Dealing with old unnamaspaced code does not seem fun. Something you had to do at work?
composer require koriym/spaceman --dev
<?php
use Koriym\Spaceman\Convert;
require dirname(__DIR__) . '/vendors/autoload.php';
$sourcePath = __DIR__ . '/service/protected/controllers';
// Rewrite php file with adding namespace declaration starting `$packageName` on directory basis
$packageName = 'application';
(new Convert($packageName))($sourcePath);