package nft

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

func executeCommand(name string, arg ...string) error {
	cmd := exec.Command(name, arg...)
	out, err := cmd.CombinedOutput()
	if err != nil {
		if len(out) > 0 {
			return errors.New(string(out))
		}
		return err
	}

	return nil
}

func checkingNFT(path string) error {
	if path == "" {
		return errors.New("path is empty")
	}

	cmd := exec.Command(path, "-V")
	out, err := cmd.CombinedOutput()
	if err != nil {
		return errors.New("nftables not found")
	}

	lines := regexp.MustCompile("\r?\n").Split(strings.TrimSpace(string(out)), -1)
	json := false
	for index, line := range lines {
		line = strings.TrimSpace(line)

		if index == 0 {
			if !strings.HasPrefix(line, "nftables") {
				return errors.New("nftables not found")
			}
			continue
		}

		if strings.HasPrefix(line, "json:") && strings.HasSuffix(line, "yes") {
			json = true
		}
	}

	if !json {
		return errors.New("nftables disabled json")
	}

	cmd = exec.Command(path, "list", "ruleset")
	out, err = cmd.CombinedOutput()

	if err != nil {
		return fmt.Errorf("nftables is not available or not supported by the kernel: %s", string(out))
	}

	return nil
}