Feature: Localization Restructuring to follow a stricter pattern

src/Localization/Middleware/LocaleMiddleware.php

@@ -0,0 +1,107 @@
+<?php
+
+namespace Modules\Core\Localization\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Collection;
+use Illuminate\Support\Facades\App;
+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
+{
+    public function __construct(private readonly LanguageCache $languages) {}
+
+    public function handle(Request $request, Closure $next): Response
+    {
+        $languages = $this->languages->all();
+
+        if ($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);
+
+        // Lets route() calls omit {locale} anywhere in the request lifecycle
+        // (controllers, views) — without this, every route() call would need
+        // locale passed explicitly every time.
+        URL::defaults(['locale' => $language->code]);
+
+        $this->shareLocaleViewData($request, $language, $languages);
+
+        return $next($request);
+    }
+
+    /**
+     * 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
+     * switcher and layout hreflang tags don't have to recompute it.
+     *
+     * `altLocales` is a collection, not a single value — firstWhere('code', '!=',
+     * ...) would only ever surface one alternate, which happens to look correct
+     * with exactly 2 configured languages (there's only one "other" to find) but
+     * silently drops every locale past the first for a 3+ language store, with no
+     * error, just fewer switcher options than actually configured. A view iterates
+     * `$altLocales` to render as many links/dropdown entries as there are
+     * alternates, whether that's 1 or 10.
+     */
+    private function shareLocaleViewData(Request $request, Language $language, Collection $languages): void
+    {
+        $route = $request->route();
+        $routeName = $route?->getName();
+
+        $altLocales = $languages
+            ->reject(fn (Language $other) => $other->code === $language->code)
+            ->map(fn (Language $other) => [
+                'code' => $other->code,
+                'name' => $other->name,
+                'url' => $routeName
+                    ? route($routeName, array_merge($route->parameters(), ['locale' => $other->code]))
+                    : url('/'.$other->code),
+            ])
+            ->values();
+
+        View::share('currentLocale', $language->code);
+        View::share('altLocales', $altLocales);
+    }
+
+    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;
+    }
+}