/*
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package externalsecret

import (
	"context"

	// nolint
	"crypto/md5"
	"fmt"
	"time"

	"github.com/go-logr/logr"
	"github.com/prometheus/client_golang/prometheus"
	v1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"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/controller/controllerutil"

	esv1alpha1 "github.com/external-secrets/external-secrets/apis/externalsecrets/v1alpha1"
	"github.com/external-secrets/external-secrets/pkg/provider"

	// Loading registered providers.
	_ "github.com/external-secrets/external-secrets/pkg/provider/register"
	schema "github.com/external-secrets/external-secrets/pkg/provider/schema"
	"github.com/external-secrets/external-secrets/pkg/template"
	utils "github.com/external-secrets/external-secrets/pkg/utils"
)

const (
	requeueAfter = time.Second * 30
)

// Reconciler reconciles a ExternalSecret object.
type Reconciler struct {
	client.Client
	Log             logr.Logger
	Scheme          *runtime.Scheme
	ControllerClass string
}

// Reconcile implements the main reconciliation loop
// for watched objects (ExternalSecret, ClusterSecretStore and SecretStore),
// and updates/creates a Kubernetes secret based on them.
func (r *Reconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	log := r.Log.WithValues("ExternalSecret", req.NamespacedName)

	syncCallsMetricLabels := prometheus.Labels{"name": req.Name, "namespace": req.Namespace}

	var externalSecret esv1alpha1.ExternalSecret

	err := r.Get(ctx, req.NamespacedName, &externalSecret)
	if apierrors.IsNotFound(err) {
		syncCallsTotal.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{}, nil
	} else if err != nil {
		log.Error(err, "could not get ExternalSecret")
		syncCallsError.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{}, nil
	}

	// patch status when done processing
	p := client.MergeFrom(externalSecret.DeepCopy())
	defer func() {
		err = r.Status().Patch(ctx, &externalSecret, p)
		if err != nil {
			log.Error(err, "unable to patch status")
		}
	}()

	store, err := r.getStore(ctx, &externalSecret)
	if err != nil {
		log.Error(err, "could not get store reference")
		conditionSynced := NewExternalSecretCondition(esv1alpha1.ExternalSecretReady, v1.ConditionFalse, esv1alpha1.ConditionReasonSecretSyncedError, err.Error())
		SetExternalSecretCondition(&externalSecret, *conditionSynced)
		syncCallsError.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{RequeueAfter: requeueAfter}, nil
	}

	log = log.WithValues("SecretStore", store.GetNamespacedName())

	// check if store should be handled by this controller instance
	if !shouldProcessStore(store, r.ControllerClass) {
		log.Info("skippig unmanaged store")
		return ctrl.Result{}, nil
	}

	storeProvider, err := schema.GetProvider(store)
	if err != nil {
		log.Error(err, "could not get store provider")
		syncCallsError.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{RequeueAfter: requeueAfter}, nil
	}

	secretClient, err := storeProvider.NewClient(ctx, store, r.Client, req.Namespace)
	if err != nil {
		log.Error(err, "could not get provider client")
		conditionSynced := NewExternalSecretCondition(esv1alpha1.ExternalSecretReady, v1.ConditionFalse, esv1alpha1.ConditionReasonSecretSyncedError, err.Error())
		SetExternalSecretCondition(&externalSecret, *conditionSynced)
		syncCallsError.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{RequeueAfter: requeueAfter}, nil
	}

	refreshInt := time.Hour
	if externalSecret.Spec.RefreshInterval != nil {
		refreshInt = externalSecret.Spec.RefreshInterval.Duration
	}

	// refresh should be skipped if
	// 1. resource generation hasn't changed
	// 2. refresh interval is 0
	// 3. if we're still within refresh-interval
	if !shouldRefresh(externalSecret) {
		log.V(1).Info("skipping refresh", "rv", getResourceVersion(externalSecret))
		return ctrl.Result{RequeueAfter: refreshInt}, nil
	}

