// Package probing is a simple but powerful ICMP echo (ping) library.
//
// Here is a very simple example that sends and receives three packets:
//
//	pinger, err := probing.NewPinger("www.google.com")
//	if err != nil {
//		panic(err)
//	}
//	pinger.Count = 3
//	err = pinger.Run() // blocks until finished
//	if err != nil {
//		panic(err)
//	}
//	stats := pinger.Statistics() // get send/receive/rtt stats
//
// Here is an example that emulates the traditional UNIX ping command:
//
//	pinger, err := probing.NewPinger("www.google.com")
//	if err != nil {
//		panic(err)
//	}
//	// Listen for Ctrl-C.
//	c := make(chan os.Signal, 1)
//	signal.Notify(c, os.Interrupt)
//	go func() {
//		for _ = range c {
//			pinger.Stop()
//		}
//	}()
//	pinger.OnRecv = func(pkt *probing.Packet) {
//		fmt.Printf("%d bytes from %s: icmp_seq=%d time=%v\n",
//			pkt.Nbytes, pkt.IPAddr, pkt.Seq, pkt.Rtt)
//	}
//	pinger.OnFinish = func(stats *probing.Statistics) {
//		fmt.Printf("\n--- %s ping statistics ---\n", stats.Addr)
//		fmt.Printf("%d packets transmitted, %d packets received, %v%% packet loss\n",
//			stats.PacketsSent, stats.PacketsRecv, stats.PacketLoss)
//		fmt.Printf("round-trip min/avg/max/stddev = %v/%v/%v/%v\n",
//			stats.MinRtt, stats.AvgRtt, stats.MaxRtt, stats.StdDevRtt)
//	}
//	fmt.Printf("PING %s (%s):\n", pinger.Addr(), pinger.IPAddr())
//	err = pinger.Run()
//	if err != nil {
//		panic(err)
//	}
//
// It sends ICMP Echo Request packet(s) and waits for an Echo Reply in response.
// If it receives a response, it calls the OnRecv callback. When it's finished,
// it calls the OnFinish callback.
//
// For a full ping example, see "cmd/ping/ping.go".
package probing

import (
	"errors"
	"math"
	"math/rand"
	"net"
	"sync"
	"sync/atomic"
	"time"
	"trial/ping/probing/icmp"

	"golang.org/x/sync/errgroup"
)

var receive_buffer_count = mcfg.GetInt("ping.recv.buf.count", 500)
var ping_ttl = mcfg.GetInt("ping.ttl", 64)

// var ping_interval = mcfg.GetDuration("ping.interval", 1000*time.Millisecond)
// var concurlimit_ping = mcfg.GetInt("concurlimit.ping", 100)
// var concurchan_ping = make(chan struct{}, concurlimit_ping)
// var lastpingtimemutex sync.Mutex
// var lastpingtime = map[string]time.Time{}

// var ETIMEDOUT error = fmt.Errorf("timeout")

// const (
// 	timeSliceLength = 8
// 	trackerLength   = len(uuid.UUID{})
// )

// New returns a new Pinger struct pointer.
func New(addr string) *Pinger {
	r := rand.New(rand.NewSource(getSeed()))
	return &Pinger{
		Count:      -1,
		Interval:   time.Second,
		RecordRtts: true,
		Size:       64, // timeSliceLength + trackerLength,
		Timeout:    time.Duration(math.MaxInt64),

		addr:     addr,
		done:     make(chan interface{}),
		id:       r.Intn(math.MaxUint16),
		ipaddr:   nil,
		ipv4:     false,
		network:  "ip",
		protocol: "udp",
	}
}

// NewPinger returns a new Pinger and resolves the address.
func NewPinger(addr string) (*Pinger, error) {
	p := New(addr)
	return p, p.Resolve()
}

// Pinger represents a packet sender/receiver.
type Pinger struct {
	// Size of packet being sent
	Size int

	// Interval is the wait time between each packet send. Default is 1s.
	Interval time.Duration

	// Timeout specifies a timeout before ping exits, regardless of how many
	// packets have been received.
	Timeout time.Duration

