package normalize

import (
	"strings"
)

// NormalizeMAC converts supported MAC forms to canonical lower-case colon-separated form.
// Accepts: xx:xx:xx:xx:xx:xx, xx-xx-xx-xx-xx-xx, xxxx.xxxx.xxxx
func NormalizeMAC(s string) (string, bool) {
	s = strings.TrimSpace(s)
	if s == "" {
		return "", false
	}
	s = strings.ToLower(s)

	// remove common separators
	s = strings.ReplaceAll(s, ":", "")
	s = strings.ReplaceAll(s, "-", "")
	s = strings.ReplaceAll(s, ".", "")

	if len(s) != 12 {
		return "", false
	}
	for i := 0; i < 12; i++ {
		c := s[i]
		if (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') {
			continue
		}
		return "", false
	}

	// canonical form aa:bb:cc:dd:ee:ff
	var b strings.Builder
	b.Grow(17)
	for i := 0; i < 12; i += 2 {
		if i > 0 {
			b.WriteByte(':')
		}
		b.WriteByte(s[i])
		b.WriteByte(s[i+1])
	}
	return b.String(), true
}