<?php

namespace Modules\Core\Localization\Services;

use Illuminate\Support\Collection;
use Illuminate\Support\Facades\Cache;
use Lunar\Models\Language;

/**
 * Cached read layer over Lunar's `languages` table — the single source both
 * Modules\Core\Localization\Middleware\LocaleMiddleware (request-time locale resolution) and
 * any other locale-aware code (e.g. Modules\Core\Catalog\Services\ProductService) read
 * from, so the language list is fetched once per cache lifetime rather than once
 * per caller. Cached forever, invalidated via forget() by
 * Modules\Core\Localization\Listeners\FlushLanguageCache on
 * LanguageCreated/LanguageUpdated/LanguageDeleted.
 */
class LanguageCache
{
    private const CACHE_KEY = 'core.localization.languages';

    public function all(): Collection
    {
        return Cache::rememberForever(
            self::CACHE_KEY,
            fn () => Language::query()->get(['id', 'code', 'name', 'default']),
        );
    }

    /**
     * The store's default language code (e.g. 'el') - the fixed fallback other
     * locale-aware code should use, as opposed to config('app.locale') which
     * App::setLocale() mutates per request and so can't serve as a stable
     * fallback.
     */
    public function defaultLocale(): ?string
    {
        return $this->all()->firstWhere('default', true)?->code;
    }

    /**
     * Every configured store locale code (e.g. ['el', 'en']) - for code that needs
     * to enumerate all locales a TranslatedText attribute was indexed under (see
     * Modules\Core\Catalog\Services\ProductService::withLocalizedFields()), rather than
     * hardcoding locale codes.
     *
     * @return array<int, string>
     */
    public function availableLocales(): array
    {
        return $this->all()->pluck('code')->all();
    }

    public function forget(): void
    {
        Cache::forget(self::CACHE_KEY);
    }
}