// Copyright 2022 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_INTL_SUPPORT
#error Internationalization is expected to be enabled.
#endif  // V8_INTL_SUPPORT

#include "src/objects/js-duration-format.h"

#include <map>
#include <memory>
#include <string>
#include <string_view>

#include "src/common/globals.h"
#include "src/execution/isolate.h"
#include "src/heap/factory.h"
#include "src/objects/intl-objects.h"
#include "src/objects/js-duration-format-inl.h"
#include "src/objects/js-number-format.h"
#include "src/objects/js-temporal-objects.h"
#include "src/objects/managed-inl.h"
#include "src/objects/objects-inl.h"
#include "src/objects/option-utils.h"
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wshadow"
#include "unicode/dtfmtsym.h"
#include "unicode/listformatter.h"
#include "unicode/locid.h"
#include "unicode/numberformatter.h"
#include "unicode/ulistformatter.h"
#include "unicode/unumberformatter.h"
#pragma GCC diagnostic pop

namespace v8 {
namespace internal {

using temporal::DurationRecord;

namespace {

// #sec-getdurationunitoptions
enum class StylesList { k3Styles, k4Styles, k5Styles };
enum class Unit {
  kYears,
  kMonths,
  kWeeks,
  kDays,
  kHours,
  kMinutes,
  kSeconds,
  kMilliseconds,
  kMicroseconds,
  kNanoseconds
};
struct DurationUnitOptions {
  JSDurationFormat::FieldStyle style;
  JSDurationFormat::Display display;
};

const std::initializer_list<const char*> kLongShortNarrowStrings = {
    "long", "short", "narrow"};
const std::initializer_list<const char*> kLongShortNarrowNumericStrings = {
    "long", "short", "narrow", "numeric"};
const std::initializer_list<const char*> kLongShortNarrowNumeric2DigitStrings =
    {"long", "short", "narrow", "numeric", "2-digit"};

const std::initializer_list<JSDurationFormat::FieldStyle>
    kLongShortNarrowEnums = {JSDurationFormat::FieldStyle::kLong,
                             JSDurationFormat::FieldStyle::kShort,
                             JSDurationFormat::FieldStyle::kNarrow};
const std::initializer_list<JSDurationFormat::FieldStyle>
    kLongShortNarrowNumericEnums = {JSDurationFormat::FieldStyle::kLong,
                                    JSDurationFormat::FieldStyle::kShort,
                                    JSDurationFormat::FieldStyle::kNarrow,
                                    JSDurationFormat::FieldStyle::kNumeric};
const std::initializer_list<JSDurationFormat::FieldStyle>
    kLongShortNarrowNumeric2DigitEnums = {
        JSDurationFormat::FieldStyle::kLong,
        JSDurationFormat::FieldStyle::kShort,
        JSDurationFormat::FieldStyle::kNarrow,
        JSDurationFormat::FieldStyle::kNumeric,
        JSDurationFormat::FieldStyle::k2Digit};

Maybe<DurationUnitOptions> GetDurationUnitOptions(
    Isolate* isolate, Unit unit, const char* unit_string,
    const char* display_field, DirectHandle<JSReceiver> options,
    JSDurationFormat::Style base_style,
    const std::vector<const char*>& value_strings,
    const std::vector<JSDurationFormat::FieldStyle>& value_enums,
    JSDurationFormat::FieldStyle digital_base,
    JSDurationFormat::FieldStyle prev_style) {
  const char* method_name = "Intl.DurationFormat";
  JSDurationFormat::FieldStyle style;
  // 1. Let style be ? GetOption(options, unit, "string", stylesList,
  // undefined).
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, style,
      GetStringOption<JSDurationFormat::FieldStyle>(
          isolate, options, unit_string, method_name, value_strings,
          value_enums, JSDurationFormat::FieldStyle::kUndefined),
      Nothing<DurationUnitOptions>());

  // 2. Let displayDefault be "always".
  JSDurationFormat::Display display_default =
      JSDurationFormat::Display::kAlways;
  // 3. If style is undefined, then
  if (style == JSDurationFormat::FieldStyle::kUndefined) {
    // a. If baseStyle is "digital", then
    if (base_style == JSDurationFormat::Style::kDigital) {
      // i. If unit is not one of "hours", "minutes", or "seconds", then
      if (unit != Unit::kHours && unit != Unit::kMinutes &&
          unit != Unit::kSeconds) {
        // a. Set displayDefault to "auto".
        display_default = JSDurationFormat::Display::kAuto;
      }
      // ii. Set style to digitalBase.
      style = digital_base;
      // b. Else
    } else {
      // i. if prevStyle is "fractional", "numeric", or "2-digit", then
      if (prev_style == JSDurationFormat::FieldStyle::kFractional ||
          prev_style == JSDurationFormat::FieldStyle::kNumeric ||
          prev_style == JSDurationFormat::FieldStyle::k2Digit) {
        // 1. If unit is not one of "minutes" or "seconds", then
        if (unit != Unit::kMinutes && unit != Unit::kSeconds) {
          // a. Set displayDefault to "auto".
          display_default = JSDurationFormat::Display::kAuto;
        }
        // 2. Set style to "numeric".
        style = JSDurationFormat::FieldStyle::kNumeric;
        // iii. Else,
      } else {
        // 1. Set displayDefault to "auto".
        display_default = JSDurationFormat::Display::kAuto;
        // 2. Set style to baseStyle.
        switch (base_style) {
          case JSDurationFormat::Style::kLong:
            style = JSDurationFormat::FieldStyle::kLong;
            break;
          case JSDurationFormat::Style::kShort:
            style = JSDurationFormat::FieldStyle::kShort;
            break;
          case JSDurationFormat::Style::kNarrow:
            style = JSDurationFormat::FieldStyle::kNarrow;
            break;
          default:
            UNREACHABLE();
        }
      }
    }
  }
  // 4. If style is "numeric", then
  if (style == JSDurationFormat::FieldStyle::kNumeric) {
    // a. If unit is one of "milliseconds", "microseconds", or "nanoseconds",
    // then
    if (unit == Unit::kMilliseconds || unit == Unit::kMicroseconds ||
        unit == Unit::kNanoseconds) {
      // i. Set style to "fractional".
      style = JSDurationFormat::FieldStyle::kFractional;
      // ii. Set displayDefault to "auto".
      display_default = JSDurationFormat::Display::kAuto;
    }
  }
  // 5. Let displayField be the string-concatenation of unit and "Display".
  // 6. Let display be ? GetOption(options, displayField, "string", « "auto",
  // "always" », displayDefault).
  JSDurationFormat::Display display;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, display,
      GetStringOption<JSDurationFormat::Display>(
          isolate, options, display_field, method_name, {"auto", "always"},
          {JSDurationFormat::Display::kAuto,
           JSDurationFormat::Display::kAlways},
          display_default),
      Nothing<DurationUnitOptions>());
  // 7. If display is "always" and style is "fractional", then
  if (display == JSDurationFormat::Display::kAlways &&
      style == JSDurationFormat::FieldStyle::kFractional) {
    // a. Throw a RangeError exception.
    THROW_NEW_ERROR_RETURN_VALUE(
        isolate,
        NewRangeError(MessageTemplate::kInvalid,
                      isolate->factory()->object_string(), options),
        Nothing<DurationUnitOptions>());
  }
  // 8. If prevStyle is "fractional", then
  if (prev_style == JSDurationFormat::FieldStyle::kFractional) {
    // a. If style is not "fractional", then
    if (style != JSDurationFormat::FieldStyle::kFractional) {
      // i. Throw a RangeError exception.
      THROW_NEW_ERROR_RETURN_VALUE(
          isolate,
          NewRangeError(MessageTemplate::kInvalid,
                        isolate->factory()->object_string(), options),
          Nothing<DurationUnitOptions>());
    }
  }
  // 7. If prevStyle is "numeric" or "2-digit", then
  if (prev_style == JSDurationFormat::FieldStyle::kNumeric ||
      prev_style == JSDurationFormat::FieldStyle::k2Digit) {
    // a. If style is not "fractional", "numeric" or "2-digit", then
    if (style != JSDurationFormat::FieldStyle::kFractional &&
        style != JSDurationFormat::FieldStyle::kNumeric &&
        style != JSDurationFormat::FieldStyle::k2Digit) {
      // i. Throw a RangeError exception.
      THROW_NEW_ERROR_RETURN_VALUE(
          isolate,
          NewRangeError(MessageTemplate::kInvalid,
                        isolate->factory()->object_string(), options),
          Nothing<DurationUnitOptions>());
    }
    // b. If unit is "minutes" or "seconds", then
    if (unit == Unit::kMinutes || unit == Unit::kSeconds) {
      // i. Set style to "2-digit".
      style = JSDurationFormat::FieldStyle::k2Digit;
    }
  }
  // 8. Return the Record { [[Style]]: style, [[Display]]: display }.
  return Just(DurationUnitOptions({style, display}));
}

