ladybird/Userland/Libraries/LibJS/Runtime/Intl/AbstractOperations.cpp

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

#include <AK/AllOf.h>
#include <AK/CharacterTypes.h>
#include <AK/QuickSort.h>
#include <AK/TypeCasts.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Intl/AbstractOperations.h>
#include <LibUnicode/Locale.h>

namespace JS::Intl {

// 6.2.2 IsStructurallyValidLanguageTag ( locale ), https://tc39.es/ecma402/#sec-isstructurallyvalidlanguagetag
static Optional<Unicode::LocaleID> is_structurally_valid_language_tag(StringView locale)
{
    // IsStructurallyValidLanguageTag returns true if all of the following conditions hold, false otherwise:

    // locale can be generated from the EBNF grammar for unicode_locale_id in Unicode Technical Standard #35 LDML § 3.2 Unicode Locale Identifier;
    auto locale_id = Unicode::parse_unicode_locale_id(locale);
    if (!locale_id.has_value())
        return {};

    // locale does not use any of the backwards compatibility syntax described in Unicode Technical Standard #35 LDML § 3.3 BCP 47 Conformance;
    // https://unicode.org/reports/tr35/#BCP_47_Conformance
    if (locale.contains('_') || locale_id->language_id.is_root || !locale_id->language_id.language.has_value())
        return {};

    // the unicode_language_id within locale contains no duplicate unicode_variant_subtag subtags; and
    if (auto& variants = locale_id->language_id.variants; !variants.is_empty()) {
        quick_sort(variants);

        for (size_t i = 0; i < variants.size() - 1; ++i) {
            if (variants[i] == variants[i + 1])
                return {};
        }
    }

    // FIXME: Handle extensions.
    // if locale contains an extensions* component, that component
    //     does not contain any other_extensions components with duplicate [alphanum-[tTuUxX]] subtags,
    //     contains at most one unicode_locale_extensions component,
    //     contains at most one transformed_extensions component, and
    //     if a transformed_extensions component that contains a tlang component is present, then
    //         the tlang component contains no duplicate unicode_variant_subtag subtags.

    return locale_id;
}

// 6.2.3 CanonicalizeUnicodeLocaleId ( locale ), https://tc39.es/ecma402/#sec-canonicalizeunicodelocaleid
static String canonicalize_unicode_locale_id(Unicode::LocaleID& locale)
{
    // 1. Let localeId be the string locale after performing the algorithm to transform it to canonical syntax per Unicode Technical Standard #35 LDML § 3.2.1 Canonical Unicode Locale Identifiers.
    // 2. Let localeId be the string localeId after performing the algorithm to transform it to canonical form.
    auto locale_id = Unicode::canonicalize_unicode_locale_id(locale);
    VERIFY(locale_id.has_value());

    // FIXME: Handle extensions.
    // 3. If localeId contains a substring extension that is a Unicode locale extension sequence, then
    //     a. Let components be ! UnicodeExtensionComponents(extension).
    //     b. Let attributes be components.[[Attributes]].
    //     c. Let keywords be components.[[Keywords]].
    //     d. Let newExtension be "u".
    //     e. For each element attr of attributes, do
    //         i. Append "-" to newExtension.
    //         ii. Append attr to newExtension.
    //     f. For each Record { [[Key]], [[Value]] } keyword in keywords, do
    //         i. Append "-" to newExtension.
    //         ii. Append keyword.[[Key]] to newExtension.
    //         iii. If keyword.[[Value]] is not the empty String, then
    //             1. Append "-" to newExtension.
    //             2. Append keyword.[[Value]] to newExtension.
    //     g. Assert: newExtension is not equal to "u".
    //     h. Let localeId be localeId with the substring corresponding to extension replaced by the string newExtension.

