//go:build linux || darwin

package main

import (
	"os"
	"os/exec"
	"runtime"

	"github.com/songgao/water"
)

var iface *water.Interface

func isAdmin() bool {
	return os.Geteuid() == 0
}

func setupInterface() {
	config := water.Config{DeviceType: water.TUN}
	if runtime.GOOS == "linux" {
		config.Name = "baalvpn"
	}

	var err error
	iface, err = water.New(config)
	if err != nil {
		panic(err)
	}

	if runtime.GOOS == "linux" {
		if err := exec.Command("ip", "addr", "add", internalIP.String()+"/32", "dev", "baalvpn").Run(); err != nil {
			panic(err)
		}
		if err := exec.Command("ip", "link", "set", "dev", "baalvpn", "up").Run(); err != nil {
			panic(err)
		}
	} else {
		if err := exec.Command("ifconfig", iface.Name(), "inet6", internalIP.String(), internalIP.String(), "prefixlen", "128", "up").Run(); err != nil {
			panic(err)
		}
		if err := exec.Command("route", "-n", "add", "-inet6", "fd00:baa1::/32", "-interface", iface.Name()).Run(); err != nil {
			panic(err)
		}
	}
}

func writePkt(pkt []byte) error {
	_, err := iface.Write(pkt)
	return err
}

func readPkt() ([]byte, error) {
	pkt := make([]byte, 2000)
	n, err := iface.Read(pkt)
	if err != nil {
		return nil, err
	}
	return pkt[:n], nil
}

func releasePkt(pkt []byte) {}