#include <AK/String.h>
#include <AK/TypeCasts.h>
#include <AK/Variant.h>
#include <LibGC/Heap.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FunctionObject.h>
#include <LibJS/Runtime/Promise.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/OffscreenCanvas.h>
#include <LibWeb/HTML/ImageBitmap.h>
#include <LibWeb/HTML/OffscreenCanvas.h>
#include <LibWeb/HTML/OffscreenCanvasRenderingContext2D.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/WebGL/WebGL2RenderingContext.h>
#include <LibWeb/WebGL/WebGLRenderingContext.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
#include <LibWeb/WebIDL/CallbackType.h>
#include <LibWeb/WebIDL/Promise.h>
#include <LibWeb/WebIDL/Tracing.h>
#include <LibWeb/WebIDL/Types.h>

namespace Web::Bindings {

void OffscreenCanvasConstructor::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(2), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.name, JS::PrimitiveString::create(vm, "OffscreenCanvas"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<OffscreenCanvasPrototype>(realm, "OffscreenCanvas"_fly_string), 0);
}

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

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

    // 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<OffscreenCanvasPrototype>(*target_realm, "OffscreenCanvas"_fly_string);
    }

    if (vm.argument_count() < 2)
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::BadArgCountMany, "OffscreenCanvas", "2");

    auto arg0 = vm.argument(0);
    auto width = TRY(throw_dom_exception_if_needed(vm, [&] { return WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, arg0, WebIDL::EnforceRange::Yes, WebIDL::Clamp::No); }));

    auto arg1 = vm.argument(1);
    auto height = TRY(throw_dom_exception_if_needed(vm, [&] { return WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, arg1, WebIDL::EnforceRange::Yes, WebIDL::Clamp::No); }));

    auto impl = TRY(throw_dom_exception_if_needed(vm, [&] { return HTML::OffscreenCanvas::construct_impl(realm, width, height); }));

    // 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 OffscreenCanvas" algorithm
    // (https://webidl.spec.whatwg.org/#js-platform-objects) are currently not handled, or are handled within HTML::OffscreenCanvas::construct_impl().

    return *impl;
}

void OffscreenCanvasPrototype::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 width_id = "width"_utf16_fly_string;
    auto native_width_getter = JS::NativeFunction::create(realm, width_getter, 0, width_id, &realm, "get"sv);
    auto native_width_setter = JS::NativeFunction::create(realm, width_setter, 1, width_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto width_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(width_id, native_width_getter, native_width_setter, width_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 height_id = "height"_utf16_fly_string;
    auto native_height_getter = JS::NativeFunction::create(realm, height_getter, 0, height_id, &realm, "get"sv);
    auto native_height_setter = JS::NativeFunction::create(realm, height_setter, 1, height_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto height_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(height_id, native_height_getter, native_height_setter, height_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 oncontextlost_id = "oncontextlost"_utf16_fly_string;
    auto native_oncontextlost_getter = JS::NativeFunction::create(realm, oncontextlost_getter, 0, oncontextlost_id, &realm, "get"sv);
    auto native_oncontextlost_setter = JS::NativeFunction::create(realm, oncontextlost_setter, 1, oncontextlost_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto oncontextlost_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(oncontextlost_id, native_oncontextlost_getter, native_oncontextlost_setter, oncontextlost_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 oncontextrestored_id = "oncontextrestored"_utf16_fly_string;
    auto native_oncontextrestored_getter = JS::NativeFunction::create(realm, oncontextrestored_getter, 0, oncontextrestored_id, &realm, "get"sv);
    auto native_oncontextrestored_setter = JS::NativeFunction::create(realm, oncontextrestored_setter, 1, oncontextrestored_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto oncontextrestored_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(oncontextrestored_id, native_oncontextrestored_getter, native_oncontextrestored_setter, oncontextrestored_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, "getContext"_utf16_fly_string, get_context, 1, default_attributes);

    object.define_native_function(realm, "transferToImageBitmap"_utf16_fly_string, transfer_to_image_bitmap, 0, default_attributes);

    object.define_native_function(realm, "convertToBlob"_utf16_fly_string, convert_to_blob, 0, default_attributes);

