/*
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"
	"encoding/json"
	"errors"
	"fmt"
	"maps"
	"slices"
	"strings"
	"time"

	"github.com/go-logr/logr"
	"github.com/prometheus/client_golang/prometheus"
	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/equality"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/selection"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/record"
	"k8s.io/utils/ptr"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/builder"
	"sigs.k8s.io/controller-runtime/pkg/cache"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	esv1beta1 "github.com/external-secrets/external-secrets/apis/externalsecrets/v1beta1"
	// Metrics.
	"github.com/external-secrets/external-secrets/pkg/controllers/externalsecret/esmetrics"
	ctrlmetrics "github.com/external-secrets/external-secrets/pkg/controllers/metrics"
	"github.com/external-secrets/external-secrets/pkg/utils"
	"github.com/external-secrets/external-secrets/pkg/utils/resolvers"

	// Loading registered generators.
	_ "github.com/external-secrets/external-secrets/pkg/generator/register"
	// Loading registered providers.
	_ "github.com/external-secrets/external-secrets/pkg/provider/register"
)

const (
	fieldOwnerTemplate = "externalsecrets.external-secrets.io/%v"

	// condition messages for "SecretSynced" reason.
	msgSynced       = "secret synced"
	msgSyncedRetain = "secret retained due to DeletionPolicy=Retain"

	// condition messages for "SecretDeleted" reason.
	msgDeleted = "secret deleted due to DeletionPolicy=Delete"

	// condition messages for "SecretMissing" reason.
	msgMissing = "secret will not be created due to CreationPolicy=Merge"

	// condition messages for "SecretSyncedError" reason.
	msgErrorGetSecretData   = "could not get secret data from provider"
	msgErrorDeleteSecret    = "could not delete secret"
	msgErrorDeleteOrphaned  = "could not delete orphaned secrets"
	msgErrorUpdateSecret    = "could not update secret"
	msgErrorUpdateImmutable = "could not update secret, target is immutable"
	msgErrorBecomeOwner     = "failed to take ownership of target secret"
	msgErrorIsOwned         = "target is owned by another ExternalSecret"

	// log messages.
	logErrorGetES                = "unable to get ExternalSecret"
	logErrorUpdateESStatus       = "unable to update ExternalSecret status"
	logErrorGetSecret            = "unable to get Secret"
	logErrorPatchSecret          = "unable to patch Secret"
	logErrorSecretCacheNotSynced = "controller caches for Secret are not in sync"
	logErrorUnmanagedStore       = "unable to determine if store is managed"

	// error formats.
	errConvert               = "error applying conversion strategy %s to keys: %w"
	errRewrite               = "error applying rewrite to keys: %w"
	errDecode                = "error applying decoding strategy %s to data: %w"
	errGenerate              = "error using generator: %w"
	errInvalidKeys           = "invalid secret keys (TIP: use rewrite or conversionStrategy to change keys): %w"
	errFetchTplFrom          = "error fetching templateFrom data: %w"
	errApplyTemplate         = "could not apply template: %w"
	errExecTpl               = "could not execute template: %w"
	errMutate                = "unable to mutate secret %s: %w"
	errUpdate                = "unable to update secret %s: %w"
	errUpdateNotFound        = "unable to update secret %s: not found"
	errDeleteCreatePolicy    = "unable to delete secret %s: creationPolicy=%s is not Owner"
	errSecretCachesNotSynced = "controller caches for secret %s are not in sync"

	// event messages.
	eventCreated                  = "secret created"
	eventUpdated                  = "secret updated"
	eventDeleted                  = "secret deleted due to DeletionPolicy=Delete"
	eventDeletedOrphaned          = "secret deleted because it was orphaned"
	eventMissingProviderSecret    = "secret does not exist at provider using spec.dataFrom[%d]"
	eventMissingProviderSecretKey = "secret does not exist at provider using spec.dataFrom[%d] (key=%s)"
)

// these errors are explicitly defined so we can detect them with `errors.Is()`.
var (
	ErrSecretImmutable     = fmt.Errorf("secret is immutable")
	ErrSecretIsOwned       = fmt.Errorf("secret is owned by another ExternalSecret")
	ErrSecretSetCtrlRef    = fmt.Errorf("could not set controller reference on secret")
	ErrSecretRemoveCtrlRef = fmt.Errorf("could not remove controller reference on secret")
)

const indexESTargetSecretNameField = ".metadata.targetSecretName"

// Reconciler reconciles a ExternalSecret object.
type Reconciler struct {
	client.Client
	SecretClient              client.Client
	Log                       logr.Logger
	Scheme                    *runtime.Scheme
	RestConfig                *rest.Config
	ControllerClass           string
	RequeueInterval           time.Duration
	ClusterSecretStoreEnabled bool
	EnableFloodGate           bool
	recorder                  record.EventRecorder
}

