#include <AK/String.h>
#include <LibGC/Heap.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FunctionObject.h>
#include <LibJS/Runtime/PrimitiveString.h>
#include <LibJS/Runtime/Realm.h>
#include <LibJS/Runtime/VM.h>
#include <LibJS/Runtime/Value.h>
#include <LibJS/Runtime/ValueInlines.h>
#include <LibWeb/Bindings/EventTarget.h>
#include <LibWeb/Bindings/ExceptionOrUtils.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/MediaSource.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/MediaSourceExtensions/MediaSource.h>
#include <LibWeb/MediaSourceExtensions/SourceBuffer.h>
#include <LibWeb/MediaSourceExtensions/SourceBufferList.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
#include <LibWeb/WebIDL/CallbackType.h>
#include <LibWeb/WebIDL/Tracing.h>

namespace Web::Bindings {

void MediaSourceConstructor::initialize(JS::Realm& realm, JS::NativeFunction& object)
{
    auto& vm = realm.vm();
    [[maybe_unused]] u8 default_attributes = JS::Attribute::Enumerable;

    object.set_prototype(&ensure_web_constructor<EventTargetPrototype>(realm, "EventTarget"_fly_string));
    object.define_direct_property(vm.names.length, JS::Value(0), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.name, JS::PrimitiveString::create(vm, "MediaSource"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<MediaSourcePrototype>(realm, "MediaSource"_fly_string), 0);
    object.define_native_accessor(realm, "canConstructInDedicatedWorker"_utf16_fly_string, can_construct_in_dedicated_worker_getter, nullptr, default_attributes);
    object.define_native_function(realm, "isTypeSupported"_utf16_fly_string, is_type_supported, 1, JS::Attribute::Enumerable | JS::Attribute::Configurable | JS::Attribute::Writable);

}

JS::ThrowCompletionOr<GC::Ref<JS::Object>> MediaSourceConstructor::construct([[maybe_unused]] InterfaceConstructor& constructor, [[maybe_unused]] JS::FunctionObject& new_target)
{
    WebIDL::log_trace(constructor.vm(), "MediaSourceConstructor::construct");
    auto& vm = constructor.vm();
    [[maybe_unused]] auto& realm = *vm.current_realm();

    // To internally create a new object implementing the interface MediaSource:

    // 3.2. Let prototype be ? Get(newTarget, "prototype").
    auto prototype = TRY(new_target.get(vm.names.prototype));

    // 3.3. If Type(prototype) is not Object, then:
    if (!prototype.is_object()) {
        // 1. Let targetRealm be ? GetFunctionRealm(newTarget).
        auto* target_realm = TRY(JS::get_function_realm(vm, new_target));

        // 2. Set prototype to the interface prototype object for interface in targetRealm.
        VERIFY(target_realm);
        prototype = &Bindings::ensure_web_prototype<MediaSourcePrototype>(*target_realm, "MediaSource"_fly_string);
    }

    auto impl = TRY(throw_dom_exception_if_needed(vm, [&] { return MediaSourceExtensions::MediaSource::construct_impl(realm); }));

    // 7. Set instance.[[Prototype]] to prototype.
    VERIFY(prototype.is_object());
    impl->set_prototype(&prototype.as_object());

    // FIXME: Steps 8...11. of the "internally create a new object implementing the interface MediaSource" algorithm
    // (https://webidl.spec.whatwg.org/#js-platform-objects) are currently not handled, or are handled within MediaSourceExtensions::MediaSource::construct_impl().

    return *impl;
}

void MediaSourcePrototype::initialize(JS::Realm& realm, JS::Object& object)
{
    [[maybe_unused]] auto& vm = realm.vm();
    [[maybe_unused]] u8 default_attributes = JS::Attribute::Enumerable | JS::Attribute::Configurable | JS::Attribute::Writable;

    object.set_prototype(GC::Ref { ensure_web_prototype<EventTargetPrototype>(realm, "EventTarget"_fly_string) });