	// Count tells pinger to stop after sending (and receiving) Count echo
	// packets. If this option is not specified, pinger will operate until
	// interrupted.
	Count int

	// Number of packets sent
	PacketsSent int

	// Number of packets received
	PacketsRecv int

	// Number of duplicate packets received
	PacketsRecvDuplicates int

	// Round trip time statistics
	minRtt    time.Duration
	maxRtt    time.Duration
	avgRtt    time.Duration
	stdDevRtt time.Duration
	stddevm2  time.Duration
	statsMu   sync.RWMutex

	// If true, keep a record of rtts of all received packets.
	// Set to false to avoid memory bloat for long running pings.
	RecordRtts bool

	// rtts is all of the Rtts
	rtts []time.Duration

	// OnSetup is called when Pinger has finished setting up the listening socket
	OnSetup func()

	// OnSend is called when Pinger sends a packet
	OnSend func(*Packet)

	// OnRecv is called when Pinger receives and processes a packet
	OnRecv func(*Packet)

	// OnRecv is called when Pinger receives and processes a packet
	OnTimeout func(*Packet)

	// OnFinish is called when Pinger exits
	OnFinish func(*Statistics)

	// OnDuplicateRecv is called when a packet is received that has already been received.
	OnDuplicateRecv func(*Packet)

	// Source is the source IP address
	Source string

	// Channel and mutex used to communicate when the Pinger should stop between goroutines.
	done chan interface{}
	lock sync.Mutex

	ipaddr *net.IPAddr
	addr   string

	ipv4          bool
	id            int
	sequence_base int
	// network is one of "ip", "ip4", or "ip6".
	network string
	// protocol is "icmp" or "udp".
	protocol string
}

// Packet represents a received and processed ICMP echo packet.
type Packet struct {
	// Host is the string address of the host being pinged.
	Host string
	// IPAddr is the address of the host being pinged.
	IPAddr *net.IPAddr
	// ID is the ICMP identifier.
	ID int
	// Seq is the ICMP sequence number.
	Seq int
	// NBytes is the number of bytes in the message.
	Nbytes int
	// TTL is the Time To Live on the packet.
	TTL int
	// Rtt is the round-trip time it took to ping.
	Rtt time.Duration
}

// Statistics represent the stats of a currently running or finished
// pinger operation.
type Statistics struct {
	// PacketsRecv is the number of packets received.
	PacketsRecv int

	// PacketsSent is the number of packets sent.
	PacketsSent int

	// PacketsRecvDuplicates is the number of duplicate responses there were to a sent packet.
	PacketsRecvDuplicates int

	// PacketLoss is the percentage of packets lost.
	PacketLoss float64

	// IPAddr is the address of the host being pinged.
	IPAddr *net.IPAddr

	// Addr is the string address of the host being pinged.
	Addr string

	// Rtts is all of the round-trip times sent via this pinger.
	Rtts []time.Duration

	// MinRtt is the minimum round-trip time sent via this pinger.
	MinRtt time.Duration

	// MaxRtt is the maximum round-trip time sent via this pinger.
	MaxRtt time.Duration

	// AvgRtt is the average round-trip time sent via this pinger.
	AvgRtt time.Duration

	// StdDevRtt is the standard deviation of the round-trip times sent via
	// this pinger.
	StdDevRtt time.Duration
}

func (p *Pinger) updateStatistics(pkt *Packet) {
	p.statsMu.Lock()
	defer p.statsMu.Unlock()

	p.PacketsRecv++
	if p.RecordRtts {
		// p.rtts = append(p.rtts, pkt.Rtt)
		p.rtts[pkt.Seq] = pkt.Rtt
	}

	if p.PacketsRecv == 1 || pkt.Rtt < p.minRtt {
		p.minRtt = pkt.Rtt
	}

	if pkt.Rtt > p.maxRtt {
		p.maxRtt = pkt.Rtt
	}

	pktCount := time.Duration(p.PacketsRecv)
	// welford's online method for stddev
	// https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm
	delta := pkt.Rtt - p.avgRtt
	p.avgRtt += delta / pktCount
	delta2 := pkt.Rtt - p.avgRtt
	p.stddevm2 += delta * delta2