// 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) (result ctrl.Result, err error) {
	log := r.Log.WithValues("ExternalSecret", req.NamespacedName)

	resourceLabels := ctrlmetrics.RefineNonConditionMetricLabels(map[string]string{"name": req.Name, "namespace": req.Namespace})
	start := time.Now()

	syncCallsError := esmetrics.GetCounterVec(esmetrics.SyncCallsErrorKey)

	// use closures to dynamically update resourceLabels
	defer func() {
		esmetrics.GetGaugeVec(esmetrics.ExternalSecretReconcileDurationKey).With(resourceLabels).Set(float64(time.Since(start)))
		esmetrics.GetCounterVec(esmetrics.SyncCallsKey).With(resourceLabels).Inc()
	}()

	externalSecret := &esv1beta1.ExternalSecret{}
	err = r.Get(ctx, req.NamespacedName, externalSecret)
	if err != nil {
		if apierrors.IsNotFound(err) {
			// NOTE: this does not actually set the condition on the ExternalSecret, because it does not exist
			//       this is a hack to disable metrics for deleted ExternalSecrets, see:
			//       https://github.com/external-secrets/external-secrets/pull/612
			conditionSynced := NewExternalSecretCondition(esv1beta1.ExternalSecretDeleted, v1.ConditionFalse, esv1beta1.ConditionReasonSecretDeleted, "Secret was deleted")
			SetExternalSecretCondition(&esv1beta1.ExternalSecret{
				ObjectMeta: metav1.ObjectMeta{
					Name:      req.Name,
					Namespace: req.Namespace,
				},
			}, *conditionSynced)

			return ctrl.Result{}, nil
		}

		log.Error(err, logErrorGetES)
		syncCallsError.With(resourceLabels).Inc()
		return ctrl.Result{}, err
	}

	// skip reconciliation if deletion timestamp is set on external secret
	if !externalSecret.GetDeletionTimestamp().IsZero() {
		log.V(1).Info("skipping ExternalSecret, it is marked for deletion")
		return ctrl.Result{}, nil
	}

	// if extended metrics is enabled, refine the time series vector
	resourceLabels = ctrlmetrics.RefineLabels(resourceLabels, externalSecret.Labels)

	// skip this ExternalSecret if it uses a ClusterSecretStore and the feature is disabled
	if shouldSkipClusterSecretStore(r, externalSecret) {
		log.V(1).Info("skipping ExternalSecret, ClusterSecretStore feature is disabled")
		return ctrl.Result{}, nil
	}

	// skip this ExternalSecret if it uses any SecretStore not managed by this controller
	skip, err := shouldSkipUnmanagedStore(ctx, req.Namespace, r, externalSecret)
	if err != nil {
		log.Error(err, logErrorUnmanagedStore)
		syncCallsError.With(resourceLabels).Inc()
		return ctrl.Result{}, err
	}
	if skip {
		log.V(1).Info("skipping ExternalSecret, uses unmanaged SecretStore")
		return ctrl.Result{}, nil
	}

	// the target secret name defaults to the ExternalSecret name, if not explicitly set
	secretName := externalSecret.Spec.Target.Name
	if secretName == "" {
		secretName = externalSecret.Name
	}

	// fetch the existing secret (from the partial cache)
	//  - please note that the ~partial cache~ is different from the ~full cache~
	//    so there can be race conditions between the two caches
	//  - the WatchesMetadata(v1.Secret{}) in SetupWithManager() is using the partial cache
	//    so we might receive a reconcile request before the full cache is updated
	//  - furthermore, when `--enable-managed-secrets-caching` is true, the full cache
	//    will ONLY include secrets with the "managed" label, so we cant use the full cache
	//    to reliably determine if a secret exists or not
	secretPartial := &metav1.PartialObjectMetadata{}
	secretPartial.SetGroupVersionKind(v1.SchemeGroupVersion.WithKind("Secret"))
	err = r.Get(ctx, client.ObjectKey{Name: secretName, Namespace: externalSecret.Namespace}, secretPartial)
	if err != nil && !apierrors.IsNotFound(err) {
		log.Error(err, logErrorGetSecret, "secretName", secretName, "secretNamespace", externalSecret.Namespace)
		syncCallsError.With(resourceLabels).Inc()
		return ctrl.Result{}, err
	}

	// if the secret exists but does not have the "managed" label, add the label
	// using a PATCH so it is visible in the cache, then requeue immediately
	if secretPartial.UID != "" && secretPartial.Labels[esv1beta1.LabelManaged] != esv1beta1.LabelManagedValue {
		fqdn := fmt.Sprintf(fieldOwnerTemplate, externalSecret.Name)
		patch := client.MergeFrom(secretPartial.DeepCopy())
		if secretPartial.Labels == nil {
			secretPartial.Labels = make(map[string]string)
		}
		secretPartial.Labels[esv1beta1.LabelManaged] = esv1beta1.LabelManagedValue
		err = r.Patch(ctx, secretPartial, patch, client.FieldOwner(fqdn))
		if err != nil {
			log.Error(err, logErrorPatchSecret, "secretName", secretName, "secretNamespace", externalSecret.Namespace)
			syncCallsError.With(resourceLabels).Inc()
			return ctrl.Result{}, err
		}
		return ctrl.Result{Requeue: true}, nil
	}

