Automatically set app locale based on browser's preferred language and server's `lang/` directory

SetLocale.php

<?php

/**
 * For Laravel 10.
 * Automatically set app locale based on browser's preferred language and server's `lang/` directory.
 * @copyright 2024 Joe Koop
 * @license MIT
 */

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\App;
use Symfony\Component\HttpFoundation\Response;

class SetLocale {
    /**
     * Handle an incoming request.
     *
     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
     */
    public function handle(Request $request, Closure $next): Response {
        $availableLocales = [];
        foreach (glob(base_path("lang") . "/*") as $path) {
            $name = pathinfo($path, PATHINFO_BASENAME);
            $name = explode(".", $name)[0];
            if (str_starts_with($name, "php_")) continue;
            $availableLocales[] = $name;
        }

        $acceptLanguage = $request->header("accept-language", "en");
        $acceptLanguage = explode(",", $acceptLanguage);
        $acceptLanguage = collect($acceptLanguage);
        $acceptLanguage = $acceptLanguage->map(fn ($a) => preg_replace('/\s+/u', '', $a)); // remove whitespace
        $acceptLanguage = $acceptLanguage->sortByDesc(function (string $item): float {
            $item = strtolower($item);
            $item = explode(";", $item);
            $item = collect($item);
            $item = $item->filter(fn ($a) => str_starts_with($a, "q=") and strlen($a) > 2);
            $item = $item->first() ?? "q=1";
            $item = substr($item, 2);
            $item = preg_replace('/[^0-9.]/u', '', $item); // remove non-decimal
            return (float) $item;
        });
        $acceptLanguage = $acceptLanguage->map(fn ($a) => explode(";", $a)[0]); // strip q=
        foreach ($acceptLanguage as $a) {
            foreach ($availableLocales as $locale) {
                if (strtolower($a) == strtolower($locale)) {
                    $acceptLanguage = $locale;
                    break(2);
                }
            }
        }
        if (!is_string($acceptLanguage)) $acceptLanguage = "en";
        App::setLocale($acceptLanguage);

        return $next($request);
    }
}