	p.stdDevRtt = time.Duration(math.Sqrt(float64(p.stddevm2 / pktCount)))
}

// SetIPAddr sets the ip address of the target host.
func (p *Pinger) SetIPAddr(ipaddr *net.IPAddr) {
	p.ipv4 = isIPv4(ipaddr.IP)

	p.ipaddr = ipaddr
	p.addr = ipaddr.String()
}

// IPAddr returns the ip address of the target host.
func (p *Pinger) IPAddr() *net.IPAddr {
	return p.ipaddr
}

// Resolve does the DNS lookup for the Pinger address and sets IP protocol.
func (p *Pinger) Resolve() error {
	if len(p.addr) == 0 {
		return errors.New("addr cannot be empty")
	}
	ipaddr, err := net.ResolveIPAddr(p.network, p.addr)
	if err != nil {
		return err
	}

	p.ipv4 = isIPv4(ipaddr.IP)

	p.ipaddr = ipaddr

	return nil
}

// SetAddr resolves and sets the ip address of the target host, addr can be a
// DNS name like "www.google.com" or IP like "127.0.0.1".
func (p *Pinger) SetAddr(addr string) error {
	oldAddr := p.addr
	p.addr = addr
	err := p.Resolve()
	if err != nil {
		p.addr = oldAddr
		return err
	}
	return nil
}

// Addr returns the string ip address of the target host.
func (p *Pinger) Addr() string {
	return p.addr
}

// SetNetwork allows configuration of DNS resolution.
// * "ip" will automatically select IPv4 or IPv6.
// * "ip4" will select IPv4.
// * "ip6" will select IPv6.
func (p *Pinger) SetNetwork(n string) {
	switch n {
	case "ip4":
		p.network = "ip4"
	case "ip6":
		p.network = "ip6"
	default:
		p.network = "ip"
	}
}

/*
	https://stackoverflow.com/questions/41423637/go-ping-library-for-unprivileged-icmp-ping-in-golang/41425527#41425527
	This library attempts to send an "unprivileged" ping via UDP. On linux, this must be enabled by setting
	sudo sysctl -w net.ipv4.ping_group_range="0   2147483647"
	If you do not wish to do this, you can set pinger.SetPrivileged(true) and use setcap to allow your binary using go-ping to bind to raw sockets (or just run as super-user):
	setcap cap_net_raw=+ep /bin/goping-binary
	getcap /bin/goping-binary to validate
*/
// SetPrivileged sets the type of ping pinger will send.
// false means pinger will send an "unprivileged" UDP ping.
// true means pinger will send a "privileged" raw ICMP ping.
// NOTE: setting to true requires that it be run with super-user privileges.
func (p *Pinger) SetPrivileged(privileged bool) {
	if privileged {
		p.protocol = "icmp"
	} else {
		p.protocol = "udp"
	}
}

// Privileged returns whether pinger is running in privileged mode.
func (p *Pinger) Privileged() bool {
	return p.protocol == "icmp"
}

// SetID sets the ICMP identifier.
func (p *Pinger) SetID(id int) {
	p.id = id
}

// ID returns the ICMP identifier.
func (p *Pinger) ID() int {
	return p.id
}

var pingipmtx sync.Mutex
var pingips = map[string]chan interface{}{}
var pingads = map[string]chan interface{}{}

