package utils

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

// GenerateCode 生成指定长度的随机邀请码（大写字母+数字）
func GenerateCode(length int) (string, error) {
	const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	code := make([]byte, length)

	for i := 0; i < length; i++ {
		num, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
		if err != nil {
			return "", err
		}
		code[i] = charset[num.Int64()]
	}

	return string(code), nil
}