//go:build !windows

package safeio

import (
	"os"
	"path/filepath"
)

// ProtectPrivateDirectory sets the private directory mode used for local authentication state.
func ProtectPrivateDirectory(path string) error {
	if err := ValidateCanonicalPath(path); err != nil {
		return err
	}
	if err := os.Chmod(path, 0o700); err != nil {
		return ErrUnsafeFile
	}
	return ValidatePrivateDirectory(path)
}

// ValidatePrivateDirectory requires a canonical, non-symlinked directory with no group or world access.
func ValidatePrivateDirectory(path string) error {
	if err := requireCanonicalDirectory(path); err != nil {
		return err
	}
	info, err := os.Lstat(path)
	if err != nil || !info.IsDir() || info.Mode()&os.ModeSymlink != 0 || !isExactPrivateMode(info.Mode(), 0o700) {
		return ErrUnsafeFile
	}
	return nil
}

// ProtectPrivateRegular sets the private file mode used for local authentication files.
func ProtectPrivateRegular(path string) error {
	if err := ValidateCanonicalPath(path); err != nil {
		return err
	}
	if err := os.Chmod(path, 0o600); err != nil {
		return ErrUnsafeFile
	}
	return ValidatePrivateRegular(path)
}

// ValidatePrivateRegular requires a canonical, single-link private regular file.
func ValidatePrivateRegular(path string) error {
	if err := ValidateCanonicalPath(path); err != nil {
		return err
	}
	if err := requireCanonicalDirectory(filepath.Dir(path)); err != nil {
		return err
	}
	info, err := os.Lstat(path)
	if err != nil || !info.Mode().IsRegular() || info.Mode()&os.ModeSymlink != 0 || !hasSingleLink(info) || !isExactPrivateMode(info.Mode(), 0o600) {
		return ErrUnsafeFile
	}
	return nil
}

func isExactPrivateMode(mode os.FileMode, permissions os.FileMode) bool {
	return mode.Perm() == permissions && mode&(os.ModeSetuid|os.ModeSetgid|os.ModeSticky) == 0
}