package logic

import (
	"context"
	"errors"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
	"google.golang.org/protobuf/types/known/emptypb"
	"net"
	"sonet/api/gen/postal"
	"sonet/internal/postal/group"
	"sonet/pkg/config"
	"sonet/pkg/grpc/client"
	"sonet/pkg/grpc/discovery"
	"sonet/pkg/grpc/interceptor"
	"sonet/pkg/plugins/cache"
	"sonet/pkg/plugins/mq"
	"sonet/pkg/protocol"
	"sonet/pkg/protocol/session"
	"sonet/pkg/utils/collect"
	"sonet/pkg/utils/logger"
	"sonet/pkg/utils/shutdown"
)

type PostalServer struct {
	postal.UnimplementedPostalServer
	endpointAddress  string                                       // websocket 前端连接地址
	broadcastAddress string                                       // postal server 在注册中心注册的地址, 其他服务可直连访问
	sessionStore     session.Store                                // k:uid 在线用户conn存储
	groupStore       *collect.ConcurrentMap[string, *group.Group] // k:gid 在线用户 groups 存储
	subjectStore     cache.MultiLevelCache                        // online subject address cache, ws gateway集群所有在线用户存储
	clientFactory    *client.GrpcDirectClientFactory
	producer         mq.Producer
}

func NewPostalServer(
	endpointAddress string,
	sessionStore session.Store,
	groupStore *collect.ConcurrentMap[string, *group.Group],
	subjectStore cache.MultiLevelCache,
	clientFactory *client.GrpcDirectClientFactory,
	producer mq.Producer) *PostalServer {
	return &PostalServer{
		endpointAddress: endpointAddress,
		sessionStore:    sessionStore,
		groupStore:      groupStore,
		subjectStore:    subjectStore,
		clientFactory:   clientFactory,
		producer:        producer,
	}
}

func (s *PostalServer) Run(conf config.GrpcConfig, registry discovery.Registry) (err error) {
	server := grpc.NewServer(
		config.GetGrpcOptions(
			conf,
			grpc.UnaryInterceptor(interceptor.RecoverInterceptor),
		)...,
	)
	if !conf.NoReflection {
		// 注册反射服务
		reflection.Register(server)
	}
	postal.RegisterPostalServer(server, s)
	listen, err := net.Listen("tcp", conf.Address)
	if err != nil {
		return
	}

	// registry discovery
	register := conf.Register
	if register.Name == "" {
		register.Name = postal.Postal_ServiceDesc.ServiceName
	}
	if register.Addr == "" {
		register.Addr = conf.Address
	}
	ctx, cancel := context.WithCancel(context.Background())
	err = registry.Registry(ctx, register)
	if err != nil {
		panic(err)
	}
	shutdown.AddHook(cancel)

	go s.processSessionStoreEvent(ctx)

	// 其他服务直连地址
	s.broadcastAddress = register.Addr

	// run serve
	logger.Infof("%s grpc server running %s\n", register.Name, listen.Addr().String())
	err = server.Serve(listen)
	return
}

func (s *PostalServer) processSessionStoreEvent(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return

		case uid := <-s.sessionStore.OnStore():
			logger.Info("uid %s online", uid)
			// todo mq event..., delay 5s
			// s.producer.Publish()

		case channel := <-s.sessionStore.OnDelete():
			logger.Info("uid %s offline", channel.Uid)
			for _, gid := range channel.Groups() {
				if g, ok := s.groupStore.Load(gid); ok {
					g.Leave(channel.Uid)
				}
			}
			// todo mq event...
		}
	}
}

func (s *PostalServer) deliverMessage(msg *postal.Message, conn session.NetConn) error {
	header := &protocol.Header{
		Magic:         protocol.Magic,
		Type:          protocol.TypeNotice,
		UrlType:       1,
		SerializeType: 1,
		Svc:           msg.Svc,
		Target:        msg.Msg,
	}
	payload := &protocol.Payload{Header: header, Body: msg.Body}
	bytes, err := protocol.EncodeSo(payload)
	if err != nil {
		logger.Error("req deliver encode notice error: ", err)
		return err
	}
	return conn.Write(bytes)
}

// receiverGates 找receiver在集群内哪些其他节点
func (s *PostalServer) clusterGateReceivers(ctx context.Context, receivers []string) (gateReceivers map[string][]string, offline []string) {
	gateReceivers = make(map[string][]string)
	for _, receiver := range receivers {
		subject := &session.GateSubject{}
		err := s.subjectStore.Load(ctx, receiver, subject)
		if err != nil {
			offline = append(offline, receiver)
			if err != cache.NotExists {
				logger.Error("load from subject store error: ", err)
				offline = append(offline, receiver)
			}
			continue
		}

		if subject.Gate == s.broadcastAddress {
			offline = append(offline, receiver)
			// 清除失效缓存
			err := s.subjectStore.Del(ctx, receiver)
			if err != nil {
				logger.Error("del subject store error: ", receiver, err)
			}
			continue
		}

		// put receiver gate addr
		gateReceivers[subject.Gate] = append(gateReceivers[subject.Gate], receiver)
	}
	return
}

func (s *PostalServer) Deliver(ctx context.Context, req *postal.ReqDeliver) (res *postal.ResDeliver, err error) {
	receiver, ok := s.sessionStore.Load(req.Receiver)
	if ok {
		var bytes []byte
		bytes, err = encodeDeliverMessage(req.Msg)
		if err != nil {
			return
		}
		// write msg
		err = receiver.Conn.Write(bytes)
		if err != nil {
			return
		}
		res = &postal.ResDeliver{Ok: true}
		return
	}

