response_write

// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.

package gin

import (
 "bufio"
 "io"
 "net"
 "net/http"
)

const (
 noWritten     = -1
 defaultStatus = http.StatusOK
)

// ResponseWriter ...
type ResponseWriter interface {
 http.ResponseWriter
 http.Hijacker
 http.Flusher
 http.CloseNotifier

 // Returns the HTTP response status code of the current request.
 Status() int

 // Returns the number of bytes already written into the response http body.
 // See Written()
 Size() int

 // Writes the string into the response body.
 WriteString(string) (int, error)

 // Returns true if the response body was already written.
 Written() bool

 // Forces to write the http header (status code + headers).
 WriteHeaderNow()

 // get the http.Pusher for server push
 Pusher() http.Pusher
}

type responseWriter struct {
 http.ResponseWriter
 size   int
 status int
}

var _ ResponseWriter = &responseWriter{}

func (w *responseWriter) reset(writer http.ResponseWriter) {
 w.ResponseWriter = writer
 w.size = noWritten
 w.status = defaultStatus
}

func (w *responseWriter) WriteHeader(code int) {
 if code > 0 && w.status != code {
  if w.Written() {
   debugPrint("[WARNING] Headers were already written. Wanted to override status code %d with %d", w.status, code)
  }
  w.status = code
 }
}

func (w *responseWriter) WriteHeaderNow() {
 if !w.Written() {
  w.size = 0
  w.ResponseWriter.WriteHeader(w.status)
 }
}

func (w *responseWriter) Write(data []byte) (n int, err error) {
 w.WriteHeaderNow()
 n, err = w.ResponseWriter.Write(data)
 w.size += n
 return
}

func (w *responseWriter) WriteString(s string) (n int, err error) {
 w.WriteHeaderNow()
 n, err = io.WriteString(w.ResponseWriter, s)
 w.size += n
 return
}

func (w *responseWriter) Status() int {
 return w.status
}

func (w *responseWriter) Size() int {
 return w.size
}

func (w *responseWriter) Written() bool {
 return w.size != noWritten
}

// Hijack implements the http.Hijacker interface.
func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
 if w.size < 0 {
  w.size = 0
 }
 return w.ResponseWriter.(http.Hijacker).Hijack()
}

// CloseNotify implements the http.CloseNotify interface.
func (w *responseWriter) CloseNotify() <-chan bool {
 return w.ResponseWriter.(http.CloseNotifier).CloseNotify()
}

// Flush implements the http.Flush interface.
func (w *responseWriter) Flush() {
 w.WriteHeaderNow()
 w.ResponseWriter.(http.Flusher).Flush()
}

func (w *responseWriter) Pusher() (pusher http.Pusher) {
 if pusher, ok := w.ResponseWriter.(http.Pusher); ok {
  return pusher
 }
 return nil
}