/*
 * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Date.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Temporal/AbstractOperations.h>
#include <LibJS/Runtime/Temporal/Calendar.h>
#include <LibJS/Runtime/Temporal/Instant.h>
#include <LibJS/Runtime/Temporal/PlainDate.h>
#include <LibJS/Runtime/Temporal/PlainDateTime.h>
#include <LibJS/Runtime/Temporal/PlainDateTimeConstructor.h>
#include <LibJS/Runtime/Temporal/PlainTime.h>
#include <LibJS/Runtime/Temporal/TimeZone.h>
#include <LibJS/Runtime/Temporal/ZonedDateTime.h>

namespace JS::Temporal {

// 5 Temporal.PlainDateTime Objects, https://tc39.es/proposal-temporal/#sec-temporal-plaindatetime-objects
PlainDateTime::PlainDateTime(i32 iso_year, u8 iso_month, u8 iso_day, u8 iso_hour, u8 iso_minute, u8 iso_second, u16 iso_millisecond, u16 iso_microsecond, u16 iso_nanosecond, Object& calendar, Object& prototype)
    : Object(prototype)
    , m_iso_year(iso_year)
    , m_iso_month(iso_month)
    , m_iso_day(iso_day)
    , m_iso_hour(iso_hour)
    , m_iso_minute(iso_minute)
    , m_iso_second(iso_second)
    , m_iso_millisecond(iso_millisecond)
    , m_iso_microsecond(iso_microsecond)
    , m_iso_nanosecond(iso_nanosecond)
    , m_calendar(calendar)
{
}

void PlainDateTime::visit_edges(Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(&m_calendar);
}

// 5.5.1 GetEpochFromISOParts ( year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/proposal-temporal/#sec-temporal-getepochfromisoparts
BigInt* get_epoch_from_iso_parts(GlobalObject& global_object, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond)
{
    auto& vm = global_object.vm();

    // 1. Assert: year, month, day, hour, minute, second, millisecond, microsecond, and nanosecond are integers.

    // 2. Assert: ! IsValidISODate(year, month, day) is true.
    VERIFY(is_valid_iso_date(year, month, day));

    // 3. Assert: ! IsValidTime(hour, minute, second, millisecond, microsecond, nanosecond) is true.
    VERIFY(is_valid_time(hour, minute, second, millisecond, microsecond, nanosecond));

    // 4. Let date be ! MakeDay(𝔽(year), 𝔽(month − 1), 𝔽(day)).
    auto date = make_day(global_object, Value(year), Value(month - 1), Value(day));

    // 5. Let time be ! MakeTime(𝔽(hour), 𝔽(minute), 𝔽(second), 𝔽(millisecond)).
    auto time = make_time(global_object, Value(hour), Value(minute), Value(second), Value(millisecond));

    // 6. Let ms be ! MakeDate(date, time).
    auto ms = make_date(date, time);

    // 7. Assert: ms is finite.
    VERIFY(ms.is_finite_number());

    // 8. Return ℝ(ms) × 10^6 + microsecond × 10^3 + nanosecond.
    return js_bigint(vm, Crypto::SignedBigInteger::create_from(static_cast<i64>(ms.as_double())).multiplied_by(Crypto::UnsignedBigInteger { 1'000'000 }).plus(Crypto::SignedBigInteger::create_from((i64)microsecond * 1000)).plus(Crypto::SignedBigInteger(nanosecond)));
}

// -864 * 10^19 - 864 * 10^14
const auto DATETIME_NANOSECONDS_MIN = "-8640086400000000000000"_sbigint;
// +864 * 10^19 + 864 * 10^14
const auto DATETIME_NANOSECONDS_MAX = "8640086400000000000000"_sbigint;

// 5.5.2 ISODateTimeWithinLimits ( year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/proposal-temporal/#sec-temporal-isodatetimewithinlimits
bool iso_date_time_within_limits(GlobalObject& global_object, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond)
{
    // 1. Assert: year, month, day, hour, minute, second, millisecond, microsecond, and nanosecond are integers.

