package links

import (
	"crypto/rand"
	"fmt"
	"math/big"
	"regexp"
)

const codeLength = 5

var (
	alphabet       = "ABCDEFGHJKMNPQRSTUVWXYZ23456789"
	alphabetLength = big.NewInt(int64(len(alphabet)))
	ValidShortCode = regexp.MustCompile(fmt.Sprintf(`^/[%s]{%d}$`, alphabet, codeLength))
)

func randInt() int {
	p, err := rand.Int(rand.Reader, alphabetLength)
	if err != nil {
		panic(err.Error())
	}

	return int(p.Int64())
}

func GenCode() string {
	var code []byte
	for i := 0; i < codeLength; i++ {
		code = append(code, alphabet[randInt()])
	}
	return string(code)
}