package tuic

import (
	"context"
	"net"
	"strings"
	"time"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/adapter/inbound"
	"github.com/sagernet/sing-box/common/listener"
	"github.com/sagernet/sing-box/common/tls"
	"github.com/sagernet/sing-box/common/uot"
	C "github.com/sagernet/sing-box/constant"
	"github.com/sagernet/sing-box/log"
	"github.com/sagernet/sing-box/option"
	qtls "github.com/sagernet/sing-quic"
	"github.com/sagernet/sing-quic/tuic"
	"github.com/sagernet/sing/common"
	"github.com/sagernet/sing/common/auth"
	E "github.com/sagernet/sing/common/exceptions"
	M "github.com/sagernet/sing/common/metadata"
	N "github.com/sagernet/sing/common/network"
	sService "github.com/sagernet/sing/service"

	"github.com/gofrs/uuid/v5"
)

func RegisterInbound(registry *inbound.Registry) {
	inbound.Register[option.TUICInboundOptions](registry, C.TypeTUIC, NewInbound)
}

type Inbound struct {
	inbound.Adapter
	router       adapter.ConnectionRouterEx
	logger       log.ContextLogger
	listener     *listener.Listener
	tlsConfig    tls.ServerConfig
	server       *tuic.Service[int]
	userNameList []string
	userManager  adapter.UserManager
}

func NewInbound(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.TUICInboundOptions) (adapter.Inbound, error) {
	options.UDPFragmentDefault = true
	if options.TLS == nil || !options.TLS.Enabled {
		return nil, C.ErrTLSRequired
	}
	tlsConfig, err := tls.NewServer(ctx, logger, common.PtrValueOrDefault(options.TLS))
	if err != nil {
		return nil, err
	}
	inbound := &Inbound{
		Adapter: inbound.NewAdapter(C.TypeTUIC, tag),
		router:  uot.NewRouter(router, logger),
		logger:  logger,
		listener: listener.New(listener.Options{
			Context: ctx,
			Logger:  logger,
			Listen:  options.ListenOptions,
		}),
		tlsConfig: tlsConfig,
	}
	var udpTimeout time.Duration
	if options.UDPTimeout != 0 {
		udpTimeout = time.Duration(options.UDPTimeout)
	} else {
		udpTimeout = C.UDPTimeout
	}
	service, err := tuic.NewService[int](tuic.ServiceOptions{
		Context:   ctx,
		Logger:    logger,
		TLSConfig: tlsConfig,
		QUICOptions: qtls.QUICOptions{
			IdleTimeout:             options.IdleTimeout.Build(),
			KeepAlivePeriod:         options.KeepAlivePeriod.Build(),
			StreamReceiveWindow:     options.StreamReceiveWindow.Value(),
			ConnectionReceiveWindow: options.ConnectionReceiveWindow.Value(),
			MaxConcurrentStreams:    options.MaxConcurrentStreams,
			InitialPacketSize:       options.InitialPacketSize,
			DisablePathMTUDiscovery: options.DisablePathMTUDiscovery,
		},
		CongestionControl: options.CongestionControl,
		AuthTimeout:       time.Duration(options.AuthTimeout),
		ZeroRTTHandshake:  options.ZeroRTTHandshake,
		Heartbeat:         time.Duration(options.Heartbeat),
		UDPTimeout:        udpTimeout,
		Handler:           inbound,
	})
	if err != nil {
		return nil, err
	}
	userManager := sService.FromContext[adapter.UserManager](ctx)

	if userManager != nil {
		creds, err := userManager.GetCredentials(C.TypeTUIC)
		if err == nil && len(creds) > 0 {
			userList := make([]int, 0, len(creds))
			userNameList := make([]string, 0, len(creds))
			userUUIDList := make([][16]byte, 0, len(creds))
			userPasswordList := make([]string, 0, len(creds))
			for i, c := range creds {
				parts := strings.SplitN(c.Credential, ":", 2)
				if len(parts) < 1 || parts[0] == "" {
					continue
				}
				userUUID, pErr := uuid.FromString(parts[0])
				if pErr != nil {
					continue
				}
				password := ""
				if len(parts) == 2 {
					password = parts[1]
				}
				userList = append(userList, i)
				userNameList = append(userNameList, c.Username)
				userUUIDList = append(userUUIDList, userUUID)
				userPasswordList = append(userPasswordList, password)
			}
			if len(userList) > 0 {
				service.UpdateUsers(userList, userUUIDList, userPasswordList)
				inbound.userNameList = userNameList
			}
		}
		inbound.userManager = userManager
	} else {
		userList := make([]int, 0, len(options.Users))
		userNameList := make([]string, 0, len(options.Users))
		userUUIDList := make([][16]byte, 0, len(options.Users))
		userPasswordList := make([]string, 0, len(options.Users))
		for index, user := range options.Users {
			if user.UUID == "" {
				return nil, E.New("missing uuid for user ", index)
			}
			userUUID, err := uuid.FromString(user.UUID)
			if err != nil {
				return nil, E.Cause(err, "invalid uuid for user ", index)
			}
			userList = append(userList, index)
			userNameList = append(userNameList, user.Name)
			userUUIDList = append(userUUIDList, userUUID)
			userPasswordList = append(userPasswordList, user.Password)
		}
		service.UpdateUsers(userList, userUUIDList, userPasswordList)
		inbound.userNameList = userNameList
	}
	inbound.server = service
	return inbound, nil
}

