package utils

import (
	"crypto/md5" // #nosec
	"encoding/hex"
	"math/rand"
	"os"
	"regexp"
	"strings"
	"time"
	"unsafe"

	jsoniter "github.com/json-iterator/go"
)

var Json = jsoniter.ConfigCompatibleWithStandardLibrary

const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)

func RandStringBytesMaskImprSrcUnsafe(n int) string {
	var src = rand.NewSource(time.Now().UnixNano())
	b := make([]byte, n)

	// A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = src.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return *(*string)(unsafe.Pointer(&b)) //#nosec
}

func MD5(plantext string) string {
	hash := md5.New() // #nosec
	hash.Write([]byte(plantext))
	return hex.EncodeToString(hash.Sum(nil))
}

func IsWindows() bool {
	return os.PathSeparator == '\\' && os.PathListSeparator == ';'
}

var ipv4Re = regexp.MustCompile(`(\d*\.).*(\.\d*)`)

func ipv4Desensitize(ipv4Addr string) string {
	return ipv4Re.ReplaceAllString(ipv4Addr, "$1****$2")
}

var ipv6Re = regexp.MustCompile(`(\w*:\w*:).*(:\w*:\w*)`)

func ipv6Desensitize(ipv6Addr string) string {
	return ipv6Re.ReplaceAllString(ipv6Addr, "$1****$2")
}

func IPDesensitize(ipAddr string) string {
	ipAddr = ipv4Desensitize(ipAddr)
	ipAddr = ipv6Desensitize(ipAddr)
	return ipAddr
}

// SplitIPAddr 传入/分割的v4v6混合地址，返回v4和v6地址与有效地址
func SplitIPAddr(v4v6Bundle string) (string, string, string) {
	ipList := strings.Split(v4v6Bundle, "/")
	ipv4 := ""
	ipv6 := ""
	validIP := ""
	if len(ipList) > 1 {
		// 双栈
		ipv4 = ipList[0]
		ipv6 = ipList[1]
		validIP = ipv4
	} else if len(ipList) == 1 {
		// 仅ipv4|ipv6
		if strings.Contains(ipList[0], ":") {
			ipv6 = ipList[0]
			validIP = ipv6
		} else {
			ipv4 = ipList[0]
			validIP = ipv4
		}
	}
	return ipv4, ipv6, validIP
}

func IsFileExists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}