#include <AK/String.h>
#include <AK/TypeCasts.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/Realm.h>
#include <LibJS/Runtime/TypedArray.h>
#include <LibJS/Runtime/VM.h>
#include <LibJS/Runtime/Value.h>
#include <LibJS/Runtime/ValueInlines.h>
#include <LibWeb/Bindings/ExceptionOrUtils.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/TextEncoder.h>
#include <LibWeb/Encoding/TextEncoder.h>
#include <LibWeb/WebIDL/AbstractOperations.h>
#include <LibWeb/WebIDL/Tracing.h>
#include <LibWeb/WebIDL/Types.h>

namespace Web::Bindings {

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

    
    object.define_direct_property(vm.names.length, JS::Value(0), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.name, JS::PrimitiveString::create(vm, "TextEncoder"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<TextEncoderPrototype>(realm, "TextEncoder"_fly_string), 0);
}

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

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

    // 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<TextEncoderPrototype>(*target_realm, "TextEncoder"_fly_string);
    }

    auto impl = TRY(throw_dom_exception_if_needed(vm, [&] { return Encoding::TextEncoder::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 TextEncoder" algorithm
    // (https://webidl.spec.whatwg.org/#js-platform-objects) are currently not handled, or are handled within Encoding::TextEncoder::construct_impl().

    return *impl;
}

void TextEncoderPrototype::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(realm.intrinsics().object_prototype());

    auto encoding_id = "encoding"_utf16_fly_string;
    auto native_encoding_getter = JS::NativeFunction::create(realm, encoding_getter, 0, encoding_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_encoding_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto encoding_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(encoding_id, native_encoding_getter, native_encoding_setter, encoding_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, "encode"_utf16_fly_string, encode, 0, default_attributes);

    object.define_native_function(realm, "encodeInto"_utf16_fly_string, encode_into, 2, default_attributes);

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

void TextEncoderPrototype::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<Encoding::TextEncoder*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<Encoding::TextEncoder*> 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(TextEncoderPrototype::encoding_getter)
{
    WebIDL::log_trace(vm, "TextEncoderPrototype::encoding_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->encoding(); }));

    return WebIDL::primitive_string_from_string(vm, R);
}

JS_DEFINE_NATIVE_FUNCTION(TextEncoderPrototype::encode)
{
    WebIDL::log_trace(vm, "TextEncoderPrototype::encode");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] Encoding::TextEncoder* idl_object = TRY(impl_from(vm));

    auto arg0 = vm.argument(0);
    String input = String {};
    if (!arg0.is_undefined())
        input = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<String> {
        return TRY(WebIDL::to_usv_string(vm, arg0));
    }(); }));

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

JS_DEFINE_NATIVE_FUNCTION(TextEncoderPrototype::encode_into)
{
    WebIDL::log_trace(vm, "TextEncoderPrototype::encode_into");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] Encoding::TextEncoder* idl_object = TRY(impl_from(vm));

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

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

    auto arg1 = vm.argument(1);
    auto destination = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ref<JS::Uint8Array>> {
        // A JavaScript value V is converted to an IDL typed array value by running the following algorithm:
        // 1. Let T be the IDL type V is being converted to.
        // 2. If V is not an Object, or V does not have a [[TypedArrayName]] internal slot with a value equal to T's name,
        //    then throw a TypeError.
        auto builtin_buffer = arg1.as_if<JS::Uint8Array>();
        if (!builtin_buffer)
            return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "Uint8Array");

        auto& viewed_array_buffer = *builtin_buffer->viewed_array_buffer();

        // 3. If the conversion is not to an IDL type associated with the [AllowResizable] extended attribute, and
        //    IsFixedLengthArrayBuffer(V.[[ViewedArrayBuffer]]) is false, then throw a TypeError.
        if (!viewed_array_buffer.is_fixed_length())
            return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "fixed-length Uint8Array");

        // 5. Return the IDL value of type T that is a reference to the same object as V.
        return GC::Ref { *builtin_buffer };
    }(); }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->encode_into(source, destination); }));
    return [&]() -> JS::Value {
        // 1. Let O be OrdinaryObjectCreate(%Object.prototype%).
        auto dictionary_object = JS::Object::create(realm, realm.intrinsics().object_prototype());

        // 1. Let key be the identifier of member.
        // 2. If V[key] exists, then:
        if (R.read.has_value()) {

        // 1. Let idlValue be V[key].
        // 2. Let value be the result of converting idlValue to a JavaScript value.
        // 3. Perform ! CreateDataPropertyOrThrow(O, key, value).
        MUST(dictionary_object->create_data_property("read"_utf16_fly_string, JS::Value(static_cast<double>(R.read.value()))));
        }

        // 1. Let key be the identifier of member.
        // 2. If V[key] exists, then:
        if (R.written.has_value()) {

        // 1. Let idlValue be V[key].
        // 2. Let value be the result of converting idlValue to a JavaScript value.
        // 3. Perform ! CreateDataPropertyOrThrow(O, key, value).
        MUST(dictionary_object->create_data_property("written"_utf16_fly_string, JS::Value(static_cast<double>(R.written.value()))));
        }

        // 4. Return O.
        return dictionary_object;
    }();
}

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

    // 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 TextEncoderEncodeIntoResult {
        .read = TRY([&]() -> JS::ThrowCompletionOr<Optional<WebIDL::UnsignedLongLong>> {
            // 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("read"_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 WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, js_member_value, WebIDL::EnforceRange::No, WebIDL::Clamp::No); }));

                // 2. Set idlDict[key] to idlMemberValue.
                return idl_member_value;
            }
            // 7. Otherwise, jsMemberValue is undefined and the member is optional.
            return OptionalNone {};
        }()),
        .written = TRY([&]() -> JS::ThrowCompletionOr<Optional<WebIDL::UnsignedLongLong>> {
            // 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("written"_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 WebIDL::convert_to_int<WebIDL::UnsignedLongLong>(vm, js_member_value, WebIDL::EnforceRange::No, WebIDL::Clamp::No); }));

                // 2. Set idlDict[key] to idlMemberValue.
                return idl_member_value;
            }
            // 7. Otherwise, jsMemberValue is undefined and the member is optional.
            return OptionalNone {};
        }()),
    };
}

} // namespace Web::Bindings