    auto source_buffers_id = "sourceBuffers"_utf16_fly_string;
    auto native_source_buffers_getter = JS::NativeFunction::create(realm, source_buffers_getter, 0, source_buffers_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_source_buffers_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto source_buffers_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(source_buffers_id, native_source_buffers_getter, native_source_buffers_setter, source_buffers_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto active_source_buffers_id = "activeSourceBuffers"_utf16_fly_string;
    auto native_active_source_buffers_getter = JS::NativeFunction::create(realm, active_source_buffers_getter, 0, active_source_buffers_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_active_source_buffers_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto active_source_buffers_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(active_source_buffers_id, native_active_source_buffers_getter, native_active_source_buffers_setter, active_source_buffers_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto ready_state_id = "readyState"_utf16_fly_string;
    auto native_ready_state_getter = JS::NativeFunction::create(realm, ready_state_getter, 0, ready_state_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_ready_state_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto ready_state_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(ready_state_id, native_ready_state_getter, native_ready_state_setter, ready_state_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto duration_id = "duration"_utf16_fly_string;
    auto native_duration_getter = JS::NativeFunction::create(realm, duration_getter, 0, duration_id, &realm, "get"sv);
    auto native_duration_setter = JS::NativeFunction::create(realm, duration_setter, 1, duration_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto duration_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(duration_id, native_duration_getter, native_duration_setter, duration_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto onsourceopen_id = "onsourceopen"_utf16_fly_string;
    auto native_onsourceopen_getter = JS::NativeFunction::create(realm, onsourceopen_getter, 0, onsourceopen_id, &realm, "get"sv);
    auto native_onsourceopen_setter = JS::NativeFunction::create(realm, onsourceopen_setter, 1, onsourceopen_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto onsourceopen_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(onsourceopen_id, native_onsourceopen_getter, native_onsourceopen_setter, onsourceopen_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto onsourceended_id = "onsourceended"_utf16_fly_string;
    auto native_onsourceended_getter = JS::NativeFunction::create(realm, onsourceended_getter, 0, onsourceended_id, &realm, "get"sv);
    auto native_onsourceended_setter = JS::NativeFunction::create(realm, onsourceended_setter, 1, onsourceended_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto onsourceended_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(onsourceended_id, native_onsourceended_getter, native_onsourceended_setter, onsourceended_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    auto onsourceclose_id = "onsourceclose"_utf16_fly_string;
    auto native_onsourceclose_getter = JS::NativeFunction::create(realm, onsourceclose_getter, 0, onsourceclose_id, &realm, "get"sv);
    auto native_onsourceclose_setter = JS::NativeFunction::create(realm, onsourceclose_setter, 1, onsourceclose_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto onsourceclose_attributes = default_attributes;

    // 5. Let desc be the PropertyDescriptor{[[Get]]: getter, [[Set]]: setter, [[Enumerable]]: true, [[Configurable]]: configurable}.

    // 7. Perform ! DefinePropertyOrThrow(target, id, desc).
    object.define_direct_accessor(onsourceclose_id, native_onsourceclose_getter, native_onsourceclose_setter, onsourceclose_attributes);

    // 8. FIXME: If attr’s type is an observable array type with type argument T, then set target’s backing observable array exotic object for attr to the result of creating an observable array exotic object in realm, given T, attr’s set an indexed value algorithm, and attr’s delete an indexed value algorithm.
    object.define_native_function(realm, "addSourceBuffer"_utf16_fly_string, add_source_buffer, 1, default_attributes);

    object.define_native_function(realm, "endOfStream"_utf16_fly_string, end_of_stream, 0, default_attributes);

    object.define_direct_property("removeSourceBuffer"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property("setLiveSeekableRange"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property("clearLiveSeekableRange"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property(vm.well_known_symbol_to_string_tag(), JS::PrimitiveString::create(vm, "MediaSource"_utf16), JS::Attribute::Configurable);
}

void MediaSourcePrototype::define_unforgeable_attributes(JS::Realm& realm, [[maybe_unused]] JS::Object& object)
{
    [[maybe_unused]] auto& vm = realm.vm();
    [[maybe_unused]] u8 default_attributes = JS::Attribute::Enumerable;
}

[[maybe_unused]] static JS::ThrowCompletionOr<MediaSourceExtensions::MediaSource*> impl_from(JS::VM& vm, JS::Value js_value)
{

    if (auto impl = js_value.as_if<MediaSourceExtensions::MediaSource>())
        return impl.ptr();
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "MediaSource");
}

[[maybe_unused]] static JS::ThrowCompletionOr<MediaSourceExtensions::MediaSource*> impl_from(JS::VM& vm)
{
    auto this_value = vm.this_value();
    if (this_value.is_nullish())
        this_value = &vm.current_realm()->global_object();
    return impl_from(vm, this_value);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourceConstructor::is_type_supported)
{
    WebIDL::log_trace(vm, "MediaSourceConstructor::is_type_supported");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    if (vm.argument_count() < 1)
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::BadArgCountOne, "isTypeSupported");

    auto arg0 = vm.argument(0);
    auto type = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<String> {
        return TRY(WebIDL::to_string(vm, arg0));
    }(); }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return MediaSourceExtensions::MediaSource::is_type_supported(vm, type); }));
    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourceConstructor::can_construct_in_dedicated_worker_getter)
{
    WebIDL::log_trace(vm, "MediaSourceConstructor::can_construct_in_dedicated_worker_getter");

