package main

import (
	"bytes"
	"context"
	"encoding/binary"
	"encoding/gob"
	"fmt"
	"log"
	"net"
	"os/exec"
	gen "slimming/proto/gen"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"github.com/songgao/packets/ethernet"
	"github.com/songgao/water"
	"github.com/songgao/water/waterutil"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

type ExchangeBuffer struct {
	BytesArray [][]byte
}

type NetCard struct {
	FrameChan chan []byte
	ifce      *water.Interface
	server    *RPCServer

	clientMap map[string]*RPCClient

	lock sync.Mutex
}

func (nc *NetCard) Lock(do func()) {
	nc.lock.Lock()
	defer nc.lock.Unlock()
	do()
}

type RPCClient struct {
	FrameChan chan *ExchangeBuffer
	conn      *grpc.ClientConn
}

func (cli *RPCClient) connect(realAddr string) {
	log.Println("rpcclient connect", realAddr)
	// defer log.Println("rpcclient exit")

	conn, err := grpc.Dial(realAddr,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
	)
	if err != nil {
		log.Printf("did not connect: %v", err)
		return
	}

	cli.conn = conn
	go cli.run()
	time.Sleep(time.Millisecond)
}

func (cli *RPCClient) run() {
	defer log.Println("rpcclient exit")
	defer func() {
		if err := recover(); err != nil {
			log.Println("recover")
			cli.conn = nil
		}
	}()

	cliService := gen.NewFrameServiceClient(cli.conn)
	stream, err := cliService.SendFrames(context.Background())
	if err != nil {
		log.Panic(err)
	}

	buf := bytes.NewBuffer(nil)
	for {
		// Contact the server and print out its response.

		buf.Reset()

		// encode gob
		enc := gob.NewEncoder(buf)
		cliBuffer := <-cli.FrameChan

		log.Printf("send to target %s source bytes: %d", waterutil.IPv4Destination(cliBuffer.BytesArray[0]), len(cliBuffer.BytesArray[0]))

		err := enc.Encode(cliBuffer.BytesArray)
		if err != nil {
			log.Panic(err)
		}

		// zstd compress
		// zenc, err := zstd.NewWriter(buf)
		// if err != nil {
		// 	log.Panic(err)
		// }
		// err = zenc.Flush()
		// if err != nil {
		// 	log.Println(err)
		// }

		// 发到对面的网卡
		err = stream.Send(&gen.Request{
			Frames: buf.Bytes(),
		})

		if err != nil {
			log.Panic(err)
		}
	}
}

func (nc *NetCard) Run() {
	go nc.runRead()
	go nc.runWrite()
	// go nc.cli.run()
	time.Sleep(time.Second)

	cmdstr := fmt.Sprintf("ip addr add %s dev stun", config.Network.Self.Virt)
	log.Println(cmdstr)
	cmd := strings.Split(cmdstr, " ")
	err := exec.Command(cmd[0], cmd[1:]...).Run()
	if err != nil {
		log.Panic(err)
	}

	cmdstr = "ip link set dev stun up"
	cmd = strings.Split(cmdstr, " ")
	err = exec.Command(cmd[0], cmd[1:]...).Run()
	if err != nil {
		log.Panic(err)
	}
	nc.server.run()
}

func NewNetCard() *NetCard {

	config := water.Config{
		DeviceType: water.TUN,
		PlatformSpecificParams: water.PlatformSpecificParams{
			Name:       "stun",
			Persist:    true,
			MultiQueue: true,
		},
	}

	ifce, err := water.New(config)
	if err != nil {
		log.Panic(err)
	}

	nc := &NetCard{
		FrameChan: make(chan []byte, 3000),
		ifce:      ifce,
		clientMap: map[string]*RPCClient{},
	}
	nc.server = newRPCServer(nc)
	return nc
}

func (nc *NetCard) runRead() {
	log.Println("start netcard read")

	var ifce *water.Interface = nc.ifce

	for {

		var bytesMap map[string]*ExchangeBuffer = make(map[string]*ExchangeBuffer)

		var ok bool
		var isLoop int32 = 1

		// 20 微秒后停止收集数据
		go func() {
			var after = time.NewTimer(time.Millisecond * 20)
			<-after.C
			atomic.StoreInt32(&isLoop, 0)
		}()

		for atomic.LoadInt32(&isLoop) > 0 {
			var rframe ethernet.Frame
			rframe.Resize(1500)
			n, err := ifce.Read([]byte(rframe))
			if err != nil {
				log.Fatal(err)
			}
			rframe = rframe[:n]

			if !waterutil.IsIPv4(rframe) || waterutil.IPv4Source(rframe).Equal(net.IPv4(0, 0, 0, 0)) {
				continue
			}

			var realAddr string = ""
			config.Lock(func() {
				if realAddr, ok = config.IPv4Nodes[binary.LittleEndian.Uint32([]byte(waterutil.IPv4Destination(rframe)))]; !ok {
					return
				}
			})

			if realAddr == "" {
				log.Printf("%s is not exists", waterutil.IPv4Destination(rframe))
				continue
			}

			// log.Printf("Payload: % x\n", rframe.Payload())

			log.Printf("Ethertype: % x %v realAddr %s\n", rframe.Ethertype(), waterutil.IsIPv4(rframe), realAddr)
			log.Printf("Src %s Dst: %s\n", waterutil.IPv4Source(rframe), waterutil.IPv4Destination(rframe))

			var buffer *ExchangeBuffer
			if buffer, ok = bytesMap[realAddr]; !ok {
				buffer = &ExchangeBuffer{BytesArray: make([][]byte, 0, 1000)}
				bytesMap[realAddr] = buffer
			}

			ifce.Write([]byte(rframe))
			buffer.BytesArray = append(buffer.BytesArray, []byte(rframe))
		}

		for dst, buffer := range bytesMap {

			var cli *RPCClient
			if cli, ok = nc.clientMap[dst]; !ok {
				cli = &RPCClient{FrameChan: make(chan *ExchangeBuffer)}
				nc.clientMap[dst] = cli
			}

			if cli.conn == nil {
				cli.connect(dst)
			} else {
				cli.FrameChan <- buffer // 网卡数据 发到对方
			}

		}

		// 写到grpc服务

		// log.Printf("Dst: %s\n", rframe.Destination()[0:4])
		// log.Printf("Src: %s\n", rframe.Source()[0:4])
		// log.Printf("Ethertype: % x\n", rframe.Ethertype())
		// log.Printf("Payload: % x\n", rframe.Payload())

	}
}

func (nc *NetCard) runWrite() {
	var ifce *water.Interface = nc.ifce
	var err error

	for wframe := range nc.FrameChan {

		log.Printf("get wframes bytes len: %d", len(wframe))
		var buf = bytes.NewBuffer(wframe)

		// zdec, err := zstd.NewReader(buf)
		// if err != nil {
		// 	log.Panic(err)
		// }
		// zdec.Close()

		dec := gob.NewDecoder(buf)
		var bufs [][]byte
		err = dec.Decode(&bufs)
		if err != nil {
			log.Panic(err)
		}

		for _, buf := range bufs {

			log.Printf("get wframes decode len: %d", len(buf))
			log.Printf("get decode frames decode source: %s dst: %s", waterutil.IPv4Source(buf), waterutil.IPv4Destination(buf))
			_, err := ifce.Write(buf)
			if err != nil {
				log.Panic(err)
			}
		}

	}

}