func notFound(ci inject.CopyInject, templates *template.Template, w http.ResponseWriter) error {
	err := ci.ServeTemplate(http.StatusNotFound, w, templates.Lookup("404.html"), nil)
	if err != nil {
		return err
	}
	return nil
}

func dirList(ci inject.CopyInject, logger termlog.Logger, w http.ResponseWriter, name string, f http.File, templates *template.Template) {
	w.Header().Set("Cache-Control", "no-store, must-revalidate")
	files, err := f.Readdir(0)
	if err != nil {
		logger.Shout("Error reading directory for listing: %s", err)
		return
	}
	data := dirData{Name: name, Files: files}
	buff := bytes.NewBuffer(make([]byte, 0, 0))
	err = templates.Lookup("dirlist.html").Execute(buff, data)
	length := buff.Len()
	if err != nil {
		logger.Shout("Error producing directory listing: %s", err)
	}
	inj, err := ci.Sniff(buff)
	if err != nil {
		logger.Shout("Failed to inject in dir listing: %s", err)
		return
	}
	w.Header().Set(
		"Content-Length", fmt.Sprintf("%d", length+inj.Extra()),
	)
	_, err = inj.Copy(w)
	if err != nil {
		logger.Shout("Failed to inject in dir listing: %s", err)
		return
	}
}

func dirList(ci inject.CopyInject, logger termlog.Logger, w http.ResponseWriter, name string, f http.File, templates *template.Template) {
	w.Header().Set("Cache-Control", "no-store, must-revalidate")
	files, err := f.Readdir(0)
	if err != nil {
		logger.Shout("Error reading directory for listing: %s", err)
		return
	}
	data := dirData{Name: name, Files: files}
	err = ci.ServeTemplate(http.StatusOK, w, templates.Lookup("dirlist.html"), data)
	if err != nil {
		logger.Shout("Failed to generate dir listing: %s", err)
	}
}

// if name is empty, filename is unknown. (used for mime type, before sniffing)
// if modtime.IsZero(), modtime is unknown.
// content must be seeked to the beginning of the file.
// The sizeFunc is called at most once. Its error, if any, is sent in the HTTP response.
func serveContent(ci inject.CopyInject, w http.ResponseWriter, r *http.Request, name string, modtime time.Time, sizeFunc func() (int64, error), content io.ReadSeeker) error {
	if checkLastModified(w, r, modtime) {
		return nil
	}
	done := checkETag(w, r)
	if done {
		return nil
	}

	code := http.StatusOK

	// If Content-Type isn't set, use the file's extension to find it, but
	// if the Content-Type is unset explicitly, do not sniff the type.
	ctypes, haveType := w.Header()["Content-Type"]
	var ctype string
	if !haveType {
		ctype = mime.TypeByExtension(filepath.Ext(name))
		if ctype == "" {
			// read a chunk to decide between utf-8 text and binary
			var buf [sniffLen]byte
			n, _ := io.ReadFull(content, buf[:])
			ctype = http.DetectContentType(buf[:n])
			_, err := content.Seek(0, os.SEEK_SET) // rewind to output whole file
			if err != nil {
				http.Error(w, "seeker can't seek", http.StatusInternalServerError)
				return err
			}
		}
		w.Header().Set("Content-Type", ctype)
	} else if len(ctypes) > 0 {
		ctype = ctypes[0]
	}

	injector, err := ci.Sniff(content)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return err
	}

	size, err := sizeFunc()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return err
	}

	if injector.Found {
		size = size + int64(injector.Extra())
	}

	if size >= 0 {
		if w.Header().Get("Content-Encoding") == "" {
			w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
		}
	}

	w.WriteHeader(code)
	if r.Method != "HEAD" {
		_, err := injector.Copy(w)
		if err != nil {
			return err
		}
	}
	return nil
}