	// fetch existing secret (from the full cache)
	// NOTE: we are using the `r.SecretClient` which we only use for managed secrets.
	//       when `enableManagedSecretsCache` is true, this is a cached client that only sees our managed secrets,
	//       otherwise it will be the normal controller-runtime client which may be cached or make direct API calls,
	//       depending on if `enabledSecretCache` is true or false.
	existingSecret := &v1.Secret{}
	err = r.SecretClient.Get(ctx, client.ObjectKey{Name: secretName, Namespace: externalSecret.Namespace}, existingSecret)
	if err != nil && !apierrors.IsNotFound(err) {
		log.Error(err, logErrorGetSecret, "secretName", secretName, "secretNamespace", externalSecret.Namespace)
		syncCallsError.With(resourceLabels).Inc()
		return ctrl.Result{}, err
	}

	// ensure the full cache is up-to-date
	// NOTE: this prevents race conditions between the partial and full cache.
	//       we return an error so we get an exponential backoff if we end up looping,
	//       for example, during high cluster load and frequent updates to the target secret by other controllers.
	if secretPartial.UID != existingSecret.UID || secretPartial.ResourceVersion != existingSecret.ResourceVersion {
		err = fmt.Errorf(errSecretCachesNotSynced, secretName)
		log.Error(err, logErrorSecretCacheNotSynced, "secretName", secretName, "secretNamespace", externalSecret.Namespace)
		syncCallsError.With(resourceLabels).Inc()
		return ctrl.Result{}, err
	}

	// refresh will be skipped if ALL the following conditions are met:
	// 1. refresh interval is not 0
	// 2. resource generation of the ExternalSecret has not changed
	// 3. the last refresh time of the ExternalSecret is within the refresh interval
	// 4. the target secret is valid:
	//     - it exists
	//     - it has the correct "managed" label
	//     - it has the correct "data-hash" annotation
	if !shouldRefresh(externalSecret) && isSecretValid(existingSecret) {
		log.V(1).Info("skipping refresh")
		return r.getRequeueResult(externalSecret), nil
	}

	// update status of the ExternalSecret when this function returns, if needed.
	// NOTE: we use the ability of deferred functions to update named return values `result` and `err`
	// NOTE: we dereference the DeepCopy of the status field because status fields are NOT pointers,
	//       so otherwise the `equality.Semantic.DeepEqual` will always return false.
	currentStatus := *externalSecret.Status.DeepCopy()
	defer func() {
		// if the status has not changed, we don't need to update it
		if equality.Semantic.DeepEqual(currentStatus, externalSecret.Status) {
			return
		}

		// update the status of the ExternalSecret, storing any error in a new variable
		// if there was no new error, we don't need to change the `result` or `err` values
		updateErr := r.Status().Update(ctx, externalSecret)
		if updateErr == nil {
			return
		}

		// if we got an update conflict, we should requeue immediately
		if apierrors.IsConflict(updateErr) {
			log.V(1).Info("conflict while updating status, will requeue")

			// we only explicitly request a requeue if the main function did not return an `err`.
			// otherwise, we get an annoying log saying that results are ignored when there is an error,
			// as errors are always retried.
			if err == nil {
				result = ctrl.Result{Requeue: true}
			}
			return
		}

		// for other errors, log and update the `err` variable if there is no error already
		// so the reconciler will requeue the request
		log.Error(updateErr, logErrorUpdateESStatus)
		if err == nil {
			err = updateErr
		}
	}()

	// retrieve the provider secret data.
	dataMap, err := r.getProviderSecretData(ctx, externalSecret)
	if err != nil {
		r.markAsFailed(msgErrorGetSecretData, err, externalSecret, syncCallsError.With(resourceLabels))
		return ctrl.Result{}, err
	}

	// if no data was found we can delete the secret if needed.
	if len(dataMap) == 0 {
		switch externalSecret.Spec.Target.DeletionPolicy {
		// delete secret and return early.
		case esv1beta1.DeletionPolicyDelete:
			// safeguard that we only can delete secrets we own.
			// this is also implemented in the es validation webhook.
			// NOTE: this error cant be fixed by retrying so we don't return an error (which would requeue immediately)
			creationPolicy := externalSecret.Spec.Target.CreationPolicy
			if creationPolicy != esv1beta1.CreatePolicyOwner {
				err = fmt.Errorf(errDeleteCreatePolicy, secretName, creationPolicy)
				r.markAsFailed(msgErrorDeleteSecret, err, externalSecret, syncCallsError.With(resourceLabels))
				return ctrl.Result{}, nil
			}

