package rand

import (
	"bytes"
	"math/rand"
	"time"
)

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

func (r *Rand) GetPassword(len int) string {
	base_num := "023456789"
	base_char_low := "abcdefghijkmnpqrstuvwxyz"
	base_char_high := "ABCDEFGHJKLMNOPQRSTUVWXYZ"
	base_sign_spec := "_"
	str := "023456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ_"
	var stringBuilder bytes.Buffer
	if len < 5 {
		len = 5
	}
	stringBuilder.WriteString(r.randomGetSomeChar(base_sign_spec, 1))
	stringBuilder.WriteString(r.randomGetSomeChar(base_num, 1))
	stringBuilder.WriteString(r.randomGetSomeChar(base_char_low, 1))
	stringBuilder.WriteString(r.randomGetSomeChar(base_char_high, 1))
	stringBuilder.WriteString(r.randomGetSomeChar(str, len-4))
	str_result := stringBuilder.String()
	arr_result := []byte(str_result)
	for i := 0; i < 4; i++ {
		num := rand.Intn(len - 1)
		arr_result[i], arr_result[num] = arr_result[num], arr_result[i]
	}
	return string(arr_result)
}