JSDurationFormat::Separator GetSeparator(const icu::Locale& l) {
  UErrorCode status = U_ZERO_ERROR;
  icu::DateFormatSymbols sym(l, status);
  if (U_FAILURE(status)) return JSDurationFormat::Separator::kColon;
  icu::UnicodeString sep;
  sym.getTimeSeparatorString(sep);
  if (sep.length() != 1) return JSDurationFormat::Separator::kColon;
  switch (sep.charAt(0)) {
    case u'.':
      return JSDurationFormat::Separator::kFullStop;
    case u'\uFF1A':
      return JSDurationFormat::Separator::kFullwidthColon;
    case u'\u066B':
      return JSDurationFormat::Separator::kArabicDecimalSeparator;
    // By default, or if we get anything else, just use ':'.
    default:
      return JSDurationFormat::Separator::kColon;
  }
}

}  // namespace
MaybeDirectHandle<JSDurationFormat> JSDurationFormat::New(
    Isolate* isolate, DirectHandle<Map> map, DirectHandle<Object> locales,
    DirectHandle<Object> input_options) {
  Factory* factory = isolate->factory();
  const char* method_name = "Intl.DurationFormat";

  // 3. Let requestedLocales be ? CanonicalizeLocaleList(locales).
  std::vector<std::string> requested_locales;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, requested_locales,
      Intl::CanonicalizeLocaleList(isolate, locales),
      DirectHandle<JSDurationFormat>());

  // 4. Let options be ? GetOptionsObject(options).
  DirectHandle<JSReceiver> options;
  ASSIGN_RETURN_ON_EXCEPTION(
      isolate, options, GetOptionsObject(isolate, input_options, method_name));

  // 5. Let matcher be ? GetOption(options, "localeMatcher", "string", «
  // "lookup", "best fit" », "best fit").
  Intl::MatcherOption matcher;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, matcher, Intl::GetLocaleMatcher(isolate, options, method_name),
      DirectHandle<JSDurationFormat>());

  // 6. Let numberingSystem be ? GetOption(options, "numberingSystem", "string",
  // undefined, undefined).
  //
  // 7. If numberingSystem is not undefined, then
  //
  // a. If numberingSystem does not match the Unicode Locale Identifier type
  // nonterminal, throw a RangeError exception.
  // Note: The matching test and throw in Step 7-a is throw inside
  // Intl::GetNumberingSystem.
  std::unique_ptr<char[]> numbering_system_str = nullptr;
  bool get;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, get,
      Intl::GetNumberingSystem(isolate, options, method_name,
                               &numbering_system_str),
      DirectHandle<JSDurationFormat>());

  // 8. Let opt be the Record { [[localeMatcher]]: matcher, [[nu]]:
  // numberingSystem }.
  // 9. Let r be ResolveLocale(%DurationFormat%.[[AvailableLocales]],
  // requestedLocales, opt, %DurationFormat%.[[RelevantExtensionKeys]],
  // %DurationFormat%.[[LocaleData]]).
  std::set<std::string> relevant_extension_keys{"nu"};
  Intl::ResolvedLocale r;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, r,
      Intl::ResolveLocale(isolate, JSDurationFormat::GetAvailableLocales(),
                          requested_locales, matcher, relevant_extension_keys),
      DirectHandle<JSDurationFormat>());

  // 10. Let locale be r.[[locale]].
  icu::Locale r_locale = r.icu_locale;
  UErrorCode status = U_ZERO_ERROR;
  // 11. Set durationFormat.[[Locale]] to locale.
  // 12. Set durationFormat.[[NumberingSystem]] to r.[[nu]].
  if (numbering_system_str != nullptr) {
    auto nu_extension_it = r.extensions.find("nu");
    if (nu_extension_it != r.extensions.end() &&
        nu_extension_it->second != numbering_system_str.get()) {
      r_locale.setUnicodeKeywordValue("nu", nullptr, status);
      DCHECK(U_SUCCESS(status));
    }
  }
  icu::Locale icu_locale = r_locale;
  if (numbering_system_str != nullptr &&
      Intl::IsValidNumberingSystem(numbering_system_str.get())) {
    r_locale.setUnicodeKeywordValue("nu", numbering_system_str.get(), status);
    DCHECK(U_SUCCESS(status));
  }
  std::string numbering_system = Intl::GetNumberingSystem(r_locale);
  Separator separator = GetSeparator(r_locale);