    // Let R be the result of running the getter steps of attribute.
    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return MediaSourceExtensions::MediaSource::can_construct_in_dedicated_worker(vm); }));

    // Return the result of converting R to a JavaScript value of the type attribute is declared as.
    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::source_buffers_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::source_buffers_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->source_buffers(); }));

    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::active_source_buffers_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::active_source_buffers_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->active_source_buffers(); }));

    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::ready_state_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::ready_state_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->ready_state(); }));

    return JS::PrimitiveString::create(vm, idl_enum_to_string(R));
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::duration_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::duration_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->duration(); }));

    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceopen_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceopen_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->onsourceopen(); }));

    return [&]() -> JS::Value {
        // 1. If the IDL nullable type T? value is null, then the JavaScript value is null.
        if (!R)
            return JS::js_null();

        // 2. Otherwise, the JavaScript value is the result of converting the IDL nullable type value to the inner IDL type T.
        return JS::Value(R->callback);
    }();
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceended_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceended_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->onsourceended(); }));

    return [&]() -> JS::Value {
        // 1. If the IDL nullable type T? value is null, then the JavaScript value is null.
        if (!R)
            return JS::js_null();

        // 2. Otherwise, the JavaScript value is the result of converting the IDL nullable type value to the inner IDL type T.
        return JS::Value(R->callback);
    }();
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceclose_getter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceclose_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto* idl_object = TRY(impl_from(vm));


    auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->onsourceclose(); }));

    return [&]() -> JS::Value {
        // 1. If the IDL nullable type T? value is null, then the JavaScript value is null.
        if (!R)
            return JS::js_null();

        // 2. Otherwise, the JavaScript value is the result of converting the IDL nullable type value to the inner IDL type T.
        return JS::Value(R->callback);
    }();
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::duration_setter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::duration_setter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    // 1. Let V be undefined.
    auto V = JS::js_undefined();

    // 2. If any arguments were passed, then set V to the value of the first argument passed.
    if (vm.argument_count() > 0)
        V = vm.argument(0);

    // 3. Let id be attribute’s identifier.

    // 4. Let idlObject be null.
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = nullptr;

    // 5. If attribute is a regular attribute:

    // 1. Let jsValue be the this value, if it is not null or undefined, or realm’s global object otherwise. (This will subsequently cause a TypeError in a few steps, if the global object does not implement target and [LegacyLenientThis] is not specified.)
    auto js_value = vm.this_value();
    if (js_value.is_nullish())
        js_value = &realm.global_object();

    // 2. FIXME: If jsValue is a platform object, then perform a security check, passing jsValue, attribute’s identifier, and "setter".

    // 3. Let validThis be true if jsValue implements target, or false otherwise.
    auto maybe_idl_object = impl_from(vm, js_value);

    // 4. If validThis is false and attribute was not specified with the [LegacyLenientThis] extended attribute, then throw a TypeError.
    idl_object = TRY(maybe_idl_object);

    auto original_steps = [&]() -> JS::ThrowCompletionOr<JS::Value> {
        // 6. Let idlValue be determined as follows:
        // -> Otherwise, idlValue is the result of converting V to an IDL value of attribute’s type.
        auto idl_value = TRY(throw_dom_exception_if_needed(vm, [&] { return V.to_double(vm); }));

        // 7. Run the setter steps of attribute with idlObject as this and idlValue as the value.
        auto setter_result = [&]() -> JS::ThrowCompletionOr<void> {
            TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->set_duration(idl_value); }));
    return {};
        }();

        if (setter_result.is_error())
            return setter_result.release_error();

        return JS::js_undefined();
    };

    // 8. Return undefined.
    return TRY(original_steps());
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceopen_setter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceopen_setter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    // 1. Let V be undefined.
    auto V = JS::js_undefined();

    // 2. If any arguments were passed, then set V to the value of the first argument passed.
    if (vm.argument_count() > 0)
        V = vm.argument(0);

    // 3. Let id be attribute’s identifier.

    // 4. Let idlObject be null.
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = nullptr;

    // 5. If attribute is a regular attribute:

    // 1. Let jsValue be the this value, if it is not null or undefined, or realm’s global object otherwise. (This will subsequently cause a TypeError in a few steps, if the global object does not implement target and [LegacyLenientThis] is not specified.)
    auto js_value = vm.this_value();
    if (js_value.is_nullish())
        js_value = &realm.global_object();

    // 2. FIXME: If jsValue is a platform object, then perform a security check, passing jsValue, attribute’s identifier, and "setter".

