package random

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

const letterBytesAll = "0123456789abcdefghijklmnopqrstvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

func init() {
	rand.Seed(time.Now().Unix())
}

func Int(n int) int {
	return rand.Intn(n)
}

func SliceRand(ids []int64) (result []int64) {
	result = make([]int64, 0)
	if len(ids) <= 0 {
		return
	}
	copy := make([]int64, 0)
	for _, id := range ids {
		copy = append(copy, id)
	}
	num := Int(len(copy)) + 1
	for i := 0; i < num; i++ {
		index := Int(len(copy))
		result = append(result, copy[index])
		copy = append(copy[:index], copy[index+1:]...)
	}
	return
}

func RandDigits(n uint) string {
	s := ""
	for n != 0 {
		s += fmt.Sprintf("%d", rand.Intn(10))
		n--
	}
	return s
}

// RandStrRandrAll 生成指定位数的随机数
func RandStrRandrAll(n int) string {
	b := make([]byte, n)
	for i := range b {
		b[i] = letterBytesAll[rand.Int63()%int64(len(letterBytesAll))]
	}
	return string(b)
}