  // 13. Let style be ? GetOption(options, "style", "string", « "long", "short",
  // "narrow", "digital" », "long").
  Style style;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, style,
      GetStringOption<Style>(
          isolate, options, "style", method_name,
          {"long", "short", "narrow", "digital"},
          {Style::kLong, Style::kShort, Style::kNarrow, Style::kDigital},
          Style::kShort),
      DirectHandle<JSDurationFormat>());

  // 14. Set durationFormat.[[Style]] to style.
  // 15. Set durationFormat.[[DataLocale]] to r.[[dataLocale]].
  DirectHandle<Managed<icu::Locale>> managed_locale =
      Managed<icu::Locale>::From(
          isolate, 0, std::shared_ptr<icu::Locale>{icu_locale.clone()});
  // 16. Let prevStyle be the empty String.
  // 17. For each row of Table 1, except the header row, in table order, do
  //   a. Let styleSlot be the Style Slot value of the current row.
  //   b. Let displaySlot be the Display Slot value of the current row.
  //   c. Let unit be the Unit value.
  //   d. Let valueList be the Values value.
  //   e. Let digitalBase be the Digital Default value.
  //   f. Let unitOptions be ? GetDurationUnitOptions(unit, options, style,
  //      valueList, digitalBase, prevStyle).
  //      of durationFormat to unitOptions.[[Style]].
  //   h. Set the value of the
  //      displaySlot slot of durationFormat to unitOptions.[[Display]].
  //   i. If unit is one of "hours", "minutes", "seconds", "milliseconds",
  //      or "microseconds", then
  //      i. Set prevStyle to unitOptions.[[Style]].
  //   g. Set the value of the styleSlot slot
  DurationUnitOptions years_option;
  DurationUnitOptions months_option;
  DurationUnitOptions weeks_option;
  DurationUnitOptions days_option;
  DurationUnitOptions hours_option;
  DurationUnitOptions minutes_option;
  DurationUnitOptions seconds_option;
  DurationUnitOptions milliseconds_option;
  DurationUnitOptions microseconds_option;
  DurationUnitOptions nanoseconds_option;

#define CALL_GET_DURATION_UNIT_OPTIONS(unit, property, strings, enums,         \
                                       digital_base, prev_style)               \
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(                                      \
      isolate, property##_option,                                              \
      GetDurationUnitOptions(                                                  \
          isolate, Unit::unit, #property, #property "Display", options, style, \
          strings, enums, JSDurationFormat::FieldStyle::digital_base,          \
          prev_style),                                                         \
      DirectHandle<JSDurationFormat>());

  // #table-durationformat
  // Table 3: Internal slots and property names of DurationFormat instances
  // relevant to Intl.DurationFormat constructor
  // [[YearsStyle]] [[YearsDisplay]] "years" « "long", "short",
  // "narrow" » "short"
  CALL_GET_DURATION_UNIT_OPTIONS(kYears, years, kLongShortNarrowStrings,
                                 kLongShortNarrowEnums, kShort,
                                 FieldStyle::kUndefined)
  // [[MonthsStyle]] [[MonthsDisplay]] "months" « "long",
  // "short", "narrow" » "short"
  CALL_GET_DURATION_UNIT_OPTIONS(kMonths, months, kLongShortNarrowStrings,
                                 kLongShortNarrowEnums, kShort,
                                 years_option.style)
  // [[WeeksStyle]] [[WeeksDisplay]] "weeks" « "long", "short",
  // "narrow" » "short"
  CALL_GET_DURATION_UNIT_OPTIONS(kWeeks, weeks, kLongShortNarrowStrings,
                                 kLongShortNarrowEnums, kShort,
                                 months_option.style)
  // [[DaysStyle]] [[DaysDisplay]] "days" « "long", "short", "narrow" »
  // "short"
  CALL_GET_DURATION_UNIT_OPTIONS(kDays, days, kLongShortNarrowStrings,
                                 kLongShortNarrowEnums, kShort,
                                 weeks_option.style)

  // [[HoursStyle]] [[HoursDisplay]] "hours" « "long", "short",
  // "narrow", "numeric", "2-digit" » "numeric"
  CALL_GET_DURATION_UNIT_OPTIONS(
      kHours, hours, kLongShortNarrowNumeric2DigitStrings,
      kLongShortNarrowNumeric2DigitEnums, kNumeric, days_option.style)
  // [[MinutesStyle]] [[MinutesDisplay]] "minutes" « "long",
  // "short", "narrow", "numeric", "2-digit" » "numeric"
  CALL_GET_DURATION_UNIT_OPTIONS(
      kMinutes, minutes, kLongShortNarrowNumeric2DigitStrings,
      kLongShortNarrowNumeric2DigitEnums, kNumeric, hours_option.style)

  // [[SecondsStyle]] [[SecondsDisplay]] "seconds" « "long",
  // "short", "narrow", "numeric", "2-digit" »
  CALL_GET_DURATION_UNIT_OPTIONS(
      kSeconds, seconds, kLongShortNarrowNumeric2DigitStrings,
      kLongShortNarrowNumeric2DigitEnums, kNumeric, minutes_option.style)

  // [[MillisecondsStyle]] [[MillisecondsDisplay]] "milliseconds" «
  // "long", "short", "narrow", "numeric" » "numeric"
  CALL_GET_DURATION_UNIT_OPTIONS(
      kMilliseconds, milliseconds, kLongShortNarrowNumericStrings,
      kLongShortNarrowNumericEnums, kNumeric, seconds_option.style)

  // [[MicrosecondsStyle]] [[MicrosecondsDisplay]] "microseconds" «
  // "long", "short", "narrow", "numeric" » "numeric"
  CALL_GET_DURATION_UNIT_OPTIONS(
      kMicroseconds, microseconds, kLongShortNarrowNumericStrings,
      kLongShortNarrowNumericEnums, kNumeric, milliseconds_option.style)

  // [[NanosecondsStyle]] [[NanosecondsDisplay]] "nanoseconds" «
  // "long", "short", "narrow", "numeric" » "numeric"
  CALL_GET_DURATION_UNIT_OPTIONS(
      kNanoseconds, nanoseconds, kLongShortNarrowNumericStrings,
      kLongShortNarrowNumericEnums, kNumeric, microseconds_option.style)

