import type { Config } from '../locale/config.ts';
import type { Translations } from '../locale/translations.ts';

import { deepGet, deepListKeys } from './helpers.ts';

const localeSpecificFlagAlt = /flags_alt\.-(.+)-/;

export function listMissingTranslations(
    translations: Translations,
    baseTranslations: Translations,
    config: Config,
): string[] {
    const expectedTranslations = [...deepListKeys(baseTranslations)];

    return expectedTranslations.filter((k) => {
        function keyMatches(...pats: string[]): boolean {
            for (const pat of pats) {
                if (pat.endsWith('.')) {
                    if (k.startsWith(pat)) {
                        return true;
                    }
                } else {
                    if (k === pat) {
                        return true;
                    }
                }
            }
            return false;
        }

        function has(k: string): boolean {
            return deepGet(translations, k) !== undefined;
        }

        if (has(k)) {
            return false;
        }

        // macrolanguage.* keys are only required for macrolanguage locales
        if (!config.macrolanguage?.enabled && keyMatches('macrolanguage.')) {
            return false;
        }

        // FAQ entries are fully customizable for a language version.
        if (keyMatches('faq.')) {
            return false;
        }

        // disclaimer is only required when optional translations are present for a non-English locale
        if ((!has('terms.content') && !has('privacy.content') || config.locale === 'en') &&
            keyMatches('terms.translationDisclaimer')
        ) {
            return false;
        }

        // optional keys
        if (keyMatches(
            'home.welcome',
            'contact.faq',
            'contact.technical',
            'contact.hate',
            'contact.team.extra',
            'contact.team.join.',
            'user.login.help',
            'terms.content.',
            'terms.update.',
            'privacy.content.',
            'privacy.consent.',
        )) {
            return false;
        }

        if (!has('home.welcome') && keyMatches('home.intro')) {
            return false;
        }

        if (!config.pronouns.enabled && keyMatches(
            'pronouns.',
            'home.header',
            'home.headerLong',
            'home.pronouns',
            'home.generator.',
            'profile.pronouns',
            'profile.pronounsInfo',
            'profile.pronounsNotFound',
            'profile.share.pronouns',
        )) {
            return false;
        }

        if (!config.pronouns.exampleCategories && keyMatches('pronouns.examples.shuffleNamed')) {
            return false;
        }

        if (!config.pronouns.generator?.enabled && keyMatches('home.generator.')) {
            return false;
        }

        if (!config.pronouns.generator?.slashes && keyMatches('pronouns.slashes.')) {
            return false;
        }

        if (!config.pronouns.plurals && keyMatches(
            'pronouns.plural',
            'pronouns.slashes.plural',
            'pronouns.slashes.pluralHonorific',
        )) {
            return false;
        }

        if (!config.pronouns.null && keyMatches('pronouns.null.')) {
            return false;
        }

        if ((!config.pronouns.null || !config.pronouns.null.morphemes) &&
            keyMatches('pronouns.null.button', 'pronouns.null.base')) {
            return false;
        }

        if (!config.pronouns.emoji && keyMatches('pronouns.emoji.')) {
            return false;
        }

        if (!config.pronouns.ask && keyMatches('pronouns.ask.')) {
            return false;
        }

        // locale specific flags
        const match = k.match(localeSpecificFlagAlt);
        if (match && match[1] !== config.locale) {
            return false;
        }

        if (!config.pronouns.honorifics && keyMatches('pronouns.slashes.pluralHonorific')) {
            return false;
        }

        if (!config.pronouns.comprehensive && keyMatches('pronouns.comprehensive.')) {
            return false;
        }

        if (!config.links.enabled && keyMatches('links.')) {
            return false;
        }

        if (!config.sources.enabled && keyMatches('sources.')) {
            return false;
        }

        if (!config.nouns.enabled && keyMatches('nouns.')) {
            return false;
        }

        if (!config.nouns.nonbinary && keyMatches('nouns.nonbinary')) {
            return false;
        }

        if (config.nouns.categories?.length === 0 && keyMatches('nouns.categories')) {
            return false;
        }

        if (!config.nouns.templates?.enabled && keyMatches('nouns.template.')) {
            return false;
        }

        if (!config.nouns.conventions?.enabled &&
            keyMatches('nouns.conventions.', 'nouns.submit.regular.', 'nouns.submit.irregular.')) {
            return false;
        }

        if (!config.nouns.declension?.enabled && keyMatches('nouns.declension.')) {
            return false;
        }

        if (!config.terminology.enabled && keyMatches('terminology.')) {
            return false;
        }

        if (!config.calendar?.enabled && keyMatches('calendar.')) {
            return false;
        }

        if (!config.blog && keyMatches('links.blogLatest', 'links.blogFeed', 'links.blogReact', 'links.blogReactAuthRequired')) {
            return false;
        }

        if (!config.api?.enabled && keyMatches('profile.header', 'api.example', 'api.query')) {
            return false;
        }

        if (!config.english.enabled && keyMatches('english.')) {
            return false;
        }

        return true;
    });
}