package utils

import (
	crand "crypto/rand"
	"fmt"
	"math"
	"math/big"
	"math/rand"
	"strconv"
	"time"
)

func RandString(l int, c ...string) string {
	var (
		chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
		str   string
		num   *big.Int
	)
	if len(c) > 0 {
		chars = c[0]
	}
	chrLen := int64(len(chars))
	for len(str) < l {
		num, _ = crand.Int(crand.Reader, big.NewInt(chrLen))
		str += string(chars[num.Int64()])
	}
	return str
}

func RandNum() string {
	seed := time.Now().UnixNano() + rand.Int63()
	return fmt.Sprintf("%05v", rand.New(rand.NewSource(seed)).Int31n(1000000))
}

func GenerateUniqueRandomNumbers(n int) string {
	rand.Seed(time.Now().UnixNano() + rand.Int63()) // 初始化随机种子

	numbers := make([]int, 0, n) // 创建一个切片来保存随机数，初始容量为n
	used := make(map[int]bool)   // 跟踪已使用的数字

	for len(numbers) < n {
		b := rand.Intn(10) // 生成0-9之间的随机数
		if !used[b] {
			numbers = append(numbers, b)
			used[b] = true
		}
	}

	var numbersStr string
	for _, v := range numbers {
		numbersStr += strconv.Itoa(v)
	}

	return numbersStr
}

func RoundToTwoDecimalPlaces(num float64) float64 {
	return math.Round(num*100) / 100
}