package transcoder import ( "compress/gzip" "net/http" "strings" "github.com/barnacs/compy/proxy" brotlidec "gopkg.in/kothar/brotli-go.v0/dec" brotlienc "gopkg.in/kothar/brotli-go.v0/enc" ) type Zip struct { proxy.Transcoder BrotliCompressionLevel int GzipCompressionLevel int SkipCompressed bool } func (t *Zip) Transcode(w *proxy.ResponseWriter, r *proxy.ResponseReader, headers http.Header) error { shouldBrotli := false shouldGzip := false for _, v := range strings.Split(headers.Get("Accept-Encoding"), ", ") { switch strings.SplitN(v, ";", 2)[0] { case "br": shouldBrotli = true case "gzip": shouldGzip = true } } // always gunzip if the client supports Brotli if r.Header().Get("Content-Encoding") == "gzip" && (shouldBrotli || !t.SkipCompressed) { gzr, err := gzip.NewReader(r.Reader) if err != nil { return err } defer gzr.Close() r.Reader = gzr r.Header().Del("Content-Encoding") w.Header().Del("Content-Encoding") } if r.Header().Get("Content-Encoding") == "br" && !t.SkipCompressed { brr := brotlidec.NewBrotliReader(r.Reader) defer brr.Close() r.Reader = brr r.Header().Del("Content-Encoding") w.Header().Del("Content-Encoding") } if shouldBrotli && compress(r) { params := brotlienc.NewBrotliParams() params.SetQuality(11) brw := brotlienc.NewBrotliWriter(params, w.Writer) defer brw.Close() w.Writer = brw w.Header().Set("Content-Encoding", "br") } else if shouldGzip && compress(r) { gzw, err := gzip.NewWriterLevel(w.Writer, 9) if err != nil { return err } defer gzw.Close() w.Writer = gzw w.Header().Set("Content-Encoding", "gzip") } return t.Transcoder.Transcode(w, r, headers) } func compress(r *proxy.ResponseReader) bool { return true // Always compression }