#include <AK/String.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/Iterator.h>
#include <LibJS/Runtime/Realm.h>
#include <LibJS/Runtime/VM.h>
#include <LibJS/Runtime/Value.h>
#include <LibJS/Runtime/ValueInlines.h>
#include <LibWeb/Bindings/Event.h>
#include <LibWeb/Bindings/ExceptionOrUtils.h>
#include <LibWeb/Bindings/FontFaceSetLoadEvent.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/FontFace.h>
#include <LibWeb/CSS/FontFaceSetLoadEvent.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
#include <LibWeb/WebIDL/Tracing.h>

namespace Web::Bindings {

void FontFaceSetLoadEventConstructor::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<EventPrototype>(realm, "Event"_fly_string));
    object.define_direct_property(vm.names.length, JS::Value(1), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.name, JS::PrimitiveString::create(vm, "FontFaceSetLoadEvent"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<FontFaceSetLoadEventPrototype>(realm, "FontFaceSetLoadEvent"_fly_string), 0);
}

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

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

    // 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<FontFaceSetLoadEventPrototype>(*target_realm, "FontFaceSetLoadEvent"_fly_string);
    }

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

    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));
    }(); }));

    auto arg1 = vm.argument(1);
    FontFaceSetLoadEventInit event_init_dict = FontFaceSetLoadEventInit {};
    if (!arg1.is_undefined())
        event_init_dict = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_font_face_set_load_event_init(vm, arg1); }));

    auto impl = TRY(throw_dom_exception_if_needed(vm, [&] { return CSS::FontFaceSetLoadEvent::construct_impl(realm, type, event_init_dict); }));

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

    return *impl;
}

void FontFaceSetLoadEventPrototype::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<EventPrototype>(realm, "Event"_fly_string) });

    auto fontfaces_id = "fontfaces"_utf16_fly_string;
    auto native_fontfaces_getter = JS::NativeFunction::create(realm, fontfaces_getter, 0, fontfaces_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_fontfaces_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto fontfaces_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(fontfaces_id, native_fontfaces_getter, native_fontfaces_setter, fontfaces_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_direct_property(vm.well_known_symbol_to_string_tag(), JS::PrimitiveString::create(vm, "FontFaceSetLoadEvent"_utf16), JS::Attribute::Configurable);
}

void FontFaceSetLoadEventPrototype::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<CSS::FontFaceSetLoadEvent*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<CSS::FontFaceSetLoadEvent*> 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(FontFaceSetLoadEventPrototype::fontfaces_getter)
{
    WebIDL::log_trace(vm, "FontFaceSetLoadEventPrototype::fontfaces_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->fontfaces(); }));

    return [&]() -> JS::Value {
        // An IDL sequence<T> value S is converted to a JavaScript value as follows:
        // 1. Let n be the length of S.
        auto sequence_length = R.size();

        // 2. Let A be a new Array object created as if by the expression [].
        auto sequence_array = MUST(JS::Array::create(realm, sequence_length));

        // 3. Initialize i to be 0.
        // 4. While i < n:
        for (size_t sequence_index = 0; sequence_index < sequence_length; ++sequence_index) {
            // 1. Let V be the value in S at index i.
            auto& sequence_element = R.at(sequence_index);

            // 2. Let E be the result of converting V to a JavaScript value.
            JS::Value js_sequence_element = JS::Value(sequence_element);

            // 3. Let P be the result of calling ! ToString(i).
            // 4. Perform ! CreateDataPropertyOrThrow(A, P, E).
            MUST(sequence_array->create_data_property(JS::PropertyKey { sequence_index }, js_sequence_element));

            // 5. Set i to i + 1.
        }

        MUST(sequence_array->set_integrity_level(JS::Object::IntegrityLevel::Frozen));

        // 5. Return A.
        return sequence_array;
    }();
}

// https://webidl.spec.whatwg.org/#es-dictionary
JS::ThrowCompletionOr<FontFaceSetLoadEventInit> convert_to_idl_value_for_font_face_set_load_event_init(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, "FontFaceSetLoadEventInit");

    // 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 FontFaceSetLoadEventInit {
        TRY(convert_to_idl_value_for_event_init(vm, js_dict)),
        TRY([&]() -> JS::ThrowCompletionOr<GC::RootVector<GC::Ref<CSS::FontFace>>> {
            // 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("fontfaces"_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<GC::RootVector<GC::Ref<CSS::FontFace>>> {
        if (!js_member_value.is_object())
            return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObject, js_member_value);

        auto method = TRY(js_member_value.get_method(vm, vm.well_known_symbol_iterator()));
        if (!method)
            return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotIterable, js_member_value);

        return TRY([&]() -> JS::ThrowCompletionOr<GC::RootVector<GC::Ref<CSS::FontFace>>> {
        // To create an IDL value of type sequence<T> given an iterable iterable and an iterator getter method, perform the following steps:
        // 1. Let iteratorRecord be ? GetIteratorFromMethod(iterable, method).
        auto iterator = TRY(JS::get_iterator_from_method(vm, js_member_value, *method));

        GC::RootVector<GC::Ref<CSS::FontFace>> sequence;

        // 2. Initialize i to be 0.
        // 3. Repeat
        for (;;) {
            // 1. Let next be ? IteratorStepValue(iteratorRecord).
            auto next = TRY(JS::iterator_step_value(vm, iterator));

            // 2. If next is done, then return an IDL sequence value of type sequence<T> of length i, where the value of the element at index j is Sj.
            if (!next.has_value())
                break;

            // 3. Initialize Si to the result of converting next to an IDL value of type T.
            auto next_value = next.release_value();
            auto sequence_item = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ref<CSS::FontFace>> {
        if (auto impl = next_value.as_if<CSS::FontFace>())
            return *impl;
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "FontFace");
    }(); }));

            // 4. Set i to i + 1.
            sequence.append(sequence_item);
        }

        return sequence;
    }());
    }(); }));

                // 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 = GC::RootVector<GC::Ref<CSS::FontFace>> {};

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

} // namespace Web::Bindings