package controller

import (
	"context"
	"fmt"
	"time"

	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"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"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/recorder"

	terdutv1alpha1 "git.ryuvia.com/niklas/terdut-operator/api/v1alpha1"
	"git.ryuvia.com/niklas/terdut-operator/internal/tdclient"
)

const deadmanFinalizerName = "terdut.ryuvia.com/terdutdeadmanswitch"

// TerdutDeadmanSwitchReconciler reconciles a TerdutDeadmanSwitch object.
type TerdutDeadmanSwitchReconciler struct {
	client.Client
	Scheme *runtime.Scheme

	OperatorNamespace string
	Recorder          recorder.EventRecorder
	NewClient         func(endpoint string) *tdclient.Client
}

// +kubebuilder:rbac:groups=terdut.ryuvia.com,resources=terdutdeadmanswitches,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=terdut.ryuvia.com,resources=terdutdeadmanswitches/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=terdut.ryuvia.com,resources=terdutdeadmanswitches/finalizers,verbs=update
// +kubebuilder:rbac:groups=terdut.ryuvia.com,resources=terdutteams,verbs=get;list;watch
// +kubebuilder:rbac:groups="",resources=secrets,verbs=get;list;watch
// +kubebuilder:rbac:groups=events.k8s.io,resources=events,verbs=create;patch

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

	var sw terdutv1alpha1.TerdutDeadmanSwitch
	if err := r.Get(ctx, req.NamespacedName, &sw); err != nil {
		if apierrors.IsNotFound(err) {
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	newClient := r.NewClient
	if newClient == nil {
		newClient = tdclient.New
	}

	if !sw.DeletionTimestamp.IsZero() {
		return r.reconcileDeadmanDelete(ctx, &sw, newClient)
	}

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

	team, tc, resolveErr := resolveTeamAndClient(ctx, r.Client, r.OperatorNamespace, sw.Namespace, sw.Spec.TeamRef, newClient)
	if resolveErr != nil {
		return r.setDeadmanNotReady(ctx, &sw, resolveErr.reason, resolveErr.message, waitInterval)
	}

	timeout, err := time.ParseDuration(sw.Spec.Timeout)
	if err != nil {
		return ctrl.Result{}, fmt.Errorf("spec.timeout %q: %w", sw.Spec.Timeout, err)
	}
	severity := sw.Spec.Severity
	if severity == "" {
		severity = "critical"
	}

	if sw.Status.SwitchID == 0 {
		if err := r.createOrAdoptDeadmanSwitch(ctx, &sw, tc, team.Status.TeamID, timeout, severity); err != nil {
			return ctrl.Result{}, err
		}
	} else if err := tc.UpdateDeadmanSwitch(ctx, team.Status.TeamID, sw.Status.SwitchID, sw.Spec.Name, sw.Spec.Matcher, int64(timeout.Seconds()), severity); err != nil {
		return ctrl.Result{}, fmt.Errorf("PUT /api/teams/%d/deadman/switches/%d: %w", team.Status.TeamID, sw.Status.SwitchID, err)
	}

	meta.SetStatusCondition(&sw.Status.Conditions, metav1.Condition{
		Type:    terdutv1alpha1.ConditionReady,
		Status:  metav1.ConditionTrue,
		Reason:  terdutv1alpha1.ReasonChildAdopted,
		Message: fmt.Sprintf("switch %d applied on team %d", sw.Status.SwitchID, team.Status.TeamID),
	})
	sw.Status.ObservedGeneration = sw.Generation
	if err := r.Status().Update(ctx, &sw); err != nil {
		return ctrl.Result{}, err
	}
	if r.Recorder != nil {
		r.Recorder.Eventf(&sw, nil, corev1.EventTypeNormal, terdutv1alpha1.ReasonChildAdopted, terdutv1alpha1.ReasonChildAdopted,
			"dead man's switch applied")
	}
	log.Info("TerdutDeadmanSwitch applied", "name", sw.Name, "switchID", sw.Status.SwitchID)

