//go:build darwin

package route

import (
	"fmt"
	"os/exec"
	"strings"
)

// addRoute adds a route via a network interface (macOS route command).
//   route add -inet -net <cidr> -interface <iface>
func addRoute(cidr, iface string) error {
	return runRoute("add", "-inet", "-net", cidr, "-interface", iface)
}

// deleteRoute removes a route via a network interface.
func deleteRoute(cidr, iface string) error {
	return runRoute("delete", "-inet", "-net", cidr, "-interface", iface)
}

// addRouteVia adds a route via a gateway IP.
func addRouteVia(cidr, gateway string) error {
	return runRoute("add", "-inet", "-net", cidr, gateway)
}

// deleteRouteVia removes a route via a gateway IP.
func deleteRouteVia(cidr, gateway string) error {
	return runRoute("delete", "-inet", "-net", cidr, gateway)
}

// defaultGateway returns the current default gateway IP.
func defaultGateway() (string, error) {
	out, err := exec.Command("route", "-n", "get", "default").Output()
	if err != nil {
		return "", err
	}
	for _, line := range strings.Split(string(out), "\n") {
		line = strings.TrimSpace(line)
		if strings.HasPrefix(line, "gateway:") {
			parts := strings.SplitN(line, ":", 2)
			if len(parts) == 2 {
				gw := strings.TrimSpace(parts[1])
				if gw != "" {
					return gw, nil
				}
			}
		}
	}
	return "", fmt.Errorf("no default gateway found")
}

func runRoute(args ...string) error {
	cmd := exec.Command("route", args...)
	if out, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("route %s: %w (%s)", strings.Join(args, " "), err, strings.TrimSpace(string(out)))
	}
	return nil
}