#undef CALL_GET_DURATION_UNIT_OPTIONS
  // 18. Set durationFormat.[[FractionalDigits]] to ? GetNumberOption(options,
  // "fractionalDigits", 0, 9, undefined).
  int fractional_digits;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, fractional_digits,
      GetNumberOption(isolate, options, factory->fractionalDigits_string(), 0,
                      9, kUndefinedFractionalDigits),
      DirectHandle<JSDurationFormat>());

  icu::number::LocalizedNumberFormatter fmt =
      icu::number::UnlocalizedNumberFormatter()
          .roundingMode(UNUM_ROUND_HALFUP)
          .locale(icu_locale);
  if (!numbering_system.empty() && numbering_system != "latn") {
    fmt = fmt.adoptSymbols(icu::NumberingSystem::createInstanceByName(
        numbering_system.c_str(), status));
    DCHECK(U_SUCCESS(status));
  }
  DirectHandle<Managed<icu::number::LocalizedNumberFormatter>>
      managed_number_formatter =
          Managed<icu::number::LocalizedNumberFormatter>::From(
              isolate, 0,
              std::make_shared<icu::number::LocalizedNumberFormatter>(fmt));

  // 19. Return durationFormat.
  DirectHandle<JSDurationFormat> duration_format =
      Cast<JSDurationFormat>(factory->NewFastOrSlowJSObjectFromMap(map));
  duration_format->set_style_flags(0);
  duration_format->set_display_flags(0);
  duration_format->set_style(style);
  duration_format->set_years_style(years_option.style);
  duration_format->set_months_style(months_option.style);
  duration_format->set_weeks_style(weeks_option.style);
  duration_format->set_days_style(days_option.style);
  duration_format->set_hours_style(hours_option.style);
  duration_format->set_minutes_style(minutes_option.style);
  duration_format->set_seconds_style(seconds_option.style);
  duration_format->set_milliseconds_style(milliseconds_option.style);
  duration_format->set_microseconds_style(microseconds_option.style);
  duration_format->set_nanoseconds_style(nanoseconds_option.style);
  duration_format->set_separator(separator);

  duration_format->set_years_display(years_option.display);
  duration_format->set_months_display(months_option.display);
  duration_format->set_weeks_display(weeks_option.display);
  duration_format->set_days_display(days_option.display);
  duration_format->set_hours_display(hours_option.display);
  duration_format->set_minutes_display(minutes_option.display);
  duration_format->set_seconds_display(seconds_option.display);
  duration_format->set_milliseconds_display(milliseconds_option.display);
  duration_format->set_microseconds_display(microseconds_option.display);
  duration_format->set_nanoseconds_display(nanoseconds_option.display);

  duration_format->set_fractional_digits(fractional_digits);

  duration_format->set_icu_locale(*managed_locale);
  duration_format->set_icu_number_formatter(*managed_number_formatter);

  return duration_format;
}

namespace {

DirectHandle<String> StyleToString(Isolate* isolate,
                                   JSDurationFormat::Style style) {
  switch (style) {
    case JSDurationFormat::Style::kLong:
      return isolate->factory()->long_string();
    case JSDurationFormat::Style::kShort:
      return isolate->factory()->short_string();
    case JSDurationFormat::Style::kNarrow:
      return isolate->factory()->narrow_string();
    case JSDurationFormat::Style::kDigital:
      return isolate->factory()->digital_string();
  }
  // Avoid undefined behavior for enum values not handled by the exhaustive
  // switch, since they're read from inside the sandbox.
  SBXCHECK(false);
}

DirectHandle<String> StyleToString(Isolate* isolate,
                                   JSDurationFormat::FieldStyle style) {
  switch (style) {
    case JSDurationFormat::FieldStyle::kLong:
      return isolate->factory()->long_string();
    case JSDurationFormat::FieldStyle::kShort:
      return isolate->factory()->short_string();
    case JSDurationFormat::FieldStyle::kNarrow:
      return isolate->factory()->narrow_string();
    case JSDurationFormat::FieldStyle::kNumeric:
      return isolate->factory()->numeric_string();
    case JSDurationFormat::FieldStyle::k2Digit:
      return isolate->factory()->two_digit_string();
    case JSDurationFormat::FieldStyle::kFractional:
      // Step 3 in Intl.DurationFormat.prototype.resolvedOptions ( )
      // e. If v is "fractional", then
      // ii. Set v to "numeric".
      return isolate->factory()->numeric_string();
    case JSDurationFormat::FieldStyle::kUndefined:
      UNREACHABLE();
  }
  // Avoid undefined behavior for enum values not handled by the exhaustive
  // switch, since they're read from inside the sandbox.
  SBXCHECK(false);
}

DirectHandle<String> DisplayToString(Isolate* isolate,
                                     JSDurationFormat::Display display) {
  switch (display) {
    case JSDurationFormat::Display::kAuto:
      return isolate->factory()->auto_string();
    case JSDurationFormat::Display::kAlways:
      return isolate->factory()->always_string();
  }
  // Avoid undefined behavior for enum values not handled by the exhaustive
  // switch, since they're read from inside the sandbox.
  SBXCHECK(false);
}

}  // namespace

DirectHandle<JSObject> JSDurationFormat::ResolvedOptions(
    Isolate* isolate, DirectHandle<JSDurationFormat> format) {
  Factory* factory = isolate->factory();
  DirectHandle<JSObject> options =
      factory->NewJSObject(isolate->object_function());

  DirectHandle<String> locale = factory->NewStringFromAsciiChecked(
      Intl::ToLanguageTag(*format->icu_locale()->raw()).FromJust().c_str());
  UErrorCode status = U_ZERO_ERROR;
  icu::UnicodeString skeleton =
      format->icu_number_formatter()->raw()->toSkeleton(status);
  DCHECK(U_SUCCESS(status));

  DirectHandle<String> numbering_system;
  CHECK(Intl::ToString(isolate,
                       JSNumberFormat::NumberingSystemFromSkeleton(skeleton))
            .ToHandle(&numbering_system));

  bool created;

#define OUTPUT_PROPERTY(s, f)                                           \
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(                               \
      isolate, created,                                                 \
      JSReceiver::CreateDataProperty(isolate, options, factory->s(), f, \
                                     Just(kDontThrow)),                 \
      DirectHandle<JSObject>());                                        \
  CHECK(created);
#define OUTPUT_STYLE_PROPERTY(p) \
  OUTPUT_PROPERTY(p##_string, StyleToString(isolate, format->p##_style()))
#define OUTPUT_DISPLAY_PROPERTY(p)   \
  OUTPUT_PROPERTY(p##Display_string, \
                  DisplayToString(isolate, format->p##_display()))
#define OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(p) \
  OUTPUT_STYLE_PROPERTY(p);                    \
  OUTPUT_DISPLAY_PROPERTY(p);

