restructured the project to comply community guideline, for others check release note

internal/http/modify_response_writer.go

@@ -0,0 +1,96 @@
+// Modified from Traefik Labs's MIT-licensed code (https://github.com/traefik/traefik/blob/master/pkg/middlewares/response_modifier.go)
+// Copyright (c) 2020-2024 Traefik Labs
+
+package http
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"net/http"
+)
+
+type ModifyResponseFunc func(*http.Response) error
+type ModifyResponseWriter struct {
+	w http.ResponseWriter
+	r *http.Request
+
+	headerSent bool
+	code       int
+
+	modifier    ModifyResponseFunc
+	modified    bool
+	modifierErr error
+}
+
+func NewModifyResponseWriter(w http.ResponseWriter, r *http.Request, f ModifyResponseFunc) *ModifyResponseWriter {
+	return &ModifyResponseWriter{
+		w:        w,
+		r:        r,
+		modifier: f,
+		code:     http.StatusOK,
+	}
+}
+
+func (w *ModifyResponseWriter) WriteHeader(code int) {
+	if w.headerSent {
+		return
+	}
+
+	if code >= http.StatusContinue && code < http.StatusOK {
+		w.w.WriteHeader(code)
+	}
+
+	defer func() {
+		w.headerSent = true
+		w.code = code
+	}()
+
+	if w.modifier == nil || w.modified {
+		w.w.WriteHeader(code)
+		return
+	}
+
+	resp := http.Response{
+		Header:  w.w.Header(),
+		Request: w.r,
+	}
+
+	if err := w.modifier(&resp); err != nil {
+		w.modifierErr = err
+		logger.Errorf("error modifying response: %s", err)
+		w.w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	w.modified = true
+	w.w.WriteHeader(code)
+}
+
+func (w *ModifyResponseWriter) Header() http.Header {
+	return w.w.Header()
+}
+
+func (w *ModifyResponseWriter) Write(b []byte) (int, error) {
+	w.WriteHeader(w.code)
+	if w.modifierErr != nil {
+		return 0, w.modifierErr
+	}
+	return w.w.Write(b)
+}
+
+// Hijack hijacks the connection.
+func (w *ModifyResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	if h, ok := w.w.(http.Hijacker); ok {
+		return h.Hijack()
+	}
+
+	return nil, nil, fmt.Errorf("not a hijacker: %T", w.w)
+}
+
+// Flush sends any buffered data to the client.
+func (w *ModifyResponseWriter) Flush() {
+	if flusher, ok := w.w.(http.Flusher); ok {
+		flusher.Flush()
+	}
+}