repo_description: A realtime distributed messaging platform
repo_topics: distributed-systems go message-queue messaging nsq queue
code: // 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)
  	})
  }
  