From ca005f7c972548aea330af39c974e60a077c5d5b Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Sun, 15 Jan 2017 10:30:41 -0800
Subject: [PATCH] Allow configuration of gzip compression level

---
 compy.go           | 5 +++--
 transcoder/gzip.go | 8 ++++++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/compy.go b/compy.go
index 98c3c1f..1654813 100644
--- a/compy.go
+++ b/compy.go
@@ -20,6 +20,7 @@ var (
 
 	jpeg   = flag.Int("jpeg", 50, "jpeg quality (1-100, 0 to disable)")
 	gif    = flag.Bool("gif", true, "transcode gifs into static images")
+	gzip   = flag.Int("gzip", -1, "gzip compression level (0-9, default 6)")
 	png    = flag.Bool("png", true, "transcode png")
 	minify = flag.Bool("minify", false, "minify css/html/js - WARNING: tends to break the web")
 )
@@ -55,9 +56,9 @@ func main() {
 
 	var ttc proxy.Transcoder
 	if *minify {
-		ttc = &tc.Gzip{tc.NewMinifier(), false}
+		ttc = &tc.Gzip{tc.NewMinifier(), *gzip, false}
 	} else {
-		ttc = &tc.Gzip{&tc.Identity{}, true}
+		ttc = &tc.Gzip{&tc.Identity{}, *gzip, true}
 	}
 
 	p.AddTranscoder("text/css", ttc)
diff --git a/transcoder/gzip.go b/transcoder/gzip.go
index 0017aaf..3aa65b9 100644
--- a/transcoder/gzip.go
+++ b/transcoder/gzip.go
@@ -9,7 +9,8 @@ import (
 
 type Gzip struct {
 	proxy.Transcoder
-	SkipGzipped bool
+	CompressionLevel int
+	SkipGzipped      bool
 }
 
 func (t *Gzip) Transcode(w *proxy.ResponseWriter, r *proxy.ResponseReader, headers http.Header) error {
@@ -33,7 +34,10 @@ func (t *Gzip) Transcode(w *proxy.ResponseWriter, r *proxy.ResponseReader, heade
 	}
 
 	if shouldGzip && compress(r) {
-		gzw := gzip.NewWriter(w.Writer)
+		gzw, err := gzip.NewWriterLevel(w.Writer, t.CompressionLevel)
+		if err != nil {
+			return err
+		}
 		defer gzw.Flush()
 		w.Writer = gzw
 		w.Header().Set("Content-Encoding", "gzip")