#include <LibGC/Heap.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FunctionObject.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/ResizeObserver.h>
#include <LibWeb/DOM/Element.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/ResizeObserver/ResizeObserver.h>
#include <LibWeb/WebIDL/CallbackType.h>
#include <LibWeb/WebIDL/Tracing.h>

namespace Web::Bindings {

void ResizeObserverConstructor::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, "ResizeObserver"_utf16), JS::Attribute::Configurable);
    object.define_direct_property(vm.names.prototype, &ensure_web_prototype<ResizeObserverPrototype>(realm, "ResizeObserver"_fly_string), 0);
}

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

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

    // 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<ResizeObserverPrototype>(*target_realm, "ResizeObserver"_fly_string);
    }

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

    auto arg0 = vm.argument(0);
    auto callback = TRY(throw_dom_exception_if_needed(vm, [&] { return [&]() -> JS::ThrowCompletionOr<GC::Ref<WebIDL::CallbackType>> {

        if (!arg0.is_function())
            return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAFunction, arg0);

        return vm.heap().allocate<WebIDL::CallbackType>(arg0.as_object(),  HTML::incumbent_realm(), WebIDL::OperationReturnsPromise::No);
    }(); }));

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

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

    return *impl;
}

void ResizeObserverPrototype::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());
    object.define_native_function(realm, "observe"_utf16_fly_string, observe, 1, default_attributes);

    object.define_native_function(realm, "unobserve"_utf16_fly_string, unobserve, 1, default_attributes);

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

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

void ResizeObserverPrototype::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<ResizeObserver::ResizeObserver*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<ResizeObserver::ResizeObserver*> 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(ResizeObserverPrototype::observe)
{
    WebIDL::log_trace(vm, "ResizeObserverPrototype::observe");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] ResizeObserver::ResizeObserver* idl_object = TRY(impl_from(vm));

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

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

    auto arg1 = vm.argument(1);
    ResizeObserverOptions options = ResizeObserverOptions {};
    if (!arg1.is_undefined())
        options = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_resize_observer_options(vm, arg1); }));

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

JS_DEFINE_NATIVE_FUNCTION(ResizeObserverPrototype::unobserve)
{
    WebIDL::log_trace(vm, "ResizeObserverPrototype::unobserve");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] ResizeObserver::ResizeObserver* idl_object = TRY(impl_from(vm));

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

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

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

JS_DEFINE_NATIVE_FUNCTION(ResizeObserverPrototype::disconnect)
{
    WebIDL::log_trace(vm, "ResizeObserverPrototype::disconnect");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] ResizeObserver::ResizeObserver* idl_object = TRY(impl_from(vm));

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

// https://webidl.spec.whatwg.org/#idl-enumeration
JS::ThrowCompletionOr<ResizeObserverBoxOptions> convert_to_idl_value_for_resize_observer_box_options(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 == "border-box"sv)
        return ResizeObserverBoxOptions::BorderBox;
    if (value_as_string == "content-box"sv)
        return ResizeObserverBoxOptions::ContentBox;
    if (value_as_string == "device-pixel-content-box"sv)
        return ResizeObserverBoxOptions::DevicePixelContentBox;
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::InvalidEnumerationValue, value_as_string, "ResizeObserverBoxOptions");
}

// https://webidl.spec.whatwg.org/#idl-enumeration
Utf16String idl_enum_to_string(ResizeObserverBoxOptions 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 ResizeObserverBoxOptions::BorderBox:
        return "border-box"_utf16;
    case ResizeObserverBoxOptions::ContentBox:
        return "content-box"_utf16;
    case ResizeObserverBoxOptions::DevicePixelContentBox:
        return "device-pixel-content-box"_utf16;
    }
    VERIFY_NOT_REACHED();
}

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

    // 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 ResizeObserverOptions {
        .box = TRY([&]() -> JS::ThrowCompletionOr<ResizeObserverBoxOptions> {
            // 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("box"_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 convert_to_idl_value_for_resize_observer_box_options(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 = ResizeObserverBoxOptions::ContentBox;

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

} // namespace Web::Bindings