//go:build !e2e_testing
// +build !e2e_testing

package overlay

import (
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"regexp"
	"strconv"
	"strings"

	"github.com/sirupsen/logrus"
	"github.com/slackhq/nebula/cidr"
	"github.com/slackhq/nebula/iputil"
)

var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)

type tun struct {
	Device    string
	cidr      *net.IPNet
	MTU       int
	Routes    []Route
	routeTree *cidr.Tree4
	l         *logrus.Logger

	io.ReadWriteCloser
}

func (t *tun) Close() error {
	if t.ReadWriteCloser != nil {
		return t.ReadWriteCloser.Close()
	}
	return nil
}

func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ int) (*tun, error) {
	return nil, fmt.Errorf("newTunFromFd not supported in FreeBSD")
}

func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, _ int, _ bool) (*tun, error) {
	routeTree, err := makeRouteTree(l, routes, false)
	if err != nil {
		return nil, err
	}

	if strings.HasPrefix(deviceName, "/dev/") {
		deviceName = strings.TrimPrefix(deviceName, "/dev/")
	}
	if !deviceNameRE.MatchString(deviceName) {
		return nil, fmt.Errorf("tun.dev must match `tun[0-9]+`")
	}
	return &tun{
		Device:    deviceName,
		cidr:      cidr,
		MTU:       defaultMTU,
		Routes:    routes,
		routeTree: routeTree,
		l:         l,
	}, nil
}

func (t *tun) Activate() error {
	var err error
	t.ReadWriteCloser, err = os.OpenFile("/dev/"+t.Device, os.O_RDWR, 0)
	if err != nil {
		return fmt.Errorf("activate failed: %v", err)
	}

	// TODO use syscalls instead of exec.Command
	t.l.Debug("command: ifconfig", t.Device, t.cidr.String(), t.cidr.IP.String())
	if err = exec.Command("/sbin/ifconfig", t.Device, t.cidr.String(), t.cidr.IP.String()).Run(); err != nil {
		return fmt.Errorf("failed to run 'ifconfig': %s", err)
	}
	t.l.Debug("command: route", "-n", "add", "-net", t.cidr.String(), "-interface", t.Device)
	if err = exec.Command("/sbin/route", "-n", "add", "-net", t.cidr.String(), "-interface", t.Device).Run(); err != nil {
		return fmt.Errorf("failed to run 'route add': %s", err)
	}
	t.l.Debug("command: ifconfig", t.Device, "mtu", strconv.Itoa(t.MTU))
	if err = exec.Command("/sbin/ifconfig", t.Device, "mtu", strconv.Itoa(t.MTU)).Run(); err != nil {
		return fmt.Errorf("failed to run 'ifconfig': %s", err)
	}
	// Unsafe path routes
	for _, r := range t.Routes {
		if r.Via == nil {
			// We don't allow route MTUs so only install routes with a via
			continue
		}

		t.l.Debug("command: route", "-n", "add", "-net", r.Cidr.String(), "-interface", t.Device)
		if err = exec.Command("/sbin/route", "-n", "add", "-net", r.Cidr.String(), "-interface", t.Device).Run(); err != nil {
			return fmt.Errorf("failed to run 'route add' for unsafe_route %s: %s", r.Cidr.String(), err)
		}
	}

	return nil
}

func (t *tun) RouteFor(ip iputil.VpnIp) iputil.VpnIp {
	r := t.routeTree.MostSpecificContains(ip)
	if r != nil {
		return r.(iputil.VpnIp)
	}

	return 0
}

func (t *tun) Cidr() *net.IPNet {
	return t.cidr
}

func (t *tun) Name() string {
	return t.Device
}

func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
	return nil, fmt.Errorf("TODO: multiqueue not implemented for freebsd")
}