package keptnwebhookcontroller

import (
	"context"
	"fmt"
	"reflect"

	"github.com/go-logr/logr"
	"github.com/keptn/lifecycle-toolkit/keptn-cert-manager/eventfilter"
	"github.com/keptn/lifecycle-toolkit/keptn-cert-manager/pkg/common"
	"github.com/pkg/errors"
	admissionregistrationv1 "k8s.io/api/admissionregistration/v1"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	apiv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
)

// ObservedObjects contains information about which Kubernetes resources should be observed by the reconciler.
type ObservedObjects struct {
	MutatingWebhooks          []string
	ValidatingWebhooks        []string
	CustomResourceDefinitions []string
	Deployments               []string
}

type CertificateReconcilerConfig struct {
	WatchResources *ObservedObjects
	MatchLabels    labels.Set
	Namespace      string
	Log            logr.Logger
	Client         client.Client
	Scheme         *runtime.Scheme
	CancelMgrFunc  context.CancelFunc
}

func NewReconciler(config CertificateReconcilerConfig) *KeptnWebhookCertificateReconciler {
	return &KeptnWebhookCertificateReconciler{
		Client:            config.Client,
		Scheme:            config.Scheme,
		CancelMgrFunc:     config.CancelMgrFunc,
		Log:               config.Log,
		Namespace:         config.Namespace,
		MatchLabels:       config.MatchLabels,
		FilterPredicate:   getFilterPredicate(config),
		ResourceRetriever: NewResourceRetriever(config),
	}
}

func getFilterPredicate(config CertificateReconcilerConfig) predicate.Predicate {
	if config.WatchResources != nil && len(config.WatchResources.Deployments) > 0 {
		return eventfilter.ForNamesAndNamespace(config.WatchResources.Deployments, config.Namespace)
	}
	return eventfilter.ForLabelsAndNamespace(labels.SelectorFromSet(config.MatchLabels), config.Namespace)
}

// KeptnWebhookCertificateReconciler reconciles a KeptnWebhookCertificate object
type KeptnWebhookCertificateReconciler struct {
	Client            client.Client
	Scheme            *runtime.Scheme
	CancelMgrFunc     context.CancelFunc
	Log               logr.Logger
	Namespace         string
	MatchLabels       labels.Set
	FilterPredicate   predicate.Predicate
	ResourceRetriever IResourceRetriever
}

//clusterrole
// +kubebuilder:rbac:groups=admissionregistration.k8s.io,resources=validatingwebhookconfigurations,verbs=get;list;watch;update;patch;
// +kubebuilder:rbac:groups=admissionregistration.k8s.io,resources=mutatingwebhookconfigurations,verbs=get;list;watch;update;patch;
// +kubebuilder:rbac:groups="apiextensions.k8s.io",resources=customresourcedefinitions,verbs=get;list;watch;update;patch;
// +kubebuilder:rbac:groups="apps",resources=deployments,verbs=get;list;watch;

//role
// +kubebuilder:rbac:groups="",namespace=keptn-system,resources=secrets,verbs=get;update;patch,resourceNames=keptn-certs
// +kubebuilder:rbac:groups="",namespace=keptn-system,resources=secrets,verbs=create;list;watch

// Reconcile is part of the main kubernetes reconciliation loop which aims to
// move the current state of the cluster closer to the desired state.
// For more details, check Reconcile and its Result here:
// - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.13.0/pkg/reconcile
func (r *KeptnWebhookCertificateReconciler) Reconcile(ctx context.Context, request ctrl.Request) (ctrl.Result, error) {
	requestInfo := common.GetRequestInfo(request)
	r.Log.Info("reconciling webhook certificates", "requestInfo", requestInfo)

	r.Log.Info("Retrieving MutatingWebhooks")
	mutatingWebhookConfigurations, err := r.ResourceRetriever.GetMutatingWebhooks(ctx)
	if err != nil {
		r.Log.Error(err, "could not find mutating webhook configuration", "requestInfo", requestInfo)
	}
	r.Log.Info(
		"Found MutatingWebhooks to inject certificates",
		"numberOfItems", len(mutatingWebhookConfigurations.Items),
		"byteSize", mutatingWebhookConfigurations.Size(),
	)

	r.Log.Info("Retrieving ValidatingWebhooks", "requestInfo", requestInfo)
	validatingWebhookConfigurations, err := r.ResourceRetriever.GetValidatingWebhooks(ctx)
	if err != nil {
		r.Log.Error(err, "could not find validating webhook configuration", "requestInfo", requestInfo)
	}
	r.Log.Info(
		"Found ValidatingWebhooks to inject certificates",
		"numberOfItems", len(validatingWebhookConfigurations.Items),
		"byteSize", validatingWebhookConfigurations.Size(),
	)

	r.Log.Info("Retrieving CRDs", "requestInfo", requestInfo)
	crds, err := r.ResourceRetriever.GetCRDs(ctx)
	if err != nil {
		r.Log.Error(err, "could not find CRDs", "requestInfo", requestInfo)
	}
	r.Log.Info(
		"Found CRDs to inject certificates",
		"numberOfItems", len(crds.Items),
		"byteSize", crds.Size(),
	)
	certSecret := newCertificateSecret(r.Client)

	if err := r.setCertificates(ctx, certSecret); err != nil {
		return reconcile.Result{}, errors.WithStack(err)
	}

	mutatingWebhookConfigs := getClientConfigsFromMutatingWebhook(mutatingWebhookConfigurations)

	validatingWebhookConfigs := getClientConfigsFromValidatingWebhook(validatingWebhookConfigurations)