    // 4. Return localeId.
    return locale_id.release_value();
}

// 6.3.1 IsWellFormedCurrencyCode ( currency ), https://tc39.es/ecma402/#sec-canonicalcodefordisplaynames
static bool is_well_formed_currency_code(StringView currency)
{
    // 1. Let normalized be the result of mapping currency to upper case as described in 6.1.
    // 2. If the number of elements in normalized is not 3, return false.
    if (currency.length() != 3)
        return false;

    // 3. If normalized contains any character that is not in the range "A" to "Z" (U+0041 to U+005A), return false.
    if (!all_of(currency, is_ascii_alpha))
        return false;

    // 4. Return true.
    return true;
}

// 9.2.1 CanonicalizeLocaleList ( locales ), https://tc39.es/ecma402/#sec-canonicalizelocalelist
Vector<String> canonicalize_locale_list(GlobalObject& global_object, Value locales)
{
    auto& vm = global_object.vm();

    // 1. If locales is undefined, then
    if (locales.is_undefined()) {
        // a. Return a new empty List.
        return {};
    }

    // 2. Let seen be a new empty List.
    Vector<String> seen;

    Object* object = nullptr;
    // 3. If Type(locales) is String or Type(locales) is Object and locales has an [[InitializedLocale]] internal slot, then
    // FIXME: When we have an Intl.Locale object, handle it it here.
    if (locales.is_string()) {
        // a. Let O be CreateArrayFromList(« locales »).
        object = Array::create_from(global_object, { locales });
    }
    // 4. Else,
    else {
        // a. Let O be ? ToObject(locales).
        object = locales.to_object(global_object);
        if (vm.exception())
            return {};
    }

    // 5. Let len be ? ToLength(? Get(O, "length")).
    auto length_value = object->get(vm.names.length);
    if (vm.exception())
        return {};
    auto length = length_value.to_length(global_object);
    if (vm.exception())
        return {};

    // 6. Let k be 0.
    // 7. Repeat, while k < len,
    for (size_t k = 0; k < length; ++k) {
        // a. Let Pk be ToString(k).
        auto property_key = PropertyName { k };

        // b. Let kPresent be ? HasProperty(O, Pk).
        auto key_present = object->has_property(property_key);
        if (vm.exception())
            return {};

        // c. If kPresent is true, then
        if (key_present) {
            // i. Let kValue be ? Get(O, Pk).
            auto key_value = object->get(property_key);
            if (vm.exception())
                return {};

            // ii. If Type(kValue) is not String or Object, throw a TypeError exception.
            if (!key_value.is_string() && !key_value.is_object()) {
                vm.throw_exception<TypeError>(global_object, ErrorType::NotAnObjectOrString, key_value.to_string_without_side_effects());
                return {};
            }

            // iii. If Type(kValue) is Object and kValue has an [[InitializedLocale]] internal slot, then
            //     1. Let tag be kValue.[[Locale]].
            // iv. Else,
            //     1. Let tag be ? ToString(kValue).
            // FIXME: When we have an Intl.Locale object, handle it it here.
            auto tag = key_value.to_string(global_object);
            if (vm.exception())
                return {};

            // v. If IsStructurallyValidLanguageTag(tag) is false, throw a RangeError exception.
            auto locale_id = is_structurally_valid_language_tag(tag);
            if (!locale_id.has_value()) {
                vm.throw_exception<RangeError>(global_object, ErrorType::IntlInvalidLanguageTag, tag);
                return {};
            }

            // vi. Let canonicalizedTag be CanonicalizeUnicodeLocaleId(tag).
            auto canonicalized_tag = JS::Intl::canonicalize_unicode_locale_id(*locale_id);

            // vii. If canonicalizedTag is not an element of seen, append canonicalizedTag as the last element of seen.
            if (!seen.contains_slow(canonicalized_tag))
                seen.append(move(canonicalized_tag));
        }

        // d. Increase k by 1.
    }

    return seen;
}

// 9.2.2 BestAvailableLocale ( availableLocales, locale ), https://tc39.es/ecma402/#sec-bestavailablelocale
static Optional<String> best_available_locale(StringView const& locale)
{
    // 1. Let candidate be locale.
    StringView candidate = locale;

    // 2. Repeat,
    while (true) {
        // a. If availableLocales contains an element equal to candidate, return candidate.
        if (Unicode::is_locale_available(candidate))
            return candidate;

