AmyUser::authorize PHP Method

    public function authorize($username, $password = null, $service = 'amy')
    {
        $username = Db::quote_literal($username);
        $service = Db::quote_literal($service);
        // bypassing the password - already logged in using external sevice API (Facebook and such)
        if (false === ($row = Db::find_first("SELECT * FROM amy.users WHERE username='{$username}' AND service='{$service}' LIMIT 1"))) {
            throw new Exception("Unable to lookup username: `{$username}' for service `{$service}'.");
        }
        if (null != $password) {
            if (md5($password) != $row['hashed_password']) {
                throw new Exception("Invalid password provided.");
            }
        }
        $this->load_user_info($row);
        Db::find("UPDATE amy.users SET last_logged_at=CURRENT_TIMESTAMP WHERE id=" . $this->userId);
        return $this;
    }

 public function on_user_sign_in($pars)
 {
     try {
         $user = new AmyUser($this->configuration);
         $user->authorize($pars['username'], $pars['password'], 'amy');
         $user->create_session();
         self::setResult($user);
     } catch (Exception $e) {
         self::raiseError('Unable to login: ' . $e->getMessage());
     }
 }