package api

import (
	"bytes"
	"net/http"
)

// Only use for bounded JSON responses, never file or runtime streams. Register
// flush before lock-release defers so a slow client cannot hold storage locks.
func deferJSONResponse(w http.ResponseWriter) (http.ResponseWriter, func()) {
	b := &jsonResponseBuffer{ResponseWriter: w}
	return b, func() {
		if b.status != 0 {
			w.WriteHeader(b.status)
		}
		if b.body.Len() > 0 {
			_, _ = w.Write(b.body.Bytes())
		}
	}
}

type jsonResponseBuffer struct {
	http.ResponseWriter
	body   bytes.Buffer
	status int
}

func (w *jsonResponseBuffer) WriteHeader(status int) {
	if w.status == 0 {
		w.status = status
	}
}
func (w *jsonResponseBuffer) Write(p []byte) (int, error) {
	if w.status == 0 {
		w.status = http.StatusOK
	}
	return w.body.Write(p)
}
func (w *jsonResponseBuffer) Unwrap() http.ResponseWriter { return w.ResponseWriter }