimal_part = String::empty();
        }
        // e. Else,
        else {
            // i. Set decimalPart to the substring of decimalPart from 0 to precision.
            decimal_part = decimal_part.substring(0, precision.get<u8>());
        }

        // f. Let secondsPart be abs(seconds) formatted as a decimal number.
        StringBuilder seconds_part;
        seconds_part.appendff("{}", fabs(seconds));

        // g. If decimalPart is not "", then
        if (!decimal_part.is_empty()) {
            // i. Set secondsPart to the string-concatenation of secondsPart, the code unit 0x002E (FULL STOP), and decimalPart.
            seconds_part.append('.');
            seconds_part.append(decimal_part);
        }

        // h. Set timePart to the string concatenation of timePart, secondsPart, and the code unit 0x0053 (LATIN CAPITAL LETTER S).
        time_part.append(seconds_part.string_view());
        time_part.append('S');
    }

    // 22. Let signPart be the code unit 0x002D (HYPHEN-MINUS) if sign < 0, and otherwise the empty String.
    auto sign_part = sign < 0 ? "-"sv : ""sv;

    // 23. Let result be the string concatenation of signPart, the code unit 0x0050 (LATIN CAPITAL LETTER P) and datePart.
    StringBuilder result;
    result.append(sign_part);
    result.append('P');
    result.append(date_part.string_view());

    // 24. If timePart is not "", then
    if (!time_part.is_empty()) {
        // a. Set result to the string concatenation of result, the code unit 0x0054 (LATIN CAPITAL LETTER T), and timePart.
        result.append('T');
        result.append(time_part.string_view());
    }

    // 25. Return result.
    return result.to_string();
}

}