LibJS: Implement Temporal.Calendar.prototype.dateUntil()

4 files changed, 227 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
index 9cd2d314e8..204162e55f 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
@@ -41,6 +41,7 @@ void CalendarPrototype::initialize(GlobalObject& global_object)
     define_native_function(vm.names.yearMonthFromFields, year_month_from_fields, 1, attr);
     define_native_function(vm.names.monthDayFromFields, month_day_from_fields, 1, attr);
     define_native_function(vm.names.dateAdd, date_add, 2, attr);
+    define_native_function(vm.names.dateUntil, date_until, 2, attr);
     define_native_function(vm.names.year, year, 1, attr);
     define_native_function(vm.names.month, month, 1, attr);
     define_native_function(vm.names.monthCode, month_code, 1, attr);
@@ -199,6 +200,38 @@ JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::date_add)
     return TRY_OR_DISCARD(create_temporal_date(global_object, result.year, result.month, result.day, *calendar));
 }
 
+// 12.4.8 Temporal.Calendar.prototype.dateUntil ( one, two [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.dateuntil
+// NOTE: This is the minimum dateUntil implementation for engines without ECMA-402.
+JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::date_until)
+{
+    // 1. Let calendar be the this value.
+    // 2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+    auto* calendar = typed_this_object(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Assert: calendar.[[Identifier]] is "iso8601".
+    VERIFY(calendar->identifier() == "iso8601"sv);
+
+    // 4. Set one to ? ToTemporalDate(one).
+    auto* one = TRY_OR_DISCARD(to_temporal_date(global_object, vm.argument(0)));
+
+    // 5. Set two to ? ToTemporalDate(two).
+    auto* two = TRY_OR_DISCARD(to_temporal_date(global_object, vm.argument(1)));
+
+    // 6. Set options to ? GetOptionsObject(options).
+    auto* options = TRY_OR_DISCARD(get_options_object(global_object, vm.argument(2)));
+
+    // 7. Let largestUnit be ? ToLargestTemporalUnit(options, « "hour", "minute", "second", "millisecond", "microsecond", "nanosecond" », "auto", "day").
+    auto largest_unit = TRY_OR_DISCARD(to_largest_temporal_unit(global_object, *options, { "hour"sv, "minute"sv, "second"sv, "millisecond"sv, "microsecond"sv, "nanosecond"sv }, "auto"sv, "day"sv));
+
+    // 8. Let result be ! DifferenceISODate(one.[[ISOYear]], one.[[ISOMonth]], one.[[ISODay]], two.[[ISOYear]], two.[[ISOMonth]], two.[[ISODay]], largestUnit).
+    auto result = difference_iso_date(global_object, one->iso_year(), one->iso_month(), one->iso_day(), two->iso_year(), two->iso_month(), two->iso_day(), largest_unit);
+
+    // 9. Return ? CreateTemporalDuration(result.[[Years]], result.[[Months]], result.[[Weeks]], result.[[Days]], 0, 0, 0, 0, 0, 0).
+    return TRY_OR_DISCARD(create_temporal_duration(global_object, result.years, result.months, result.weeks, result.days, 0, 0, 0, 0, 0, 0));
+}
+
 // 12.4.9 Temporal.Calendar.prototype.year ( temporalDateLike ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.year
 // NOTE: This is the minimum year implementation for engines without ECMA-402.
 JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::year)
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
index ef08bc2c7b..4c32e4a7d6 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
@@ -25,6 +25,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(year_month_from_fields);
     JS_DECLARE_NATIVE_FUNCTION(month_day_from_fields);
     JS_DECLARE_NATIVE_FUNCTION(date_add);
+    JS_DECLARE_NATIVE_FUNCTION(date_until);
     JS_DECLARE_NATIVE_FUNCTION(year);
     JS_DECLARE_NATIVE_FUNCTION(month);
     JS_DECLARE_NATIVE_FUNCTION(month_code);
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
index 493ad6c750..21aa82fe5e 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
@@ -142,6 +142,191 @@ ThrowCompletionOr<PlainDate*> to_temporal_date(GlobalObject& global_object, Valu
     return create_temporal_date(global_object, result.year, result.month, result.day, *calendar);
 }
 
+// 3.5.3 DifferenceISODate ( y1, m1, d1, y2, m2, d2, largestUnit ), https://tc39.es/proposal-temporal/#sec-temporal-differenceisodate
+DifferenceISODateResult difference_iso_date(GlobalObject& global_object, i32 year1, u8 month1, u8 day1, i32 year2, u8 month2, u8 day2, StringView largest_unit)
+{
+    // 1. Assert: largestUnit is one of "year", "month", "week", or "day".
+    VERIFY(largest_unit.is_one_of("year"sv, "month"sv, "week"sv, "day"sv));
+
+    // 2. If largestUnit is "year" or "month", then
+    if (largest_unit.is_one_of("year"sv, "month"sv)) {
+        // a. Let sign be -(! CompareISODate(y1, m1, d1, y2, m2, d2)).
