package controller

import (
	"context"
	"fmt"

	"k8s.io/apimachinery/pkg/runtime"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/log"

	bindv1alpha1 "git.unkin.net/unkin/bind-operator/api/v1alpha1"
	"git.unkin.net/unkin/bind-operator/internal/bind"
)

// DNSRecordReconciler applies individual record sets to a zone via TSIG dynamic
// update — the external-dns write path as a CRD.
type DNSRecordReconciler struct {
	client.Client
	Scheme *runtime.Scheme
	Exec   *bind.Executor
}

// +kubebuilder:rbac:groups=bind.unkin.net,resources=dnsrecords,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=bind.unkin.net,resources=dnsrecords/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=bind.unkin.net,resources=bindzones;bindtsigkeys,verbs=get;list;watch

func (r *DNSRecordReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	logger := log.FromContext(ctx)

	var record bindv1alpha1.DNSRecord
	if err := r.Get(ctx, req.NamespacedName, &record); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	var zone bindv1alpha1.BindZone
	if err := r.Get(ctx, client.ObjectKey{Namespace: record.Namespace, Name: record.Spec.ZoneRef}, &zone); err != nil {
		return r.setPhase(ctx, &record, "Error", "ZoneMissing", err.Error())
	}
	cluster, err := getCluster(ctx, r.Client, record.Namespace, zone.Spec.ClusterRef)
	if err != nil {
		return r.setPhase(ctx, &record, "Error", "ClusterMissing", err.Error())
	}
	primaryPod := primaryPodName(cluster.Name)
	name := fqdn(record.Spec.Name, zone.Spec.ZoneName)

	creds, err := resolveTSIG(ctx, r.Client, record.Namespace, zone.Spec.UpdateKeyRef)
	if err != nil {
		return r.setPhase(ctx, &record, "Error", "NoUpdateKey", fmt.Sprintf("zone %s: %v", zone.Name, err))
	}

	// Deletion via finalizer: remove the RRset.
	if !record.DeletionTimestamp.IsZero() {
		if controllerutil.ContainsFinalizer(&record, finalizer) {
			if primaryReady(ctx, r.Client, cluster) && r.Exec != nil {
				_ = r.Exec.NSUpdate(ctx, record.Namespace, primaryPod, zone.Spec.ZoneName, creds,
					[]bind.RecordUpdate{{FQDN: name, Type: record.Spec.Type, Delete: true}})
			}
			controllerutil.RemoveFinalizer(&record, finalizer)
			if err := r.Update(ctx, &record); err != nil {
				return ctrl.Result{}, err
			}
		}
		return ctrl.Result{}, nil
	}

	if !controllerutil.ContainsFinalizer(&record, finalizer) {
		controllerutil.AddFinalizer(&record, finalizer)
		if err := r.Update(ctx, &record); err != nil {
			return ctrl.Result{}, err
		}
	}

	if !primaryReady(ctx, r.Client, cluster) || r.Exec == nil {
		return r.setPhase(ctx, &record, "Pending", "PrimaryNotReady", "waiting for cluster primary")
	}

	ttl := zone.Spec.DefaultTTL
	if record.Spec.TTL != nil {
		ttl = *record.Spec.TTL
	}
	update := bind.RecordUpdate{FQDN: name, Type: record.Spec.Type, TTL: ttl, Values: record.Spec.Values}
	if err := r.Exec.NSUpdate(ctx, record.Namespace, primaryPod, zone.Spec.ZoneName, creds, []bind.RecordUpdate{update}); err != nil {
		return r.setPhase(ctx, &record, "Error", "UpdateFailed", err.Error())
	}

	record.Status.FQDN = name
	record.Status.Phase = "Applied"
	record.Status.ObservedGeneration = record.Generation
	setReady(&record.Status.Conditions, record.Generation, true, "Applied", "record applied via dynamic update")
	if err := r.Status().Update(ctx, &record); err != nil {
		return ctrl.Result{}, err
	}
	logger.Info("record applied", "record", name, "type", record.Spec.Type)
	return ctrl.Result{}, nil
}

func (r *DNSRecordReconciler) setPhase(ctx context.Context, record *bindv1alpha1.DNSRecord, phase, reason, msg string) (ctrl.Result, error) {
	record.Status.Phase = phase
	record.Status.ObservedGeneration = record.Generation
	setReady(&record.Status.Conditions, record.Generation, phase == "Applied", reason, msg)
	if err := r.Status().Update(ctx, record); err != nil {
		return ctrl.Result{}, err
	}
	if phase == "Error" || phase == "Pending" {
		return ctrl.Result{RequeueAfter: requeueShort}, nil
	}
	return ctrl.Result{}, nil
}

func (r *DNSRecordReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&bindv1alpha1.DNSRecord{}).
		Complete(r)
}