  // #table-durationformat-resolvedoptions-properties
  // Table 4: Resolved Options of DurationFormat Instances
  // [[Locale]] "locale"
  OUTPUT_PROPERTY(locale_string, locale);
  // [[NumberingSystem]] "numberingSystem"
  OUTPUT_PROPERTY(numberingSystem_string, numbering_system);
  // [[Style]] "style"
  OUTPUT_PROPERTY(style_string, StyleToString(isolate, format->style()));

  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(years);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(months);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(weeks);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(days);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(hours);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(minutes);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(seconds);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(milliseconds);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(microseconds);
  OUTPUT_STYLE_AND_DISPLAY_PROPERTIES(nanoseconds);

  // [[FractionalDigits]] "fractionalDigits"

  // c. If p is "fractionalDigits", then
  int32_t fractional_digits = format->fractional_digits();
  // i. If v is not undefined, set v to 𝔽(v).
  if (kUndefinedFractionalDigits != fractional_digits) {
    DirectHandle<Smi> fractional_digits_obj =
        direct_handle(Smi::FromInt(fractional_digits), isolate);
    // f. If v is not undefined, then
    // i. Perform ! CreateDataPropertyOrThrow(options, p, v).
    OUTPUT_PROPERTY(fractionalDigits_string, fractional_digits_obj);
  }
#undef OUTPUT_PROPERTY
#undef OUTPUT_STYLE_PROPERTY
#undef OUTPUT_DISPLAY_PROPERTY
#undef OUTPUT_STYLE_AND_DISPLAY_PROPERTIES

  return options;
}

namespace {

UNumberUnitWidth ToUNumberUnitWidth(JSDurationFormat::FieldStyle style) {
  switch (style) {
    case JSDurationFormat::FieldStyle::kShort:
      return UNumberUnitWidth::UNUM_UNIT_WIDTH_SHORT;
    case JSDurationFormat::FieldStyle::kLong:
      return UNumberUnitWidth::UNUM_UNIT_WIDTH_FULL_NAME;
    case JSDurationFormat::FieldStyle::kNarrow:
      return UNumberUnitWidth::UNUM_UNIT_WIDTH_NARROW;
    default:
      UNREACHABLE();
  }
  // Avoid undefined behavior for enum values not handled by the exhaustive
  // switch, since they're read from inside the sandbox.
  SBXCHECK(false);
}

struct Part {
  enum Type { kFormatted, kSeparator };
  Type part_type;
  std::string type;
  icu::number::FormattedNumber formatted;
};

char16_t SeparatorToChar(JSDurationFormat::Separator separator) {
  switch (separator) {
    case JSDurationFormat::Separator::kColon:
      return u':';
    case JSDurationFormat::Separator::kFullStop:
      return u'.';
    case JSDurationFormat::Separator::kFullwidthColon:
      return u'\uFF1A';
    case JSDurationFormat::Separator::kArabicDecimalSeparator:
      return u'\u066B';
  }
}

bool FormattedToParts(const char*, icu::number::FormattedNumber&, bool, bool,
                      JSDurationFormat::Separator,
                      std::vector<std::vector<Part>>*,
                      std::vector<icu::UnicodeString>*);

bool Output(const char* type, double value,
            const icu::number::LocalizedNumberFormatter& fmt, bool addToLast,
            bool display_negative_sign, bool negative_duration,
            JSDurationFormat::Separator separator,
            std::vector<std::vector<Part>>* parts,
            std::vector<icu::UnicodeString>* strings) {
  icu::number::LocalizedNumberFormatter nfOpts(fmt);
  // i. If displayNegativeSign is true, then
  if (display_negative_sign) {
    // 1. Set displayNegativeSign to false.
    display_negative_sign = false;
    // 2. If value is 0 and DurationRecordSign(duration) is -1, then
    if (value == 0.0 && negative_duration) {
      // a. Set value to negative-zero.
      value = -0.0;
    }
  } else {  // ii. Else,
    // 1. Perform ! CreateDataPropertyOrThrow(nfOpts, "signDisplay", "never").
    nfOpts = nfOpts.sign(UNumberSignDisplay::UNUM_SIGN_NEVER);
  }

  UErrorCode status = U_ZERO_ERROR;
  icu::number::FormattedNumber formatted = nfOpts.formatDouble(value, status);
  DCHECK(U_SUCCESS(status));
  return FormattedToParts(type, formatted, addToLast, display_negative_sign,
                          separator, parts, strings);
}

bool FormattedToParts(const char* type, icu::number::FormattedNumber& formatted,
                      bool addToLast, bool display_negative_sign,
                      JSDurationFormat::Separator separator,
                      std::vector<std::vector<Part>>* parts,
                      std::vector<icu::UnicodeString>* strings) {
  UErrorCode status = U_ZERO_ERROR;
  icu::UnicodeString unit_string = formatted.toString(status);
  DCHECK(U_SUCCESS(status));
  Part p = {Part::Type::kFormatted, std::string(type), std::move(formatted)};
  if (addToLast && !strings->empty()) {
    strings->back().append(SeparatorToChar(separator));
    strings->back() += unit_string;

    if (parts != nullptr) {
      icu::number::FormattedNumber dummy;
      Part s = {Part::Type::kSeparator, std::string(), std::move(dummy)};
      parts->back().push_back(std::move(s));
      parts->back().push_back(std::move(p));
    }
    return display_negative_sign;
  }
  strings->push_back(unit_string);
  if (parts != nullptr) {
    std::vector<Part> v;
    v.push_back(std::move(p));
    parts->push_back(std::move(v));
  }
  return display_negative_sign;
}

bool OutputLongShortOrNarrow(const char* type, double value,
                             JSDurationFormat::Display display,
                             const icu::number::LocalizedNumberFormatter& fmt,
                             bool addToLast, bool display_negative_sign,
                             bool negative_duration,
                             JSDurationFormat::Separator separator,
                             std::vector<std::vector<Part>>* parts,
                             std::vector<icu::UnicodeString>* strings) {
  if (value == 0 && display == JSDurationFormat::Display::kAuto)
    return display_negative_sign;
  return Output(type, value, fmt, addToLast, display_negative_sign,
                negative_duration, separator, parts, strings);
}

