#include <AK/TypeCasts.h>
#include <LibGC/Heap.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FunctionObject.h>
#include <LibJS/Runtime/Promise.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/XRRenderState.h>
#include <LibWeb/Bindings/XRSession.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/WebIDL/CallbackType.h>
#include <LibWeb/WebIDL/Promise.h>
#include <LibWeb/WebIDL/Tracing.h>
#include <LibWeb/WebXR/XRSession.h>

namespace Web::Bindings {

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

JS::ThrowCompletionOr<GC::Ref<JS::Object>> XRSessionConstructor::construct([[maybe_unused]] InterfaceConstructor& constructor, [[maybe_unused]] JS::FunctionObject& new_target)
{
    WebIDL::log_trace(constructor.vm(), "XRSessionConstructor::construct");
    return constructor.vm().throw_completion<JS::TypeError>(JS::ErrorType::NotAConstructor, "XRSession");
}

void XRSessionPrototype::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 onend_id = "onend"_utf16_fly_string;
    auto native_onend_getter = JS::NativeFunction::create(realm, onend_getter, 0, onend_id, &realm, "get"sv);
    auto native_onend_setter = JS::NativeFunction::create(realm, onend_setter, 1, onend_id, &realm, "set"sv);

    // 4. Let configurable be false if attr is unforgeable and true otherwise.
    auto onend_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(onend_id, native_onend_getter, native_onend_setter, onend_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, "updateRenderState"_utf16_fly_string, update_render_state, 0, default_attributes);

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

    object.define_direct_property("updateTargetFrameRate"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property("requestReferenceSpace"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property("requestAnimationFrame"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

    object.define_direct_property("cancelAnimationFrame"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);

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

void XRSessionPrototype::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<WebXR::XRSession*> impl_from(JS::VM& vm, JS::Value js_value)
{

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

[[maybe_unused]] static JS::ThrowCompletionOr<WebXR::XRSession*> 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(XRSessionPrototype::onend_getter)
{
    WebIDL::log_trace(vm, "XRSessionPrototype::onend_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->onend(); }));

    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(XRSessionPrototype::onend_setter)
{
    WebIDL::log_trace(vm, "XRSessionPrototype::onend_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]] WebXR::XRSession* 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_onend(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(XRSessionPrototype::update_render_state)
{
    WebIDL::log_trace(vm, "XRSessionPrototype::update_render_state");
    [[maybe_unused]] auto& realm = *vm.current_realm();
    [[maybe_unused]] WebXR::XRSession* idl_object = TRY(impl_from(vm));

    auto arg0 = vm.argument(0);
    XRRenderStateInit state = XRRenderStateInit {};
    if (!arg0.is_undefined())
        state = TRY(throw_dom_exception_if_needed(vm, [&] { return convert_to_idl_value_for_xr_render_state_init(vm, arg0); }));

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

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

    [[maybe_unused]] auto R = TRY(throw_dom_exception_if_needed(vm, [&] { return idl_object->end(); }));
        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<XRVisibilityState> convert_to_idl_value_for_xr_visibility_state(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 == "visible"sv)
        return XRVisibilityState::Visible;
    if (value_as_string == "visible-blurred"sv)
        return XRVisibilityState::VisibleBlurred;
    if (value_as_string == "hidden"sv)
        return XRVisibilityState::Hidden;
    return vm.throw_completion<JS::TypeError>(JS::ErrorType::InvalidEnumerationValue, value_as_string, "XRVisibilityState");
}

// https://webidl.spec.whatwg.org/#idl-enumeration
Utf16String idl_enum_to_string(XRVisibilityState 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 XRVisibilityState::Visible:
        return "visible"_utf16;
    case XRVisibilityState::VisibleBlurred:
        return "visible-blurred"_utf16;
    case XRVisibilityState::Hidden:
        return "hidden"_utf16;
    }
    VERIFY_NOT_REACHED();
}

} // namespace Web::Bindings