package vobc

import (
	"container/list"
	"encoding/binary"
	"fmt"
	"math"
	"net"
	"sync"

	"github.com/panjf2000/gnet/v2"
	"go.uber.org/zap"
	"joylink.club/bj-rtsts-server/config"
)

var (
	running                bool
	mutex                  sync.Mutex
	receiveTrainLifeSignal uint16                          //接收列车消息生命信号
	sendTrainLifeSignal    uint16                          //发送的列车消息生命信号
	trainLifeSignalInit    bool                            //列车生命信号是否初始化
	limit                  uint16      = 10000             //用于处理生命信号循环使用产生的各种特殊处理
	vobcMsgInfoChan        chan []byte = make(chan []byte) //列车消息队列
	//处理方法列表
	handlerList list.List
)

func init() {
	go func() {
		for {
			info := <-vobcMsgInfoChan
			for e := handlerList.Front(); e != nil; e = e.Next() {
				func() {
					defer func() {
						r := recover()
						if r != nil {
							zap.S().Errorf("列车信息处理函数报错")
						}
					}()
					handler := e.Value.(VobcDataHandler)
					handler(info)
				}()
			}
		}
	}()
}

type VobcDataHandler func([]byte)

type udpServer struct {
	gnet.BuiltinEventEngine

	eng       gnet.Engine
	addr      string
	multicore bool
}

// udp 启动时运行
func (server *udpServer) OnBoot(eng gnet.Engine) gnet.Action {
	server.eng = eng
	zap.S().Infof("vobc udp server with multi-core=%t is listening on %s", server.multicore, server.addr)
	return gnet.None
}

// OnTraffic 接收到数据后的解析
func (server *udpServer) OnTraffic(c gnet.Conn) gnet.Action {
	defer func() {
		if r := recover(); r != nil {
			zap.L().Error("vobc udp服务数据解析异常", zap.Any("panic", r))
		}
	}()
	buf, _ := c.Next(-1)
	lifeSignal := binary.BigEndian.Uint16(buf[0:2])
	if !trainLifeSignalInit {
		trainLifeSignalInit = true
	} else if receiveTrainLifeSignal < limit {
		if lifeSignal < receiveTrainLifeSignal || lifeSignal > receiveTrainLifeSignal-limit {
			zap.S().Debugf("丢弃列车信息[%d-%d]", lifeSignal, receiveTrainLifeSignal)
			return gnet.None
		}
	} else if receiveTrainLifeSignal < math.MaxUint16-10000 {
		if lifeSignal < receiveTrainLifeSignal {
			zap.S().Debugf("丢弃列车信息[%d-%d]", lifeSignal, receiveTrainLifeSignal)
			return gnet.None
		}
	} else {
		if lifeSignal < receiveTrainLifeSignal && lifeSignal > receiveTrainLifeSignal+10000 {
			zap.S().Debugf("丢弃列车信息[%d-%d]", lifeSignal, receiveTrainLifeSignal)
			return gnet.None
		}
	}
	receiveTrainLifeSignal = lifeSignal
	// trainInfo := decoderVobcTrainInfo(buf)
	//消息队列
	vobcMsgInfoChan <- buf
	return gnet.None
}

// 注册处理vobc处理方法
func RegisterTrainInfoHandler(handler VobcDataHandler) {
	handlerList.PushBack(handler)
}

// 创建UDP服务
func RunUdpServer() {
	server := &udpServer{addr: fmt.Sprintf("udp://:%d", config.Config.Vobc.LocalPort), multicore: false}
	err := gnet.Run(server, server.addr, gnet.WithMulticore(server.multicore))
	zap.L().Fatal("vobc udp服务启动失败", zap.Error(err))
}

// 发送列车速度到VOBC
func SendTrainSpeedTask(speed float32) error {
	if running {
		return nil
	}
	mutex.Lock()
	defer mutex.Unlock()
	trainInfo := &SendTrainInfo{
		LifeSignal: sendTrainLifeSignal,
		Speed:      uint16(speed),
	}
	err := sendVobcMsg(encoderVobcTrainInfo(trainInfo))
	if err != nil {
		zap.S().Error(err)
	}
	sendTrainLifeSignal++
	return err
}

// UDP停止
func Stop() {
	mutex.Lock()
	defer mutex.Unlock()
	running = false
}

// Vobc 消息发送消息
func sendVobcMsg(buf []byte) error {
	defer func() {
		if r := recover(); r != nil {
			zap.S().Error("发送列车速度信息失败", r)
		}
	}()
	addr := fmt.Sprintf("%v:%v", config.Config.Vobc.Ip, config.Config.Vobc.RemotePort)
	remoteAddr, _ := net.ResolveUDPAddr("udp", addr)
	conn, err := net.DialUDP("udp", nil, remoteAddr)
	if err != nil {
		zap.S().Error("UDP通信失败", err)
		return err
	}
	defer func(conn *net.UDPConn) {
		err := conn.Close()
		if err != nil {
			zap.S().Error(err)
		}
	}(conn)
	_, err = conn.Write(buf)
	return err
}

// 将道岔转为动力学的消息
func encoderVobcTrainInfo(info *SendTrainInfo) []byte {
	var data []byte
	data = binary.BigEndian.AppendUint16(data, info.LifeSignal)
	data = binary.BigEndian.AppendUint16(data, info.Speed)
	return data
}