bool OutputLongShortNarrowOrNumeric(
    const char* type, double value, JSDurationFormat::Display display,
    JSDurationFormat::FieldStyle style,
    const icu::number::LocalizedNumberFormatter& fmt, icu::MeasureUnit unit,
    bool addToLast, bool display_negative_sign, bool negative_duration,
    JSDurationFormat::Separator separator,
    std::vector<std::vector<Part>>* parts,
    std::vector<icu::UnicodeString>* strings) {
  if (value == 0 && display == JSDurationFormat::Display::kAuto)
    return display_negative_sign;
  if (style == JSDurationFormat::FieldStyle::kNumeric) {
    return Output(type, value,
                  fmt.grouping(UNumberGroupingStrategy::UNUM_GROUPING_OFF),
                  addToLast, display_negative_sign, negative_duration,
                  separator, parts, strings);
  }
  return OutputLongShortOrNarrow(
      type, value, display, fmt.unit(unit).unitWidth(ToUNumberUnitWidth(style)),
      addToLast, display_negative_sign, negative_duration, separator, parts,
      strings);
}

bool OutputLongShortNarrowNumericOr2Digit(
    const char* type, double value, JSDurationFormat::Display display,
    JSDurationFormat::FieldStyle style,
    const icu::number::LocalizedNumberFormatter& fmt, icu::MeasureUnit unit,
    bool maybeAddToLast, bool displayRequired, bool display_negative_sign,
    bool negative_duration, JSDurationFormat::Separator separator,
    std::vector<std::vector<Part>>* parts,
    std::vector<icu::UnicodeString>* strings) {
  // k. If value is not 0 or display is not "auto" or displayRequired is "true",
  // then
  if ((value != 0) || (display != JSDurationFormat::Display::kAuto) ||
      displayRequired) {
    if (style == JSDurationFormat::FieldStyle::k2Digit) {
      return Output(type, value,
                    fmt.integerWidth(icu::number::IntegerWidth::zeroFillTo(2))
                        .grouping(UNumberGroupingStrategy::UNUM_GROUPING_OFF),
                    maybeAddToLast, display_negative_sign, negative_duration,
                    separator, parts, strings);
    }
    bool addToLast =
        maybeAddToLast && (JSDurationFormat::FieldStyle::kNumeric == style);
    return OutputLongShortNarrowOrNumeric(
        type, value, display, style, fmt, unit, addToLast,
        display_negative_sign, negative_duration, separator, parts, strings);
  }
  return display_negative_sign;
}

bool DisplayRequired(DirectHandle<JSDurationFormat> df,
                     const DurationRecord& record) {
  // 9-h. Let displayRequired be "false".
  // 9-i. Let hoursStyle be durationFormat.[[HoursStyle]].
  // 9-j-i. If hoursStyle is "numeric" or "2-digit", then
  if (df->hours_style() == JSDurationFormat::FieldStyle::kNumeric ||
      df->hours_style() == JSDurationFormat::FieldStyle::k2Digit) {
    // 1. Let hoursDisplay be durationFormat.[[HoursDisplay]].
    // 2. Let hoursValue be durationFormat.[[HoursValue]].
    // 3. If hoursDisplay is "always" or hoursValue is not 0, then
    if (df->hours_display() == JSDurationFormat::Display::kAlways ||
        record.time_duration.hours != 0) {
      // a. Let secondsDisplay be durationFormat.[[SecondsDisplay]].
      // c. If secondsDisplay is "always" or duration.[[Second]] is not 0, or
      // duration.[[Milliseconds]] is not 0, or duration.[[Microseconds]] is not
      // 0, or duration.[[Nanoseconds]] is not 0, then
      if (df->seconds_display() == JSDurationFormat::Display::kAlways ||
          record.time_duration.seconds != 0 ||
          record.time_duration.milliseconds != 0 ||
          record.time_duration.microseconds != 0 ||
          record.time_duration.nanoseconds != 0) {
        // i. Set displayRequired to "true".
        return true;
      }
    }
  }
  return false;
}

void DurationRecordToListOfFormattedNumber(
    DirectHandle<JSDurationFormat> df,
    const icu::number::LocalizedNumberFormatter& fmt,
    const DurationRecord& record, std::vector<std::vector<Part>>* parts,
    std::vector<icu::UnicodeString>* strings) {
  JSDurationFormat::Separator separator = df->separator();
  // 4. Let displayNegativeSign be true.
  bool display_negative_sign = true;
  bool negative_duration = DurationRecord::Sign(record) == -1;

  display_negative_sign = OutputLongShortOrNarrow(
      "year", record.years, df->years_display(),
      fmt.unit(icu::MeasureUnit::getYear())
          .unitWidth(ToUNumberUnitWidth(df->years_style())),
      false, display_negative_sign, negative_duration, separator, parts,
      strings);
  display_negative_sign = OutputLongShortOrNarrow(
      "month", record.months, df->months_display(),
      fmt.unit(icu::MeasureUnit::getMonth())
          .unitWidth(ToUNumberUnitWidth(df->months_style())),
      false, display_negative_sign, negative_duration, separator, parts,
      strings);
  display_negative_sign = OutputLongShortOrNarrow(
      "week", record.weeks, df->weeks_display(),
      fmt.unit(icu::MeasureUnit::getWeek())
          .unitWidth(ToUNumberUnitWidth(df->weeks_style())),
      false, display_negative_sign, negative_duration, separator, parts,
      strings);
  display_negative_sign = OutputLongShortOrNarrow(
      "day", record.time_duration.days, df->days_display(),
      fmt.unit(icu::MeasureUnit::getDay())
          .unitWidth(ToUNumberUnitWidth(df->days_style())),
      false, display_negative_sign, negative_duration, separator, parts,
      strings);
  display_negative_sign = OutputLongShortNarrowNumericOr2Digit(
      "hour", record.time_duration.hours, df->hours_display(),
      df->hours_style(), fmt, icu::MeasureUnit::getHour(), false, false,
      display_negative_sign, negative_duration, separator, parts, strings);
  bool minuteCouldAddToLast =
      df->hours_style() == JSDurationFormat::FieldStyle::kNumeric ||
      df->hours_style() == JSDurationFormat::FieldStyle::k2Digit;
  display_negative_sign = OutputLongShortNarrowNumericOr2Digit(
      "minute", record.time_duration.minutes, df->minutes_display(),
      df->minutes_style(), fmt, icu::MeasureUnit::getMinute(),
      minuteCouldAddToLast, DisplayRequired(df, record), display_negative_sign,
      negative_duration, separator, parts, strings);
  int32_t fractional_digits = df->fractional_digits();
  int32_t maximumFractionDigits;
  int32_t minimumFractionDigits;
  // 2. If durationFormat.[[FractionalDigits]] is undefined, then
  if (fractional_digits == JSDurationFormat::kUndefinedFractionalDigits) {
    // a. Let maximumFractionDigits be 9𝔽.
    maximumFractionDigits = 9;
    // b. Let minimumFractionDigits be +0𝔽.
    minimumFractionDigits = 0;
  } else {  // 3. Else,
    // a. Let maximumFractionDigits be 𝔽(durationFormat.[[FractionalDigits]]).
    maximumFractionDigits = fractional_digits;
    // b. Let minimumFractionDigits be 𝔽(durationFormat.[[FractionalDigits]]).
    minimumFractionDigits = fractional_digits;
  }
  // 4. Perform ! CreateDataPropertyOrThrow(nfOpts, "maximumFractionDigits",
  // maximumFractionDigits ).
  // 5. Perform ! CreateDataPropertyOrThrow(nfOpts, "minimumFractionDigits",
  // minimumFractionDigits ).
  icu::number::LocalizedNumberFormatter nfOps =
      fmt.precision(icu::number::Precision::minMaxFraction(
                        minimumFractionDigits, maximumFractionDigits))
          // 6. Perform ! CreateDataPropertyOrThrow(nfOpts, "roundingMode",
          // "trunc").
          .roundingMode(UNumberFormatRoundingMode::UNUM_ROUND_DOWN);

