response.go

package bingo

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

const (
    noWritten     = -1
    defaultStatus = 200
)

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()
    }

    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
}

// 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()
}

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

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