	return ctrl.Result{RequeueAfter: resyncInterval}, nil
}

// createOrAdoptDeadmanSwitch implements this resource's own idempotent-
// create shape (DESIGN.md §4.4, §5): there's no unique-name constraint
// server-side to 409 on, so this lists first and matches by name (the
// server's own derived name, when spec.name is empty) rather than adopting
// after a conflict the API would never actually raise.
func (r *TerdutDeadmanSwitchReconciler) createOrAdoptDeadmanSwitch(
	ctx context.Context, sw *terdutv1alpha1.TerdutDeadmanSwitch, tc *tdclient.Client,
	teamID int64, timeout time.Duration, severity string,
) error {
	existing, err := tc.ListDeadmanSwitches(ctx, teamID)
	if err != nil {
		return fmt.Errorf("GET /api/teams/%d/deadman/switches: %w", teamID, err)
	}
	if sw.Spec.Name != "" {
		for _, s := range existing {
			if s.Name == sw.Spec.Name {
				sw.Status.SwitchID = s.ID
				return nil
			}
		}
	}

	created, err := tc.CreateDeadmanSwitch(ctx, teamID, sw.Spec.Name, sw.Spec.Matcher, int64(timeout.Seconds()), severity)
	if err != nil {
		return fmt.Errorf("POST /api/teams/%d/deadman/switches: %w", teamID, err)
	}
	sw.Status.SwitchID = created.ID
	return nil
}

func (r *TerdutDeadmanSwitchReconciler) setDeadmanNotReady(
	ctx context.Context, sw *terdutv1alpha1.TerdutDeadmanSwitch, reason, message string, d time.Duration,
) (ctrl.Result, error) {
	meta.SetStatusCondition(&sw.Status.Conditions, metav1.Condition{
		Type:    terdutv1alpha1.ConditionReady,
		Status:  metav1.ConditionFalse,
		Reason:  reason,
		Message: message,
	})
	sw.Status.ObservedGeneration = sw.Generation
	if err := r.Status().Update(ctx, sw); err != nil {
		return ctrl.Result{}, err
	}
	if r.Recorder != nil {
		r.Recorder.Eventf(sw, nil, corev1.EventTypeWarning, reason, reason, message)
	}
	return ctrl.Result{RequeueAfter: d}, nil
}

// reconcileDeadmanDelete calls the real DELETE this resource actually has
// (unlike TerdutEscalationRule) if the team is still resolvable and a
// switch was ever created, then removes the finalizer unconditionally.
func (r *TerdutDeadmanSwitchReconciler) reconcileDeadmanDelete(
	ctx context.Context, sw *terdutv1alpha1.TerdutDeadmanSwitch, newClient func(string) *tdclient.Client,
) (ctrl.Result, error) {
	if !controllerutil.ContainsFinalizer(sw, deadmanFinalizerName) {
		return ctrl.Result{}, nil
	}

	if sw.Status.SwitchID != 0 {
		if team, tc, resolveErr := resolveTeamAndClient(
			ctx, r.Client, r.OperatorNamespace, sw.Namespace, sw.Spec.TeamRef, newClient,
		); resolveErr == nil {
			if err := tc.DeleteDeadmanSwitch(ctx, team.Status.TeamID, sw.Status.SwitchID); err != nil {
				if r.Recorder != nil {
					r.Recorder.Eventf(sw, nil, corev1.EventTypeWarning, "DeleteFailed", "DeleteFailed", err.Error())
				}
				return ctrl.Result{}, err
			}
		}
	}

	controllerutil.RemoveFinalizer(sw, deadmanFinalizerName)
	return ctrl.Result{}, r.Update(ctx, sw)
}

// SetupWithManager sets up the controller with the Manager.
func (r *TerdutDeadmanSwitchReconciler) SetupWithManager(mgr ctrl.Manager) error {
	if r.NewClient == nil {
		r.NewClient = tdclient.New
	}
	if r.Recorder == nil {
		r.Recorder = mgr.GetEventRecorder("terdutdeadmanswitch-controller")
	}
	return ctrl.NewControllerManagedBy(mgr).
		For(&terdutv1alpha1.TerdutDeadmanSwitch{}).
		Named("terdutdeadmanswitch").
		Complete(r)
}