package service

import (
	"crypto/rand"
	"math/big"
	"strings"
)

// Characters: A-H, J-N, P-Y, 2-9 (no O/0/I/1)
const keyChars = "ABCDEFGHJKMNPQRSTUVWXY23456789"

func GenerateKey(prefix string) (string, error) {
	groups := make([]string, 4)
	for i := range groups {
		group := make([]byte, 4)
		for j := range group {
			idx, err := rand.Int(rand.Reader, big.NewInt(int64(len(keyChars))))
			if err != nil {
				return "", err
			}
			group[j] = keyChars[idx.Int64()]
		}
		groups[i] = string(group)
	}
	return prefix + strings.Join(groups, "-"), nil
}