compy/transcoder/zip.go

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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(t.BrotliCompressionLevel)
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, t.GzipCompressionLevel)
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 r.Header().Get("Content-Encoding") == ""
}