package transport

import (
	"context"
	"net"
	"strconv"
	"sync"

	toki "git.toki-labs.com/toki/common-proto-socket/go"
	"go.uber.org/zap"
	"google.golang.org/protobuf/proto"

	edgenode "iop/apps/edge/internal/node"
	iop "iop/proto/gen/iop"
)

const (
	heartbeatIntervalSec = 30
	heartbeatWaitSec     = 10
)

func edgeParserMap() toki.ParserMap {
	return toki.ParserMap{
		toki.TypeNameOf(&iop.RunEvent{}): func(b []byte) (proto.Message, error) {
			m := &iop.RunEvent{}
			return m, proto.Unmarshal(b, m)
		},
		toki.TypeNameOf(&iop.RegisterRequest{}): func(b []byte) (proto.Message, error) {
			m := &iop.RegisterRequest{}
			return m, proto.Unmarshal(b, m)
		},
		toki.TypeNameOf(&iop.NodeCommandResponse{}): func(b []byte) (proto.Message, error) {
			m := &iop.NodeCommandResponse{}
			return m, proto.Unmarshal(b, m)
		},
	}
}

// Server wraps proto-socket TcpServer and manages node connections.
type Server struct {
	tcp        *toki.TcpServer
	listen     string
	registry   *edgenode.Registry
	nodeStore  *edgenode.NodeStore
	logger     *zap.Logger
	handlerMu  sync.RWMutex
	onRunEvent func(*iop.RunEvent)
}

func NewServer(listen string, registry *edgenode.Registry, nodeStore *edgenode.NodeStore, logger *zap.Logger) (*Server, error) {
	host, portStr, err := net.SplitHostPort(listen)
	if err != nil {
		return nil, err
	}
	port, err := strconv.Atoi(portStr)
	if err != nil {
		return nil, err
	}

	s := &Server{listen: listen, registry: registry, nodeStore: nodeStore, logger: logger}
	s.tcp = toki.NewTcpServer(host, port, func(conn net.Conn) *toki.TcpClient {
		return toki.NewTcpClient(conn, heartbeatIntervalSec, heartbeatWaitSec, edgeParserMap())
	})
	s.tcp.OnClientConnected = s.onNodeConnected
	return s, nil
}

func (s *Server) Start(ctx context.Context) error {
	if err := s.tcp.Start(ctx); err != nil {
		return err
	}
	s.logger.Info("edge listening for nodes", zap.String("addr", s.listen))
	return nil
}

func (s *Server) Stop() error {
	return s.tcp.Stop()
}

func (s *Server) SetRunEventHandler(handler func(*iop.RunEvent)) {
	s.handlerMu.Lock()
	s.onRunEvent = handler
	s.handlerMu.Unlock()
}

func (s *Server) onNodeConnected(client *toki.TcpClient) {
	s.logger.Info("node connection established")

	toki.AddListenerTyped[*iop.RunEvent](&client.Communicator, func(e *iop.RunEvent) {
		s.logger.Debug("run event received",
			zap.String("run_id", e.GetRunId()),
			zap.String("type", e.GetType()),
		)
		s.handlerMu.RLock()
		handler := s.onRunEvent
		s.handlerMu.RUnlock()
		if handler != nil {
			handler(e)
		}
	})

	toki.AddRequestListenerTyped[*iop.RegisterRequest, *iop.RegisterResponse](
		&client.Communicator,
		func(req *iop.RegisterRequest) (*iop.RegisterResponse, error) {
			rec, ok := s.nodeStore.FindByToken(req.GetToken())
			if !ok {
				s.logger.Warn("unknown token", zap.String("token_prefix", safePrefix(req.GetToken())))
				return &iop.RegisterResponse{Accepted: false, Reason: "unknown token"}, nil
			}

			if _, ok := s.registry.Get(rec.ID); ok {
				s.logger.Warn("node already connected", zap.String("node_id", rec.ID))
				return &iop.RegisterResponse{Accepted: false, Reason: "node already connected"}, nil
			}

			cfg, err := edgenode.BuildConfigPayload(rec)
			if err != nil {
				s.logger.Error("build config payload failed",
					zap.String("node_id", rec.ID),
					zap.Error(err),
				)
				return &iop.RegisterResponse{Accepted: false, Reason: "internal config error"}, nil
			}

			entry := &edgenode.NodeEntry{
				NodeID: rec.ID,
				Alias:  rec.Alias,
				Client: client,
			}
			client.AddDisconnectListener(func(_ *toki.TcpClient) {
				s.registry.Unregister(rec.ID)
				s.logger.Info("node unregistered", zap.String("node_id", rec.ID))
			})
			s.registry.Register(entry)
			s.logger.Info("node registered",
				zap.String("node_id", rec.ID),
				zap.String("alias", rec.Alias),
			)

			return &iop.RegisterResponse{
				Accepted: true,
				NodeId:   rec.ID,
				Alias:    rec.Alias,
				Config:   cfg,
			}, nil
		},
	)
}

func safePrefix(s string) string {
	if len(s) > 8 {
		return s[:8] + "..."
	}
	return s
}