package outbound

import (
	"context"
	"crypto/tls"
	"net"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/common/dialer"
	"github.com/sagernet/sing-box/common/mux"
	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/v2ray"
	"github.com/sagernet/sing/common"
	"github.com/sagernet/sing/common/bufio"
	E "github.com/sagernet/sing/common/exceptions"
	M "github.com/sagernet/sing/common/metadata"
	N "github.com/sagernet/sing/common/network"
	"github.com/sagernet/sing/protocol/trojan"
)

var _ adapter.Outbound = (*Trojan)(nil)

type Trojan struct {
	myOutboundAdapter
	dialer          N.Dialer
	serverAddr      M.Socksaddr
	key             [56]byte
	multiplexDialer N.Dialer
	tlsConfig       *tls.Config
	transport       adapter.V2RayClientTransport
}

func NewTrojan(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.TrojanOutboundOptions) (*Trojan, error) {
	outbound := &Trojan{
		myOutboundAdapter: myOutboundAdapter{
			protocol: C.TypeTrojan,
			network:  options.Network.Build(),
			router:   router,
			logger:   logger,
			tag:      tag,
		},
		dialer:     dialer.New(router, options.DialerOptions),
		serverAddr: options.ServerOptions.Build(),
		key:        trojan.Key(options.Password),
	}
	var err error
	if options.TLS != nil {
		outbound.tlsConfig, err = dialer.TLSConfig(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(ctx, (*trojanDialer)(outbound), common.PtrValueOrDefault(options.Multiplex))
	if err != nil {
		return nil, err
	}
	return outbound, nil
}

func (h *Trojan) 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 *Trojan) 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 *Trojan) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
	return NewEarlyConnection(ctx, h, conn, metadata)
}

func (h *Trojan) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
	return NewPacketConnection(ctx, h, conn, metadata)
}

type trojanDialer Trojan

func (h *trojanDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
	ctx, metadata := adapter.AppendContext(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 = dialer.TLSClient(ctx, conn, h.tlsConfig)
		}
	}
	if err != nil {
		return nil, err
	}
	switch N.NetworkName(network) {
	case N.NetworkTCP:
		return trojan.NewClientConn(conn, h.key, destination), nil
	case N.NetworkUDP:
		return &bufio.BindPacketConn{PacketConn: trojan.NewClientPacketConn(conn, h.key), Addr: 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
}