//go:build windows

package backup

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

	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
	"golang.org/x/sys/windows"
)

func replaceRestoreFile(target string, contents []byte, mode os.FileMode) error {
	if safeio.ValidateCanonicalPath(target) != nil || mode&os.ModeType != 0 || mode.Perm() == 0 {
		return safeio.ErrUnsafeFile
	}
	parent := filepath.Dir(target)
	resolved, err := filepath.EvalSymlinks(parent)
	if err != nil || resolved != parent || !safeWindowsRestoreTarget(target) {
		return safeio.ErrUnsafeFile
	}
	temporary, err := os.CreateTemp(parent, ".tht-restore-*.tmp")
	if err != nil {
		return safeio.ErrUnsafeFile
	}
	temporaryPath := temporary.Name()
	defer os.Remove(temporaryPath)
	if err := temporary.Chmod(mode.Perm()); err == nil {
		_, err = temporary.Write(contents)
	}
	if err == nil {
		err = temporary.Sync()
	}
	closeErr := temporary.Close()
	if err == nil {
		err = closeErr
	}
	if err != nil || !safeWindowsRestoreTarget(target) {
		return safeio.ErrUnsafeFile
	}
	from, fromErr := windows.UTF16PtrFromString(temporaryPath)
	to, toErr := windows.UTF16PtrFromString(target)
	if fromErr != nil || toErr != nil {
		return safeio.ErrUnsafeFile
	}
	if err := windows.MoveFileEx(from, to, windows.MOVEFILE_REPLACE_EXISTING|windows.MOVEFILE_WRITE_THROUGH); err != nil {
		return safeio.ErrUnsafeFile
	}
	return nil
}

func safeWindowsRestoreTarget(target string) bool {
	info, err := os.Lstat(target)
	if errors.Is(err, os.ErrNotExist) {
		return true
	}
	return err == nil && info.Mode().IsRegular() && info.Mode()&os.ModeSymlink == 0
}