func (h *Inbound) NewConnectionEx(ctx context.Context, conn net.Conn, source M.Socksaddr, destination M.Socksaddr, onClose N.CloseHandlerFunc) {
	ctx = log.ContextWithNewID(ctx)
	var metadata adapter.InboundContext
	metadata.Inbound = h.Tag()
	metadata.InboundType = h.Type()
	//nolint:staticcheck
	metadata.InboundDetour = h.listener.ListenOptions().Detour
	//nolint:staticcheck
	metadata.OriginDestination = h.listener.UDPAddr()
	metadata.Source = source
	metadata.Destination = destination
	h.logger.InfoContext(ctx, "inbound connection from ", metadata.Source)
	userID, _ := auth.UserFromContext[int](ctx)
	if userName := h.userNameList[userID]; userName != "" {
		metadata.User = userName
		h.logger.InfoContext(ctx, "[", userName, "] inbound connection to ", metadata.Destination)
	} else {
		h.logger.InfoContext(ctx, "inbound connection to ", metadata.Destination)
	}
	h.router.RouteConnectionEx(ctx, conn, metadata, onClose)
}

func (h *Inbound) NewPacketConnectionEx(ctx context.Context, conn N.PacketConn, source M.Socksaddr, destination M.Socksaddr, onClose N.CloseHandlerFunc) {
	ctx = log.ContextWithNewID(ctx)
	var metadata adapter.InboundContext
	metadata.Inbound = h.Tag()
	metadata.InboundType = h.Type()
	//nolint:staticcheck
	metadata.InboundDetour = h.listener.ListenOptions().Detour
	//nolint:staticcheck
	metadata.OriginDestination = h.listener.UDPAddr()
	metadata.Source = source
	metadata.Destination = destination
	h.logger.InfoContext(ctx, "inbound packet connection from ", metadata.Source)
	userID, _ := auth.UserFromContext[int](ctx)
	if userName := h.userNameList[userID]; userName != "" {
		metadata.User = userName
		h.logger.InfoContext(ctx, "[", userName, "] inbound packet connection to ", metadata.Destination)
	} else {
		h.logger.InfoContext(ctx, "inbound packet connection to ", metadata.Destination)
	}
	h.router.RoutePacketConnectionEx(ctx, conn, metadata, onClose)
}

func (h *Inbound) Start(stage adapter.StartStage) error {
	if stage != adapter.StartStateStart {
		return nil
	}
	if h.tlsConfig != nil {
		err := h.tlsConfig.Start()
		if err != nil {
			return err
		}
	}
	if h.userManager != nil {
		go h.credentialLoop()
	}
	packetConn, err := h.listener.ListenUDP()
	if err != nil {
		return err
	}
	return h.server.Start(packetConn)
}

func (h *Inbound) syncCredentials() {
	creds, err := h.userManager.GetCredentials(C.TypeTUIC)
	if err != nil || len(creds) == 0 {
		return
	}
	userList := make([]int, 0, len(creds))
	userNameList := make([]string, 0, len(creds))
	userUUIDList := make([][16]byte, 0, len(creds))
	userPasswordList := make([]string, 0, len(creds))
	for i, c := range creds {
		parts := strings.SplitN(c.Credential, ":", 2)
		if len(parts) < 1 || parts[0] == "" {
			continue
		}
		userUUID, pErr := uuid.FromString(parts[0])
		if pErr != nil {
			continue
		}
		password := ""
		if len(parts) == 2 {
			password = parts[1]
		}
		userList = append(userList, i)
		userNameList = append(userNameList, c.Username)
		userUUIDList = append(userUUIDList, userUUID)
		userPasswordList = append(userPasswordList, password)
	}
	if len(userList) > 0 {
		h.server.UpdateUsers(userList, userUUIDList, userPasswordList)
		h.userNameList = userNameList
	}
}

func (h *Inbound) credentialLoop() {
	h.syncCredentials()
	ticker := time.NewTicker(30 * time.Second)
	defer ticker.Stop()
	for range ticker.C {
		h.syncCredentials()
	}
}

func (h *Inbound) Close() error {
	return common.Close(
		h.listener,
		h.tlsConfig,
		common.PtrOrNil(h.server),
	)
}