	areMutatingWebhookConfigsValid := certSecret.areWebhookConfigsValid(mutatingWebhookConfigs)
	areValidatingWebhookConfigsValid := certSecret.areWebhookConfigsValid(validatingWebhookConfigs)
	areCRDConversionsConfigValid := certSecret.areCRDConversionsValid(crds)
	isCertSecretRecent := certSecret.isRecent()

	if isCertSecretRecent && areMutatingWebhookConfigsValid && areValidatingWebhookConfigsValid && areCRDConversionsConfigValid {
		r.Log.Info("secret for certificates up to date, skipping update", "requestInfo", requestInfo)
		r.cancelMgr()
		return reconcile.Result{RequeueAfter: common.SuccessDuration}, nil
	}

	if err = r.updateConfigurations(ctx, certSecret, crds, mutatingWebhookConfigs, mutatingWebhookConfigurations, validatingWebhookConfigs, validatingWebhookConfigurations); err != nil {
		return reconcile.Result{}, errors.WithStack(err)
	}

	r.cancelMgr()
	return reconcile.Result{RequeueAfter: common.SuccessDuration}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *KeptnWebhookCertificateReconciler) SetupWithManager(mgr ctrl.Manager) error {
	if r.FilterPredicate == nil {
		return errors.New("KeptnWebhookCertificateReconciler requires a FilterPredicate to be set")
	}
	return ctrl.NewControllerManagedBy(mgr).
		For(&appsv1.Deployment{}).
		WithEventFilter(r.FilterPredicate).
		Owns(&corev1.Secret{}).
		Complete(r)
}

func (r *KeptnWebhookCertificateReconciler) setCertificates(ctx context.Context, certSecret *certificateSecret) error {
	err := certSecret.setSecretFromReader(ctx, r.Namespace, r.Log)
	if err != nil {
		r.Log.Error(err, "could not get secret")
		return err
	}

	err = certSecret.setCertificates(r.Namespace)
	if err != nil {
		r.Log.Error(err, "could not validate certificate")
		return err
	}

	return nil
}

func (r *KeptnWebhookCertificateReconciler) updateConfigurations(ctx context.Context, certSecret *certificateSecret, crds *apiv1.CustomResourceDefinitionList, mutatingWebhookConfigs []*admissionregistrationv1.WebhookClientConfig, mutatingWebhookConfigurationList *admissionregistrationv1.MutatingWebhookConfigurationList, validatingWebhookConfigs []*admissionregistrationv1.WebhookClientConfig, validatingWebhookConfigurationList *admissionregistrationv1.ValidatingWebhookConfigurationList) error {
	if err := certSecret.createOrUpdateIfNecessary(ctx); err != nil {
		return err
	}

	bundle, err := certSecret.loadCombinedBundle()
	if err != nil {
		return err
	}

	for i := range mutatingWebhookConfigurationList.Items {
		r.Log.Info("injecting certificate into mutating webhook config", "mwc", mutatingWebhookConfigurationList.Items[i].Name)
		if err := r.updateClientConfigurations(ctx, bundle, mutatingWebhookConfigs, &mutatingWebhookConfigurationList.Items[i]); err != nil {
			return err
		}
	}

	for i := range validatingWebhookConfigurationList.Items {
		r.Log.Info("injecting certificate into validating webhook config", "vwc", validatingWebhookConfigurationList.Items[i].Name)
		if err := r.updateClientConfigurations(ctx, bundle, validatingWebhookConfigs, &validatingWebhookConfigurationList.Items[i]); err != nil {
			return err
		}
	}

	if err = r.updateCRDsConfiguration(ctx, crds, bundle); err != nil {
		return err
	}
	return nil
}

func (r *KeptnWebhookCertificateReconciler) cancelMgr() {
	if r.CancelMgrFunc != nil {
		r.Log.Info("stopping manager after certificates creation")
		r.CancelMgrFunc()
	}
}

func (r *KeptnWebhookCertificateReconciler) updateClientConfigurations(ctx context.Context, bundle []byte,
	webhookClientConfigs []*admissionregistrationv1.WebhookClientConfig, webhookConfig client.Object) error {
	if webhookConfig == nil || reflect.ValueOf(webhookConfig).IsNil() {
		return nil
	}

	for i := range webhookClientConfigs {
		webhookClientConfigs[i].CABundle = bundle
	}

	if err := r.Client.Update(ctx, webhookConfig); err != nil {
		return err
	}
	return nil
}

func (r *KeptnWebhookCertificateReconciler) updateCRDsConfiguration(ctx context.Context, crds *apiv1.CustomResourceDefinitionList, bundle []byte) error {
	fail := false
	for _, crd := range crds.Items {
		if err := r.updateCRDConfiguration(ctx, crd.Name, bundle); err != nil {
			fail = true
		}

	}
	if fail {
		return common.ErrCouldNotUpdateCRD
	}
	return nil
}

func (r *KeptnWebhookCertificateReconciler) updateCRDConfiguration(ctx context.Context, crdName string, bundle []byte) error {
	var crd apiv1.CustomResourceDefinition
	if err := r.Client.Get(ctx, types.NamespacedName{Name: crdName}, &crd); err != nil {
		return err
	}

	if !hasConversionWebhook(crd) {
		r.Log.Info(fmt.Sprintf("no conversion webhook config for %s, no cert will be provided", crdName))
		return nil
	}

	r.Log.Info(
		"Found conversion webhook in CRD, updating client certificate",
		"crd", crdName,
	)

	// update crd
	crd.Spec.Conversion.Webhook.ClientConfig.CABundle = bundle
	if err := r.Client.Update(ctx, &crd); err != nil {
		return err
	}
	return nil
}

func hasConversionWebhook(crd apiv1.CustomResourceDefinition) bool {
	return crd.Spec.Conversion != nil && crd.Spec.Conversion.Webhook != nil && crd.Spec.Conversion.Webhook.ClientConfig != nil
}