Feature: Updating Product Service to handle multiple locales, fetching the correct locale, or, the default locale as fallback

src/Localization/Listeners/FlushLanguageCache.php

@@ -5,12 +5,14 @@ namespace Modules\Core\Localization\Listeners;
 use Modules\Core\Localization\Events\LanguageCreated;
 use Modules\Core\Localization\Events\LanguageDeleted;
 use Modules\Core\Localization\Events\LanguageUpdated;
-use Modules\Core\Localization\LocaleMiddleware;
+use Modules\Core\Localization\Services\LanguageCache;
 
 class FlushLanguageCache
 {
+    public function __construct(private readonly LanguageCache $languages) {}
+
     public function handle(LanguageCreated|LanguageUpdated|LanguageDeleted $event): void
     {
-        LocaleMiddleware::forgetLanguagesCache();
+        $this->languages->forget();
     }
 }

src/Localization/LocaleMiddleware.php

@@ -6,19 +6,19 @@ use Closure;
 use Illuminate\Http\Request;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Facades\App;
-use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Facades\URL;
 use Illuminate\Support\Facades\View;
 use Lunar\Models\Language;
+use Modules\Core\Localization\Services\LanguageCache;
 use Symfony\Component\HttpFoundation\Response;
 
 class LocaleMiddleware
 {
-    private const CACHE_KEY = 'core.localization.languages';
+    public function __construct(private readonly LanguageCache $languages) {}
 
     public function handle(Request $request, Closure $next): Response
     {
-        $languages = $this->availableLanguages();
+        $languages = $this->languages->all();
 
         if ($languages->isEmpty()) {
             return $next($request);
@@ -45,22 +45,6 @@ class LocaleMiddleware
         return $next($request);
     }
 
-    public static function forgetLanguagesCache(): void
-    {
-        Cache::forget(self::CACHE_KEY);
-    }
-
-    /**
-     * The store's default language code (e.g. 'el') - the fixed fallback other
-     * locale-aware code (Modules\Core\Catalog\ProductService) should use, as
-     * opposed to config('app.locale') which App::setLocale() mutates per
-     * request and so can't serve as a stable fallback.
-     */
-    public static function defaultLocale(): ?string
-    {
-        return (new self)->availableLanguages()->firstWhere('default', true)?->code;
-    }
-
     /**
      * Shares the current locale and every OTHER available locale (each with its
      * own URL for the current page) with all views, so the header language
@@ -120,12 +104,4 @@ class LocaleMiddleware
         return $languages->firstWhere('default', true)?->code
             ?? $languages->first()->code;
     }
-
-    private function availableLanguages(): Collection
-    {
-        return Cache::rememberForever(
-            self::CACHE_KEY,
-            fn () => Language::query()->get(['id', 'code', 'name', 'default']),
-        );
-    }
 }

src/Localization/Services/LanguageCache.php

@@ -0,0 +1,58 @@
+<?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\LocaleMiddleware (request-time locale resolution) and
+ * any other locale-aware code (e.g. Modules\Core\Catalog\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\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);
+    }
+}