package rand

import (
	"bytes"
	"math/rand"
)

func (rr *Rand) randomGetSomeChar(str string, l int) string {
	bytes := []byte(str)
	var result []byte
	//r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := 0; i < l; i++ {
		//result = append(result, bytes[r.Intn(len(bytes))])
		result = append(result, bytes[rand.Intn(len(bytes))])
	}
	return string(result)
}

// 长度选填 默认32位
func (rr *Rand) GetPassword(length ...int) string {
	baseNum := "023456789"
	baseCharLow := "abcdefghijkmnpqrstuvwxyz"
	baseCharHigh := "ABCDEFGHJKLMNOPQRSTUVWXYZ"
	baseSignSpec := "_"
	str := "023456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ_"
	var stringBuilder bytes.Buffer
	lenPassword := 32
	if len(length) > 0 {
		lenPassword = length[0]
	}
	if lenPassword < 5 {
		lenPassword = 5
	}
	stringBuilder.WriteString(rr.randomGetSomeChar(baseSignSpec, 1))
	stringBuilder.WriteString(rr.randomGetSomeChar(baseNum, 1))
	stringBuilder.WriteString(rr.randomGetSomeChar(baseCharLow, 1))
	stringBuilder.WriteString(rr.randomGetSomeChar(baseCharHigh, 1))
	stringBuilder.WriteString(rr.randomGetSomeChar(str, lenPassword-4))
	strResult := stringBuilder.String()
	arrResult := []byte(strResult)
	for i := 0; i < 4; i++ {
		num := rand.Intn(lenPassword - 1)
		arrResult[i], arrResult[num] = arrResult[num], arrResult[i]
	}
	return string(arrResult)
}