package util

import (
	"errors"
	"fmt"
	"runtime"

	"golang.org/x/sys/windows/registry"
)

func OSVersion() (string, error) {
	switch osName := runtime.GOOS; osName {
	case "windows":
		verKey, err := registry.OpenKey(registry.LOCAL_MACHINE, "Software\\Microsoft\\Windows NT\\CurrentVersion", registry.QUERY_VALUE)
		if err != nil {
			return "", err
		}
		major, _, err := verKey.GetIntegerValue("CurrentMajorVersionNumber")
		if err != nil {
			return "", err
		}
		minor, _, err := verKey.GetIntegerValue("CurrentMinorVersionNumber")
		if err != nil {
			return "", err
		}
		return fmt.Sprintf("%d.%d", major, minor), nil
	}
	return "", errors.New("unknown OS")
}