refactor: changed file structure

internal/middleware/gzip.go

@@ -0,0 +1,32 @@
+package middleware
+
+import (
+	"compress/gzip"
+	"io"
+	"net/http"
+	"strings"
+)
+
+func Gzip(next http.Handler, useGzip bool) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") ||
+			!useGzip {
+			next.ServeHTTP(w, r)
+			return
+		}
+		w.Header().Set("Content-Encoding", "gzip")
+		gz := gzip.NewWriter(w)
+		defer gz.Close()
+		gzw := gzipResponseWriter{Writer: gz, ResponseWriter: w}
+		next.ServeHTTP(gzw, r)
+	})
+}
+
+type gzipResponseWriter struct {
+	io.Writer
+	http.ResponseWriter
+}
+
+func (w gzipResponseWriter) Write(b []byte) (int, error) {
+	return w.Writer.Write(b)
+}