fix: move implementation to "internal" package

internal/handler/middleware/gzip.go

@@ -0,0 +1,40 @@
+package middleware
+
+import (
+	"compress/gzip"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+
+	"spend-sparrow/internal/log"
+)
+
+type gzipResponseWriter struct {
+	io.Writer
+	http.ResponseWriter
+}
+
+func (w gzipResponseWriter) Write(b []byte) (int, error) {
+	return w.Writer.Write(b)
+}
+
+func Gzip(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		w.Header().Set("Content-Encoding", "gzip")
+		gz := gzip.NewWriter(w)
+		wrapper := gzipResponseWriter{Writer: gz, ResponseWriter: w}
+
+		next.ServeHTTP(wrapper, r)
+
+		err := gz.Close()
+		if err != nil && !errors.Is(err, http.ErrBodyNotAllowed) {
+			log.Error("Gzip: could not close Writer: %v", err)
+		}
+	})
+}