package webhook

import (
	"context"
	"fmt"
	"time"

	"github.com/go-logr/logr"
	"github.com/kyverno/kyverno/api/kyverno"
	"github.com/kyverno/kyverno/pkg/config"
	"github.com/kyverno/kyverno/pkg/controllers"
	"github.com/kyverno/kyverno/pkg/logging"
	"github.com/kyverno/kyverno/pkg/tls"
	controllerutils "github.com/kyverno/kyverno/pkg/utils/controller"
	runtimeutils "github.com/kyverno/kyverno/pkg/utils/runtime"
	"golang.org/x/exp/maps"
	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	admissionregistrationv1informers "k8s.io/client-go/informers/admissionregistration/v1"
	appsv1informers "k8s.io/client-go/informers/apps/v1"
	corev1informers "k8s.io/client-go/informers/core/v1"
	admissionregistrationv1listers "k8s.io/client-go/listers/admissionregistration/v1"
	appsv1listers "k8s.io/client-go/listers/apps/v1"
	corev1listers "k8s.io/client-go/listers/core/v1"
	"k8s.io/client-go/util/workqueue"
)

const (
	maxRetries = 10
)

var (
	none   = admissionregistrationv1.SideEffectClassNone
	fail   = admissionregistrationv1.Fail
	ignore = admissionregistrationv1.Ignore
	None   = &none
	Fail   = &fail
	Ignore = &ignore
)

type controller struct {
	// clients
	vwcClient controllerutils.ObjectClient[*admissionregistrationv1.ValidatingWebhookConfiguration]

	// listers
	vwcLister        admissionregistrationv1listers.ValidatingWebhookConfigurationLister
	secretLister     corev1listers.SecretNamespaceLister
	deploymentLister appsv1listers.DeploymentNamespaceLister

	// queue
	queue workqueue.TypedRateLimitingInterface[any]

	// config
	controllerName      string
	logger              logr.Logger
	webhookName         string
	path                string
	server              string
	servicePort         int32
	rules               []admissionregistrationv1.RuleWithOperations
	failurePolicy       *admissionregistrationv1.FailurePolicyType
	sideEffects         *admissionregistrationv1.SideEffectClass
	runtime             runtimeutils.Runtime
	configuration       config.Configuration
	labelSelector       *metav1.LabelSelector
	caSecretName        string
	webhooksDeleted     bool
	autoDeleteWebhooks  bool
	webhookCleanupSetup func(context.Context, logr.Logger) error
	postWebhookCleanup  func(context.Context, logr.Logger) error
}

