// Copyright 2025 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.

package osutil

import (
	"archive/tar"
	"compress/gzip"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
)

func TarGzDirectory(dir string, writer io.Writer) error {
	gzw := gzip.NewWriter(writer)
	defer gzw.Close()
	return tarDirectory(dir, gzw)
}

func tarDirectory(dir string, writer io.Writer) error {
	tw := tar.NewWriter(writer)
	defer tw.Close()

	return filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
		if err != nil || path == dir {
			return err
		}
		typ := d.Type()
		if !typ.IsDir() && !typ.IsRegular() {
			// Only folders and regular files.
			return nil
		}
		relPath, err := filepath.Rel(dir, path)
		if err != nil {
			return err
		}
		relPath = filepath.ToSlash(relPath)
		info, err := d.Info()
		if err != nil {
			return err
		}
		header, err := tar.FileInfoHeader(info, "")
		if err != nil {
			return err
		}
		header.Name = relPath
		if typ.IsDir() && !strings.HasSuffix(header.Name, "/") {
			header.Name += "/"
		}
		if err := tw.WriteHeader(header); err != nil {
			return err
		}
		if typ.IsDir() {
			return nil
		}
		// Write the file content.
		f, err := os.Open(path)
		if err != nil {
			return err
		}
		_, err = io.Copy(tw, f)
		f.Close()
		return err
	})
}