  if (df->milliseconds_style() == JSDurationFormat::FieldStyle::kFractional) {
    // 1. Set value to value + AddFractionalDigits(durationFormat, duration).
    double value = record.time_duration.nanoseconds / 1e9 +
                   record.time_duration.microseconds / 1e6 +
                   record.time_duration.milliseconds / 1e3 +
                   record.time_duration.seconds;

    OutputLongShortNarrowNumericOr2Digit(
        "second", value, df->seconds_display(), df->seconds_style(), nfOps,
        icu::MeasureUnit::getSecond(), true, false, display_negative_sign,
        negative_duration, separator, parts, strings);
    return;
  }
  display_negative_sign = OutputLongShortNarrowNumericOr2Digit(
      "second", record.time_duration.seconds, df->seconds_display(),
      df->seconds_style(), fmt, icu::MeasureUnit::getSecond(), true, false,
      display_negative_sign, negative_duration, separator, parts, strings);

  if (df->microseconds_style() == JSDurationFormat::FieldStyle::kFractional) {
    // 1. Set value to value + AddFractionalDigits(durationFormat, duration).
    double value = record.time_duration.nanoseconds / 1e6 +
                   record.time_duration.microseconds / 1e3 +
                   record.time_duration.milliseconds;

    OutputLongShortNarrowOrNumeric(
        "millisecond", value, df->milliseconds_display(),
        df->milliseconds_style(), nfOps, icu::MeasureUnit::getMillisecond(),
        false, display_negative_sign, negative_duration, separator, parts,
        strings);
    return;
  }
  display_negative_sign = OutputLongShortNarrowOrNumeric(
      "millisecond", record.time_duration.milliseconds,
      df->milliseconds_display(), df->milliseconds_style(), fmt,
      icu::MeasureUnit::getMillisecond(), false, display_negative_sign,
      negative_duration, separator, parts, strings);

  if (df->nanoseconds_style() == JSDurationFormat::FieldStyle::kFractional) {
    // 1. Set value to value + AddFractionalDigits(durationFormat, duration).
    double value = record.time_duration.nanoseconds / 1e3 +
                   record.time_duration.microseconds;
    OutputLongShortNarrowOrNumeric(
        "microsecond", value, df->microseconds_display(),
        df->microseconds_style(), nfOps, icu::MeasureUnit::getMicrosecond(),
        false, display_negative_sign, negative_duration, separator, parts,
        strings);
    return;
  }
  display_negative_sign = OutputLongShortNarrowOrNumeric(
      "microsecond", record.time_duration.microseconds,
      df->microseconds_display(), df->microseconds_style(), fmt,
      icu::MeasureUnit::getMicrosecond(), false, display_negative_sign,
      negative_duration, separator, parts, strings);

  OutputLongShortNarrowOrNumeric(
      "nanosecond", record.time_duration.nanoseconds, df->nanoseconds_display(),
      df->nanoseconds_style(), fmt, icu::MeasureUnit::getNanosecond(), false,
      display_negative_sign, negative_duration, separator, parts, strings);
}

UListFormatterWidth StyleToWidth(JSDurationFormat::Style style) {
  switch (style) {
    case JSDurationFormat::Style::kLong:
      return ULISTFMT_WIDTH_WIDE;
    case JSDurationFormat::Style::kNarrow:
      return ULISTFMT_WIDTH_NARROW;
    case JSDurationFormat::Style::kShort:
    case JSDurationFormat::Style::kDigital:
      return ULISTFMT_WIDTH_SHORT;
  }
  UNREACHABLE();
}

// The last two arguments passed to the  Format function is only needed
// for Format function to output detail structure and not needed if the
// Format only needs to output a String.
template <typename T, bool Details,
          MaybeDirectHandle<T> (*Format)(Isolate*, const icu::FormattedValue&,
                                         const std::vector<std::vector<Part>>*,
                                         JSDurationFormat::Separator separator)>
MaybeDirectHandle<T> PartitionDurationFormatPattern(
    Isolate* isolate, DirectHandle<JSDurationFormat> df,
    const DurationRecord& record, const char* method_name) {
  // 4. Let lfOpts be ! OrdinaryObjectCreate(null).
  // 5. Perform ! CreateDataPropertyOrThrow(lfOpts, "type", "unit").
  UListFormatterType type = ULISTFMT_TYPE_UNITS;
  // 6. Let listStyle be durationFormat.[[Style]].
  // 7. If listStyle is "digital", then
  // a. Set listStyle to "short".
  // 8. Perform ! CreateDataPropertyOrThrow(lfOpts, "style", listStyle).
  UListFormatterWidth list_style = StyleToWidth(df->style());
  // 9. Let lf be ! Construct(%ListFormat%, « durationFormat.[[Locale]], lfOpts
  // »).
  UErrorCode status = U_ZERO_ERROR;
  icu::Locale icu_locale = *df->icu_locale()->raw();
  std::unique_ptr<icu::ListFormatter> formatter(
      icu::ListFormatter::createInstance(icu_locale, type, list_style, status));
  DCHECK(U_SUCCESS(status));

  std::vector<std::vector<Part>> list;
  std::vector<std::vector<Part>>* parts = Details ? &list : nullptr;
  std::vector<icu::UnicodeString> string_list;