    // 2. Let ns be ! GetEpochFromISOParts(year, month, day, hour, minute, second, millisecond, microsecond, nanosecond).
    auto ns = get_epoch_from_iso_parts(global_object, year, month, day, hour, minute, second, millisecond, microsecond, nanosecond);

    // 3. If ns ≤ -8.64 × 10^21 - 8.64 × 10^16, then
    if (ns->big_integer() <= DATETIME_NANOSECONDS_MIN) {
        // a. Return false.
        return false;
    }

    // 4. If ns ≥ 8.64 × 10^21 + 8.64 × 10^16, then
    if (ns->big_integer() >= DATETIME_NANOSECONDS_MAX) {
        // a. Return false.
        return false;
    }
    // 5. Return true.
    return true;
}

// 5.5.3 InterpretTemporalDateTimeFields ( calendar, fields, options ), https://tc39.es/proposal-temporal/#sec-temporal-interprettemporaldatetimefields
Optional<ISODateTime> interpret_temporal_date_time_fields(GlobalObject& global_object, Object& calendar, Object& fields, Object& options)
{
    auto& vm = global_object.vm();

    Optional<TemporalTime> time_result;

    // 1. Let timeResult be ? ToTemporalTimeRecord(fields).
    time_result = to_temporal_time_record(global_object, fields);
    if (vm.exception())
        return {};

    // 2. Let temporalDate be ? DateFromFields(calendar, fields, options).
    auto* temporal_date = date_from_fields(global_object, calendar, fields, options);
    if (vm.exception())
        return {};

    // 3. Let overflow be ? ToTemporalOverflow(options).
    auto overflow = to_temporal_overflow(global_object, options);
    if (vm.exception())
        return {};

    // 4. Let timeResult be ? RegulateTime(timeResult.[[Hour]], timeResult.[[Minute]], timeResult.[[Second]], timeResult.[[Millisecond]], timeResult.[[Microsecond]], timeResult.[[Nanosecond]], overflow).
    time_result = regulate_time(global_object, time_result->hour, time_result->minute, time_result->second, time_result->millisecond, time_result->microsecond, time_result->nanosecond, *overflow);
    if (vm.exception())
        return {};

    // 5. Return the Record { [[Year]]: temporalDate.[[ISOYear]], [[Month]]: temporalDate.[[ISOMonth]], [[Day]]: temporalDate.[[ISODay]], [[Hour]]: timeResult.[[Hour]], [[Minute]]: timeResult.[[Minute]], [[Second]]: timeResult.[[Second]], [[Millisecond]]: timeResult.[[Millisecond]], [[Microsecond]]: timeResult.[[Microsecond]], [[Nanosecond]]: timeResult.[[Nanosecond]] }.
    return ISODateTime {
        .year = temporal_date->iso_year(),
        .month = temporal_date->iso_month(),
        .day = temporal_date->iso_day(),
        .hour = static_cast<u8>(time_result->hour),
        .minute = static_cast<u8>(time_result->minute),
        .second = static_cast<u8>(time_result->second),
        .millisecond = static_cast<u16>(time_result->millisecond),
        .microsecond = static_cast<u16>(time_result->microsecond),
        .nanosecond = static_cast<u16>(time_result->nanosecond),
    };
}

// 5.5.4 ToTemporalDateTime ( item [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal-totemporaldatetime
PlainDateTime* to_temporal_date_time(GlobalObject& global_object, Value item, Object* options)
{
    auto& vm = global_object.vm();

    // 1. If options is not present, set options to ! OrdinaryObjectCreate(null).
    if (!options)
        options = Object::create(global_object, nullptr);

    Object* calendar;
    ISODateTime result;

    // 2. If Type(item) is Object, then
    if (item.is_object()) {
        auto& item_object = item.as_object();

        // a. If item has an [[InitializedTemporalDateTime]] internal slot, then
        if (is<PlainDateTime>(item_object)) {
            // i. Return item.
            return &static_cast<PlainDateTime&>(item_object);
        }

        // b. If item has an [[InitializedTemporalZonedDateTime]] internal slot, then
        if (is<ZonedDateTime>(item_object)) {
            auto& zoned_date_time = static_cast<ZonedDateTime&>(item_object);

            // i. Let instant be ! CreateTemporalInstant(item.[[Nanoseconds]]).
            auto* instant = create_temporal_instant(global_object, zoned_date_time.nanoseconds());