// Run runs the pinger. This is a blocking function that will exit when it's
// done. If Count or Interval are not specified, it will run continuously until
// it is interrupted.
func (p *Pinger) Run() (err error) {
	// 同一地址，只能有一个实例运行，排队等待
	pingipmtx.Lock()
	pingipchan := pingips[p.ipaddr.String()]
	if pingipchan == nil {
		pingipchan = make(chan interface{}, 1)
		pingips[p.ipaddr.String()] = pingipchan
	}
	pingadchan := pingads[p.addr]
	if pingadchan == nil {
		pingadchan = make(chan interface{}, 1)
		pingads[p.addr] = pingadchan
	}
	pingipmtx.Unlock()
	pingipchan <- 1
	pingadchan <- 1
	var last_send_time time.Time
	defer func() {
		d := p.Interval - time.Since(last_send_time)
		if d > 0 {
			time.Sleep(d) // 两次运行之间至少间隔
		}
		<-pingipchan
		<-pingadchan
	}()
	// sleeptime := time.Duration(0)
	// for sleeptime >= 0 {
	// 	time.Sleep(sleeptime)
	// 	lastpingtimemutex.Lock()
	// 	alastpingtime := lastpingtime[p.ipaddr.String()]
	// 	sleeptime = ping_interval_one_host - time.Since(alastpingtime)
	// 	if sleeptime <= 0 {
	// 		lastpingtime[p.ipaddr.String()] = time.Now()
	// 	} else {
	// 		// logger.Error(fmt.Sprint("ping", p.addr, "[", p.ipaddr.String(), "]", "同一地址至少间隔一秒"))
	// 	}
	// 	lastpingtimemutex.Unlock()
	// }
	// defer func() {
	// 	lastpingtimemutex.Lock()
	// 	lastpingtime[p.ipaddr.String()] = time.Now()
	// 	lastpingtimemutex.Unlock()
	// }()
	// concurchan_ping <- struct{}{}
	// defer func() {
	// 	<-concurchan_ping
	// }()
	last_send_time, err = p.run()
	return
}

func (p *Pinger) init() *mpinfo {
	pinfo := getPingInfo(p.ipaddr)
	pinfo.host = p.addr
	pinfo.size = p.Size
	pinfo.timeout = p.Timeout
	p.sequence_base = pinfo.lastseq
	if p.RecordRtts {
		p.rtts = make([]time.Duration, p.Count)
	}
	return pinfo
}

func (p *Pinger) run() (time.Time, error) {
	pinfo := p.init()
	defer p.finish()

	err := MPConn(p.ipv4, p.protocol).Listen()
	if err != nil {
		return time.Time{}, err
	}

	if handler := p.OnSetup; handler != nil {
		handler()
	}

	var g errgroup.Group
	var last_send_time time.Time

	g.Go(func() (err error) {
		defer p.Stop()
		last_send_time, err = p.runLoop(pinfo)
		return err
	})

	return last_send_time, g.Wait()
}

func (p *Pinger) runLoop(pinfo *mpinfo) (time.Time, error) {
	timeout := time.NewTimer(p.Timeout)
	interval := time.NewTimer(0)
	timeout.Stop()
	defer func() {
		interval.Stop()
		timeout.Stop()
	}()
	received := make(chan interface{}, 1)

	last_send_time := time.Now()
	pinfo.OnSend = func(pkt *icmp.Packet) {
		last_send_time = pkt.SendTime
		seq := pkt.Seq - p.sequence_base
		if seq < 0 || seq >= p.Count {
			return
		}
		p.PacketsSent++
		if p.OnSend != nil {
			p.OnSend(&Packet{
				Host:   p.addr,
				IPAddr: pkt.IPAddr,
				ID:     p.id,
				Seq:    seq,
				Nbytes: pkt.Nbytes,
				TTL:    pkt.TTL,
				Rtt:    pkt.Rtt,
			})
		}
	}
	pinfo.OnRecv = func(pkt *icmp.Packet) {
		seq := pkt.Seq - p.sequence_base
		if seq < 0 || seq >= p.Count {
			return
		}
		inpkt := &Packet{
			Host:   p.addr,
			IPAddr: pkt.IPAddr,
			ID:     p.id,
			Seq:    seq,
			Nbytes: pkt.Nbytes,
			TTL:    pkt.TTL,
			Rtt:    pkt.Rtt,
		}
		if p.OnRecv != nil {
			p.OnRecv(inpkt)
		}
		p.updateStatistics(inpkt)
		received <- nil
	}
	pinfo.OnRecvDup = func(pkt *icmp.Packet) {
		seq := pkt.Seq - p.sequence_base
		if seq < 0 || seq >= p.Count {
			return
		}
		inpkt := &Packet{
			Host:   p.addr,
			IPAddr: pkt.IPAddr,
			ID:     p.id,
			Seq:    seq,
			Nbytes: pkt.Nbytes,
			TTL:    pkt.TTL,
			Rtt:    pkt.Rtt,
		}
		if p.OnDuplicateRecv != nil {
			p.OnDuplicateRecv(inpkt)
		}
	}
	pinfo.OnRecvTimeout = func(pkt *icmp.Packet) {
		seq := pkt.Seq - p.sequence_base
		if seq < 0 || seq >= p.Count {
			return
		}
		outpkt := &Packet{
			Host:   p.addr,
			IPAddr: pkt.IPAddr,
			ID:     p.id,
			Seq:    seq,
			Nbytes: pkt.Nbytes,
			TTL:    pkt.TTL,
			Rtt:    pkt.Rtt,
		}
		if p.OnTimeout != nil {
			p.OnTimeout(outpkt)
		}
	}
	for {
		select {
		case <-p.done:
			return last_send_time, nil