  DurationRecordToListOfFormattedNumber(
      df, *(df->icu_number_formatter()->raw()), record, parts, &string_list);

  icu::FormattedList formatted = formatter->formatStringsToValue(
      string_list.data(), static_cast<int32_t>(string_list.size()), status);
  DCHECK(U_SUCCESS(status));
  return Format(isolate, formatted, parts, df->separator());
}

// #sec-todurationrecord
// ToDurationRecord is almost the same as temporal::ToPartialDuration
// except:
// 1) In the beginning it will throw RangeError if the type of input is String,
// 2) In the end it will throw RangeError if IsValidDurationRecord return false.
Maybe<DurationRecord> ToDurationRecord(Isolate* isolate, Handle<Object> input,
                                       const DurationRecord& default_value) {
  // 1-a. If Type(input) is String, throw a RangeError exception.
  if (IsString(*input)) {
    THROW_NEW_ERROR_RETURN_VALUE(
        isolate,
        NewRangeError(MessageTemplate::kInvalid,
                      isolate->factory()->object_string(), input),
        Nothing<DurationRecord>());
  }
  // Step 1-b - 23. Same as ToTemporalPartialDurationRecord.
  DurationRecord record;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, record,
      temporal::ToPartialDuration(isolate, input, default_value),
      Nothing<DurationRecord>());
  // 24. If IsValidDurationRecord(result) is false, throw a RangeError
  // exception.
  if (!temporal::IsValidDuration(isolate, record)) {
    THROW_NEW_ERROR_RETURN_VALUE(
        isolate,
        NewRangeError(MessageTemplate::kInvalid,
                      isolate->factory()->object_string(), input),
        Nothing<DurationRecord>());
  }
  return Just(record);
}

template <typename T, bool Details,
          MaybeDirectHandle<T> (*Format)(Isolate*, const icu::FormattedValue&,
                                         const std::vector<std::vector<Part>>*,
                                         JSDurationFormat::Separator)>
MaybeDirectHandle<T> FormatCommon(Isolate* isolate,
                                  DirectHandle<JSDurationFormat> df,
                                  Handle<Object> duration,
                                  const char* method_name) {
  // 1. Let df be this value.
  // 2. Perform ? RequireInternalSlot(df, [[InitializedDurationFormat]]).
  // 3. Let record be ? ToDurationRecord(duration).
  DurationRecord record;
  MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE(
      isolate, record,
      ToDurationRecord(isolate, duration, {0, 0, 0, {0, 0, 0, 0, 0, 0, 0}}),
      DirectHandle<T>());
  // 5. Let parts be ! PartitionDurationFormatPattern(df, record).
  return PartitionDurationFormatPattern<T, Details, Format>(isolate, df, record,
                                                            method_name);
}

}  // namespace

MaybeDirectHandle<String> FormattedToString(
    Isolate* isolate, const icu::FormattedValue& formatted,
    const std::vector<std::vector<Part>>* parts, JSDurationFormat::Separator) {
  DCHECK_NULL(parts);
  return Intl::FormattedToString(isolate, formatted);
}

MaybeDirectHandle<JSArray> FormattedListToJSArray(
    Isolate* isolate, const icu::FormattedValue& formatted,
    const std::vector<std::vector<Part>>* parts,
    JSDurationFormat::Separator separator) {
  DCHECK_NOT_NULL(parts);
  Factory* factory = isolate->factory();
  DirectHandle<JSArray> array = factory->NewJSArray(0);
  icu::ConstrainedFieldPosition cfpos;
  cfpos.constrainCategory(UFIELD_CATEGORY_LIST);
  int index = 0;
  int part_index = 0;
  UErrorCode status = U_ZERO_ERROR;
  icu::UnicodeString string = formatted.toString(status);
  while (formatted.nextPosition(cfpos, status) && U_SUCCESS(status)) {
    if (cfpos.getField() == ULISTFMT_ELEMENT_FIELD) {
      for (auto& it : parts->at(part_index++)) {
        switch (it.part_type) {
          case Part::Type::kSeparator: {
            icu::UnicodeString sep(SeparatorToChar(separator));
            DirectHandle<String> separator_string;
            ASSIGN_RETURN_ON_EXCEPTION(isolate, separator_string,
                                       Intl::ToString(isolate, sep));
            Intl::AddElement(isolate, array, index++, factory->literal_string(),
                             separator_string);
          } break;
          case Part::Type::kFormatted:
            DirectHandle<String> type_string =
                factory->NewStringFromAsciiChecked(it.type.c_str());
            Maybe<int> index_after_add = Intl::AddNumberElements(
                isolate, it.formatted, array, index, type_string);
            MAYBE_RETURN(index_after_add, MaybeDirectHandle<JSArray>());
            index = index_after_add.FromJust();
            break;
        }
      }
    } else {
      DirectHandle<String> substring;
      ASSIGN_RETURN_ON_EXCEPTION(
          isolate, substring,
          Intl::ToString(isolate, string, cfpos.getStart(), cfpos.getLimit()));
      Intl::AddElement(isolate, array, index++, factory->literal_string(),
                       substring);
    }
  }
  if (U_FAILURE(status)) {
    THROW_NEW_ERROR(isolate, NewTypeError(MessageTemplate::kIcuError));
  }
  JSObject::ValidateElements(*array);
  return array;
}

MaybeDirectHandle<String> JSDurationFormat::Format(
    Isolate* isolate, DirectHandle<JSDurationFormat> df,
    Handle<Object> duration) {
  const char* method_name = "Intl.DurationFormat.prototype.format";
  return FormatCommon<String, false, FormattedToString>(isolate, df, duration,
                                                        method_name);
}

MaybeDirectHandle<JSArray> JSDurationFormat::FormatToParts(
    Isolate* isolate, DirectHandle<JSDurationFormat> df,
    Handle<Object> duration) {
  const char* method_name = "Intl.DurationFormat.prototype.formatToParts";
  return FormatCommon<JSArray, true, FormattedListToJSArray>(
      isolate, df, duration, method_name);
}

const std::set<std::string>& JSDurationFormat::GetAvailableLocales() {
  return JSNumberFormat::GetAvailableLocales();
}

}  // namespace internal
}  // namespace v8