function checkAuth(string $login, string $password)
{
$users = require __DIR__ . '/usersDB.php';

foreach ($users as $user) {
if ($user['login'] === $login
&& $user['password'] === $password
) {
return true;
}
}

return false;
}

function getUserLogin()
{
$loginFromCookie = isset($_COOKIE['login']) ? $_COOKIE['login'] : '';
$passwordFromCookie = isset($_COOKIE['password']) ? $_COOKIE['password'] : '';

if (checkAuth($loginFromCookie, $passwordFromCookie)) {
return $loginFromCookie;
}

return null;
}