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

void OffscreenCanvasPrototype::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<HTML::OffscreenCanvas*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<HTML::OffscreenCanvas*> 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(OffscreenCanvasPrototype::width_getter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::width_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->width(); }));

    return JS::Value(static_cast<double>(R));
}

JS_DEFINE_NATIVE_FUNCTION(OffscreenCanvasPrototype::height_getter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::height_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->height(); }));

    return JS::Value(static_cast<double>(R));
}

JS_DEFINE_NATIVE_FUNCTION(OffscreenCanvasPrototype::oncontextlost_getter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::oncontextlost_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->oncontextlost(); }));

    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(OffscreenCanvasPrototype::oncontextrestored_getter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::oncontextrestored_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->oncontextrestored(); }));

    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(OffscreenCanvasPrototype::width_setter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::width_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]] HTML::OffscreenCanvas* 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 WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, V, WebIDL::EnforceRange::Yes, WebIDL::Clamp::No); }));

        // 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_width(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(OffscreenCanvasPrototype::height_setter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::height_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]] HTML::OffscreenCanvas* 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 WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, V, WebIDL::EnforceRange::Yes, WebIDL::Clamp::No); }));

        // 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_height(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(OffscreenCanvasPrototype::oncontextlost_setter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::oncontextlost_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]] HTML::OffscreenCanvas* 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_oncontextlost(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(OffscreenCanvasPrototype::oncontextrestored_setter)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::oncontextrestored_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]] HTML::OffscreenCanvas* 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_oncontextrestored(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(OffscreenCanvasPrototype::get_context)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::get_context");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] HTML::OffscreenCanvas* idl_object = TRY(impl_from(vm));

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

    auto arg0 = vm.argument(0);
    auto context_id = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_offscreen_rendering_context_id(vm, arg0); }));

    auto arg1 = vm.argument(1);
    JS::Value options = JS::js_null();
    if (!arg1.is_undefined())
        options = TRY(throw_dom_exception_if_needed(vm, [&] { return arg1; }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->get_context(context_id, options); }));
    return R.visit(
        [&](GC::Ref<HTML::OffscreenCanvasRenderingContext2D> const& visited_union_value0) -> JS::Value
        {
            return JS::Value(visited_union_value0);
        },
        [&](GC::Ref<WebGL::WebGLRenderingContext> const& visited_union_value1) -> JS::Value
        {
            return JS::Value(visited_union_value1);
        },
        [&](GC::Ref<WebGL::WebGL2RenderingContext> const& visited_union_value2) -> JS::Value
        {
            return JS::Value(visited_union_value2);
        },
        [](Empty) -> JS::Value
        {
            return JS::js_null();
        }
    );
}

JS_DEFINE_NATIVE_FUNCTION(OffscreenCanvasPrototype::transfer_to_image_bitmap)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::transfer_to_image_bitmap");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] HTML::OffscreenCanvas* idl_object = TRY(impl_from(vm));

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

JS_DEFINE_NATIVE_FUNCTION(OffscreenCanvasPrototype::convert_to_blob)
{
    WebIDL::log_trace(vm, "OffscreenCanvasPrototype::convert_to_blob");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    auto steps = [&realm, &vm]() -> JS::ThrowCompletionOr<GC::Ref<WebIDL::Promise>> {
        (void)realm;
    [[maybe_unused]] HTML::OffscreenCanvas* idl_object = TRY(impl_from(vm));

    auto arg0 = vm.argument(0);
    ImageEncodeOptions options = ImageEncodeOptions {};
    if (!arg0.is_undefined())
        options = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_image_encode_options(vm, arg0); }));

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

    auto maybe_R = steps();

    // And then, if an exception E was thrown:
    // 1. If op has a return type that is a promise type, then return ! Call(%Promise.reject%, %Promise%, «E»).
    // 2. Otherwise, end these steps and allow the exception to propagate.
    if (maybe_R.is_throw_completion())
        return WebIDL::create_rejected_promise(realm, maybe_R.error_value())->promise();

    return GC::Ref { as<JS::Promise>(*maybe_R.release_value()->promise()) };
}

// https://webidl.spec.whatwg.org/#idl-enumeration
JS::ThrowCompletionOr<OffscreenRenderingContextId> convert_to_idl_value_for_offscreen_rendering_context_id(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 == "2d"sv)
        return OffscreenRenderingContextId::_2d;
    if (value_as_string == "bitmaprenderer"sv)
        return OffscreenRenderingContextId::Bitmaprenderer;
    if (value_as_string == "webgl"sv)
        return OffscreenRenderingContextId::Webgl;
    if (value_as_string == "webgl2"sv)
        return OffscreenRenderingContextId::Webgl2;
    if (value_as_string == "webgpu"sv)
        return OffscreenRenderingContextId::Webgpu;
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::InvalidEnumerationValue, value_as_string, "OffscreenRenderingContextId");
}