			// delete the secret, if it exists
			if existingSecret.UID != "" {
				err = r.Delete(ctx, existingSecret)
				if err != nil && !apierrors.IsNotFound(err) {
					r.markAsFailed(msgErrorDeleteSecret, err, externalSecret, syncCallsError.With(resourceLabels))
					return ctrl.Result{}, err
				}
				r.recorder.Event(externalSecret, v1.EventTypeNormal, esv1beta1.ReasonDeleted, eventDeleted)
			}

			r.markAsDone(externalSecret, start, log, esv1beta1.ConditionReasonSecretDeleted, msgDeleted)
			return r.getRequeueResult(externalSecret), nil
		// In case provider secrets don't exist the kubernetes secret will be kept as-is.
		case esv1beta1.DeletionPolicyRetain:
			r.markAsDone(externalSecret, start, log, esv1beta1.ConditionReasonSecretSynced, msgSyncedRetain)
			return r.getRequeueResult(externalSecret), nil
		// noop, handled below
		case esv1beta1.DeletionPolicyMerge:
		}
	}

	// mutationFunc is a function which can be applied to a secret to make it match the desired state.
	mutationFunc := func(secret *v1.Secret) error {
		// get information about the current owner of the secret
		//  - we ignore the API version as it can change over time
		//  - we ignore the UID for consistency with the SetControllerReference function
		currentOwner := metav1.GetControllerOf(secret)
		ownerIsESKind := false
		ownerIsCurrentES := false
		if currentOwner != nil {
			currentOwnerGK := schema.FromAPIVersionAndKind(currentOwner.APIVersion, currentOwner.Kind).GroupKind()
			ownerIsESKind = currentOwnerGK.String() == esv1beta1.ExtSecretGroupKind
			ownerIsCurrentES = ownerIsESKind && currentOwner.Name == externalSecret.Name
		}

		// if another ExternalSecret is the owner, we should return an error
		// otherwise the controller will fight with itself to update the secret.
		// note, this does not prevent other controllers from owning the secret.
		if ownerIsESKind && !ownerIsCurrentES {
			return fmt.Errorf("%w: %s", ErrSecretIsOwned, currentOwner.Name)
		}

		// if the CreationPolicy is Owner, we should set ourselves as the owner of the secret
		if externalSecret.Spec.Target.CreationPolicy == esv1beta1.CreatePolicyOwner {
			err = controllerutil.SetControllerReference(externalSecret, secret, r.Scheme)
			if err != nil {
				return fmt.Errorf("%w: %w", ErrSecretSetCtrlRef, err)
			}
		}

		// if the creation policy is not Owner, we should remove ourselves as the owner
		// this could happen if the creation policy was changed after the secret was created
		if externalSecret.Spec.Target.CreationPolicy != esv1beta1.CreatePolicyOwner && ownerIsCurrentES {
			err = controllerutil.RemoveControllerReference(externalSecret, secret, r.Scheme)
			if err != nil {
				return fmt.Errorf("%w: %w", ErrSecretRemoveCtrlRef, err)
			}
		}

		// initialize maps within the secret so it's safe to set values
		if secret.Annotations == nil {
			secret.Annotations = make(map[string]string)
		}
		if secret.Labels == nil {
			secret.Labels = make(map[string]string)
		}
		if secret.Data == nil {
			secret.Data = make(map[string][]byte)
		}

		// get the list of keys that are managed by this ExternalSecret
		keys, err := getManagedDataKeys(secret, externalSecret.Name)
		if err != nil {
			return err
		}

		// remove any data keys that are managed by this ExternalSecret, so we can re-add them
		// this ensures keys added by templates are not left behind when they are removed from the template
		for _, key := range keys {
			delete(secret.Data, key)
		}

		// WARNING: this will remove any labels or annotations managed by this ExternalSecret
		//          so any updates to labels and annotations should be done AFTER this point
		err = r.applyTemplate(ctx, externalSecret, secret, dataMap)
		if err != nil {
			return fmt.Errorf(errApplyTemplate, err)
		}

		// set the immutable flag on the secret if requested by the ExternalSecret
		if externalSecret.Spec.Target.Immutable {
			secret.Immutable = ptr.To(true)
		}

