package utils

import (
	"crypto/rand"
	"encoding/base64"
	"math/big"
	"strconv"
	"strings"
)

var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

func RandString(length int) (string, error) {
	b := make([]rune, length)
	for i := range b {
		idx, err := rand.Int(rand.Reader, big.NewInt(int64(len(letterRunes))))
		if err != nil {
			return "", err
		}

		b[i] = letterRunes[idx.Int64()]
	}

	return string(b), nil
}

func IsInt(str string) bool {
	_, err := strconv.ParseInt(str, 10, 64)
	return err == nil
}

func Base64Decode(s string) string {
	b, err := base64.StdEncoding.DecodeString(s)
	if err != nil {
		return ""
	}
	return string(b)
}

func Base64Encode(s string) string {
	return base64.StdEncoding.EncodeToString([]byte(s))
}

func StringMax(str string, max int, suffix ...string) string {
	if len(str) > max {
		return str[:max] + strings.Join(suffix, "")
	}

	return str
}