You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ghttp_middleware_handler_response.go
    path of file: ./repos/gf/net/ghttp
    
    the code of the file until where you have to start completion: // Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package ghttp

import (
	"net/http"

	"github.com/gogf/gf/v2/errors/gcode"
	"github.com/gogf/gf/v2/errors/gerror"
)

// DefaultHandlerResponse is the default implementation of HandlerResponse.
type DefaultHandlerResponse struct {
	Code    int         `json:"code"    dc:"Error code"`
	Message string      `json:"message" dc:"Error message"`
	Data    interface{} `json:"data"    dc:"Result data for certain request according API definition"`
}

// MiddlewareHandlerResponse is the default middleware handling handler response object and its error.
func MiddlewareHandlerResponse(r *Reques
    
func MiddlewareHandlerResponse(r *Request) {
	r.Middleware.Next()

	// There's custom buffer content, it then exits current handler.
	if r.Response.BufferLength() > 0 {
		return
	}

	var (
		msg  string
		err  = r.GetError()
		res  = r.GetHandlerResponse()
		code = gerror.Code(err)
	)
	if err != nil {
		if code == gcode.CodeNil {
			code = gcode.CodeInternalError
		}
		msg = err.Error()
	} else {
		if r.Response.Status > 0 && r.Response.Status != http.StatusOK {
			msg = http.StatusText(r.Response.Status)
			switch r.Response.Status {
			case http.StatusNotFound:
				code = gcode.CodeNotFound
			case http.StatusForbidden:
				code = gcode.CodeNotAuthorized
			default:
				code = gcode.CodeUnknown
			}
			// It creates error as it can be retrieved by other middlewares.
			err = gerror.NewCode(code, msg)
			r.SetError(err)
		} else {
			code = gcode.CodeOK
		}
	}

	r.Response.WriteJson(DefaultHandlerResponse{
		Code:    code.Code(),
		Message: msg,
		Data:    res,
	})
}