		// we also use a label to keep track of the owner of the secret
		// this lets us remove secrets that are no longer needed if the target secret name changes
		if externalSecret.Spec.Target.CreationPolicy == esv1beta1.CreatePolicyOwner {
			lblValue := utils.ObjectHash(fmt.Sprintf("%v/%v", externalSecret.Namespace, externalSecret.Name))
			secret.Labels[esv1beta1.LabelOwner] = lblValue
		} else {
			// the label should not be set if the creation policy is not Owner
			delete(secret.Labels, esv1beta1.LabelOwner)
		}

		secret.Labels[esv1beta1.LabelManaged] = esv1beta1.LabelManagedValue
		secret.Annotations[esv1beta1.AnnotationDataHash] = utils.ObjectHash(secret.Data)

		return nil
	}

	switch externalSecret.Spec.Target.CreationPolicy {
	case esv1beta1.CreatePolicyNone:
		log.V(1).Info("secret creation skipped due to CreationPolicy=None")
		err = nil
	case esv1beta1.CreatePolicyMerge:
		// update the secret, if it exists
		if existingSecret.UID != "" {
			err = r.updateSecret(ctx, existingSecret, mutationFunc, externalSecret, secretName)
		} else {
			// if the secret does not exist, we wait until the next refresh interval
			// rather than returning an error which would requeue immediately
			r.markAsDone(externalSecret, start, log, esv1beta1.ConditionReasonSecretMissing, msgMissing)
			return r.getRequeueResult(externalSecret), nil
		}
	case esv1beta1.CreatePolicyOrphan:
		// create the secret, if it does not exist
		if existingSecret.UID == "" {
			err = r.createSecret(ctx, mutationFunc, externalSecret, secretName)
		} else {
			// if the secret exists, we should update it
			err = r.updateSecret(ctx, existingSecret, mutationFunc, externalSecret, secretName)
		}
	case esv1beta1.CreatePolicyOwner:
		// we may have orphaned secrets to clean up,
		// for example, if the target secret name was changed
		err = r.deleteOrphanedSecrets(ctx, externalSecret, secretName)
		if err != nil {
			r.markAsFailed(msgErrorDeleteOrphaned, err, externalSecret, syncCallsError.With(resourceLabels))
			return ctrl.Result{}, err
		}

		// create the secret, if it does not exist
		if existingSecret.UID == "" {
			err = r.createSecret(ctx, mutationFunc, externalSecret, secretName)
		} else {
			// if the secret exists, we should update it
			err = r.updateSecret(ctx, existingSecret, mutationFunc, externalSecret, secretName)
		}
	}
	if err != nil {
		// if we got an update conflict, we should requeue immediately
		if apierrors.IsConflict(err) {
			log.V(1).Info("conflict while updating secret, will requeue")
			return ctrl.Result{Requeue: true}, nil
		}

		// detect errors indicating that we failed to set ourselves as the owner of the secret
		// NOTE: this error cant be fixed by retrying so we don't return an error (which would requeue immediately)
		if errors.Is(err, ErrSecretSetCtrlRef) {
			r.markAsFailed(msgErrorBecomeOwner, err, externalSecret, syncCallsError.With(resourceLabels))
			return ctrl.Result{}, nil
		}

		// detect errors indicating that the secret has another ExternalSecret as owner
		// NOTE: this error cant be fixed by retrying so we don't return an error (which would requeue immediately)
		if errors.Is(err, ErrSecretIsOwned) {
			r.markAsFailed(msgErrorIsOwned, err, externalSecret, syncCallsError.With(resourceLabels))
			return ctrl.Result{}, nil
		}

		// detect errors indicating that the secret is immutable
		// NOTE: this error cant be fixed by retrying so we don't return an error (which would requeue immediately)
		if errors.Is(err, ErrSecretImmutable) {
			r.markAsFailed(msgErrorUpdateImmutable, err, externalSecret, syncCallsError.With(resourceLabels))
			return ctrl.Result{}, nil
		}

		r.markAsFailed(msgErrorUpdateSecret, err, externalSecret, syncCallsError.With(resourceLabels))
		return ctrl.Result{}, err
	}

	r.markAsDone(externalSecret, start, log, esv1beta1.ConditionReasonSecretSynced, msgSynced)
	return r.getRequeueResult(externalSecret), nil
}

// getRequeueResult create a result with requeueAfter based on the ExternalSecret refresh interval.
func (r *Reconciler) getRequeueResult(externalSecret *esv1beta1.ExternalSecret) ctrl.Result {
	// default to the global requeue interval
	// note, this will never be used because the CRD has a default value of 1 hour
	refreshInterval := r.RequeueInterval
	if externalSecret.Spec.RefreshInterval != nil {
		refreshInterval = externalSecret.Spec.RefreshInterval.Duration
	}

	// if the refresh interval is <= 0, we should not requeue
	if refreshInterval <= 0 {
		return ctrl.Result{}
	}

	// if the last refresh time is not set, requeue after the refresh interval
	// note, this should not happen, as we only call this function on ExternalSecrets
	// that have been reconciled at least once
	if externalSecret.Status.RefreshTime.IsZero() {
		return ctrl.Result{RequeueAfter: refreshInterval}
	}

	timeSinceLastRefresh := time.Since(externalSecret.Status.RefreshTime.Time)

