LibJS: Implement Temporal.TimeZone.prototype.getNextTransition()

6 files changed, 63 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
index f59917044a..ee32feb079 100644
--- a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
+++ b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
@@ -205,6 +205,7 @@ namespace JS {
     P(getMilliseconds)                       \
     P(getMinutes)                            \
     P(getMonth)                              \
+    P(getNextTransition)                     \
     P(getOffsetNanosecondsFor)               \
     P(getOffsetStringFor)                    \
     P(getOwnPropertyDescriptor)              \
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
index 13205ebd06..1703359caa 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
@@ -177,6 +177,15 @@ i64 get_iana_time_zone_offset_nanoseconds([[maybe_unused]] BigInt const& epoch_n
     return 0;
 }
 
+// 11.6.6 GetIANATimeZoneNextTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezonenexttransition
+BigInt* get_iana_time_zone_next_transition(GlobalObject&, [[maybe_unused]] BigInt const& epoch_nanoseconds, [[maybe_unused]] StringView time_zone_identifier)
+{
+    // The abstract operation GetIANATimeZoneNextTransition is an implementation-defined algorithm that returns an integer representing the number of nanoseconds since the Unix epoch in UTC that corresponds to the first time zone transition after epochNanoseconds in the IANA time zone identified by timeZoneIdentifier or null if no such transition exists.
+
+    // TODO: Implement this
+    return nullptr;
+}
+
 // https://tc39.es/proposal-temporal/#prod-TimeZoneNumericUTCOffset
 static bool parse_time_zone_numeric_utc_offset_syntax(String const& offset_string, StringView& sign, StringView& hours, Optional<StringView>& minutes, Optional<StringView>& seconds, Optional<StringView>& fraction)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
index 93537bfd1e..0f65f729af 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
@@ -41,6 +41,7 @@ ThrowCompletionOr<TimeZone*> create_temporal_time_zone(GlobalObject&, String con
 ISODateTime get_iso_parts_from_epoch(BigInt const& epoch_nanoseconds);
 MarkedValueList get_iana_time_zone_epoch_value(GlobalObject&, StringView time_zone_identifier, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond);
 i64 get_iana_time_zone_offset_nanoseconds(BigInt const& epoch_nanoseconds, String const& time_zone_identifier);
+BigInt* get_iana_time_zone_next_transition(GlobalObject&, BigInt const& epoch_nanoseconds, StringView time_zone_identifier);
 ThrowCompletionOr<double> parse_time_zone_offset_string(GlobalObject&, String const&);
 String format_time_zone_offset_string(double offset_nanoseconds);
 ThrowCompletionOr<Object*> to_temporal_time_zone(GlobalObject&, Value temporal_time_zone_like);
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
index b76255bdae..53260273a1 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
@@ -33,6 +33,7 @@ void TimeZonePrototype::initialize(GlobalObject& global_object)
     define_native_function(vm.names.getOffsetStringFor, get_offset_string_for, 1, attr);
     define_native_function(vm.names.getPlainDateTimeFor, get_plain_date_time_for, 1, attr);
     define_native_function(vm.names.getPossibleInstantsFor, get_possible_instants_for, 1, attr);
+    define_native_function(vm.names.getNextTransition, get_next_transition, 1, attr);
     define_native_function(vm.names.toString, to_string, 0, attr);
     define_native_function(vm.names.toJSON, to_json, 0, attr);
 
@@ -140,6 +141,31 @@ JS_DEFINE_NATIVE_FUNCTION(TimeZonePrototype::get_possible_instants_for)
     return Array::create_from(global_object, possible_instants);
 }
 
+// 11.4.9 Temporal.TimeZone.prototype.getNextTransition ( startingPoint ), https://tc39.es/proposal-temporal/#sec-temporal.timezone.prototype.getnexttransition
+JS_DEFINE_NATIVE_FUNCTION(TimeZonePrototype::get_next_transition)
+{
+    // 1. Let timeZone be the this value.
+    // 2. Perform ? RequireInternalSlot(timeZone, [[InitializedTemporalTimeZone]]).
+    auto* time_zone = TRY(typed_this_object(global_object));
+
+    // 3. Set startingPoint to ? ToTemporalInstant(startingPoint).
+    auto* starting_point = TRY(to_temporal_instant(global_object, vm.argument(0)));
+
+    // 4. If timeZone.[[OffsetNanoseconds]] is not undefined, return null.
+    if (!time_zone->offset_nanoseconds().has_value())
+        return js_null();
+
+    // 5. Let transition be ? GetIANATimeZoneNextTransition(startingPoint.[[Nanoseconds]], timeZone.[[Identifier]]).
+    auto* transition = get_iana_time_zone_next_transition(global_object, starting_point->nanoseconds(), time_zone->identifier());
+
+    // 6. If transition is null, return null.
+    if (!transition)
+        return js_null();
+
+    // 7. Return ! CreateTemporalInstant(transition).
+    return MUST(create_temporal_instant(global_object, *transition));
+}
+
 // 11.4.11 Temporal.TimeZone.prototype.toString ( ), https://tc39.es/proposal-temporal/#sec-temporal.timezone.prototype.tostring
 JS_DEFINE_NATIVE_FUNCTION(TimeZonePrototype::to_string)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.h
index f41e1193ba..aeb30812d1 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.h
@@ -25,6 +25,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(get_offset_string_for);
     JS_DECLARE_NATIVE_FUNCTION(get_plain_date_time_for);
     JS_DECLARE_NATIVE_FUNCTION(get_possible_instants_for);
+    JS_DECLARE_NATIVE_FUNCTION(get_next_transition);
     JS_DECLARE_NATIVE_FUNCTION(to_string);
     JS_DECLARE_NATIVE_FUNCTION(to_json);
 };
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.getNextTransition.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.getNextTransition.js
new file mode 100644
index 0000000000..d92abb3111
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/TimeZone/TimeZone.prototype.getNextTransition.js
@@ -0,0 +1,25 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.TimeZone.prototype.getNextTransition).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const timeZone = new Temporal.TimeZone("UTC");
+        const instant = new Temporal.Instant(0n);
+        expect(timeZone.getNextTransition(instant)).toBeNull();
+    });
+
+    test("custom offset", () => {
+        const timeZone = new Temporal.TimeZone("+01:30");
+        const instant = new Temporal.Instant(0n);
+        expect(timeZone.getNextTransition(instant)).toBeNull();
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.TimeZone object", () => {
+        expect(() => {
+            Temporal.TimeZone.prototype.getNextTransition.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.TimeZone");
+    });
+});