    // 3. Let validThis be true if jsValue implements target, or false otherwise.
    auto maybe_idl_object = impl_from(vm, js_value);

    // 4. If validThis is false and attribute was not specified with the [LegacyLenientThis] extended attribute, then throw a TypeError.
    idl_object = TRY(maybe_idl_object);

    auto original_steps = [&]() -> JS::ThrowCompletionOr<JS::Value> {
        // 6. Let idlValue be determined as follows:
        // -> Otherwise, idlValue is the result of converting V to an IDL value of attribute’s type.
        auto idl_value = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {
        GC::Ptr<WebIDL::CallbackType> value;
        if (V.is_object()) {

        if (!V.is_nullish()) {

            value = TRY([&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {

        return vm.heap().allocate<WebIDL::CallbackType>(V.as_object(),  HTML::incumbent_realm(), WebIDL::OperationReturnsPromise::No);
    }());
        }
        }
        return value;
    }(); }));

        // 7. Run the setter steps of attribute with idlObject as this and idlValue as the value.
        auto setter_result = [&]() -> JS::ThrowCompletionOr<void> {
            TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->set_onsourceopen(idl_value); }));
    return {};
        }();

        if (setter_result.is_error())
            return setter_result.release_error();

        return JS::js_undefined();
    };

    // 8. Return undefined.
    return TRY(original_steps());
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceended_setter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceended_setter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    // 1. Let V be undefined.
    auto V = JS::js_undefined();

    // 2. If any arguments were passed, then set V to the value of the first argument passed.
    if (vm.argument_count() > 0)
        V = vm.argument(0);

    // 3. Let id be attribute’s identifier.

    // 4. Let idlObject be null.
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = nullptr;

    // 5. If attribute is a regular attribute:

    // 1. Let jsValue be the this value, if it is not null or undefined, or realm’s global object otherwise. (This will subsequently cause a TypeError in a few steps, if the global object does not implement target and [LegacyLenientThis] is not specified.)
    auto js_value = vm.this_value();
    if (js_value.is_nullish())
        js_value = &realm.global_object();

    // 2. FIXME: If jsValue is a platform object, then perform a security check, passing jsValue, attribute’s identifier, and "setter".

    // 3. Let validThis be true if jsValue implements target, or false otherwise.
    auto maybe_idl_object = impl_from(vm, js_value);

    // 4. If validThis is false and attribute was not specified with the [LegacyLenientThis] extended attribute, then throw a TypeError.
    idl_object = TRY(maybe_idl_object);

    auto original_steps = [&]() -> JS::ThrowCompletionOr<JS::Value> {
        // 6. Let idlValue be determined as follows:
        // -> Otherwise, idlValue is the result of converting V to an IDL value of attribute’s type.
        auto idl_value = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {
        GC::Ptr<WebIDL::CallbackType> value;
        if (V.is_object()) {

        if (!V.is_nullish()) {

            value = TRY([&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {

        return vm.heap().allocate<WebIDL::CallbackType>(V.as_object(),  HTML::incumbent_realm(), WebIDL::OperationReturnsPromise::No);
    }());
        }
        }
        return value;
    }(); }));

        // 7. Run the setter steps of attribute with idlObject as this and idlValue as the value.
        auto setter_result = [&]() -> JS::ThrowCompletionOr<void> {
            TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->set_onsourceended(idl_value); }));
    return {};
        }();

        if (setter_result.is_error())
            return setter_result.release_error();

        return JS::js_undefined();
    };

    // 8. Return undefined.
    return TRY(original_steps());
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::onsourceclose_setter)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::onsourceclose_setter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    // 1. Let V be undefined.
    auto V = JS::js_undefined();

    // 2. If any arguments were passed, then set V to the value of the first argument passed.
    if (vm.argument_count() > 0)
        V = vm.argument(0);

    // 3. Let id be attribute’s identifier.

    // 4. Let idlObject be null.
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = nullptr;

    // 5. If attribute is a regular attribute:

    // 1. Let jsValue be the this value, if it is not null or undefined, or realm’s global object otherwise. (This will subsequently cause a TypeError in a few steps, if the global object does not implement target and [LegacyLenientThis] is not specified.)
    auto js_value = vm.this_value();
    if (js_value.is_nullish())
        js_value = &realm.global_object();

    // 2. FIXME: If jsValue is a platform object, then perform a security check, passing jsValue, attribute’s identifier, and "setter".

