package dns

import (
	"fmt"
	"net"

	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/klog/v2"

	"github.com/cert-manager/cert-manager/pkg/acme/webhook/apis/acme/v1alpha1"
	"github.com/cert-manager/cert-manager/pkg/issuer/acme/dns/util"
)

const (
	providerName = "sthome"
	shell        = "/bin/bash"
	acmeAuthCmd  = "/acme/acmeauth.sh"

	dnsserver_net  = "10.0.0.15"
	dnsserver_lan  = "192.168.2.1"
	hostserver_net = "truenas.sthome.net"
	hostserver_lan = "truenas.sthome.lan"
)

// LocalDNSProviderSolver implements the provider-specific logic needed to
// 'present' an ACME challenge TXT record for your own DNS provider.
// To do so, it must implement the `github.com/cert-manager/cert-manager/pkg/acme/webhook.Solver`
// interface.
type LocalDNSProviderSolver struct {
	client kubernetes.Interface
}

// Name is used as the name for this DNS solver when referencing it on the ACME
// Issuer resource.
// This should be unique **within the group name**, i.e. you can have two
// solvers configured with the same Name() **so long as they do not co-exist
// within a single webhook deployment**.
// For example, `cloudflare` may be used as the name of a solver.
func (p *LocalDNSProviderSolver) Name() string {
	return providerName
}

// Present is responsible for actually presenting the DNS record with the
// DNS provider.
// This method should tolerate being called multiple times with the same value.
// cert-manager itself will later perform a self check to ensure that the
// solver has correctly configured the DNS provider.
func (loc *LocalDNSProviderSolver) Present(ch *v1alpha1.ChallengeRequest) error {
	//domainName := extractDomainName(ch.ResolvedZone)
	cfg, err := loadConfig(ch.Config)
	if err != nil {
		return err
	}

	klog.InfoS("CZ: Presenting challenge", "dnsName", ch.DNSName, "resolvedZone", ch.ResolvedZone, "resolvedFQDN", ch.ResolvedFQDN)

	/*
		provider, cfg, err := loc.init(ch.Config, ch.ResourceNamespace)
		if err != nil {
			return fmt.Errorf("failed initializing sthome provider: %v", err)
		}
	*/
	if !cfg.IsAllowedZone(ch.ResolvedZone) {
		return fmt.Errorf("zone %s may not be edited per config (allowed zones are %v)", ch.ResolvedZone, cfg.AllowedZones)
	}
	/*
		ctx := context.Background()
		records, err := loc.getExistingRecords(ctx, provider, ch.ResolvedZone, ch.ResolvedFQDN)
		if err != nil {
			return fmt.Errorf("failed loading existing records for %s in domain %s: %v", ch.ResolvedFQDN, ch.ResolvedZone, err)
		}

		// Add the record, only if it doesn't exist already
		content := quote(ch.Key)
		if _, ok := findRecord(records, content); !ok {
			disabled := false
			records = append(records, sthome.Record{Disabled: &disabled, Content: &content})
		}
	*/
	// TODO: do something more useful with the decoded configuration
	klog.Infof("Decoded configuration %v\n", cfg)
	klog.Infof("Presenting record for %s, type: %s, uid: %s, key: %s, ns: %s, fqdn: %s, zone: %s, allowambcred: %t, cfg: %s",
		ch.DNSName,
		ch.UID,
		ch.Type,
		ch.Key,
		ch.ResourceNamespace,
		ch.ResolvedFQDN,
		ch.ResolvedZone,
		ch.AllowAmbientCredentials,
		ch.Config,
	)
	// TODO: convert shell script to golang
	localip := getOutboundIP(dnsserver_net)
	success, _ := Execute(
		shell,
		acmeAuthCmd,
		"set",
		ch.DNSName,
		ch.ResolvedFQDN,
		ch.Key,
		"-l",
		localip,
		"-v",
	)
	klog.Infof("Execute set TXT returned success: %t", success)
	return nil
}

// CleanUp should delete the relevant TXT record from the DNS provider console.
// If multiple TXT records exist with the same record name (e.g.
// _acme-challenge.example.com) then **only** the record with the same `key`
// value provided on the ChallengeRequest should be cleaned up.
// This is in order to facilitate multiple DNS validations for the same domain
// concurrently.
func (loc *LocalDNSProviderSolver) CleanUp(ch *v1alpha1.ChallengeRequest) error {
	//domainName := extractDomainName(ch.ResolvedZone)
	// TODO: add code that deletes a record from the DNS provider's console
	localip := getOutboundIP(dnsserver_net)
	success, _ := Execute(
		shell,
		acmeAuthCmd,
		"unset",
		ch.DNSName,
		ch.ResolvedFQDN,
		ch.Key,
		"-l",
		localip,
		"-v",
	)
	klog.Infof("Execute unset TXT returned success: %t", success)
	return nil
}

// Initialize will be called when the webhook first starts.
// This method can be used to instantiate the webhook, i.e. initialising
// connections or warming up caches.
// Typically, the kubeClientConfig parameter is used to build a Kubernetes
// client that can be used to fetch resources from the Kubernetes API, e.g.
// Secret resources containing credentials used to authenticate with DNS
// provider accounts.
// The stopCh can be used to handle early termination of the webhook, in cases
// where a SIGTERM or similar signal is sent to the webhook process.
func (loc *LocalDNSProviderSolver) Initialize(kubeClientConfig *rest.Config, stopCh <-chan struct{}) error {
	cl, err := kubernetes.NewForConfig(kubeClientConfig)
	if err != nil {
		return fmt.Errorf("failed to get kubernetes client: %w", err)
	}
	loc.client = cl
	klog.InfoS("CZ: Successfully initialised kubernetes client!")
	return 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)
}

// Get preferred outbound ip of this machine
func getOutboundIP(dest string) string {
	conn, err := net.Dial("udp", dest+":80")
	if err != nil {
		klog.Errorf("net.Dial error: %s", err)
		return "0.0.0.0"
	}
	defer conn.Close()

	localAddr := conn.LocalAddr().(*net.UDPAddr)

	return localAddr.IP.String()
}