+        auto sign = -compare_iso_date(year1, month1, day1, year2, month2, day2);
+
+        // b. If sign is 0, return the Record { [[Years]]: 0, [[Months]]: 0, [[Weeks]]: 0, [[Days]]: 0 }.
+        if (sign == 0)
+            return { .years = 0, .months = 0, .weeks = 0, .days = 0 };
+
+        // c. Let start be the Record { [[Year]]: y1, [[Month]]: m1, [[Day]]: d1 }.
+        auto start = ISODate { .year = year1, .month = month1, .day = day1 };
+
+        // d. Let end be the Record { [[Year]]: y2, [[Month]]: m2, [[Day]]: d2 }.
+        auto end = ISODate { .year = year2, .month = month2, .day = day2 };
+
+        // e. Let years be end.[[Year]] − start.[[Year]].
+        double years = end.year - start.year;
+
+        // f. Let mid be ! AddISODate(y1, m1, d1, years, 0, 0, 0, "constrain").
+        auto mid = MUST(add_iso_date(global_object, year1, month1, day1, years, 0, 0, 0, "constrain"sv));
+
+        // g. Let midSign be -(! CompareISODate(mid.[[Year]], mid.[[Month]], mid.[[Day]], y2, m2, d2)).
+        auto mid_sign = -compare_iso_date(mid.year, mid.month, mid.day, year2, month2, day2);
+
+        // h. If midSign is 0, then
+        if (mid_sign == 0) {
+            // i. If largestUnit is "year", return the Record { [[Years]]: years, [[Months]]: 0, [[Weeks]]: 0, [[Days]]: 0 }.
+            if (largest_unit == "year"sv)
+                return { .years = years, .months = 0, .weeks = 0, .days = 0 };
+
+            // ii. Return the Record { [[Years]]: 0, [[Months]]: years × 12, [[Weeks]]: 0, [[Days]]: 0 }.
+            return { .years = 0, .months = years * 12, .weeks = 0, .days = 0 };
+        }
+
+        // i. Let months be end.[[Month]] − start.[[Month]].
+        double months = end.month - start.month;
+
+        // j. If midSign is not equal to sign, then
+        if (mid_sign != sign) {
+            // i. Set years to years - sign.
+            years -= sign;
+
+            // ii. Set months to months + sign × 12.
+            months += sign * 12;
+        }
+
+        // k. Set mid to ! AddISODate(y1, m1, d1, years, months, 0, 0, "constrain").
+        mid = MUST(add_iso_date(global_object, year1, month1, day1, years, months, 0, 0, "constrain"sv));
+
+        // l. Set midSign to -(! CompareISODate(mid.[[Year]], mid.[[Month]], mid.[[Day]], y2, m2, d2)).
+        mid_sign = -compare_iso_date(mid.year, mid.month, mid.day, year2, month2, day2);
+
+        // m. If midSign is 0, then
+        if (mid_sign == 0) {
+            // i. If largestUnit is "year", return the Record { [[Years]]: years, [[Months]]: months, [[Weeks]]: 0, [[Days]]: 0 }.
+            if (largest_unit == "year"sv)
+                return { .years = years, .months = months, .weeks = 0, .days = 0 };
+
+            // ii. Return the Record { [[Years]]: 0, [[Months]]: months + years × 12, [[Weeks]]: 0, [[Days]]: 0 }.
+            return { .years = 0, .months = months + years * 12, .weeks = 0, .days = 0 };
+        }
+
+        // n. If midSign is not equal to sign, then
+        if (mid_sign != sign) {
+            // i. Set months to months - sign.
+            months -= sign;
+
+            // ii. If months is equal to -sign, then
+            if (months == -sign) {
+                // 1. Set years to years - sign.
+                years -= sign;
+
+                // 2. Set months to 11 × sign.
+                months = 11 * sign;
+            }
+
+            // iii. Set mid to ! AddISODate(y1, m1, d1, years, months, 0, 0, "constrain").
+            mid = MUST(add_iso_date(global_object, year1, month1, day1, years, months, 0, 0, "constrain"sv));
+
+            // FIXME: This is not used (spec issue, see https://github.com/tc39/proposal-temporal/issues/1483).
+            // iv. Set midSign to -(! CompareISODate(mid.[[Year]], mid.[[Month]], mid.[[Day]], y2, m2, d2)).
+            mid_sign = -compare_iso_date(mid.year, mid.month, mid.day, year2, month2, day2);
+        }
+
+        // o. Let days be 0.
+        double days = 0;
+
+        // p. If mid.[[Month]] = end.[[Month]], then
+        if (mid.month == end.month) {
+            // i. Assert: mid.[[Year]] = end.[[Year]].
+            VERIFY(mid.year == end.year);
+
+            // ii. Set days to end.[[Day]] - mid.[[Day]].
+            days = end.day - mid.day;
+        }
+        // q. Else if sign < 0, set days to -mid.[[Day]] - (! ISODaysInMonth(end.[[Year]], end.[[Month]]) - end.[[Day]]).