	secret := &v1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Name:      externalSecret.Spec.Target.Name,
			Namespace: externalSecret.Namespace,
		},
		Data: make(map[string][]byte),
	}
	_, err = ctrl.CreateOrUpdate(ctx, r.Client, secret, func() error {
		err = controllerutil.SetControllerReference(&externalSecret, &secret.ObjectMeta, r.Scheme)
		if err != nil {
			return fmt.Errorf("could not set ExternalSecret controller reference: %w", err)
		}
		mergeTemplate(secret, externalSecret)
		// prepare templateFrom data
		templateData, err := r.getTemplateData(ctx, &externalSecret)
		if err != nil {
			return fmt.Errorf("error fetching templateFrom data: %w", err)
		}
		log.Info("found template data", "tpl_data", templateData)
		for k, v := range templateData {
			secret.Data[k] = v
		}
		// overwrite provider data
		data, err := r.getProviderSecretData(ctx, secretClient, &externalSecret)
		if err != nil {
			return fmt.Errorf("could not get secret data from provider: %w", err)
		}
		for k, v := range data {
			secret.Data[k] = v
		}
		err = template.Execute(externalSecret.Spec.Target.Template, secret, data)
		if err != nil {
			return fmt.Errorf("could not execute template: %w", err)
		}
		return nil
	})

	if err != nil {
		log.Error(err, "could not reconcile ExternalSecret")
		conditionSynced := NewExternalSecretCondition(esv1alpha1.ExternalSecretReady, v1.ConditionFalse, esv1alpha1.ConditionReasonSecretSyncedError, err.Error())
		SetExternalSecretCondition(&externalSecret, *conditionSynced)
		syncCallsError.With(syncCallsMetricLabels).Inc()
		return ctrl.Result{RequeueAfter: requeueAfter}, nil
	}

	conditionSynced := NewExternalSecretCondition(esv1alpha1.ExternalSecretReady, v1.ConditionTrue, esv1alpha1.ConditionReasonSecretSynced, "Secret was synced")
	SetExternalSecretCondition(&externalSecret, *conditionSynced)
	externalSecret.Status.RefreshTime = metav1.NewTime(time.Now())
	externalSecret.Status.SyncedResourceVersion = getResourceVersion(externalSecret)
	syncCallsTotal.With(syncCallsMetricLabels).Inc()
	log.V(1).Info("reconciled secret")

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

// shouldProcessStore returns true if the store should be processed.
func shouldProcessStore(store esv1alpha1.GenericStore, class string) bool {
	if store.GetSpec().Controller == "" || store.GetSpec().Controller == class {
		return true
	}
	return false
}

func getResourceVersion(es esv1alpha1.ExternalSecret) string {
	return fmt.Sprintf("%d-%s", es.ObjectMeta.GetGeneration(), hashMeta(es.ObjectMeta))
}

func hashMeta(m metav1.ObjectMeta) string {
	type meta struct {
		annotations map[string]string
		labels      map[string]string
	}
	h := md5.New() //nolint
	_, _ = h.Write([]byte(fmt.Sprintf("%v", meta{
		annotations: m.Annotations,
		labels:      m.Labels,
	})))
	return fmt.Sprintf("%x", h.Sum(nil))
}

func shouldRefresh(es esv1alpha1.ExternalSecret) bool {
	// refresh if resource version changed
	if es.Status.SyncedResourceVersion != getResourceVersion(es) {
		return true
	}
	// skip refresh if refresh interval is 0
	if es.Spec.RefreshInterval == nil && es.Status.SyncedResourceVersion != "" {
		return false
	}
	if es.Status.RefreshTime.IsZero() {
		return true
	}
	return !es.Status.RefreshTime.Add(es.Spec.RefreshInterval.Duration).After(time.Now())
}

// we do not want to force-override the label/annotations
// and only copy the necessary key/value pairs.
func mergeTemplate(secret *v1.Secret, externalSecret esv1alpha1.ExternalSecret) {
	if secret.ObjectMeta.Labels == nil {
		secret.ObjectMeta.Labels = make(map[string]string)
	}
	if secret.ObjectMeta.Annotations == nil {
		secret.ObjectMeta.Annotations = make(map[string]string)
	}
	if externalSecret.Spec.Target.Template == nil {
		utils.MergeStringMap(secret.ObjectMeta.Labels, externalSecret.ObjectMeta.Labels)
		utils.MergeStringMap(secret.ObjectMeta.Annotations, externalSecret.ObjectMeta.Annotations)
		return
	}
	// if template is defined: use those labels/annotations
	secret.Type = externalSecret.Spec.Target.Template.Type
	utils.MergeStringMap(secret.ObjectMeta.Labels, externalSecret.Spec.Target.Template.Metadata.Labels)
	utils.MergeStringMap(secret.ObjectMeta.Annotations, externalSecret.Spec.Target.Template.Metadata.Annotations)
}

