package firewall

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
)

func stageFile(path string, data []byte) (string, error) {
	f, err := os.CreateTemp(filepath.Dir(path), ".debtik-*")
	if err != nil {
		return "", err
	}
	name := f.Name()
	_, err = f.Write(data)
	if err == nil {
		err = f.Sync()
	}
	closed := f.Close()
	if err == nil {
		err = closed
	}
	if err != nil {
		os.Remove(name)
		return "", err
	}
	return name, nil
}
func writeAtomic(path string, data []byte) error {
	name, err := stageFile(path, data)
	if err != nil {
		return err
	}
	defer os.Remove(name)
	return os.Rename(name, path)
}
func saveFileGroup(files map[string][]byte) error {
	staged := map[string]string{}
	original := map[string][]byte{}
	exists := map[string]bool{}
	defer func() {
		for _, name := range staged {
			os.Remove(name)
		}
	}()
	for path, data := range files {
		old, err := os.ReadFile(path)
		if err != nil && !os.IsNotExist(err) {
			return err
		}
		exists[path] = err == nil
		original[path] = old
		name, err := stageFile(path, data)
		if err != nil {
			return err
		}
		staged[path] = name
	}
	var renamed []string
	for path, name := range staged {
		if err := os.Rename(name, path); err != nil {
			failures := []error{err}
			for _, oldPath := range renamed {
				var restore error
				if exists[oldPath] {
					restore = writeAtomic(oldPath, original[oldPath])
				} else {
					restore = os.Remove(oldPath)
				}
				if restore != nil {
					failures = append(failures, fmt.Errorf("restore %s: %w", oldPath, restore))
				}
			}
			return errors.Join(failures...)
		}
		renamed = append(renamed, path)
	}
	return nil
}