func NewController(
	controllerName string,
	vwcClient controllerutils.ObjectClient[*admissionregistrationv1.ValidatingWebhookConfiguration],
	vwcInformer admissionregistrationv1informers.ValidatingWebhookConfigurationInformer,
	secretInformer corev1informers.SecretInformer,
	deploymentInformer appsv1informers.DeploymentInformer,
	webhookName string,
	path string,
	server string,
	servicePort int32,
	webhookServerPort int32,
	labelSelector *metav1.LabelSelector,
	rules []admissionregistrationv1.RuleWithOperations,
	failurePolicy *admissionregistrationv1.FailurePolicyType,
	sideEffects *admissionregistrationv1.SideEffectClass,
	configuration config.Configuration,
	caSecretName string,
	runtime runtimeutils.Runtime,
	autoDeleteWebhooks bool,
	webhookCleanupSetup func(context.Context, logr.Logger) error,
	postWebhookCleanup func(context.Context, logr.Logger) error,
) controllers.Controller {
	queue := workqueue.NewTypedRateLimitingQueueWithConfig(
		workqueue.DefaultTypedControllerRateLimiter[any](),
		workqueue.TypedRateLimitingQueueConfig[any]{Name: controllerName},
	)
	c := controller{
		vwcClient:           vwcClient,
		vwcLister:           vwcInformer.Lister(),
		secretLister:        secretInformer.Lister().Secrets(config.KyvernoNamespace()),
		deploymentLister:    deploymentInformer.Lister().Deployments(config.KyvernoNamespace()),
		queue:               queue,
		controllerName:      controllerName,
		logger:              logging.ControllerLogger(controllerName),
		webhookName:         webhookName,
		path:                path,
		server:              server,
		servicePort:         servicePort,
		rules:               rules,
		failurePolicy:       failurePolicy,
		sideEffects:         sideEffects,
		configuration:       configuration,
		labelSelector:       labelSelector,
		caSecretName:        caSecretName,
		runtime:             runtime,
		autoDeleteWebhooks:  autoDeleteWebhooks,
		webhookCleanupSetup: webhookCleanupSetup,
		postWebhookCleanup:  postWebhookCleanup,
	}
	if _, _, err := controllerutils.AddDefaultEventHandlers(c.logger, vwcInformer.Informer(), queue); err != nil {
		c.logger.Error(err, "failed to register event handlers")
	}
	if _, err := controllerutils.AddEventHandlersT(
		secretInformer.Informer(),
		func(obj *corev1.Secret) {
			if obj.GetNamespace() == config.KyvernoNamespace() && obj.GetName() == caSecretName {
				c.enqueue()
			}
		},
		func(_, obj *corev1.Secret) {
			if obj.GetNamespace() == config.KyvernoNamespace() && obj.GetName() == caSecretName {
				c.enqueue()
			}
		},
		func(obj *corev1.Secret) {
			if obj.GetNamespace() == config.KyvernoNamespace() && obj.GetName() == caSecretName {
				c.enqueue()
			}
		},
	); err != nil {
		c.logger.Error(err, "failed to register event handlers")
	}
	if autoDeleteWebhooks {
		if _, err := controllerutils.AddEventHandlersT(
			deploymentInformer.Informer(),
			func(obj *appsv1.Deployment) {
			},
			func(_, obj *appsv1.Deployment) {
				if obj.GetNamespace() == config.KyvernoNamespace() && obj.GetName() == config.KyvernoDeploymentName() {
					c.enqueueCleanupAfter(1 * time.Second)
				}
			},
			func(obj *appsv1.Deployment) {
				if obj.GetNamespace() == config.KyvernoNamespace() && obj.GetName() == config.KyvernoDeploymentName() {
					c.enqueueCleanup()
				}
			},
		); err != nil {
			c.logger.Error(err, "failed to register event handlers")
		}
	}

	configuration.OnChanged(c.enqueue)
	return &c
}

func (c *controller) Run(ctx context.Context, workers int) {
	if c.autoDeleteWebhooks {
		if err := c.webhookCleanupSetup(ctx, c.logger); err != nil {
			c.logger.Error(err, "failed to setup webhook cleanup")
		}
	}
	c.enqueue()
	controllerutils.Run(ctx, c.logger, c.controllerName, time.Second, c.queue, workers, maxRetries, c.reconcile)
}

func (c *controller) enqueue() {
	c.queue.Add(c.webhookName)
}

func (c *controller) enqueueCleanup() {
	c.queue.Add(config.KyvernoDeploymentName())
}

func (c *controller) enqueueCleanupAfter(duration time.Duration) {
	c.queue.AddAfter(config.KyvernoDeploymentName(), duration)
}

func (c *controller) reconcile(ctx context.Context, logger logr.Logger, key, _, _ string) error {
	if c.autoDeleteWebhooks && c.runtime.IsGoingDown() {
		return c.reconcileWebhookDeletion(ctx)
	}

