package nomino

import (
	"crypto/rand"
	"strings"

	"github.com/deatil/go-encoding/base62"
	"github.com/google/uuid"
)

func uuidGen(*Config) (string, error) {
	u, err := uuid.NewRandom()
	if err != nil {
		return "", err
	}
	return u.String(), nil
}

// UUID generates a UUIDv4.
func UUID() Generator {
	return uuidGen
}

type randConf struct {
	length int
}

// RandomOption is an option for the Random Generator
type RandomOption func(*randConf)

// RandomLength controls the length of the string generated by Random
func RandomLength(length int) RandomOption {
	return func(c *randConf) {
		c.length = length
	}
}

func getRandomBytes(l int) []byte {
	key := make([]byte, l)
	rand.Read(key)
	e := base62.StdEncoding.Encode(key)
	return e[:l]
}

// Random generates a random string containing the characters [A-Za-z0-9].
// By default, it will be eight characters long.
func Random(opts ...RandomOption) Generator {
	c := randConf{8}
	for _, opt := range opts {
		opt(&c)
	}
	return func(*Config) (string, error) {
		var buff strings.Builder
		buff.Grow(c.length)
		for buff.Len() < c.length {
			buff.Write(getRandomBytes(c.length - buff.Len()))
		}
		return buff.String(), nil
	}
}