        // b. Let pos be the character index of the last occurrence of "-" (U+002D) within candidate. If that character does not occur, return undefined.
        auto pos = candidate.find_last('-');
        if (!pos.has_value())
            return {};

        // c. If pos ≥ 2 and the character "-" occurs at index pos-2 of candidate, decrease pos by 2.
        if ((*pos >= 2) && (candidate[*pos - 2] == '-'))
            pos = *pos - 2;

        // d. Let candidate be the substring of candidate from position 0, inclusive, to position pos, exclusive.
        candidate = candidate.substring_view(0, *pos);
    }
}

// 9.2.3 LookupMatcher ( availableLocales, requestedLocales ), https://tc39.es/ecma402/#sec-lookupmatcher
static LocaleResult lookup_matcher(Vector<String> const& requested_locales)
{
    // 1. Let result be a new Record.
    LocaleResult result {};

    // 2. For each element locale of requestedLocales, do
    for (auto const& locale : requested_locales) {
        // a. Let noExtensionsLocale be the String value that is locale with any Unicode locale extension sequences removed.
        auto const& no_extensions_locale = locale; // FIXME: Handle extensions.

        // b. Let availableLocale be BestAvailableLocale(availableLocales, noExtensionsLocale).
        auto available_locale = best_available_locale(no_extensions_locale);

        // c. If availableLocale is not undefined, then
        if (available_locale.has_value()) {
            // i. Set result.[[locale]] to availableLocale.
            result.locale = available_locale.release_value();

            // FIXME: Handle extensions.
            // ii. If locale and noExtensionsLocale are not the same String value, then
            //     1. Let extension be the String value consisting of the substring of the Unicode locale extension sequence within locale.
            //     2. Set result.[[extension]] to extension.

            // iii. Return result.
            return result;
        }
    }

    // 3. Let defLocale be DefaultLocale().
    // 4. Set result.[[locale]] to defLocale.
    result.locale = Unicode::default_locale();

    // 5. Return result.
    return result;
}

// 9.2.4 BestFitMatcher ( availableLocales, requestedLocales ), https://tc39.es/ecma402/#sec-bestfitmatcher
static LocaleResult best_fit_matcher(Vector<String> const& requested_locales)
{
    // The algorithm is implementation dependent, but should produce results that a typical user of the requested locales would
    // perceive as at least as good as those produced by the LookupMatcher abstract operation.
    return lookup_matcher(requested_locales);
}

// 9.2.7 ResolveLocale ( availableLocales, requestedLocales, options, relevantExtensionKeys, localeData ), https://tc39.es/ecma402/#sec-resolvelocale
LocaleResult resolve_locale(Vector<String> const& requested_locales, LocaleOptions const& options, [[maybe_unused]] Vector<StringView> relevant_extension_keys)
{
    // 1. Let matcher be options.[[localeMatcher]].
    auto const& matcher = options.locale_matcher;
    LocaleResult result;

    // 2. If matcher is "lookup", then
    if (matcher.is_string() && (matcher.as_string().string() == "lookup"sv)) {
        // a. Let r be LookupMatcher(availableLocales, requestedLocales).
        result = lookup_matcher(requested_locales);
    }
    // 3. Else,
    else {
        // a. Let r be BestFitMatcher(availableLocales, requestedLocales).
        result = best_fit_matcher(requested_locales);
    }
    // 4. Let foundLocale be r.[[locale]].
    // 5. Let result be a new Record.
    // 6. Set result.[[dataLocale]] to foundLocale.

