package main

import (
	"flag"
	"fmt"
	"net"
	"os"
	"os/signal"
	proto "standard/etcd/openapi/server/proto"
	"strings"
	"syscall"
	"time"

	"go.etcd.io/etcd/client/v3"
	"golang.org/x/net/context"
	"google.golang.org/grpc"
)

const schema = "openapi"

var host = "127.0.0.1" //服务器主机
var (
	Port        = flag.Int("Port", 3000, "listening port")                           //服务器监听端口
	ServiceName = flag.String("ServiceName", "greet_service", "service name")        //服务名称
	EtcdAddr    = flag.String("EtcdAddr", "192.168.150.41:2379", "register etcd address") //etcd的地址
)
var cli *clientv3.Client

//rpc服务接口
type greetServer struct{}

func (gs *greetServer) Morning(ctx context.Context, req *proto.GreetRequest) (*proto.GreetResponse, error) {
	fmt.Printf("Morning 调用: %s\n", req.Name)
	return &proto.GreetResponse{
		Message: "Good morning, " + req.Name,
		From:    fmt.Sprintf("127.0.0.1:%d", *Port),
	}, nil
}

func (gs *greetServer) Night(ctx context.Context, req *proto.GreetRequest) (*proto.GreetResponse, error) {
	fmt.Printf("Night 调用: %s\n", req.Name)
	return &proto.GreetResponse{
		Message: "Good night, " + req.Name,
		From:    fmt.Sprintf("127.0.0.1:%d", *Port),
	}, nil
}

//将服务地址注册到etcd中
func register(etcdAddr, serviceName, serverAddr string, ttl int64) error {
	var err error

	if cli == nil {
		//构建etcd client
		cli, err = clientv3.New(clientv3.Config{
			Endpoints:   strings.Split(etcdAddr, ";"),
			DialTimeout: 15 * time.Second,
			Username:      "root",
			Password:      "JmZMbqQ1nc",
		})
		if err != nil {
			fmt.Printf("连接etcd失败：%s\n", err)
			return err
		}
	}

	//与etcd建立长连接，并保证连接不断(心跳检测)
	ticker := time.NewTicker(time.Second * time.Duration(ttl))
	go func() {
		key :="/" + schema + "/" + serviceName + "/" + serverAddr
		for {
			resp, err := cli.Get(context.Background(), key)
			//fmt.Printf("resp:%+v\n", resp)
			if err != nil {
				fmt.Printf("获取服务地址失败：%s", err)
			} else if resp.Count == 0 { //尚未注册
				err = keepAlive(serviceName, serverAddr, ttl)
				if err != nil {
					fmt.Printf("保持连接失败：%s", err)
				}
			}
			<-ticker.C
		}
	}()

	return nil
}

//保持服务器与etcd的长连接
func keepAlive(serviceName, serverAddr string, ttl int64) error {
	//创建租约
	leaseResp, err := cli.Grant(context.Background(), ttl)
	if err != nil {
		fmt.Printf("创建租期失败：%s\n", err)
		return err
	}

	//将服务地址注册到etcd中
	key := "/" + schema + "/" + serviceName + "/" + serverAddr
	_, err = cli.Put(context.Background(), key, serverAddr, clientv3.WithLease(leaseResp.ID))
	if err != nil {
		fmt.Printf("注册服务失败：%s", err)
		return err
	}

	//建立长连接
	ch, err := cli.KeepAlive(context.Background(), leaseResp.ID)
	if err != nil {
		fmt.Printf("建立长连接失败：%s\n", err)
		return err
	}

	//清空keepAlive返回的channel
	go func() {
		for {
			<-ch
		}
	}()
	return nil
}

//取消注册
func unRegister(serviceName, serverAddr string) {
	if cli != nil {
		key :="/" + schema + "/" + serviceName + "/" + serverAddr
		cli.Delete(context.Background(), key)
	}
}

func main() {
	flag.Parse()

	//监听网络
	listener, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", *Port))
	if err != nil {
		fmt.Println("监听网络失败：", err)
		return
	}
	defer listener.Close()

	//创建grpc句柄
	srv := grpc.NewServer()
	defer srv.GracefulStop()

	//将greetServer结构体注册到grpc服务中
	proto.RegisterGreetServer(srv, &greetServer{})

	//将服务地址注册到etcd中
	serverAddr := fmt.Sprintf("%s:%d", host, *Port)
	fmt.Printf("greeting server address: %s\n", serverAddr)
	register(*EtcdAddr, *ServiceName, serverAddr, 5)

	//关闭信号处理
	ch := make(chan os.Signal, 1)
	signal.Notify(ch, syscall.SIGTERM, syscall.SIGINT, syscall.SIGKILL, syscall.SIGHUP, syscall.SIGQUIT)
	go func() {
		s := <-ch
		unRegister(*ServiceName, serverAddr)
		if i, ok := s.(syscall.Signal); ok {
			os.Exit(int(i))
		} else {
			os.Exit(0)
		}
	}()

	//监听服务
	err = srv.Serve(listener)
	if err != nil {
		fmt.Println("监听异常：", err)
		return
	}
}