laravel too many redirects errors - php

Question

Here is my routes file:
Route::get('/', 'WebController#index');
Route::group(['prefix' => 'cn'], function () {
Route::get('/', 'WebController#index');
Route::group(['namespace' => 'ACL', 'prefix' => 'auth'], function () {
Route::get('login', 'AuthController#login');
Route::post('login', 'AuthController#login');
Route::get('logout', 'AuthController#logout');
});
Route::group(['middleware' => ['auth', 'token']], function () {
Route::get("/intentional", 'IntentionalOrderController#index');
Route::get("/intentional/add", 'IntentionalOrderController#create');
Route::post("/intentional/add", 'IntentionalOrderController#store');
Route::get("/intentional/selfOrder", 'IntentionalOrderController#selfOrder');
Route::post("/intentional/selfOrder", 'IntentionalOrderController#storeSelfOrder');
});
});
Route::group(['prefix' => 'en'], function () {
Route::get('/', 'WebController#index');
Route::group(['namespace' => 'ACL', 'prefix' => 'auth'], function () {
Route::get('login', 'AuthController#login');
Route::post('login', 'AuthController#login');
Route::get('logout', 'AuthController#logout');
});
Route::group(['middleware' => ['auth', 'token']], function () {
Route::get("/intentional", 'IntentionalOrderController#index');
Route::get("/intentional/add", 'IntentionalOrderController#create');
Route::post("/intentional/add", 'IntentionalOrderController#store');
Route::get("/intentional/selfOrder", 'IntentionalOrderController#selfOrder');
Route::post("/intentional/selfOrder", 'IntentionalOrderController#storeSelfOrder');
});
});
The problem is:
When I enter the /en or /cn url, the browser will say too many redirects; but when I enter /en/auth/login or any other url, it will work just fine.
Althought I can fix this by renaming /cn to /cn/index, but still I don't understand why this is not working.
PS:
1. My laravel version is 5.1
2. Debug environment is wamp
3. Browser is chrome
Update:
here is my WebController and BaseController
<?php namespace App\Http\Controllers;
class WebController extends BaseController
{
public function index()
{
return view(config('app.locale') . ".web.index", ["title" => trans('common.smart_fabric'), "active" => "0"]);
}
}
<?php namespace App\Http\Controllers;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Request;
class BaseController extends Controller
{
public function __construct()
{
$locale = Request::segment(1);
if ($locale) {
switch ($locale) {
case 'cn':
App::setLocale('cn');
break;
case 'en':
App::setLocale('en');
break;
default:
App::setLocale('cn');
}
}
}