From 78384073b0376d04179e33be64ed4767422de343 Mon Sep 17 00:00:00 2001
From: Adhityaa <c.adhityaa@gmail.com>
Date: Mon, 11 Jun 2018 15:01:58 +0530
Subject: [PATCH] api: allow gzipped response

---
 api/config.go        |  2 ++
 api/errors.go        |  1 +
 api/router_static.go | 31 +++++++++++++++++++++++++------
 api/utils_gzip.go    | 18 ++++++++++++++++++
 4 files changed, 46 insertions(+), 6 deletions(-)
 create mode 100644 api/utils_gzip.go

diff --git a/api/config.go b/api/config.go
index ee61c73..b08d462 100644
--- a/api/config.go
+++ b/api/config.go
@@ -24,6 +24,8 @@ func parseConfig() error {
 
 		"STATIC": binPath,
 
+		"GZIP_STATIC": "false",
+
 		"SMTP_USERNAME":     "",
 		"SMTP_PASSWORD":     "",
 		"SMTP_HOST":         "",
diff --git a/api/errors.go b/api/errors.go
index 10fda74..2240a2d 100644
--- a/api/errors.go
+++ b/api/errors.go
@@ -37,3 +37,4 @@ var errorSessionAlreadyInUse = errors.New("Session is already in use.")
 var errorCannotReadResponse = errors.New("Cannot read response.")
 var errorNotModerator = errors.New("You need to be a moderator to do that.")
 var errorNotADirectory = errors.New("The given path is not a directory.")
+var errorGzip = errors.New("Cannot GZip content.")
diff --git a/api/router_static.go b/api/router_static.go
index f23f63c..59038b7 100644
--- a/api/router_static.go
+++ b/api/router_static.go
@@ -25,7 +25,8 @@ type staticHtmlPlugs struct {
 }
 
 func initStaticRouter(router *mux.Router) error {
-	asset := make(map[string]string)
+	asset := make(map[string][]byte)
+	gzippedAsset := make(map[string][]byte)
 
 	for _, dir := range []string{"js", "css", "images"} {
 		sl := string(os.PathSeparator)
@@ -52,12 +53,30 @@ func initStaticRouter(router *mux.Router) error {
 				prefix += "window.commento_cdn='" + os.Getenv("CDN_PREFIX") + "';\n"
 			}
 
-			asset[p] = prefix + string(contents)
+			gzip := (os.Getenv("GZIP_STATIC") == "true")
 
-			router.HandleFunc(p, func(w http.ResponseWriter, r *http.Request) {
-				w.Header().Set("Content-Type", mime.TypeByExtension(path.Ext(r.URL.Path)))
-				fmt.Fprint(w, asset[r.URL.Path])
-			})
+			asset[p] = []byte(prefix + string(contents))
+			if gzip {
+				gzippedAsset[p], err = gzipStatic(asset[p])
+				if err != nil {
+					logger.Errorf("error gzipping %s: %v", p, err)
+					return err
+				}
+			}
+
+			// faster than checking inside the handler
+			if !gzip {
+				router.HandleFunc(p, func(w http.ResponseWriter, r *http.Request) {
+					w.Header().Set("Content-Type", mime.TypeByExtension(path.Ext(r.URL.Path)))
+					w.Write(asset[r.URL.Path])
+				})
+			} else {
+				router.HandleFunc(p, func(w http.ResponseWriter, r *http.Request) {
+					w.Header().Set("Content-Type", mime.TypeByExtension(path.Ext(r.URL.Path)))
+					w.Header().Set("Content-Encoding", "gzip")
+					w.Write(gzippedAsset[r.URL.Path])
+				})
+			}
 		}
 	}
 
diff --git a/api/utils_gzip.go b/api/utils_gzip.go
new file mode 100644
index 0000000..c44a8af
--- /dev/null
+++ b/api/utils_gzip.go
@@ -0,0 +1,18 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+)
+
+func gzipStatic(b []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	g := gzip.NewWriter(&buf)
+	if _, err := g.Write(b); err != nil {
+		g.Close()
+		return []byte{}, err
+	}
+
+	g.Close()
+	return buf.Bytes(), nil
+}