    // FIXME: Handle extensions.
    // 7. If r has an [[extension]] field, then
    //     a. Let components be ! UnicodeExtensionComponents(r.[[extension]]).
    //     b. Let keywords be components.[[Keywords]].
    // 8. Let supportedExtension be "-u".
    // 9. For each element key of relevantExtensionKeys, do
    //     a. Let foundLocaleData be localeData.[[<foundLocale>]].
    //     b. Assert: Type(foundLocaleData) is Record.
    //     c. Let keyLocaleData be foundLocaleData.[[<key>]].
    //     d. Assert: Type(keyLocaleData) is List.
    //     e. Let value be keyLocaleData[0].
    //     f. Assert: Type(value) is either String or Null.
    //     g. Let supportedExtensionAddition be "".
    //     h. If r has an [[extension]] field, then
    //         i. If keywords contains an element whose [[Key]] is the same as key, then
    //             1. Let entry be the element of keywords whose [[Key]] is the same as key.
    //             2. Let requestedValue be entry.[[Value]].
    //             3. If requestedValue is not the empty String, then
    //                 a. If keyLocaleData contains requestedValue, then
    //                     i. Let value be requestedValue.
    //                     ii. Let supportedExtensionAddition be the string-concatenation of "-", key, "-", and value.
    //             4. Else if keyLocaleData contains "true", then
    //                 a. Let value be "true".
    //                 b. Let supportedExtensionAddition be the string-concatenation of "-" and key.
    //     i. If options has a field [[<key>]], then
    //         i. Let optionsValue be options.[[<key>]].
    //         ii. Assert: Type(optionsValue) is either String, Undefined, or Null.
    //         iii. If Type(optionsValue) is String, then
    //             1. Let optionsValue be the string optionsValue after performing the algorithm steps to transform Unicode extension values to canonical syntax per Unicode Technical Standard #35 LDML § 3.2.1 Canonical Unicode Locale Identifiers, treating key as ukey and optionsValue as uvalue productions.
    //             2. Let optionsValue be the string optionsValue after performing the algorithm steps to replace Unicode extension values with their canonical form per Unicode Technical Standard #35 LDML § 3.2.1 Canonical Unicode Locale Identifiers, treating key as ukey and optionsValue as uvalue productions.
    //             3. If optionsValue is the empty String, then
    //                 a. Let optionsValue be "true".
    //         iv. If keyLocaleData contains optionsValue, then
    //             1. If SameValue(optionsValue, value) is false, then
    //                 a. Let value be optionsValue.
    //                 b. Let supportedExtensionAddition be "".
    //     j. Set result.[[<key>]] to value.
    //     k. Append supportedExtensionAddition to supportedExtension.
    // 10. If the number of elements in supportedExtension is greater than 2, then
    //     a. Let foundLocale be InsertUnicodeExtensionAndCanonicalize(foundLocale, supportedExtension).
    // 11. Set result.[[locale]] to foundLocale.

    // 12. Return result.
    return result;
}

// 9.2.13 GetOption ( options, property, type, values, fallback ), https://tc39.es/ecma402/#sec-getoption
Value get_option(GlobalObject& global_object, Value options, PropertyName const& property, Value::Type type, Vector<StringView> const& values, Fallback fallback)
{
    auto& vm = global_object.vm();

    // 1. Assert: Type(options) is Object.
    VERIFY(options.is_object());

    // 2. Let value be ? Get(options, property).
    auto value = options.get(global_object, property);
    if (vm.exception())
        return {};

    // 3. If value is undefined, return fallback.
    if (value.is_undefined()) {
        return fallback.visit(
            [](Empty) { return js_undefined(); },
            [](bool f) { return Value(f); },
            [&vm](StringView f) { return Value(js_string(vm, f)); });
    }

    // 4. Assert: type is "boolean" or "string".
    VERIFY((type == Value::Type::Boolean) || (type == Value::Type::String));

    // 5. If type is "boolean", then
    if (type == Value::Type::Boolean) {
        // a. Let value be ! ToBoolean(value).
        value = Value(value.to_boolean());
    }
    // 6. If type is "string", then
    else {
        // a. Let value be ? ToString(value).
        value = value.to_primitive_string(global_object);
        if (vm.exception())
            return {};
    }

    // 7. If values is not undefined and values does not contain an element equal to value, throw a RangeError exception.
    if (!values.is_empty()) {
        // Note: Every location in the spec that invokes GetOption with type=boolean also has values=undefined.
        VERIFY(value.is_string());
        if (!values.contains_slow(value.as_string().string())) {
            vm.throw_exception<RangeError>(global_object, ErrorType::OptionIsNotValidValue, value.to_string_without_side_effects(), property.as_string());
            return {};
        }
    }

    // 8. Return value.
    return value;
}

}