    // 3. Let validThis be true if jsValue implements target, or false otherwise.
    auto maybe_idl_object = impl_from(vm, js_value);

    // 4. If validThis is false and attribute was not specified with the [LegacyLenientThis] extended attribute, then throw a TypeError.
    idl_object = TRY(maybe_idl_object);

    auto original_steps = [&]() -> JS::ThrowCompletionOr<JS::Value> {
        // 6. Let idlValue be determined as follows:
        // -> Otherwise, idlValue is the result of converting V to an IDL value of attribute’s type.
        auto idl_value = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {
        GC::Ptr<WebIDL::CallbackType> value;
        if (V.is_object()) {

        if (!V.is_nullish()) {

            value = TRY([&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::CallbackType>> {

        return vm.heap().allocate<WebIDL::CallbackType>(V.as_object(),  HTML::incumbent_realm(), WebIDL::OperationReturnsPromise::No);
    }());
        }
        }
        return value;
    }(); }));

        // 7. Run the setter steps of attribute with idlObject as this and idlValue as the value.
        auto setter_result = [&]() -> JS::ThrowCompletionOr<void> {
            TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->set_onsourceclose(idl_value); }));
    return {};
        }();

        if (setter_result.is_error())
            return setter_result.release_error();

        return JS::js_undefined();
    };

    // 8. Return undefined.
    return TRY(original_steps());
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::add_source_buffer)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::add_source_buffer");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = TRY(impl_from(vm));

    if (vm.argument_count() < 1)
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::BadArgCountOne, "addSourceBuffer");

    auto arg0 = vm.argument(0);
    auto type = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<String> {
        return TRY(WebIDL::to_string(vm, arg0));
    }(); }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->add_source_buffer(type); }));
    return JS::Value(R);
}

JS_DEFINE_NATIVE_FUNCTION(MediaSourcePrototype::end_of_stream)
{
    WebIDL::log_trace(vm, "MediaSourcePrototype::end_of_stream");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] MediaSourceExtensions::MediaSource* idl_object = TRY(impl_from(vm));

    auto arg0 = vm.argument(0);
    Optional<EndOfStreamError> error {};
    if (!arg0.is_undefined())
        error = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_end_of_stream_error(vm, arg0); }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->end_of_stream(error); }));
    return JS::js_undefined();
}

// https://webidl.spec.whatwg.org/#idl-enumeration
JS::ThrowCompletionOr<ReadyState> convert_to_idl_value_for_ready_state(JS::VM& vm, JS::Value value)
{
    // 1. Let S be the result of calling ? ToString(V).
    auto value_as_string = TRY(value.to_utf16_string(vm));

    // 2. If S is not one of E’s enumeration values, then throw a TypeError.
    // 3. Return the enumeration value of type E that is equal to S.
    if (value_as_string == "closed"sv)
        return ReadyState::Closed;
    if (value_as_string == "open"sv)
        return ReadyState::Open;
    if (value_as_string == "ended"sv)
        return ReadyState::Ended;
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::InvalidEnumerationValue, value_as_string, "ReadyState");
}

// https://webidl.spec.whatwg.org/#idl-enumeration
Utf16String idl_enum_to_string(ReadyState value)
{
    // The result of converting an IDL enumeration type value to a JavaScript value is the String value that represents the same sequence of code units as the enumeration value.
    switch (value) {
    case ReadyState::Closed:
        return "closed"_utf16;
    case ReadyState::Open:
        return "open"_utf16;
    case ReadyState::Ended:
        return "ended"_utf16;
    }
    VERIFY_NOT_REACHED();
}

// https://webidl.spec.whatwg.org/#idl-enumeration
JS::ThrowCompletionOr<EndOfStreamError> convert_to_idl_value_for_end_of_stream_error(JS::VM& vm, JS::Value value)
{
    // 1. Let S be the result of calling ? ToString(V).
    auto value_as_string = TRY(value.to_utf16_string(vm));

    // 2. If S is not one of E’s enumeration values, then throw a TypeError.
    // 3. Return the enumeration value of type E that is equal to S.
    if (value_as_string == "network"sv)
        return EndOfStreamError::Network;
    if (value_as_string == "decode"sv)
        return EndOfStreamError::Decode;
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::InvalidEnumerationValue, value_as_string, "EndOfStreamError");
}

// https://webidl.spec.whatwg.org/#idl-enumeration
Utf16String idl_enum_to_string(EndOfStreamError value)
{
    // The result of converting an IDL enumeration type value to a JavaScript value is the String value that represents the same sequence of code units as the enumeration value.
    switch (value) {
    case EndOfStreamError::Network:
        return "network"_utf16;
    case EndOfStreamError::Decode:
        return "decode"_utf16;
    }
    VERIFY_NOT_REACHED();
}

} // namespace Web::Bindings