package cli

import (
	"flag"
	"fmt"
	"io"
	"os"
	"strings"
	"syscall"
)

type RoutesUpdateDeps struct {
	LockFile string
	Update   func(iface string) (ok bool, message string)
	Stdout   io.Writer
	Stderr   io.Writer
}

func RunRoutesUpdate(args []string, deps RoutesUpdateDeps) int {
	if deps.Update == nil || deps.LockFile == "" {
		return 1
	}
	stdout := deps.Stdout
	if stdout == nil {
		stdout = os.Stdout
	}
	stderr := deps.Stderr
	if stderr == nil {
		stderr = os.Stderr
	}

	fs := flag.NewFlagSet("routes-update", flag.ContinueOnError)
	fs.SetOutput(stderr)
	iface := fs.String("iface", "", "VPN interface (empty/auto = detect active)")
	if err := fs.Parse(args); err != nil {
		return 2
	}

	lock, err := os.OpenFile(deps.LockFile, os.O_CREATE|os.O_RDWR, 0o644)
	if err != nil {
		fmt.Fprintf(stderr, "lock open error: %v\n", err)
		return 1
	}
	defer lock.Close()

	if err := syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
		fmt.Fprintln(stdout, "routes update already running")
		return 0
	}
	defer func() {
		_ = syscall.Flock(int(lock.Fd()), syscall.LOCK_UN)
	}()

	ok, message := deps.Update(*iface)
	if ok {
		fmt.Fprintln(stdout, strings.TrimSpace(message))
		return 0
	}
	msg := strings.TrimSpace(message)
	if msg == "" {
		msg = "routes update failed"
	}
	fmt.Fprintln(stderr, msg)
	return 1
}