// Package point is a shell of V2Ray to run on various of systems.
// Point server is a full functionality proxying system. It consists of an inbound and an outbound
// connection, as well as any number of inbound and outbound detours. It provides a way internally
// to route network packets.
package point

import (
	"github.com/v2ray/v2ray-core/app"
	"github.com/v2ray/v2ray-core/app/controller"
	"github.com/v2ray/v2ray-core/app/router"
	"github.com/v2ray/v2ray-core/common/log"
	v2net "github.com/v2ray/v2ray-core/common/net"
	"github.com/v2ray/v2ray-core/common/retry"
	"github.com/v2ray/v2ray-core/proxy"
	proxyrepo "github.com/v2ray/v2ray-core/proxy/repo"
	"github.com/v2ray/v2ray-core/transport/ray"
)

// Point shell of V2Ray.
type Point struct {
	port   v2net.Port
	ich    proxy.InboundConnectionHandler
	och    proxy.OutboundConnectionHandler
	idh    []*InboundDetourHandler
	odh    map[string]proxy.OutboundConnectionHandler
	router router.Router
	space  *controller.SpaceController
}

// NewPoint returns a new Point server based on given configuration.
// The server is not started at this point.
func NewPoint(pConfig PointConfig) (*Point, error) {
	var vpoint = new(Point)
	vpoint.port = pConfig.Port()

	if pConfig.LogConfig() != nil {
		logConfig := pConfig.LogConfig()
		if len(logConfig.AccessLog()) > 0 {
			err := log.InitAccessLogger(logConfig.AccessLog())
			if err != nil {
				return nil, err
			}
		}

		if len(logConfig.ErrorLog()) > 0 {
			err := log.InitErrorLogger(logConfig.ErrorLog())
			if err != nil {
				return nil, err
			}
		}

		log.SetLogLevel(logConfig.LogLevel())
	}

	vpoint.space = controller.New()
	vpoint.space.Bind(vpoint)

	ichConfig := pConfig.InboundConfig().Settings()
	ich, err := proxyrepo.CreateInboundConnectionHandler(pConfig.InboundConfig().Protocol(), vpoint.space.ForContext("vpoint-default-inbound"), ichConfig)
	if err != nil {
		log.Error("Failed to create inbound connection handler: %v", err)
		return nil, err
	}
	vpoint.ich = ich

	ochConfig := pConfig.OutboundConfig().Settings()
	och, err := proxyrepo.CreateOutboundConnectionHandler(pConfig.OutboundConfig().Protocol(), vpoint.space.ForContext("vpoint-default-outbound"), ochConfig)
	if err != nil {
		log.Error("Failed to create outbound connection handler: %v", err)
		return nil, err
	}
	vpoint.och = och

	detours := pConfig.InboundDetours()
	if len(detours) > 0 {
		vpoint.idh = make([]*InboundDetourHandler, len(detours))
		for idx, detourConfig := range detours {
			detourHandler := &InboundDetourHandler{
				space:  vpoint.space.ForContext(detourConfig.Tag()),
				config: detourConfig,
			}
			err := detourHandler.Initialize()
			if err != nil {
				return nil, err
			}
			vpoint.idh[idx] = detourHandler
		}
	}

	outboundDetours := pConfig.OutboundDetours()
	if len(outboundDetours) > 0 {
		vpoint.odh = make(map[string]proxy.OutboundConnectionHandler)
		for _, detourConfig := range outboundDetours {
			detourHandler, err := proxyrepo.CreateOutboundConnectionHandler(detourConfig.Protocol(), vpoint.space.ForContext(detourConfig.Tag()), detourConfig.Settings())
			if err != nil {
				log.Error("Failed to create detour outbound connection handler: %v", err)
				return nil, err
			}
			vpoint.odh[detourConfig.Tag()] = detourHandler
		}
	}

	routerConfig := pConfig.RouterConfig()
	if routerConfig != nil {
		r, err := router.CreateRouter(routerConfig.Strategy(), routerConfig.Settings())
		if err != nil {
			log.Error("Failed to create router: %v", err)
			return nil, BadConfiguration
		}
		vpoint.router = r
	}

	return vpoint, nil
}

func (this *Point) Close() {
	this.ich.Close()
	for _, idh := range this.idh {
		idh.Close()
	}
}

// Start starts the Point server, and return any error during the process.
// In the case of any errors, the state of the server is unpredicatable.
func (this *Point) Start() error {
	if this.port <= 0 {
		log.Error("Invalid port %d", this.port)
		return BadConfiguration
	}

	err := retry.Timed(100 /* times */, 100 /* ms */).On(func() error {
		err := this.ich.Listen(this.port)
		if err != nil {
			return err
		}
		log.Warning("Point server started on port %d", this.port)
		return nil
	})
	if err != nil {
		return err
	}

	for _, detourHandler := range this.idh {
		err := detourHandler.Start()
		if err != nil {
			return err
		}
	}

	return nil
}

// Dispatches a Packet to an OutboundConnection.
// The packet will be passed through the router (if configured), and then sent to an outbound
// connection with matching tag.
func (this *Point) DispatchToOutbound(context app.Context, packet v2net.Packet) ray.InboundRay {
	direct := ray.NewRay()
	dest := packet.Destination()

	dispatcher := this.och

	if this.router != nil {
		tag, err := this.router.TakeDetour(dest)
		if err == nil {
			handler, found := this.odh[tag]
			if found {
				dispatcher = handler
			}
		}
	}

	go this.FilterPacketAndDispatch(packet, direct, dispatcher)
	return direct
}

func (this *Point) FilterPacketAndDispatch(packet v2net.Packet, link ray.OutboundRay, dispatcher proxy.OutboundConnectionHandler) {
	// Filter empty packets
	chunk := packet.Chunk()
	moreChunks := packet.MoreChunks()
	changed := false
	for chunk == nil && moreChunks {
		changed = true
		chunk, moreChunks = <-link.OutboundInput()
	}
	if chunk == nil && !moreChunks {
		close(link.OutboundOutput())
		return
	}

	if changed {
		packet = v2net.NewPacket(packet.Destination(), chunk, moreChunks)
	}

	dispatcher.Dispatch(packet, link)
}