		case <-timeout.C:
			return last_send_time, nil

		case <-interval.C:
			if p.Count > 0 && p.PacketsSent >= p.Count {
				timeout.Reset(p.Timeout)
			} else {
				if err := MPConn(p.ipv4, p.protocol).Ping(pinfo); err != nil {
					logger.Errorf("sending packet: %s", err)
				}
				interval.Reset(p.Interval)
			}
		case <-received:
			if p.Count > 0 && p.PacketsRecv >= p.Count {
				return last_send_time, nil
			}
		}
	}
}

// func (p *Pinger) ping(pinfo *mpinfo, received chan interface{}) error {

// sleeptime := time.Duration(0)
// for sleeptime >= 0 {
// 	time.Sleep(sleeptime)
// 	lastpingtimemutex.Lock()
// 	alastpingtime := lastpingtime[p.ipaddr.String()]
// 	sleeptime = ping_interval - time.Since(alastpingtime)
// 	if sleeptime <= 0 {
// 		lastpingtime[p.ipaddr.String()] = time.Now()
// 	} else {
// 		// logger.Error(fmt.Sprint("ping", p.addr, "[", p.ipaddr.String(), "]", "同一地址至少间隔一秒"))
// 	}
// 	lastpingtimemutex.Unlock()
// }
// defer func() {
// 	lastpingtimemutex.Lock()
// 	lastpingtime[p.ipaddr.String()] = time.Now()
// 	lastpingtimemutex.Unlock()
// }()

// return MPConn(p.ipv4, p.protocol).Ping(pinfo)
// }

func (p *Pinger) Stop() {
	p.lock.Lock()
	defer p.lock.Unlock()

	open := true
	select {
	case _, open = <-p.done:
	default:
	}

	if open {
		close(p.done)
	}
}

func (p *Pinger) finish() {
	handler := p.OnFinish
	if handler != nil {
		s := p.Statistics()
		handler(s)
	}
}

// Statistics returns the statistics of the pinger. This can be run while the
// pinger is running or after it is finished. OnFinish calls this function to
// get it's finished statistics.
func (p *Pinger) Statistics() *Statistics {
	p.statsMu.RLock()
	defer p.statsMu.RUnlock()
	sent := p.PacketsSent
	loss := float64(sent-p.PacketsRecv) / float64(sent) * 100
	s := Statistics{
		PacketsSent:           sent,
		PacketsRecv:           p.PacketsRecv,
		PacketsRecvDuplicates: p.PacketsRecvDuplicates,
		PacketLoss:            loss,
		Rtts:                  p.rtts,
		Addr:                  p.addr,
		IPAddr:                p.ipaddr,
		MaxRtt:                p.maxRtt,
		MinRtt:                p.minRtt,
		AvgRtt:                p.avgRtt,
		StdDevRtt:             p.stdDevRtt,
	}
	return &s
}

func isIPv4(ip net.IP) bool {
	return len(ip.To4()) == net.IPv4len
}

var seed = time.Now().UnixNano()

// getSeed returns a goroutine-safe unique seed
func getSeed() int64 {
	return atomic.AddInt64(&seed, 1)
}