// Copyright (C) 2023-2024  Umorpha Systems
// SPDX-License-Identifier: AGPL-3.0-or-later

package source

import (
	"archive/tar"
	"bytes"
	"embed"
	"io"
	"path"
	"sort"
	"strings"
)

func readFile(fs embed.FS, filename string) []byte {
	// No need to bother checking for errors--an embed.FS will
	// never have an error other than "file does not exist", and
	// it's a programming error (not a runtime error) to call this
	// function for a file that doesn't exist.
	fh, _ := fs.Open(filename)
	ret, _ := io.ReadAll(fh)
	_ = fh.Close()
	return ret
}

func genTar(fn func(w *tar.Writer)) []byte {
	var buf bytes.Buffer
	w := tar.NewWriter(&buf)
	fn(w)
	_ = w.Close()
	return buf.Bytes()
}

func tarDir(w *tar.Writer, fs embed.FS, fsDir, tarPrefix string) {
	w.WriteHeader(&tar.Header{
		Typeflag: tar.TypeDir,
		Name:     tarPrefix,
		Mode:     0755,
	})

	entries, _ := fs.ReadDir(fsDir)
	var names []string
	for _, entry := range entries {
		name := entry.Name()
		if entry.IsDir() {
			name += "/"
		}
		names = append(names, name)
	}
	sort.Strings(names)

	for _, name := range names {
		fpath := path.Join(fsDir, name)
		if strings.HasSuffix(name, "/") {
			tarDir(w, fs, fpath, tarPrefix+name)
		} else {
			fb := readFile(fs, fpath)
			w.WriteHeader(&tar.Header{
				Typeflag: tar.TypeReg,
				Name:     tarPrefix + name,
				Size:     int64(len(fb)),
				Mode:     0644,
			})
			_, _ = w.Write(fb)
		}
	}
}

var Tarball = genTar(func(w *tar.Writer) { tarDir(w, fs, ".", "eclipse/") })