package wireguard

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

// Status of a WireGuard interface.
type Status string

const (
	StatusUp   Status = "UP"
	StatusDown Status = "DOWN"
)

// Up brings up the given interface via wg-quick.
func Up(iface string) error {
	return run("wg-quick", "up", iface)
}

// Down brings down the given interface via wg-quick.
func Down(iface string) error {
	return run("wg-quick", "down", iface)
}

// Reload applies config changes to a running interface without a full restart,
// using `wg syncconf` against a stripped config (wg-quick strip).
func Reload(iface, confPath string) error {
	strip := exec.Command("wg-quick", "strip", confPath)
	stripped, err := strip.Output()
	if err != nil {
		return fmt.Errorf("wg-quick strip: %w", err)
	}
	sync := exec.Command("wg", "syncconf", iface, "/dev/stdin")
	sync.Stdin = strings.NewReader(string(stripped))
	if out, err := sync.CombinedOutput(); err != nil {
		return fmt.Errorf("wg syncconf: %w: %s", err, out)
	}
	return nil
}

// IsUp checks whether the interface currently exists / is up.
func IsUp(iface string) bool {
	cmd := exec.Command("wg", "show", iface)
	return cmd.Run() == nil
}

func GetStatus(iface string) Status {
	if IsUp(iface) {
		return StatusUp
	}
	return StatusDown
}

// EnableService enables and starts the systemd wg-quick@<iface>.service unit.
func EnableService(iface string) error {
	if err := run("systemctl", "enable", "wg-quick@"+iface); err != nil {
		return err
	}
	return run("systemctl", "start", "wg-quick@"+iface)
}

// DisableService stops and disables the systemd wg-quick@<iface>.service unit.
func DisableService(iface string) error {
	if err := run("systemctl", "stop", "wg-quick@"+iface); err != nil {
		return err
	}
	return run("systemctl", "disable", "wg-quick@"+iface)
}

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