package server

import (
	"io/fs"
	"net/http"
)

// filesOnly wraps an http.FileSystem so that directories do not exist as
// far as http.FileServer is concerned. FileServer asks the filesystem for
// the directory first and generates its index from what it gets back;
// refusing the Open is therefore the whole control, and it leaves the
// path handling, content sniffing and range support of FileServer intact.
//
// Enumerating what a binary ships is a capability no caller needs, and
// the embedded set grows as a project seeded from this template adds to
// it.
type filesOnly struct {
	inner http.FileSystem
}

// Open serves a file and refuses a directory with fs.ErrNotExist, which
// http.FileServer maps to 404 — the same answer a path that is not
// embedded at all gets.
func (f filesOnly) Open(name string) (http.File, error) {
	file, err := f.inner.Open(name)
	if err != nil {
		// Unwrapped on purpose: http.FileServer inspects this error,
		// and wrapping hides fs.ErrNotExist from it.
		//nolint:wrapcheck // see above.
		return nil, err
	}

	info, err := file.Stat()
	if err != nil {
		_ = file.Close()

		//nolint:wrapcheck // as above.
		return nil, err
	}

	if info.IsDir() {
		_ = file.Close()

		return nil, fs.ErrNotExist
	}

	return file, nil
}