package a2s

import (
	"context"
	"errors"
	"fmt"
	"log"
	"net"
	"sync/atomic"
	"time"

	"github.com/cespare/xxhash/v2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
)

type (
	//GRPC 服务端
	Server struct{}
)

var (
	reqAmout = make([]int32, 9999, 9999)
)

// Call 远程调用
func (s *Server) Call(ctx context.Context,
	in *Request) (*Response, error) {
	topicIndex := int(xxhash.Sum64([]byte(in.GetTopic()))) % 9999
	if topicIndex < 0 {
		topicIndex *= -1
	}
	atomic.AddInt32(&(reqAmout[topicIndex]), 1)
	defer func() {
		fmt.Print(".")
		atomic.AddInt32(&(reqAmout[topicIndex]), -1)
	}()
	fmt.Print(">")
	msgId, ch, err := SendMessage2Nats(in.GetTopic(), in.GetTimeout(), in.GetData())
	if err != nil {
		return &Response{}, err
	}

	//等候
	select {
	case <-ctx.Done():
		w.Del(msgId)
		return &Response{Code: 203, Msg: "客户端主动关闭连接"}, errors.New("client close the connection")
	case <-time.After(time.Duration(in.Timeout) * time.Second):
		//超时
		w.Del(msgId)
		return &Response{Code: 500, Msg: "远程方法调用超时"}, errors.New("call remote method timeout")
	case ret := <-ch:
		w.Del(msgId)
		return &Response{Code: 200, Msg: "ok", Data: ret}, nil
	}
	return &Response{Code: 503, Msg: "未知错误"}, errors.New("unknow error")
}

// ViewState 查看状态
func (s *Server) ViewState(ctx context.Context, req *StateReq) (*StateResp, error) {
	topicIndex := int(xxhash.Sum64([]byte(req.GetTopic()))) % 9999
	if topicIndex < 0 {
		topicIndex *= -1
	}
	return &StateResp{CurrentRequest: reqAmout[topicIndex]}, nil
}

// startServer 开启RPC服务
func StartServer(listen string) {
	// 监听本地端口
	lis, err := net.Listen("tcp", listen)
	if err != nil {
		log.Printf("监听端口失败: %s\n", err)
		return
	} else {
		log.Printf("监听端口:%s\n", listen)
	}
	// 创建gRPC服务器
	s := grpc.NewServer()
	// 注册服务
	RegisterCallerServer(s, new(Server))
	reflection.Register(s)
	err = s.Serve(lis)
	if err != nil {
		log.Printf("开启服务失败: %s\n", err)
		return
	}
}