#include <AK/TypeCasts.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.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/ExceptionOrUtils.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/ReadableStreamDefaultReader.h>
#include <LibWeb/Streams/ReadableStream.h>
#include <LibWeb/Streams/ReadableStreamDefaultReader.h>
#include <LibWeb/WebIDL/Promise.h>
#include <LibWeb/WebIDL/Tracing.h>

namespace Web::Bindings {

void ReadableStreamDefaultReaderConstructor::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(1), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.name, JS::PrimitiveString::create(vm, "ReadableStreamDefaultReader"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<ReadableStreamDefaultReaderPrototype>(realm, "ReadableStreamDefaultReader"_fly_string), 0);
}

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

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

    // 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<ReadableStreamDefaultReaderPrototype>(*target_realm, "ReadableStreamDefaultReader"_fly_string);
    }

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

    auto arg0 = vm.argument(0);
    auto stream = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ref<Streams::ReadableStream>> {
        if (auto impl = arg0.as_if<Streams::ReadableStream>())
            return *impl;
        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "ReadableStream");
    }(); }));

    auto impl = TRY(throw_dom_exception_if_needed(vm, [&] { return Streams::ReadableStreamDefaultReader::construct_impl(realm, stream); }));

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

    return *impl;
}

void ReadableStreamDefaultReaderPrototype::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 closed_id = "closed"_utf16_fly_string;
    auto native_closed_getter = JS::NativeFunction::create(realm, closed_getter, 0, closed_id, &realm, "get"sv);
    GC::Ptr<JS::NativeFunction> native_closed_setter;

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto closed_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(closed_id, native_closed_getter, native_closed_setter, closed_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, "read"_utf16_fly_string, read, 0, default_attributes);

    object.define_native_function(realm, "releaseLock"_utf16_fly_string, release_lock, 0, default_attributes);

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

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

void ReadableStreamDefaultReaderPrototype::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<Streams::ReadableStreamDefaultReader*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<Streams::ReadableStreamDefaultReader*> 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(ReadableStreamDefaultReaderPrototype::closed_getter)
{
    WebIDL::log_trace(vm, "ReadableStreamDefaultReaderPrototype::closed_getter");
    [[maybe_unused]] auto& realm = *vm.current_realm();

    auto steps = [&]() -> JS::ThrowCompletionOr<GC::Ptr<WebIDL::Promise>> {
        // 1. Let idlObject be null.
        [[maybe_unused]] auto* idl_object = TRY(impl_from(vm));
        auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->closed(); }));
        return R;
    };

    auto maybe_R = steps();

    // 2. And then, if an exception E was thrown:

    // 1. If attribute’s type is a promise type, then return ! Call(%Promise.reject%, %Promise%, «E»).
    if (maybe_R.is_throw_completion())
        return WebIDL::create_rejected_promise(realm, maybe_R.error_value())->promise();

    // 2. Otherwise, end these steps and allow the exception to propagate.
    auto R = maybe_R.release_value();

    // 4. Return the result of converting R to a JavaScript value of the type attribute is declared as.
    return GC::Ref { as<JS::Promise>(*R->promise()) };
}

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

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

JS_DEFINE_NATIVE_FUNCTION(ReadableStreamDefaultReaderPrototype::release_lock)
{
    WebIDL::log_trace(vm, "ReadableStreamDefaultReaderPrototype::release_lock");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] Streams::ReadableStreamDefaultReader* idl_object = TRY(impl_from(vm));

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

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

    auto arg0 = vm.argument(0);
    Optional<JS::Value> reason {};
    if (!arg0.is_undefined())
        reason = TRY(throw_dom_exception_if_needed(vm, [&] { return arg0; }));

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->cancel(reason); }));
        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/#es-dictionary
JS::ThrowCompletionOr<ReadableStreamReadResult> convert_to_idl_value_for_readable_stream_read_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, "ReadableStreamReadResult");

    // 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 ReadableStreamReadResult {
        .done = TRY([&]() -> JS::ThrowCompletionOr<Optional<bool>> {
            // 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("done"_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_boolean(); }));

                // 2. Set idlDict[key] to idlMemberValue.
                return idl_member_value;
            }
            // 7. Otherwise, jsMemberValue is undefined and the member is optional.
            return OptionalNone {};
        }()),
        .value = TRY([&]() -> JS::ThrowCompletionOr<Optional<JS::Value>> {
            // 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("value"_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; }));

                // 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