/**
     * @api {post} /auth/register/email 邮箱注册
     * @apiDescription 注册时, 请求体将不可避免地用明文传参.所以建议开启SSL.
     * @apiVersion 2.0.0
     * @apiPermission none
     * @apiName registerByEmail
     * @apiGroup Auth
     *
     * @apiParam {String{3..16}} username  用户名.
     * @apiParam {String{..32}} email  用户邮箱.
     * @apiParam {String{6}} captch  验证码.
     * @apiParam {String} password  密码.
     *
     * @apiSuccessExample 成功响应:
            {
                "ret": 200,
                "data": {},
                "msg": ""
            }
     */
    public function registerByEmail()
    {
        $domain = new Domain();
        /** ============== 格式检查 ============== */
        /** ------- 用户名检查 ------- */
        $this->username = trim($this->username);
        if (!\App\Helper\Validator::checkUsernameFormat($this->username)) {
            throw new BadRequestException('用户名格式错误, 请检查用户名格式是否正确. 只可以含有?.@_所有中英文和emoji.');
        }
        /** ------- 邮箱检查   ------- */
        $this->email = trim($this->email);
        if (!\App\Helper\Validator::checkEmailFormat($this->email)) {
            throw new BadRequestException('邮箱格式错误, 必须形如 [email protected] 的格式');
        }
        /** ============== 正式检查 ============== */
        // 检查可用性(重复)
        if (!$domain->isEmailAvailable($this->email)) {
            throw new BadRequestException('邮箱已被使用');
        }
        /** ------- captch validating ------- */
        $this->captch = trim($this->captch);
        $correctCaptch = $domain->getLastCaptch($this->email);
        if ($correctCaptch == null) {
            throw new BadRequestException('未发送验证码');
        }
        if ($this->captch != $correctCaptch) {
            throw new BadRequestException('验证码错误或过期');
        }
        /** ------- password validating ------- */
        // 密码不进行 trim()
        /** ------- 完成注册 ------- */
        $domain->registerUserByEmail($this->username, $this->email, $this->password, 1);

        // 目前规定, 失败才返回消息
        //\PhalApi\DI()->response->setMsg("注册成功");

        return array();
    }