package obfsvpn

import (
	"context"
	"net"
	"strconv"

	pt "git.torproject.org/pluggable-transports/goptlib.git"
	"gitlab.com/yawning/obfs4.git/common/ntor"
	"gitlab.com/yawning/obfs4.git/transports/base"
	"gitlab.com/yawning/obfs4.git/transports/obfs4"
)

// IATMode determines the amount of time sent between packets.
type IATMode int

// Valid IAT modes.
const (
	IATNone IATMode = iota
	IATEnabled
	IATParanoid
)

// Dialer contains options for connecting to an address and obfuscating traffic
// with the obfs4 protocol.
// It performs the ntor handshake on all dialed connections.
type Dialer struct {
	Dialer net.Dialer

	NodeID    *ntor.NodeID
	PublicKey *ntor.PublicKey
	IATMode   IATMode

	cf base.ClientFactory
}

// Dial creates an outbound net.Conn and performs the ntor handshake.
func (d *Dialer) Dial(ctx context.Context, network, address string) (net.Conn, error) {
	if d.cf == nil {
		cf, err := (&obfs4.Transport{}).ClientFactory("")
		if err != nil {
			return nil, err
		}
		d.cf = cf
	}
	ptArgs := make(pt.Args)
	ptArgs.Add("node-id", d.NodeID.Hex())
	ptArgs.Add("public-key", d.PublicKey.Hex())
	ptArgs.Add("iat-mode", strconv.Itoa(int(d.IATMode)))
	args, err := d.cf.ParseArgs(&ptArgs)
	if err != nil {
		return nil, err
	}
	return d.cf.Dial(network, address, func(network, address string) (net.Conn, error) {
		return d.Dialer.DialContext(ctx, network, address)
	}, args)
}