            // ii. Return ? BuiltinTimeZoneGetPlainDateTimeFor(item.[[TimeZone]], instant, item.[[Calendar]]).
            return builtin_time_zone_get_plain_date_time_for(global_object, &zoned_date_time.time_zone(), *instant, zoned_date_time.calendar());
        }

        // c. If item has an [[InitializedTemporalDate]] internal slot, then
        if (is<PlainDate>(item_object)) {
            auto& plain_date = static_cast<PlainDate&>(item_object);

            // i. Return ? CreateTemporalDateTime(item.[[ISOYear]], item.[[ISOMonth]], item.[[ISODay]], 0, 0, 0, 0, 0, 0, item.[[Calendar]]).
            return create_temporal_date_time(global_object, plain_date.iso_year(), plain_date.iso_month(), plain_date.iso_day(), 0, 0, 0, 0, 0, 0, plain_date.calendar());
        }

        // d. Let calendar be ? GetTemporalCalendarWithISODefault(item).
        calendar = get_temporal_calendar_with_iso_default(global_object, item_object);
        if (vm.exception())
            return {};

        // e. Let fieldNames be ? CalendarFields(calendar, « "day", "hour", "microsecond", "millisecond", "minute", "month", "monthCode", "nanosecond", "second", "year" »).
        auto field_names = calendar_fields(global_object, *calendar, { "day"sv, "hour"sv, "microsecond"sv, "millisecond"sv, "minute"sv, "month"sv, "monthCode"sv, "nanosecond"sv, "second"sv, "year"sv });
        if (vm.exception())
            return {};

        // f. Let fields be ? PrepareTemporalFields(item, fieldNames, «»).
        auto* fields = prepare_temporal_fields(global_object, item_object, field_names, {});
        if (vm.exception())
            return {};

        // g. Let result be ? InterpretTemporalDateTimeFields(calendar, fields, options).
        auto maybe_result = interpret_temporal_date_time_fields(global_object, *calendar, *fields, *options);
        if (vm.exception())
            return {};
        result = move(*maybe_result);
    }
    // 3. Else,
    else {
        // a. Perform ? ToTemporalOverflow(options).
        (void)to_temporal_overflow(global_object, *options);
        if (vm.exception())
            return {};

        // b. Let string be ? ToString(item).
        auto string = item.to_string(global_object);
        if (vm.exception())
            return {};

        // c. Let result be ? ParseTemporalDateTimeString(string).
        auto maybe_result = parse_temporal_date_time_string(global_object, string);
        if (vm.exception())
            return {};
        result = move(*maybe_result);

        // d. Assert: ! IsValidISODate(result.[[Year]], result.[[Month]], result.[[Day]]) is true.
        VERIFY(is_valid_iso_date(result.year, result.month, result.day));

        // e. Assert: ! IsValidTime(result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]]) is true.
        VERIFY(is_valid_time(result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond));

        // f. Let calendar be ? ToTemporalCalendarWithISODefault(result.[[Calendar]]).
        calendar = to_temporal_calendar_with_iso_default(global_object, result.calendar.has_value() ? js_string(vm, *result.calendar) : js_undefined());
        if (vm.exception())
            return {};
    }

    // 4. Return ? CreateTemporalDateTime(result.[[Year]], result.[[Month]], result.[[Day]], result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]], calendar).
    return create_temporal_date_time(global_object, result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond, *calendar);
}

// 5.5.5 BalanceISODateTime ( year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/proposal-temporal/#sec-temporal-balanceisodatetime
ISODateTime balance_iso_date_time(i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, i64 nanosecond)
{
    // NOTE: The only use of this AO is in BuiltinTimeZoneGetPlainDateTimeFor, where we know that all values
    // but `nanosecond` are in their usual range, hence why that's the only outlier here. The range for that
    // is -86400000000000 to 86400000000999, so an i32 is not enough.

    // 1. Assert: year, month, day, hour, minute, second, millisecond, microsecond, and nanosecond are integers.