// https://webidl.spec.whatwg.org/#idl-enumeration
Utf16String idl_enum_to_string(OffscreenRenderingContextId 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 OffscreenRenderingContextId::_2d:
        return "2d"_utf16;
    case OffscreenRenderingContextId::Bitmaprenderer:
        return "bitmaprenderer"_utf16;
    case OffscreenRenderingContextId::Webgl:
        return "webgl"_utf16;
    case OffscreenRenderingContextId::Webgl2:
        return "webgl2"_utf16;
    case OffscreenRenderingContextId::Webgpu:
        return "webgpu"_utf16;
    }
    VERIFY_NOT_REACHED();
}

// https://webidl.spec.whatwg.org/#es-dictionary
JS::ThrowCompletionOr<ImageEncodeOptions> convert_to_idl_value_for_image_encode_options(JS::VM& vm, JS::Value js_dict)
{
    // 1. If jsDict is not an Object and jsDict is neither undefined nor null, then throw a TypeError.
    if (!js_dict.is_object() && !js_dict.is_nullish())
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "ImageEncodeOptions");

    // 2. Let idlDict be an empty ordered map, representing a dictionary of type D.
    // 3. Let dictionaries be a list consisting of D and all of D’s inherited dictionaries, in order from least to most derived.
    // 4. For each dictionary dictionary in dictionaries, in order:
    // NB: We defer construction until the return initializer because some members may not be default-constructible. Inherited dictionaries are represented by the generated C++ struct inheritance.

    // 5. Return idlDict.
    return ImageEncodeOptions {
        .quality = TRY([&]() -> JS::ThrowCompletionOr<Optional<double>> {
            // 1. Let key be the identifier of member.
            // 2. If jsDict is either undefined or null, then:
            //     1. Let jsMemberValue be undefined.
            // 3. Otherwise,
            //     1. Let jsMemberValue be ? Get(jsDict, key).
            auto js_member_value = JS::js_undefined();
            if (js_dict.is_object())
                js_member_value = TRY(js_dict.as_object().get("quality"_utf16_fly_string));

            // 4. If jsMemberValue is not undefined, then:
            if (!js_member_value.is_undefined()) {
                // 1. Let idlMemberValue be the result of converting jsMemberValue to an IDL value whose type is the type member is declared to be of.
                auto idl_member_value = TRY(throw_dom_exception_if_needed(vm, [&] { return js_member_value.to_double(vm); }));

                // 2. Set idlDict[key] to idlMemberValue.
                return idl_member_value;
            }
            // 7. Otherwise, jsMemberValue is undefined and the member is optional.
            return OptionalNone {};
        }()),
        .type = TRY([&]() -> JS::ThrowCompletionOr<String> {
            // 1. Let key be the identifier of member.
            // 2. If jsDict is either undefined or null, then:
            //     1. Let jsMemberValue be undefined.
            // 3. Otherwise,
            //     1. Let jsMemberValue be ? Get(jsDict, key).
            auto js_member_value = JS::js_undefined();
            if (js_dict.is_object())
                js_member_value = TRY(js_dict.as_object().get("type"_utf16_fly_string));

            // 4. If jsMemberValue is not undefined, then:
            if (!js_member_value.is_undefined()) {
                // 1. Let idlMemberValue be the result of converting jsMemberValue to an IDL value whose type is the type member is declared to be of.
                auto idl_member_value = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<String> {
        return TRY(WebIDL::to_string(vm, js_member_value));
    }(); }));

                // 2. Set idlDict[key] to idlMemberValue.
                return idl_member_value;
            }
            // 5. Otherwise, if jsMemberValue is undefined but member has a default value, then:
            // 1. Let idlMemberValue be the result of converting member's default value to an IDL value whose type is the type member is declared to be of.
            auto idl_member_value = "image/png"_string;

            // 2. Set idlDict[key] to idlMemberValue.
            return idl_member_value;
        }()),
    };
}

} // namespace Web::Bindings