Aknaproff/app/Http/Middleware/LocaleMiddleware.php

<?php

namespace App\Http\Middleware;

use App\UserSetting;
use Closure;
use Illuminate\Support\Facades\Session;

class LocaleMiddleware
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {

        if (empty(Session::get('locale'))) {
            $userSetting = UserSetting::where('user_id', auth()->user()->id)->first();

            $locale = 'en';
            if (!empty($userSetting)) {
                if (!in_array($userSetting->language, ['en', 'ru', 'est'])) {
                    $locale = $userSetting->language;
                }
            }
            
            Session::put('locale', $locale);
            app()->setLocale($locale);
        }

        return $next($request);
    }
}