package main

import (
	"flag"
	"fmt"
	"io"
	"math"
	"os"
	"strconv"
	"strings"
)

type config struct {
	inbound  uint16
	outbound uint16
	proxyUID uint32
	exclude  []uint16
}

func parse(args []string) (config, error) {
	flags := flag.NewFlagSet("mesh-init", flag.ContinueOnError)
	flags.SetOutput(io.Discard)
	inbound := flags.Uint("inbound", 4143, "inbound proxy port")
	outbound := flags.Uint("outbound", 4140, "outbound proxy port")
	uid := flags.Uint64("proxy-uid", 2102, "proxy user ID")
	exclude := flags.String("ignore-inbound", "4190,4191", "inbound ports excluded from interception")
	if err := flags.Parse(args); err != nil {
		return config{}, err
	}
	if flags.NArg() != 0 || *inbound == 0 || *inbound > math.MaxUint16 || *outbound == 0 || *outbound > math.MaxUint16 || *uid > math.MaxUint32 {
		return config{}, fmt.Errorf("invalid proxy configuration")
	}
	result := config{inbound: uint16(*inbound), outbound: uint16(*outbound), proxyUID: uint32(*uid)}
	if *exclude != "" {
		for _, item := range strings.Split(*exclude, ",") {
			port, err := strconv.ParseUint(item, 10, 16)
			if err != nil || port == 0 {
				return config{}, fmt.Errorf("invalid inbound exclusion %q", item)
			}
			result.exclude = append(result.exclude, uint16(port))
		}
	}
	return result, nil
}

func main() {
	value, err := parse(os.Args[1:])
	if err == nil {
		err = install(value)
	}
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	fmt.Println("NAT_READY")
}