+        else if (sign < 0) {
+            days = -mid.day - (iso_days_in_month(end.year, end.month) - end.day);
+        }
+        // r. Else, set days to end.[[Day]] + (! ISODaysInMonth(mid.[[Year]], mid.[[Month]]) - mid.[[Day]]).
+        else {
+            days = end.day + (iso_days_in_month(mid.year, mid.month) - mid.day);
+        }
+
+        // s. If largestUnit is "month", then
+        if (largest_unit == "month"sv) {
+            // i. Set months to months + years × 12.
+            months += years * 12;
+
+            // ii. Set years to 0.
+            years = 0;
+        }
+
+        // t. Return the Record { [[Years]]: years, [[Months]]: months, [[Weeks]]: 0, [[Days]]: days }.
+        return { .years = years, .months = months, .weeks = 0, .days = days };
+    }
+    // 3. If largestUnit is "day" or "week", then
+    else {
+        ISODate smaller;
+        ISODate greater;
+        i8 sign;
+
+        // a. If ! CompareISODate(y1, m1, d1, y2, m2, d2) < 0, then
+        if (compare_iso_date(year1, month1, day1, year2, month2, day2) < 0) {
+            // i. Let smaller be the Record { [[Year]]: y1, [[Month]]: m1, [[Day]]: d1 }.
+            smaller = { .year = year1, .month = month1, .day = day1 };
+
+            // ii. Let greater be the Record { [[Year]]: y2, [[Month]]: m2, [[Day]]: d2 }.
+            greater = { .year = year2, .month = month2, .day = day2 };
+
+            // iii. Let sign be 1.
+            sign = 1;
+        }
+        // b. Else,
+        else {
+            // i. Let smaller be the Record { [[Year]]: y2, [[Month]]: m2, [[Day]]: d2 }.
+            smaller = { .year = year2, .month = month2, .day = day2 };
+
+            // ii. Let greater be the Record { [[Year]]: y1, [[Month]]: m1, [[Day]]: d1 }.
+            greater = { .year = year1, .month = month1, .day = day1 };
+
+            // iii. Let sign be −1.
+            sign = -1;
+        }
+
+        // c. Let days be ! ToISODayOfYear(greater.[[Year]], greater.[[Month]], greater.[[Day]]) − ! ToISODayOfYear(smaller.[[Year]], smaller.[[Month]], smaller.[[Day]]).
+        double days = to_iso_day_of_year(greater.year, greater.month, greater.day) - to_iso_day_of_year(smaller.year, smaller.month, smaller.day);
+
+        // d. Let year be smaller.[[Year]].
+        auto year = smaller.year;
+
+        // e. Repeat, while year < greater.[[Year]],
+        while (year < greater.year) {
+            // i. Set days to days + ! ISODaysInYear(year).
+            days += iso_days_in_year(year);
+
+            // ii. Set year to year + 1.
+            year++;
+        }
+
+        // f. Let weeks be 0.
+        double weeks = 0;
+
+        // g. If largestUnit is "week", then
+        if (largest_unit == "week"sv) {
+            // i. Set weeks to floor(days / 7).
+            weeks = floor(days / 7);
+
+            // ii. Set days to days modulo 7.
+            days = fmod(days, 7);
+        }
+
+        // h. Return the Record { [[Years]]: 0, [[Months]]: 0, [[Weeks]]: weeks × sign, [[Days]]: days × sign }.
+        // NOTE: We set weeks and days conditionally to avoid negative zero for 0 * -1.
+        return { .years = 0, .months = 0, .weeks = (weeks != 0) ? weeks * sign : 0, .days = (days != 0) ? days * sign : 0 };
+    }
+    VERIFY_NOT_REACHED();
+}
+
 // 3.5.4 RegulateISODate ( year, month, day, overflow ), https://tc39.es/proposal-temporal/#sec-temporal-regulateisodate
 ThrowCompletionOr<ISODate> regulate_iso_date(GlobalObject& global_object, double year, double month, double day, StringView overflow)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
index 4d89285e8b..bbce1b366f 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
@@ -41,8 +41,16 @@ struct ISODate {
     u8 day;
 };
 
+struct DifferenceISODateResult {
+    double years;
+    double months;
+    double weeks;
+    double days;
+};
+
 ThrowCompletionOr<PlainDate*> create_temporal_date(GlobalObject&, i32 iso_year, u8 iso_month, u8 iso_day, Object& calendar, FunctionObject const* new_target = nullptr);
 ThrowCompletionOr<PlainDate*> to_temporal_date(GlobalObject&, Value item, Object* options = nullptr);
+DifferenceISODateResult difference_iso_date(GlobalObject&, i32 year1, u8 month1, u8 day1, i32 year2, u8 month2, u8 day2, StringView largest_unit);
 ThrowCompletionOr<ISODate> regulate_iso_date(GlobalObject&, double year, double month, double day, StringView overflow);
 bool is_valid_iso_date(i32 year, u8 month, u8 day);
 ISODate balance_iso_date(double year, double month, double day);