package gns

import (
	"errors"
	"fmt"
	"gitee.com/liumou_site/gcs"
	"github.com/spf13/cast"
	"math/rand"
	"net"
	"os"
	"runtime"
	"strings"
	"time"

	"gitee.com/liumou_site/logger"
	"golang.org/x/net/icmp"
	"golang.org/x/net/ipv4"
)

// PingLoss 通过调用系统命令进行ping检测丢包率
func (p *PingCmdAPI) PingLoss(host string, pack int) (err error, loss int) {
	loss = 100
	var arg []string
	arg = append(arg, "ping")
	if runtime.GOOS == "windows" {
		arg = append(arg, "-n")
	} else {
		arg = append(arg, "-c")
	}
	arg = append(arg, cast.ToString(pack))
	arg = append(arg, cast.ToString(host))
	gc := gcs.NewShell()
	gc.RunShell(arg...)
	for index, line := range strings.Split(gc.Strings, "\n") {
		if strings.Contains(line, "packet loss") {
			fmt.Println(index, ": ", line)
			parts := strings.Split(line, ", ")
			loss = cast.ToInt(strings.TrimSuffix(parts[2], "% packet loss"))
			fmt.Printf("丢包率：%s\n", strings.TrimSuffix(parts[2], "% packet loss"))
		}
		if strings.Contains(line, "% 丢失)") {
			fmt.Println(index, ": ", line)
			parts := strings.Split(line, ", ")
			loss = cast.ToInt(strings.TrimSuffix(parts[2], "% 丢失)"))
			fmt.Printf("丢包率：%s\n", strings.TrimSuffix(parts[2], "% packet loss"))
		}
	}
	if err != nil {
		fmt.Println(err)
	}
	return
}

// PingCmd 通过调用系统命令进行ping检测
func (p *PingCmdAPI) PingCmd(host string) error {
	p.host = host
	_, _, c := p.shellSystem()
	return c
}

// Ping 通过net模块构造数据实现icmp请求达到Ping检测主机在线的效果
func Ping(host string, req int, debug bool) error {
	var Data = []byte("Test Request Package Information")
	ping, err := create(host, req, Data)
	ping.debug = debug
	if err != nil {
		fmt.Println(err)
		return err
	}
	err = ping.icmp(3)
	if err != nil {
		return err
	}
	return nil
}

// getIp4 获取远程主机IPV4地址
func getIp4(host string) (string, error) {
	adders, err := net.LookupHost(host)
	if err != nil {
		return "", err
	}
	if len(adders) < 1 {
		return "", errors.New("unknown host")
	}
	rd := rand.New(rand.NewSource(time.Now().UnixNano()))
	//fmt.Println(adders[rd.Intn(len(adders))])
	return adders[rd.Intn(len(adders))], nil
}

type Reply struct {
	Time  int64
	TTL   uint8
	Error error
}

func MarshalMsg(req int, data []byte) ([]byte, error) {
	xid, xseq := os.Getpid()&0xffff, req
	wm := icmp.Message{
		Type: ipv4.ICMPTypeEcho, Code: 0,
		Body: &icmp.Echo{
			ID: xid, Seq: xseq,
			Data: data,
		},
	}
	return wm.Marshal(nil)
}

type ping struct {
	Addr  string // 需要检测的IPV4地址
	Conn  net.Conn
	Data  []byte
	debug bool // 显示检测过程信息
}

// dail 发起拨号请求
func (p *ping) dail() (err error) {
	p.Conn, err = net.Dial("ip4:icmp", p.Addr)
	if err != nil {
		logger.Error(err.Error())
		return err
	}
	return nil
}

// SetDeadline 设置截止时间
func (p *ping) SetDeadline(timeout int) error {
	return p.Conn.SetDeadline(time.Now().Add(time.Duration(timeout) * time.Second))
}

// Close 关闭连接
func (p *ping) Close() error {
	return p.Conn.Close()
}

// icmp 开始进行Ping操作
func (p *ping) icmp(count int) error {
	if err := p.dail(); err != nil {
		return err
	}
	if p.debug {
		fmt.Println("Start ping from ", p.Conn.LocalAddr())
	}
	err := p.SetDeadline(10)
	if err != nil {
		return fmt.Errorf("截止时间设置失败")
	}
	for i := 0; i < count; i++ {
		r := msg(p.Conn, p.Data)
		if r.Error != nil {
			if opt, ok := r.Error.(*net.OpError); ok && opt.Timeout() {
				if p.debug {
					fmt.Printf("From %s reply: TimeOut\n", p.Addr)
				}
				if err := p.dail(); err != nil {
					err = fmt.Errorf("找不到远程主机")
					fmt.Println(err.Error())
					return err
				}
			} else {
				if p.debug {
					fmt.Printf("From %s reply: %s\n", p.Addr, r.Error)
				}
			}
			return r.Error
		} else {
			if p.debug {
				fmt.Printf("From %s reply: time=%d ttl=%d\n", p.Addr, r.Time, r.TTL)
			}
		}
		time.Sleep(1e9)
	}
	return nil
}

func (p *ping) PingCount(count int) (reply []Reply) {
	if err := p.dail(); err != nil {
		fmt.Println("Not found remote host")
		return
	}
	err := p.SetDeadline(10)
	if err != nil {
		fmt.Println("截止时间设置失败")
		return
	}
	for i := 0; i < count; i++ {
		r := msg(p.Conn, p.Data)
		reply = append(reply, r)
		time.Sleep(1e9)
	}
	return
}

// create 开始创建实例
func create(addr string, req int, data []byte) (*ping, error) {
	wb, err := MarshalMsg(req, data)
	if err != nil {
		return nil, err
	}
	addr, err = getIp4(addr)
	if err != nil {
		return nil, err
	}
	return &ping{Data: wb, Addr: addr}, nil
}

// 发送Ping消息
func msg(c net.Conn, wb []byte) (reply Reply) {
	start := time.Now()

	if _, reply.Error = c.Write(wb); reply.Error != nil {
		return
	}

	rb := make([]byte, 1500)
	var n int
	n, reply.Error = c.Read(rb)
	if reply.Error != nil {
		return
	}

	duration := time.Now().Sub(start)
	ttl := rb[8]
	rb = func(b []byte) []byte {
		if len(b) < 20 {
			return b
		}
		children := int(b[0]&0x0f) << 2
		return b[children:]
	}(rb)
	var rm *icmp.Message
	rm, reply.Error = icmp.ParseMessage(1, rb[:n])
	if reply.Error != nil {
		return
	}

	switch rm.Type {
	case ipv4.ICMPTypeEchoReply:
		t := int64(duration / time.Millisecond)
		reply = Reply{t, ttl, nil}
	case ipv4.ICMPTypeDestinationUnreachable:
		reply.Error = errors.New("destination Unreachable")
	default:
		reply.Error = fmt.Errorf("not ICMPTypeEchoReply %v", rm)
	}
	return
}