/**
  * POST /sessions/login
  */
 public function login()
 {
     if (isset($_REQUEST['email']) && isset($_REQUEST['password'])) {
         $email = $_REQUEST['email'];
         $password = $_REQUEST['password'];
         $user = User::find_by_email_and_password($email, $password);
         if ($user) {
             $user_id = $user->getId();
             setcookie('user_id', $user_id, time() + 86400 * 30, "/");
             if ($user->existsMail) {
                 echo "el mail ya existe no puede infresar de nuevo";
             }
             $session = new Session($user->getId());
             $session->save();
             self::redirect_to('');
         } else {
             $error = 'El usuario no existe';
             require 'app/views/sessions/modal.php';
         }
     } else {
         require 'app/views/sessions/modal.php';
     }
 }