// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fsys

import (
	"io/fs"
	"path/filepath"
)

// Copied from path/filepath.

// WalkDir is like filepath.WalkDir but over the virtual file system.
func WalkDir(root string, fn fs.WalkDirFunc) error {
	info, err := Lstat(root)
	if err != nil {
		err = fn(root, nil, err)
	} else {
		err = walkDir(root, fs.FileInfoToDirEntry(info), fn)
	}
	if err == filepath.SkipDir || err == filepath.SkipAll {
		return nil
	}
	return err
}

// walkDir recursively descends path, calling walkDirFn.
func walkDir(path string, d fs.DirEntry, walkDirFn fs.WalkDirFunc) error {
	if err := walkDirFn(path, d, nil); err != nil || !d.IsDir() {
		if err == filepath.SkipDir && d.IsDir() {
			// Successfully skipped directory.
			err = nil
		}
		return err
	}

	dirs, err := ReadDir(path)
	if err != nil {
		// Second call, to report ReadDir error.
		err = walkDirFn(path, d, err)
		if err != nil {
			if err == filepath.SkipDir && d.IsDir() {
				err = nil
			}
			return err
		}
	}

	for _, d1 := range dirs {
		path1 := filepath.Join(path, d1.Name())
		if err := walkDir(path1, d1, walkDirFn); err != nil {
			if err == filepath.SkipDir {
				break
			}
			return err
		}
	}
	return nil
}