	if c.autoDeleteWebhooks && key == config.KyvernoDeploymentName() {
		return c.reconcileWebhookDeletion(ctx)
	}
	if key != c.webhookName {
		return nil
	}
	caData, err := tls.ReadRootCASecret(c.caSecretName, config.KyvernoNamespace(), c.secretLister)
	if err != nil {
		return err
	}
	desired, err := c.build(c.configuration, caData)
	if err != nil {
		return err
	}
	observed, err := c.vwcLister.Get(desired.Name)
	if err != nil {
		if apierrors.IsNotFound(err) {
			_, err := c.vwcClient.Create(ctx, desired, metav1.CreateOptions{})
			return err
		}
		return err
	}
	_, err = controllerutils.Update(ctx, observed, c.vwcClient, func(w *admissionregistrationv1.ValidatingWebhookConfiguration) error {
		w.Labels = desired.Labels
		w.Annotations = desired.Annotations
		w.OwnerReferences = desired.OwnerReferences
		w.Webhooks = desired.Webhooks
		return nil
	})
	return err
}

func (c *controller) reconcileWebhookDeletion(ctx context.Context) error {
	if c.autoDeleteWebhooks {
		if c.runtime.IsGoingDown() {
			if c.webhooksDeleted {
				return nil
			}
			c.webhooksDeleted = true
			if err := c.vwcClient.Delete(ctx, c.webhookName, metav1.DeleteOptions{}); err != nil && !apierrors.IsNotFound(err) {
				c.logger.Error(err, "failed to clean up validating webhook configuration", "label", kyverno.LabelWebhookManagedBy)
				return err
			} else if err == nil {
				c.logger.V(4).Info("successfully deleted validating webhook configurations", "label", kyverno.LabelWebhookManagedBy)
			}

			if err := c.postWebhookCleanup(ctx, c.logger); err != nil {
				c.logger.Error(err, "failed to clean up temporary rbac")
				return err
			} else {
				c.logger.V(4).Info("successfully deleted temporary rbac")
			}
		} else {
			if err := c.webhookCleanupSetup(ctx, c.logger); err != nil {
				c.logger.Error(err, "failed to reconcile webhook cleanup setup")
				return err
			}
			c.logger.V(4).Info("reconciled webhook cleanup setup")
		}
	}
	return nil
}

func objectMeta(name string, annotations map[string]string, labels map[string]string, owner ...metav1.OwnerReference) metav1.ObjectMeta {
	desiredLabels := make(map[string]string)
	defaultLabels := map[string]string{
		kyverno.LabelWebhookManagedBy: kyverno.ValueKyvernoApp,
	}
	maps.Copy(desiredLabels, labels)
	maps.Copy(desiredLabels, defaultLabels)
	return metav1.ObjectMeta{
		Name:            name,
		Labels:          desiredLabels,
		Annotations:     annotations,
		OwnerReferences: owner,
	}
}

func (c *controller) build(cfg config.Configuration, caBundle []byte) (*admissionregistrationv1.ValidatingWebhookConfiguration, error) {
	return &admissionregistrationv1.ValidatingWebhookConfiguration{
			ObjectMeta: objectMeta(c.webhookName, cfg.GetWebhookAnnotations(), cfg.GetWebhookLabels()),
			Webhooks: []admissionregistrationv1.ValidatingWebhook{{
				Name:                    fmt.Sprintf("%s.%s.svc", config.KyvernoServiceName(), config.KyvernoNamespace()),
				ClientConfig:            c.clientConfig(caBundle),
				Rules:                   c.rules,
				FailurePolicy:           c.failurePolicy,
				SideEffects:             c.sideEffects,
				AdmissionReviewVersions: []string{"v1"},
				ObjectSelector:          c.labelSelector,
				MatchConditions:         cfg.GetMatchConditions(),
			}},
		},
		nil
}

func (c *controller) clientConfig(caBundle []byte) admissionregistrationv1.WebhookClientConfig {
	clientConfig := admissionregistrationv1.WebhookClientConfig{
		CABundle: caBundle,
	}
	if c.server == "" {
		clientConfig.Service = &admissionregistrationv1.ServiceReference{
			Namespace: config.KyvernoNamespace(),
			Name:      config.KyvernoServiceName(),
			Path:      &c.path,
			Port:      &c.servicePort,
		}
	} else {
		url := fmt.Sprintf("https://%s%s", c.server, c.path)
		clientConfig.URL = &url
	}
	return clientConfig
}