	// if the last refresh time is in the future, we should requeue immediately
	// note, this should not happen, as we always refresh an ExternalSecret
	// that has a last refresh time in the future
	if timeSinceLastRefresh < 0 {
		return ctrl.Result{Requeue: true}
	}

	// if there is time remaining, requeue after the remaining time
	if timeSinceLastRefresh < refreshInterval {
		return ctrl.Result{RequeueAfter: refreshInterval - timeSinceLastRefresh}
	}

	// otherwise, requeue immediately
	return ctrl.Result{Requeue: true}
}

func (r *Reconciler) markAsDone(externalSecret *esv1beta1.ExternalSecret, start time.Time, log logr.Logger, reason, msg string) {
	oldReadyCondition := GetExternalSecretCondition(externalSecret.Status, esv1beta1.ExternalSecretReady)
	newReadyCondition := NewExternalSecretCondition(esv1beta1.ExternalSecretReady, v1.ConditionTrue, reason, msg)
	SetExternalSecretCondition(externalSecret, *newReadyCondition)

	externalSecret.Status.RefreshTime = metav1.NewTime(start)
	externalSecret.Status.SyncedResourceVersion = getResourceVersion(externalSecret)

	// if the status or reason has changed, log at the appropriate verbosity level
	if oldReadyCondition == nil || oldReadyCondition.Status != newReadyCondition.Status || oldReadyCondition.Reason != newReadyCondition.Reason {
		if newReadyCondition.Reason == esv1beta1.ConditionReasonSecretDeleted {
			log.Info("deleted secret")
		} else {
			log.Info("reconciled secret")
		}
	} else {
		log.V(1).Info("reconciled secret")
	}
}

func (r *Reconciler) markAsFailed(msg string, err error, externalSecret *esv1beta1.ExternalSecret, counter prometheus.Counter) {
	r.recorder.Event(externalSecret, v1.EventTypeWarning, esv1beta1.ReasonUpdateFailed, err.Error())
	conditionSynced := NewExternalSecretCondition(esv1beta1.ExternalSecretReady, v1.ConditionFalse, esv1beta1.ConditionReasonSecretSyncedError, msg)
	SetExternalSecretCondition(externalSecret, *conditionSynced)
	counter.Inc()
}

func (r *Reconciler) deleteOrphanedSecrets(ctx context.Context, externalSecret *esv1beta1.ExternalSecret, secretName string) error {
	ownerLabel := utils.ObjectHash(fmt.Sprintf("%v/%v", externalSecret.Namespace, externalSecret.Name))

	// we use a PartialObjectMetadataList to avoid loading the full secret objects
	// and because the Secrets partials are always cached due to WatchesMetadata() in SetupWithManager()
	secretListPartial := &metav1.PartialObjectMetadataList{}
	secretListPartial.SetGroupVersionKind(v1.SchemeGroupVersion.WithKind("SecretList"))
	listOpts := &client.ListOptions{
		LabelSelector: labels.SelectorFromSet(map[string]string{
			esv1beta1.LabelOwner: ownerLabel,
		}),
		Namespace: externalSecret.Namespace,
	}
	if err := r.List(ctx, secretListPartial, listOpts); err != nil {
		return err
	}

	// delete all secrets that are not the target secret
	for _, secretPartial := range secretListPartial.Items {
		if secretPartial.GetName() != secretName {
			err := r.Delete(ctx, &secretPartial)
			if err != nil && !apierrors.IsNotFound(err) {
				return err
			}
			r.recorder.Event(externalSecret, v1.EventTypeNormal, esv1beta1.ReasonDeleted, eventDeletedOrphaned)
		}
	}

	return nil
}

// createSecret creates a new secret with the given mutation function.
func (r *Reconciler) createSecret(ctx context.Context, mutationFunc func(secret *v1.Secret) error, es *esv1beta1.ExternalSecret, secretName string) error {
	fqdn := fmt.Sprintf(fieldOwnerTemplate, es.Name)

	// define and mutate the new secret
	newSecret := &v1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Name:      secretName,
			Namespace: es.Namespace,
		},
		Data: make(map[string][]byte),
	}
	if err := mutationFunc(newSecret); err != nil {
		return err
	}

	// note, we set field owner even for Create
	if err := r.Create(ctx, newSecret, client.FieldOwner(fqdn)); err != nil {
		return err
	}

	// set the binding reference to the secret
	// https://github.com/external-secrets/external-secrets/pull/2263
	es.Status.Binding = v1.LocalObjectReference{Name: newSecret.Name}

	r.recorder.Event(es, v1.EventTypeNormal, esv1beta1.ReasonCreated, eventCreated)
	return nil
}

func (r *Reconciler) updateSecret(ctx context.Context, existingSecret *v1.Secret, mutationFunc func(secret *v1.Secret) error, es *esv1beta1.ExternalSecret, secretName string) error {
	fqdn := fmt.Sprintf(fieldOwnerTemplate, es.Name)

