Refactor middleware to separate package

1 files changed, 56 insertions, 0 deletions

diff --git a/middleware/gzip.go b/middleware/gzip.go
new file mode 100644
index 0000000..2ceb77e
--- /dev/null
+++ b/middleware/gzip.go
@@ -0,0 +1,56 @@
+package middleware
+
+import (
+	"compress/gzip"
+	"net/http"
+	"strings"
+)
+
+type gzipResponseWriter struct {
+	gzip.Writer
+	http.ResponseWriter
+}
+
+func newGzipResponseWriter(w http.ResponseWriter) *gzipResponseWriter {
+	gzrw := new(gzipResponseWriter)
+	gzrw.Writer = *gzip.NewWriter(w)
+	gzrw.ResponseWriter = w
+
+	return gzrw
+}
+
+func (gzrw *gzipResponseWriter) Close() error {
+	return gzrw.Writer.Close()
+}
+
+func (gzrw *gzipResponseWriter) Header() http.Header {
+	return gzrw.ResponseWriter.Header()
+}
+
+func (gzrw *gzipResponseWriter) Write(p []byte) (int, error) {
+	n, err := gzrw.Writer.Write(p)
+	return n, err
+}
+
+func (gzrw *gzipResponseWriter) WriteHeader(statuscode int) {
+	gzrw.ResponseWriter.WriteHeader(statuscode)
+}
+
+// Middleware to conditionally gzip a response
+func Gzip(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		acceptedEncodings := r.Header.Get("Accept-Encoding")
+
+		if !strings.Contains(acceptedEncodings, "gzip") {
+			Logger.DebugContext(r.Context(), "Using gzip middleware but client does not support gzip encoding")
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		w.Header().Add("Content-Encoding", "gzip")
+		gzrw := newGzipResponseWriter(w)
+		defer gzrw.Close()
+
+		next.ServeHTTP(gzrw, r)
+	})
+}