	// 用户连接不在当前gateway
	// todo 向一致性 hash 下一个节点传递
	gateReceivers, offline := s.clusterGateReceivers(ctx, []string{req.Receiver})
	if offline != nil && len(offline) > 0 {
		res = &postal.ResDeliver{Code: int32(postal.DeliverResult_ReceiverOffline.Number())}
		return
	}

	for postalAddr := range gateReceivers {
		// gateway集群中转发消息
		clusterAddr, err := PostalAddr2Cluster(postalAddr)
		if err != nil {
			logger.Errorf("parse postal server addr error: %s", postalAddr, err)
			continue
		}
		conn, err := s.clientFactory.GetConn(context.Background(), clusterAddr)
		if err != nil {
			logger.Error("get postal cluster conn error: ", err)
			return nil, err
		}
		clusterClient := postal.NewPostalClusterClient(conn)

		reqRedirect := &postal.ReqRedirect{
			Ttl:            3, // TODO 转发n次就丢弃
			RedirectMethod: methodRedirectDeliver,
			Deliver:        req,
		}
		resp, err := clusterClient.Redirect(ctx, reqRedirect)
		return resp, err
	}

	return nil, nil
}

func (s *PostalServer) DeliverBatch(ctx context.Context, req *postal.ReqDeliverBatch) (res *postal.ResDeliver, err error) {
	bytes, err := encodeDeliverMessage(req.Msg)
	if err != nil {
		return
	}

	var redirectReceivers []string
	for _, receiverId := range req.Receivers {
		receiver, ok := s.sessionStore.Load(receiverId)
		if !ok {
			redirectReceivers = append(redirectReceivers, receiverId)
			continue
		}
		err = receiver.Conn.Write(bytes)
		if err != nil {
			logger.Errorf("deliver to %s error: ", receiver, err)
		}
	}

	if len(redirectReceivers) == 0 {
		return &postal.ResDeliver{Ok: true}, nil
	}

	// todo 向一致性 hash 下个节点传递
	gateReceivers, offline := s.clusterGateReceivers(ctx, redirectReceivers)
	if len(offline) > 0 {
		logger.Warning("offline redirect receivers: ", offline)
	}

	if len(gateReceivers) > 0 {
		for postalAddr, receivers := range gateReceivers {
			// gateway集群中转发消息
			clusterAddr, err := PostalAddr2Cluster(postalAddr)
			if err != nil {
				logger.Errorf("parse postal server addr error: %s", postalAddr, err)
				continue
			}
			conn, err := s.clientFactory.GetConn(ctx, clusterAddr)
			if err != nil {
				logger.Error("get postal cluster conn error: ", err)
				continue
			}
			clusterClient := postal.NewPostalClusterClient(conn)

			req.Receivers = receivers
			reqRedirect := &postal.ReqRedirect{
				Ttl:            3, // TODO 转发n次就丢弃
				RedirectMethod: methodRedirectDeliverBatch,
				DeliverBatch:   req,
			}
			_, err = clusterClient.Redirect(ctx, reqRedirect)
			if err != nil {
				logger.Error("redirect batch error: ", err)
			}
		}
	}
	return &postal.ResDeliver{Ok: true}, nil
}

// DeliverGroup postal broadcast
func (s *PostalServer) DeliverGroup(ctx context.Context, req *postal.ReqDeliverGroup) (res *postal.ResDeliver, err error) {
	bytes, err := encodeDeliverMessage(req.Msg)
	if err != nil {
		return
	}

	res = &postal.ResDeliver{Ok: true}
	g, ok := s.groupStore.Load(req.Gid)
	if !ok {
		return
	}
	g.Write(bytes)
	return
}

// GroupJoin uid consistent hash
func (s *PostalServer) GroupJoin(ctx context.Context, req *postal.ReqGroupJoin) (emp *emptypb.Empty, err error) {
	channel, ok := s.sessionStore.Load(req.Uid)
	if !ok {
		err = errors.New("uid not online")
		return
	}
	for _, gid := range req.Gids {
		g, _ := s.groupStore.ComputeIfAbsent(gid, func(gid string) *group.Group { return group.NewGroup(gid) })
		g.Join(req.Uid, channel.Conn)
		channel.GroupJoin(gid)
	}
	return
}

// GroupLeave uid consistent hash
func (s *PostalServer) GroupLeave(ctx context.Context, req *postal.ReqGroupLeave) (emp *emptypb.Empty, err error) {
	channel, ok := s.sessionStore.Load(req.Uid)
	if !ok {
		err = errors.New("uid not online")
		return
	}
	for _, gid := range req.Gids {
		g, ok := s.groupStore.Load(gid)
		if !ok {
			continue
		}
		g.Leave(req.Uid)
		channel.GroupLeave(gid)
	}
	return
}

// GroupDissolve postal broadcast
func (s *PostalServer) GroupDissolve(ctx context.Context, req *postal.ReqGroupDissolve) (emp *emptypb.Empty, err error) {
	s.groupStore.Delete(req.Gid)
	return
}

func (s *PostalServer) Endpoint(context.Context, *emptypb.Empty) (*postal.ResEndpoint, error) {
	res := &postal.ResEndpoint{
		Endpoint: s.endpointAddress,
	}
	return res, nil
}