package tool

import (
	"fmt"
	"strings"
)

const deviceHashSalt uint32 = 0x5A3C7E9B

// DeviceIdToHash encodes a device id to an 8-char uppercase hex string.
// Algorithm mirrors frontend: id XOR salt → hex.
// e.g. 1 → "5A3C7E9A", 42 → "5A3C7EA1"
func DeviceIdToHash(id int64) string {
	return strings.ToUpper(fmt.Sprintf("%08x", uint32(id)^deviceHashSalt))
}

// HashToDeviceId decodes an 8-char hex hash back to a device id.
func HashToDeviceId(hash string) (int64, error) {
	var n uint32
	_, err := fmt.Sscanf(strings.ToLower(hash), "%08x", &n)
	if err != nil {
		return 0, err
	}
	return int64(n ^ deviceHashSalt), nil
}