	// fail if the secret does not exist
	// this should never happen because we check this before calling this function
	if existingSecret.UID == "" {
		return fmt.Errorf(errUpdateNotFound, secretName)
	}

	// set the binding reference to the secret
	// https://github.com/external-secrets/external-secrets/pull/2263
	es.Status.Binding = v1.LocalObjectReference{Name: secretName}

	// mutate a copy of the existing secret with the mutation function
	updatedSecret := existingSecret.DeepCopy()
	if err := mutationFunc(updatedSecret); err != nil {
		return fmt.Errorf(errMutate, updatedSecret.Name, err)
	}

	// if the secret does not need to be updated, return early
	if equality.Semantic.DeepEqual(existingSecret, updatedSecret) {
		return nil
	}

	// if the existing secret is immutable, we can only update the object metadata
	if ptr.Deref(existingSecret.Immutable, false) {
		// check if the metadata was changed
		metadataChanged := !equality.Semantic.DeepEqual(existingSecret.ObjectMeta, updatedSecret.ObjectMeta)

		// check if the immutable data/type was changed
		var dataChanged bool
		if metadataChanged {
			// update the `existingSecret` object with the metadata from `updatedSecret`
			// this lets us compare the objects to see if the immutable data/type was changed
			existingSecret.ObjectMeta = *updatedSecret.ObjectMeta.DeepCopy()
			dataChanged = !equality.Semantic.DeepEqual(existingSecret, updatedSecret)

			// because we use labels and annotations to keep track of the secret,
			// we need to update the metadata, regardless of if the immutable data was changed
			// NOTE: we are using the `existingSecret` object here, as we ONLY want to update the metadata,
			//       and we previously copied the metadata from the `updatedSecret` object
			if err := r.Update(ctx, existingSecret, client.FieldOwner(fqdn)); err != nil {
				// if we get a conflict, we should return early to requeue immediately
				// note, we don't wrap this error so we can handle it in the caller
				if apierrors.IsConflict(err) {
					return err
				}
				return fmt.Errorf(errUpdate, existingSecret.Name, err)
			}
		} else {
			// we know there was some change in the secret (or we would have returned early)
			// we know the metadata was NOT changed (metadataChanged == false)
			// so, the only thing that could have changed is the immutable data/type fields
			dataChanged = true
		}

		// if the immutable data was changed, we should return an error
		if dataChanged {
			return fmt.Errorf(errUpdate, existingSecret.Name, ErrSecretImmutable)
		}
	}

	// update the secret
	if err := r.Update(ctx, updatedSecret, client.FieldOwner(fqdn)); err != nil {
		// if we get a conflict, we should return early to requeue immediately
		// note, we don't wrap this error so we can handle it in the caller
		if apierrors.IsConflict(err) {
			return err
		}
		return fmt.Errorf(errUpdate, updatedSecret.Name, err)
	}

	r.recorder.Event(es, v1.EventTypeNormal, esv1beta1.ReasonUpdated, eventUpdated)
	return nil
}

// getManagedDataKeys returns the list of data keys in a secret which are managed by a specified owner.
func getManagedDataKeys(secret *v1.Secret, fieldOwner string) ([]string, error) {
	return getManagedFieldKeys(secret, fieldOwner, func(fields map[string]any) []string {
		dataFields := fields["f:data"]
		if dataFields == nil {
			return nil
		}
		df, ok := dataFields.(map[string]any)
		if !ok {
			return nil
		}

		return slices.Collect(maps.Keys(df))
	})
}

func getManagedFieldKeys(
	secret *v1.Secret,
	fieldOwner string,
	process func(fields map[string]any) []string,
) ([]string, error) {
	fqdn := fmt.Sprintf(fieldOwnerTemplate, fieldOwner)
	var keys []string
	for _, v := range secret.ObjectMeta.ManagedFields {
		if v.Manager != fqdn {
			continue
		}
		fields := make(map[string]any)
		err := json.Unmarshal(v.FieldsV1.Raw, &fields)
		if err != nil {
			return nil, fmt.Errorf("error unmarshaling managed fields: %w", err)
		}
		for _, key := range process(fields) {
			if key == "." {
				continue
			}
			keys = append(keys, strings.TrimPrefix(key, "f:"))
		}
	}
	return keys, nil
}

func getResourceVersion(es *esv1beta1.ExternalSecret) string {
	return fmt.Sprintf("%d-%s", es.ObjectMeta.GetGeneration(), hashMeta(es.ObjectMeta))
}