// getStore returns the store with the provided ExternalSecret.
func (r *Reconciler) getStore(ctx context.Context, externalSecret *esv1alpha1.ExternalSecret) (esv1alpha1.GenericStore, error) {
	ref := types.NamespacedName{
		Name: externalSecret.Spec.SecretStoreRef.Name,
	}

	if externalSecret.Spec.SecretStoreRef.Kind == esv1alpha1.ClusterSecretStoreKind {
		var store esv1alpha1.ClusterSecretStore
		err := r.Get(ctx, ref, &store)
		if err != nil {
			return nil, fmt.Errorf("could not get ClusterSecretStore %q, %w", ref.Name, err)
		}

		return &store, nil
	}

	ref.Namespace = externalSecret.Namespace

	var store esv1alpha1.SecretStore
	err := r.Get(ctx, ref, &store)
	if err != nil {
		return nil, fmt.Errorf("could not get SecretStore %q, %w", ref.Name, err)
	}
	return &store, nil
}

// getProviderSecretData returns the provider's secret data with the provided ExternalSecret.
func (r *Reconciler) getProviderSecretData(ctx context.Context, providerClient provider.SecretsClient, externalSecret *esv1alpha1.ExternalSecret) (map[string][]byte, error) {
	providerData := make(map[string][]byte)

	for _, remoteRef := range externalSecret.Spec.DataFrom {
		secretMap, err := providerClient.GetSecretMap(ctx, remoteRef)
		if err != nil {
			return nil, fmt.Errorf("key %q from ExternalSecret %q: %w", remoteRef.Key, externalSecret.Name, err)
		}

		providerData = utils.MergeByteMap(providerData, secretMap)
	}

	for _, secretRef := range externalSecret.Spec.Data {
		secretData, err := providerClient.GetSecret(ctx, secretRef.RemoteRef)
		if err != nil {
			return nil, fmt.Errorf("key %q from ExternalSecret %q: %w", secretRef.RemoteRef.Key, externalSecret.Name, err)
		}

		providerData[secretRef.SecretKey] = secretData
	}

	err := providerClient.Close()
	if err != nil {
		return nil, fmt.Errorf("error closing the connection: %w", err)
	}

	return providerData, nil
}

func (r *Reconciler) getTemplateData(ctx context.Context, externalSecret *esv1alpha1.ExternalSecret) (map[string][]byte, error) {
	out := make(map[string][]byte)
	if externalSecret.Spec.Target.Template == nil {
		return out, nil
	}
	for _, tpl := range externalSecret.Spec.Target.Template.TemplateFrom {
		if tpl.ConfigMap != nil {
			var cm v1.ConfigMap
			err := r.Client.Get(ctx, types.NamespacedName{
				Name:      tpl.ConfigMap.Name,
				Namespace: externalSecret.Namespace,
			}, &cm)
			if err != nil {
				return nil, err
			}
			for _, k := range tpl.ConfigMap.Items {
				val, ok := cm.Data[k.Key]
				if !ok {
					return nil, fmt.Errorf("error in configmap %s: missing key %s", tpl.ConfigMap.Name, k.Key)
				}
				out[k.Key] = []byte(val)
			}
		}
		if tpl.Secret != nil {
			var sec v1.Secret
			err := r.Client.Get(ctx, types.NamespacedName{
				Name:      tpl.Secret.Name,
				Namespace: externalSecret.Namespace,
			}, &sec)
			if err != nil {
				return nil, err
			}
			for _, k := range tpl.Secret.Items {
				val, ok := sec.Data[k.Key]
				if !ok {
					return nil, fmt.Errorf("error in secret %s: missing key %s", tpl.Secret.Name, k.Key)
				}
				out[k.Key] = val
			}
		}
	}
	return out, nil
}

// SetupWithManager returns a new controller builder that will be started by the provided Manager.
func (r *Reconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&esv1alpha1.ExternalSecret{}).
		Owns(&v1.Secret{}).
		Complete(r)
}