package dns

import (
	"bytes"
	"fmt"
	"io"
	"os/exec"
	"sync"

	"github.com/stuurmcp/cert-manager-webhook-sthome/pkg/util"
	"k8s.io/klog/v2"
)

const (
	nsupdateCmd = "nsupdate"
	ttl         = "7200"
)

type output struct {
	buf   *bytes.Buffer
	lines []string
	*sync.Mutex
}

func AddTxtRecord(nameservers []string, domain string, fulldomain string, recordvalue string) error {
	return processTXT("add", nameservers, domain, fulldomain, recordvalue)
}

func DeleteTxtRecord(nameservers []string, domain string, fulldomain string, recordvalue string) error {
	return processTXT("delete", nameservers, domain, fulldomain, recordvalue)
}

func processTXT(action string, nameservers []string, domain string, fulldomain string, recordvalue string) error {
	for _, ns := range nameservers {
		klog.Infof("======= ns: %s =======", ns)
		zone := extractDomainName(domain)
		nsucmd := " gsstsig\n server " + ns + "\n zone " + zone + "\n class IN\n update " + action + " " + fulldomain + " " + ttl + " TXT " + recordvalue + "\n send\n"
		out, err := nsupdate(nsucmd)
		if err != nil {
			return err
		}
		for _, line := range out.lines {
			klog.Infof(line)
		}
	}
	return nil
}

func newOutput() *output {
	return &output{
		buf:   &bytes.Buffer{},
		lines: []string{},
		Mutex: &sync.Mutex{},
	}
}

func (rw *output) Write(p []byte) (int, error) {
	rw.Lock()
	defer rw.Unlock()
	return rw.buf.Write(p)
}

func nsupdate(nsucmd string) (*output, error) {
	klog.Infof("nsupdate\n%s", nsucmd) // for debugging
	cmd := exec.Command(nsupdateCmd)
	stdout := newOutput()
	cmd.Stdout = stdout
	stdinR, stdinW := io.Pipe()
	stderrR, stderrW := io.Pipe()
	cmd.Stdin = stdinR
	cmd.Stderr = stderrW
	err := cmd.Start()
	if err != nil {
		return stdout, fmt.Errorf("could not start %s command: %v", nsupdateCmd, err)
	}

	go func() {
		io.WriteString(stdinW, nsucmd)
		stdinW.Close()
	}()
	errBuf := new(bytes.Buffer)
	go func() {
		io.Copy(errBuf, stderrR)
		stderrR.Close()
	}()

	err = cmd.Wait()
	if err != nil {
		return stdout, fmt.Errorf("%s did not run successfully: %v stderr: %s", nsupdateCmd, err, errBuf.String())
	}
	return stdout, nil
}

func extractDomainName(zone string) string {
	authZone, err := util.FindZoneByFqdn(zone, util.RecursiveNameservers)
	if err != nil {
		klog.Errorf("could not get zone by fqdn %v", err)
		return zone
	}
	return util.UnFqdn(authZone)
}