    // 2. Let balancedTime be ! BalanceTime(hour, minute, second, millisecond, microsecond, nanosecond).
    auto balanced_time = balance_time(hour, minute, second, millisecond, microsecond, nanosecond);

    // 3. Let balancedDate be ! BalanceISODate(year, month, day + balancedTime.[[Days]]).
    auto balanced_date = balance_iso_date(year, month, day + balanced_time.days);

    // 4. Return the Record { [[Year]]: balancedDate.[[Year]], [[Month]]: balancedDate.[[Month]], [[Day]]: balancedDate.[[Day]], [[Hour]]: balancedTime.[[Hour]], [[Minute]]: balancedTime.[[Minute]], [[Second]]: balancedTime.[[Second]], [[Millisecond]]: balancedTime.[[Millisecond]], [[Microsecond]]: balancedTime.[[Microsecond]], [[Nanosecond]]: balancedTime.[[Nanosecond]] }.
    return ISODateTime { .year = balanced_date.year, .month = balanced_date.month, .day = balanced_date.day, .hour = balanced_time.hour, .minute = balanced_time.minute, .second = balanced_time.second, .millisecond = balanced_time.millisecond, .microsecond = balanced_time.microsecond, .nanosecond = balanced_time.nanosecond };
}

// 5.5.6 CreateTemporalDateTime ( isoYear, isoMonth, isoDay, hour, minute, second, millisecond, microsecond, nanosecond, calendar [ , newTarget ] ), https://tc39.es/proposal-temporal/#sec-temporal-createtemporaldatetime
PlainDateTime* create_temporal_date_time(GlobalObject& global_object, i32 iso_year, u8 iso_month, u8 iso_day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond, Object& calendar, FunctionObject* new_target)
{
    auto& vm = global_object.vm();

    // 1. Assert: isoYear, isoMonth, isoDay, hour, minute, second, millisecond, microsecond, and nanosecond are integers.
    // 2. Assert: Type(calendar) is Object.

    // 3. If ! IsValidISODate(isoYear, isoMonth, isoDay) is false, throw a RangeError exception.
    if (!is_valid_iso_date(iso_year, iso_month, iso_day)) {
        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDateTime);
        return {};
    }

    // 4. If ! IsValidTime(hour, minute, second, millisecond, microsecond, nanosecond) is false, throw a RangeError exception.
    if (!is_valid_time(hour, minute, second, millisecond, microsecond, nanosecond)) {
        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDateTime);
        return {};
    }

    // 5. If ! ISODateTimeWithinLimits(isoYear, isoMonth, isoDay, hour, minute, second, millisecond, microsecond, nanosecond) is false, then
    if (!iso_date_time_within_limits(global_object, iso_year, iso_month, iso_day, hour, minute, second, millisecond, microsecond, nanosecond)) {
        // a. Throw a RangeError exception.
        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDateTime);
        return {};
    }

    // 6. If newTarget is not present, set it to %Temporal.PlainDateTime%.
    if (!new_target)
        new_target = global_object.temporal_plain_date_time_constructor();

    // 7. Let object be ? OrdinaryCreateFromConstructor(newTarget, "%Temporal.PlainDateTime.prototype%", « [[InitializedTemporalDateTime]], [[ISOYear]], [[ISOMonth]], [[ISODay]], [[ISOHour]], [[ISOMinute]], [[ISOSecond]], [[ISOMillisecond]], [[ISOMicrosecond]], [[ISONanosecond]], [[Calendar]] »).
    // 8. Set object.[[ISOYear]] to isoYear.
    // 9. Set object.[[ISOMonth]] to isoMonth.
    // 10. Set object.[[ISODay]] to isoDay.
    // 11. Set object.[[ISOHour]] to hour.
    // 12. Set object.[[ISOMinute]] to minute.
    // 13. Set object.[[ISOSecond]] to second.
    // 14. Set object.[[ISOMillisecond]] to millisecond.
    // 15. Set object.[[ISOMicrosecond]] to microsecond.
    // 16. Set object.[[ISONanosecond]] to nanosecond.
    // 17. Set object.[[Calendar]] to calendar.
    auto* object = ordinary_create_from_constructor<PlainDateTime>(global_object, *new_target, &GlobalObject::temporal_plain_date_prototype, iso_year, iso_month, iso_day, hour, minute, second, millisecond, microsecond, nanosecond, calendar);
    if (vm.exception())
        return {};

    // 18. Return object.
    return object;
}

}