package scans

import (
	"encoding/hex"
	"fmt"
	"strconv"
	"strings"
)

// NormalizeMAC приводит ввод пользователя к виду aa:bb:cc:dd:ee:ff (как в FDB/ARP).
func NormalizeMAC(s string) string {
	s = strings.ToLower(strings.TrimSpace(s))
	if s == "" {
		return ""
	}
	s = strings.ReplaceAll(s, "-", ":")
	if strings.Count(s, ":") == 5 {
		parts := strings.Split(s, ":")
		if len(parts) != 6 {
			return ""
		}
		var b [6]byte
		for i, p := range parts {
			n, err := strconv.ParseUint(strings.TrimSpace(p), 16, 8)
			if err != nil {
				return ""
			}
			b[i] = byte(n)
		}
		return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x", b[0], b[1], b[2], b[3], b[4], b[5])
	}
	if strings.HasPrefix(s, "0x") {
		h := strings.TrimPrefix(s, "0x")
		h = strings.ReplaceAll(h, ":", "")
		if len(h) != 12 {
			return ""
		}
		raw, err := hex.DecodeString(h)
		if err != nil || len(raw) != 6 {
			return ""
		}
		return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x", raw[0], raw[1], raw[2], raw[3], raw[4], raw[5])
	}
	if len(s) == 12 {
		raw, err := hex.DecodeString(s)
		if err != nil || len(raw) != 6 {
			return ""
		}
		return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x", raw[0], raw[1], raw[2], raw[3], raw[4], raw[5])
	}
	return ""
}