//go:build !confonly
// +build !confonly

package grpc

import (
	"context"
	gonet "net"
	"sync"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/backoff"
	"google.golang.org/grpc/connectivity"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/credentials/insecure"

	core "github.com/v2fly/v2ray-core/v5"
	"github.com/v2fly/v2ray-core/v5/common"
	"github.com/v2fly/v2ray-core/v5/common/net"
	"github.com/v2fly/v2ray-core/v5/common/session"
	"github.com/v2fly/v2ray-core/v5/transport/internet"
	"github.com/v2fly/v2ray-core/v5/transport/internet/grpc/encoding"
	"github.com/v2fly/v2ray-core/v5/transport/internet/tls"
)

func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.MemoryStreamConfig) (internet.Connection, error) {
	newError("creating connection to ", dest).WriteToLog(session.ExportIDToError(ctx))

	conn, err := dialgRPC(ctx, dest, streamSettings)
	if err != nil {
		return nil, newError("failed to dial Grpc").Base(err)
	}
	return internet.Connection(conn), nil
}

func init() {
	common.Must(internet.RegisterTransportDialer(protocolName, Dial))
}

type dialerCanceller func()

var (
	globalDialerMap    map[net.Destination]*grpc.ClientConn
	globalDialerAccess sync.Mutex
)

func dialgRPC(ctx context.Context, dest net.Destination, streamSettings *internet.MemoryStreamConfig) (net.Conn, error) {
	grpcSettings := streamSettings.ProtocolSettings.(*Config)

	config := tls.ConfigFromStreamSettings(streamSettings)

	transportCredentials := insecure.NewCredentials()
	if config != nil {
		transportCredentials = credentials.NewTLS(config.GetTLSConfig(tls.WithDestination(dest)))
	}
	dialOption := grpc.WithTransportCredentials(transportCredentials)

	conn, canceller, err := getGrpcClient(ctx, dest, dialOption, streamSettings)
	if err != nil {
		return nil, newError("Cannot dial grpc").Base(err)
	}
	client := encoding.NewGunServiceClient(conn)
	gunService, err := client.(encoding.GunServiceClientX).TunCustomName(ctx, grpcSettings.ServiceName)
	if err != nil {
		canceller()
		return nil, newError("Cannot dial grpc").Base(err)
	}
	return encoding.NewGunConn(gunService, nil), nil
}

func getGrpcClient(ctx context.Context, dest net.Destination, dialOption grpc.DialOption, streamSettings *internet.MemoryStreamConfig) (*grpc.ClientConn, dialerCanceller, error) {
	globalDialerAccess.Lock()
	defer globalDialerAccess.Unlock()

	if globalDialerMap == nil {
		globalDialerMap = make(map[net.Destination]*grpc.ClientConn)
	}

	canceller := func() {
		globalDialerAccess.Lock()
		defer globalDialerAccess.Unlock()
		delete(globalDialerMap, dest)
	}

	// TODO Should support chain proxy to the same destination
	if client, found := globalDialerMap[dest]; found && client.GetState() != connectivity.Shutdown {
		return client, canceller, nil
	}

	conn, err := grpc.Dial(
		dest.Address.String()+":"+dest.Port.String(),
		dialOption,
		grpc.WithConnectParams(grpc.ConnectParams{
			Backoff: backoff.Config{
				BaseDelay:  500 * time.Millisecond,
				Multiplier: 1.5,
				Jitter:     0.2,
				MaxDelay:   19 * time.Second,
			},
			MinConnectTimeout: 5 * time.Second,
		}),
		grpc.WithContextDialer(func(ctxGrpc context.Context, s string) (gonet.Conn, error) {
			rawHost, rawPort, err := net.SplitHostPort(s)
			if err != nil {
				return nil, err
			}
			if len(rawPort) == 0 {
				rawPort = "443"
			}
			port, err := net.PortFromString(rawPort)
			if err != nil {
				return nil, err
			}
			address := net.ParseAddress(rawHost)
			detachedContext := core.ToBackgroundDetachedContext(ctx)
			return internet.DialSystem(detachedContext, net.TCPDestination(address, port), streamSettings.SocketSettings)
		}),
	)
	globalDialerMap[dest] = conn
	return conn, canceller, err
}