package trojan

import (
	"context"
	"net"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/adapter/outbound"
	"github.com/sagernet/sing-box/common/dialer"
	"github.com/sagernet/sing-box/common/mux"
	"github.com/sagernet/sing-box/common/tls"
	C "github.com/sagernet/sing-box/constant"
	"github.com/sagernet/sing-box/log"
	"github.com/sagernet/sing-box/option"
	"github.com/sagernet/sing-box/transport/trojan"
	"github.com/sagernet/sing-box/transport/v2ray"
	"github.com/sagernet/sing/common"
	"github.com/sagernet/sing/common/bufio"
	E "github.com/sagernet/sing/common/exceptions"
	"github.com/sagernet/sing/common/logger"
	M "github.com/sagernet/sing/common/metadata"
	N "github.com/sagernet/sing/common/network"
)

func RegisterOutbound(registry *outbound.Registry) {
	outbound.Register[option.TrojanOutboundOptions](registry, C.TypeTrojan, NewOutbound)
}

type Outbound struct {
	outbound.Adapter
	logger          logger.ContextLogger
	dialer          N.Dialer
	serverAddr      M.Socksaddr
	key             [56]byte
	multiplexDialer *mux.Client
	tlsConfig       tls.Config
	transport       adapter.V2RayClientTransport
}

func NewOutbound(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.TrojanOutboundOptions) (adapter.Outbound, error) {
	outboundDialer, err := dialer.New(ctx, options.DialerOptions, options.ServerIsDomain())
	if err != nil {
		return nil, err
	}
	outbound := &Outbound{
		Adapter:    outbound.NewAdapterWithDialerOptions(C.TypeTrojan, tag, options.Network.Build(), options.DialerOptions),
		logger:     logger,
		dialer:     outboundDialer,
		serverAddr: options.ServerOptions.Build(),
		key:        trojan.Key(options.Password),
	}
	if options.TLS != nil {
		outbound.tlsConfig, err = tls.NewClient(ctx, options.Server, common.PtrValueOrDefault(options.TLS))
		if err != nil {
			return nil, err
		}
	}
	if options.Transport != nil {
		outbound.transport, err = v2ray.NewClientTransport(ctx, outbound.dialer, outbound.serverAddr, common.PtrValueOrDefault(options.Transport), outbound.tlsConfig)
		if err != nil {
			return nil, E.Cause(err, "create client transport: ", options.Transport.Type)
		}
	}
	outbound.multiplexDialer, err = mux.NewClientWithOptions((*trojanDialer)(outbound), logger, common.PtrValueOrDefault(options.Multiplex))
	if err != nil {
		return nil, err
	}
	return outbound, nil
}

func (h *Outbound) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
	if h.multiplexDialer == nil {
		switch N.NetworkName(network) {
		case N.NetworkTCP:
			h.logger.InfoContext(ctx, "outbound connection to ", destination)
		case N.NetworkUDP:
			h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
		}
		return (*trojanDialer)(h).DialContext(ctx, network, destination)
	} else {
		switch N.NetworkName(network) {
		case N.NetworkTCP:
			h.logger.InfoContext(ctx, "outbound multiplex connection to ", destination)
		case N.NetworkUDP:
			h.logger.InfoContext(ctx, "outbound multiplex packet connection to ", destination)
		}
		return h.multiplexDialer.DialContext(ctx, network, destination)
	}
}

func (h *Outbound) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
	if h.multiplexDialer == nil {
		h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
		return (*trojanDialer)(h).ListenPacket(ctx, destination)
	} else {
		h.logger.InfoContext(ctx, "outbound multiplex packet connection to ", destination)
		return h.multiplexDialer.ListenPacket(ctx, destination)
	}
}

func (h *Outbound) InterfaceUpdated() {
	if h.transport != nil {
		h.transport.Close()
	}
	if h.multiplexDialer != nil {
		h.multiplexDialer.Reset()
	}
	return
}

func (h *Outbound) Close() error {
	return common.Close(common.PtrOrNil(h.multiplexDialer), h.transport)
}

type trojanDialer Outbound

func (h *trojanDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
	ctx, metadata := adapter.ExtendContext(ctx)
	metadata.Outbound = h.Tag()
	metadata.Destination = destination
	var conn net.Conn
	var err error
	if h.transport != nil {
		conn, err = h.transport.DialContext(ctx)
	} else {
		conn, err = h.dialer.DialContext(ctx, N.NetworkTCP, h.serverAddr)
		if err == nil && h.tlsConfig != nil {
			conn, err = tls.ClientHandshake(ctx, conn, h.tlsConfig)
		}
	}
	if err != nil {
		common.Close(conn)
		return nil, err
	}
	switch N.NetworkName(network) {
	case N.NetworkTCP:
		return trojan.NewClientConn(conn, h.key, destination), nil
	case N.NetworkUDP:
		return bufio.NewBindPacketConn(trojan.NewClientPacketConn(conn, h.key), destination), nil
	default:
		return nil, E.Extend(N.ErrUnknownNetwork, network)
	}
}

func (h *trojanDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
	conn, err := h.DialContext(ctx, N.NetworkUDP, destination)
	if err != nil {
		return nil, err
	}
	return conn.(net.PacketConn), nil
}
