Feature: Adding Locale Middleware

src/Localization/LanguageCacheObserver.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Modules\Core\Localization;
+
+use Lunar\Models\Contracts\Language as LanguageContract;
+
+class LanguageCacheObserver
+{
+    public function saved(LanguageContract $language): void
+    {
+        LocaleMiddleware::forgetLanguagesCache();
+    }
+
+    public function deleted(LanguageContract $language): void
+    {
+        LocaleMiddleware::forgetLanguagesCache();
+    }
+}

src/Localization/LocaleMiddleware.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace Modules\Core\Localization;
+
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\App;
+use Illuminate\Support\Facades\Cache;
+use Lunar\Models\Language;
+use Symfony\Component\HttpFoundation\Response;
+
+class LocaleMiddleware
+{
+    private const CACHE_KEY = 'core.localization.languages';
+
+    public function handle(Request $request, Closure $next): Response
+    {
+        $languages = $this->availableLanguages();
+
+        if ($languages->isEmpty()) {
+            return $next($request);
+        }
+
+        $segment = (string) $request->segment(1);
+        $language = $languages->firstWhere('code', $segment);
+
+        if (! $language) {
+            return $this->redirectToLocalizedUrl($request, $languages);
+        }
+
+        App::setLocale($language->code);
+        $request->attributes->set('locale', $language->code);
+        $request->attributes->set('language', $language);
+
+        return $next($request);
+    }
+
+    public static function forgetLanguagesCache(): void
+    {
+        Cache::forget(self::CACHE_KEY);
+    }
+
+    private function redirectToLocalizedUrl(Request $request, Collection $languages): Response
+    {
+        $locale = $this->negotiateLocale($request, $languages);
+
+        $path = trim($request->getPathInfo(), '/');
+        $target = '/'.$locale.($path !== '' ? '/'.$path : '');
+
+        $query = $request->getQueryString();
+        if ($query) {
+            $target .= '?'.$query;
+        }
+
+        return redirect($target);
+    }
+
+    private function negotiateLocale(Request $request, Collection $languages): string
+    {
+        $preferred = $request->getPreferredLanguage($languages->pluck('code')->all());
+
+        if ($preferred) {
+            return $preferred;
+        }
+
+        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/Providers/CoreServiceProvider.php

@@ -4,12 +4,15 @@ namespace Modules\Core\Providers;
 
 use Illuminate\Support\Facades\Blade;
 use Illuminate\Support\ServiceProvider;
+use Lunar\Models\Language;
 use Modules\Core\Command\AnonymizeCommand;
 use Modules\Core\Command\ExportCleanupCommand;
 use Modules\Core\Command\ExportCommand;
 use Modules\Core\Command\ImportCommand;
 use Modules\Core\Command\InstallLunarCommand;
 use Modules\Core\Command\MigrateImportCommand;
+use Modules\Core\Localization\LanguageCacheObserver;
+use Modules\Core\Localization\LocaleMiddleware;
 
 class CoreServiceProvider extends ServiceProvider
 {
@@ -24,6 +27,9 @@ class CoreServiceProvider extends ServiceProvider
         Blade::anonymousComponentPath(__DIR__ . '/../../resources/views', 'core');
         $this->loadMigrationsFrom(__DIR__ . '/../../database/migrations');
 
+        $this->app['router']->aliasMiddleware('locale', LocaleMiddleware::class);
+        Language::observe(LanguageCacheObserver::class);
+
         $this->publishes([
             __DIR__ . '/../../config/core.php' => config_path('core.php'),
             __DIR__ . '/../../config/scout.php' => config_path('scout.php'),