/*
 * Copyright (c) 2021-2025, Tim Flynn <trflynn89@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/TypeCasts.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Intl/AbstractOperations.h>
#include <LibJS/Runtime/Intl/DisplayNames.h>
#include <LibJS/Runtime/Intl/DisplayNamesPrototype.h>
#include <LibUnicode/DisplayNames.h>

namespace JS::Intl {

GC_DEFINE_ALLOCATOR(DisplayNamesPrototype);

// 12.3 Properties of the Intl.DisplayNames Prototype Object, https://tc39.es/ecma402/#sec-properties-of-intl-displaynames-prototype-object
DisplayNamesPrototype::DisplayNamesPrototype(Realm& realm)
    : PrototypeObject(realm.intrinsics().object_prototype())
{
}

void DisplayNamesPrototype::initialize(Realm& realm)
{
    Base::initialize(realm);

    auto& vm = this->vm();

    // 12.3.4 Intl.DisplayNames.prototype [ %Symbol.toStringTag% ], https://tc39.es/ecma402/#sec-intl.displaynames.prototype-%symbol.tostringtag%
    define_direct_property(vm.well_known_symbol_to_string_tag(), PrimitiveString::create(vm, "Intl.DisplayNames"_string), Attribute::Configurable);

    u8 attr = Attribute::Writable | Attribute::Configurable;
    define_native_function(realm, vm.names.resolvedOptions, resolved_options, 0, attr);
    define_native_function(realm, vm.names.of, of, 1, attr);
}

// 12.3.2 Intl.DisplayNames.prototype.resolvedOptions ( ), https://tc39.es/ecma402/#sec-Intl.DisplayNames.prototype.resolvedOptions
JS_DEFINE_NATIVE_FUNCTION(DisplayNamesPrototype::resolved_options)
{
    auto& realm = *vm.current_realm();

    // 1. Let displayNames be this value.
    // 2. Perform ? RequireInternalSlot(displayNames, [[InitializedDisplayNames]]).
    auto display_names = TRY(typed_this_object(vm));

    // 3. Let options be OrdinaryObjectCreate(%Object.prototype%).
    auto options = Object::create(realm, realm.intrinsics().object_prototype());

    // 4. For each row of Table 18, except the header row, in table order, do
    //     a. Let p be the Property value of the current row.
    //     b. Let v be the value of displayNames's internal slot whose name is the Internal Slot value of the current row.
    //     c. If v is not undefined, then
    //         i. Perform ! CreateDataPropertyOrThrow(options, p, v).
    MUST(options->create_data_property_or_throw(vm.names.locale, PrimitiveString::create(vm, display_names->locale())));
    MUST(options->create_data_property_or_throw(vm.names.style, PrimitiveString::create(vm, display_names->style_string())));
    MUST(options->create_data_property_or_throw(vm.names.type, PrimitiveString::create(vm, display_names->type_string())));
    MUST(options->create_data_property_or_throw(vm.names.fallback, PrimitiveString::create(vm, display_names->fallback_string())));

    if (display_names->has_language_display())
        MUST(options->create_data_property_or_throw(vm.names.languageDisplay, PrimitiveString::create(vm, display_names->language_display_string())));

    // 5. Return options.
    return options;
}

// 12.3.3 Intl.DisplayNames.prototype.of ( code ), https://tc39.es/ecma402/#sec-Intl.DisplayNames.prototype.of
JS_DEFINE_NATIVE_FUNCTION(DisplayNamesPrototype::of)
{
    auto code = vm.argument(0);

    // 1. Let displayNames be this value.
    // 2. Perform ? RequireInternalSlot(displayNames, [[InitializedDisplayNames]]).
    auto display_names = TRY(typed_this_object(vm));

    // 3. Let code be ? ToString(code).
    code = PrimitiveString::create(vm, TRY(code.to_string(vm)));

    // 4. Let code be ? CanonicalCodeForDisplayNames(displayNames.[[Type]], code).
    code = TRY(canonical_code_for_display_names(vm, display_names->type(), code.as_string().utf8_string_view()));
    auto code_string = code.as_string().utf8_string_view();

    // 5. Let fields be displayNames.[[Fields]].
    // 6. If fields has a field [[<code>]], return fields.[[<code>]].
    Optional<Utf16String> result;

    switch (display_names->type()) {
    case DisplayNames::Type::Language:
        result = Unicode::language_display_name(display_names->locale(), code_string, display_names->language_display());
        break;
    case DisplayNames::Type::Region:
        result = Unicode::region_display_name(display_names->locale(), code_string);
        break;
    case DisplayNames::Type::Script:
        result = Unicode::script_display_name(display_names->locale(), code_string);
        break;
    case DisplayNames::Type::Currency:
        result = Unicode::currency_display_name(display_names->locale(), code_string, display_names->style());
        break;
    case DisplayNames::Type::Calendar:
        result = Unicode::calendar_display_name(display_names->locale(), code_string);
        break;
    case DisplayNames::Type::DateTimeField:
        result = Unicode::date_time_field_display_name(display_names->locale(), code_string, display_names->style());
        break;
    default:
        VERIFY_NOT_REACHED();
    }

    if (result.has_value())
        return PrimitiveString::create(vm, result.release_value());

    // 7. If displayNames.[[Fallback]] is "code", return code.
    if (display_names->fallback() == DisplayNames::Fallback::Code)
        return code;

    // 8. Return undefined.
    return js_undefined();
}

}