compress.go

// Copyright 2013 The Gorilla Authors. All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

// copied from https://github.com/gorilla/handlers/blob/master/compress.go

package http_api

import (

    "compress/flate"

    "compress/gzip"

    "io"

    "net/http"

    "strings"

)

type compressResponseWriter struct {

    io.Writer

    http.ResponseWriter

    http.Hijacker

}

func (w *compressResponseWriter) Header() http.Header {

    return w.ResponseWriter.Header()

}

func (w *compressResponseWriter) WriteHeader(c int) {

    w.ResponseWriter.Header().Del("Content-Length")

    w.ResponseWriter.WriteHeader(c)

}

func (w *compressResponseWriter) Write(b []byte) (int, error) {

    h := w.ResponseWriter.Header()

    if h.Get("Content-Type") == "" {

        h.Set("Content-Type", http.DetectContentType(b))

    }

    h.Del("Content-Length")

    return w.Writer.Write(b)

}

// CompressHandler gzip compresses HTTP responses for clients that support it

// via the 'Accept-Encoding' header.

func CompressHandler(h http.Handler) http.Handler {

    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

    L:

        for _, enc := range strings.Split(r.Header.Get("Accept-Encoding"), ",") {

            switch strings.TrimSpace(enc) {

            case "gzip":

                w.Header().Set("Content-Encoding", "gzip")

                w.Header().Add("Vary", "Accept-Encoding")

                gw := gzip.NewWriter(w)

                defer gw.Close()

                h, hok := w.(http.Hijacker)

                if !hok { /* w is not Hijacker... oh well... */

                    h = nil

                }

                w = &compressResponseWriter{

                    Writer:         gw,

                    ResponseWriter: w,

                    Hijacker:       h,

                }

                break L

            case "deflate":

                w.Header().Set("Content-Encoding", "deflate")

                w.Header().Add("Vary", "Accept-Encoding")

                fw, _ := flate.NewWriter(w, flate.DefaultCompression)

                defer fw.Close()

                h, hok := w.(http.Hijacker)

                if !hok { /* w is not Hijacker... oh well... */

                    h = nil

                }

                w = &compressResponseWriter{

                    Writer:         fw,

                    ResponseWriter: w,

                    Hijacker:       h,

                }

                break L

            }

        }

        h.ServeHTTP(w, r)

    })

}