// IP段
'1', '2020-11-26 17:11:39.515', '2020-11-26 17:11:39.515', '1.0.1.0', '1.0.3.255', '福建', '電信'
'2', '2020-11-26 17:11:43.553', '2020-11-26 17:11:43.553', '1.0.8.0', '1.0.15.255', '廣東', '電信'
'3', '2020-11-26 17:11:47.563', '2020-11-26 17:11:47.563', '1.0.32.0', '1.0.63.255', '廣東', '電信'
'4', '2020-11-26 17:11:53.621', '2020-11-26 17:11:53.621', '1.1.0.0', '1.1.0.255', '福建', '電信'
'5', '2020-11-26 17:11:57.635', '2020-11-26 17:11:57.635', '1.1.2.0', '1.1.7.255', '福建', '電信'
'6', '2020-11-26 17:11:59.642', '2020-11-26 17:11:59.642', '1.1.8.0', '1.1.63.255', '廣東', '電信'
'7', '2020-11-26 17:12:05.671', '2020-11-26 17:12:05.671', '1.2.0.0', '1.2.1.255', '福建', '電信'
'8', '2020-11-26 17:12:07.674', '2020-11-26 17:12:07.674', '1.2.2.0', '1.2.2.255', '北京', '聯通'
'9', '2020-11-26 17:12:13.690', '2020-11-26 17:12:13.690', '1.2.5.0', '1.2.7.255', '北京', '電信'

// 單個ping
// IsAlivePing : 檢測目標IP是否能夠ping通，target為目標IP
func IsAlivePing(target string) (bool, error) {
 pinger, err := ping.NewPinger(target)
 if err != nil {
 return false, err
 }
 pinger.Count = 10
 PINGTIME := time.Duration(1000)
 pinger.Timeout = time.Duration(PINGTIME * time.Millisecond)
 pinger.SetPrivileged(true) // 選擇icmp，不選擇udp
 pinger.Run()
 stats := pinger.Statistics()
 // 判斷是否有接收到的包
 if stats.PacketsRecv >= 1 {
 return true, nil
 }
 return false, nil
}

// 多個ping：得到死IP
// FilterActiveIPs : 過濾活IP，篩選出死IP
func FilterActiveIPs(ips []string) (inactiveIPs []string) {
 var lock sync.Mutex
 var wg sync.WaitGroup
 wg.Add(len(ips))
 for _, ip := range ips {
 go func(ip string) {
 defer wg.Done()
 // 判斷是死ip，并且格式正確
 isAlive, err := IsAlivePing(ip)
 if !isAlive  err == nil {
 RandomSleep(2) // 睡眠[1,2]秒，二次確認是否為死IP
 if isAlive, _ := IsAlivePing(ip); !isAlive {
  RandomSleep(2) // 再睡眠[1,2]秒，三次確認是否為死IP
  if isAlive, _ := IsAlivePing(ip); !isAlive {
  lock.Lock()
  defer lock.Unlock()
  inactiveIPs = append(inactiveIPs, ip)
  }
 }
 }
 }(ip)
 }
 wg.Wait()
 return inactiveIPs
}

// 多個ping：得到活IP
// FilterInactiveIPs : 過濾死IP，篩選出活IP
func FilterInactiveIPs(ips []string) (activeIPs []string) {
 var lock sync.Mutex
 var wg sync.WaitGroup
 wg.Add(len(ips))
 for _, ip := range ips {
 go func(ip string) {
 defer wg.Done()
 // 判斷是活ip，并且格式正確
 if isAlive, err := IsAlivePing(ip); isAlive  err == nil {
 lock.Lock()
 defer lock.Unlock()
 activeIPs = append(activeIPs, ip)
 }
 }(ip)
 }
 wg.Wait()
 return activeIPs
}

// RandomSleep : 隨機睡眠[1,t]秒
func RandomSleep(t int) {
 rand.Seed(time.Now().UnixNano())
 r := time.Duration(rand.Intn(t) + 1)
 time.Sleep(r * time.Second)
}

// Separation : 分解IP段
func (i *impl) Separation(minIP, maxIP string) []string {
	shouldStrs := make([]string, 0) // 這是IP段的所有IP
	// for i := 0; i  l; i = i + 2 {
	min, _ := IPString2Long(minIP) // 這里有一個轉化，我默認給的是正確的IP，如果兄弟們不確定傳入的IP格式是否正確，那么要判斷err
	max, _ := IPString2Long(maxIP)
	for min = max {
		minIPstr, _ := Long2IPString(min)
		xxxip := net.ParseIP(minIPstr).To4()
		if xxxip[3] != 0  xxxip[3] != 255 { // 兄弟們，這個判斷取決于你們想不想要兩個端點
			shouldStrs = append(shouldStrs, minIPstr)
		}
		min++
	}

 // TODO： 兄弟們，可以把這句刪除了
	fmt.Printf("IP段%s--%s不包括兩端的長度: %d\n", minIP, maxIP, len(shouldStrs))
	return shouldStrs
}

// Long2IPString 把數值轉為ip字符串
func Long2IPString(i uint) (string, error) {
	if i > math.MaxUint32 {
		return "", errors.New("beyond the scope of ipv4")
	}

	ip := make(net.IP, net.IPv4len)
	ip[0] = byte(i >> 24)
	ip[1] = byte(i >> 16)
	ip[2] = byte(i >> 8)
	ip[3] = byte(i)

	return ip.String(), nil
}

// IPString2Long 把ip字符串轉為數值
func IPString2Long(ip string) (uint, error) {
	b := net.ParseIP(ip).To4()
	if b == nil {
		return 0, errors.New("invalid ipv4 format")
	}

	return uint(b[3]) | uint(b[2])8 | uint(b[1])16 | uint(b[0])24, nil
}