// hashMeta returns a consistent hash of the `metadata.labels` and `metadata.annotations` fields of the given object.
func hashMeta(m metav1.ObjectMeta) string {
	type meta struct {
		annotations map[string]string
		labels      map[string]string
	}
	objectMeta := meta{
		annotations: m.Annotations,
		labels:      m.Labels,
	}
	return utils.ObjectHash(objectMeta)
}

func shouldSkipClusterSecretStore(r *Reconciler, es *esv1beta1.ExternalSecret) bool {
	return !r.ClusterSecretStoreEnabled && es.Spec.SecretStoreRef.Kind == esv1beta1.ClusterSecretStoreKind
}

// shouldSkipUnmanagedStore iterates over all secretStore references in the externalSecret spec,
// fetches the store and evaluates the controllerClass property.
// Returns true if any storeRef points to store with a non-matching controllerClass.
func shouldSkipUnmanagedStore(ctx context.Context, namespace string, r *Reconciler, es *esv1beta1.ExternalSecret) (bool, error) {
	var storeList []esv1beta1.SecretStoreRef

	if es.Spec.SecretStoreRef.Name != "" {
		storeList = append(storeList, es.Spec.SecretStoreRef)
	}

	for _, ref := range es.Spec.Data {
		if ref.SourceRef != nil {
			storeList = append(storeList, ref.SourceRef.SecretStoreRef)
		}
	}

	for _, ref := range es.Spec.DataFrom {
		if ref.SourceRef != nil && ref.SourceRef.SecretStoreRef != nil {
			storeList = append(storeList, *ref.SourceRef.SecretStoreRef)
		}

		// verify that generator's controllerClass matches
		if ref.SourceRef != nil && ref.SourceRef.GeneratorRef != nil {
			_, obj, err := resolvers.GeneratorRef(ctx, r.Client, r.Scheme, namespace, ref.SourceRef.GeneratorRef)
			if err != nil {
				if apierrors.IsNotFound(err) {
					// skip non-existent generators
					continue
				}
				if errors.Is(err, resolvers.ErrUnableToGetGenerator) {
					// skip generators that we can't get (e.g. due to being invalid)
					continue
				}
				return false, err
			}
			skipGenerator, err := shouldSkipGenerator(r, obj)
			if err != nil {
				return false, err
			}
			if skipGenerator {
				return true, nil
			}
		}
	}

	for _, ref := range storeList {
		var store esv1beta1.GenericStore

		switch ref.Kind {
		case esv1beta1.SecretStoreKind, "":
			store = &esv1beta1.SecretStore{}
		case esv1beta1.ClusterSecretStoreKind:
			store = &esv1beta1.ClusterSecretStore{}
			namespace = ""
		}

		err := r.Get(ctx, types.NamespacedName{
			Name:      ref.Name,
			Namespace: namespace,
		}, store)
		if err != nil {
			if apierrors.IsNotFound(err) {
				// skip non-existent stores
				continue
			}
			return false, err
		}
		class := store.GetSpec().Controller
		if class != "" && class != r.ControllerClass {
			return true, nil
		}
	}
	return false, nil
}

func shouldRefresh(es *esv1beta1.ExternalSecret) bool {
	// if the refresh interval is 0, and we have synced previously, we should not refresh
	if es.Spec.RefreshInterval.Duration <= 0 && es.Status.SyncedResourceVersion != "" {
		return false
	}

	// if the ExternalSecret has been updated, we should refresh
	if es.Status.SyncedResourceVersion != getResourceVersion(es) {
		return true
	}

	// if the last refresh time is zero, we should refresh
	if es.Status.RefreshTime.IsZero() {
		return true
	}

	// if the last refresh time is in the future, we should refresh
	if es.Status.RefreshTime.Time.After(time.Now()) {
		return true
	}

	// if the last refresh time + refresh interval is before now, we should refresh
	return es.Status.RefreshTime.Add(es.Spec.RefreshInterval.Duration).Before(time.Now())
}

// isSecretValid checks if the secret exists, and it's data is consistent with the calculated hash.
func isSecretValid(existingSecret *v1.Secret) bool {
	// if target secret doesn't exist, we need to refresh
	if existingSecret.UID == "" {
		return false
	}

	// if the managed label is missing or incorrect, then it's invalid
	if existingSecret.Labels[esv1beta1.LabelManaged] != esv1beta1.LabelManagedValue {
		return false
	}

	// if the data-hash annotation is missing or incorrect, then it's invalid
	// this is how we know if the data has chanced since we last updated the secret
	if existingSecret.Annotations[esv1beta1.AnnotationDataHash] != utils.ObjectHash(existingSecret.Data) {
		return false
	}

	return true
}

// SetupWithManager returns a new controller builder that will be started by the provided Manager.
func (r *Reconciler) SetupWithManager(mgr ctrl.Manager, opts controller.Options) error {
	r.recorder = mgr.GetEventRecorderFor("external-secrets")

	// index ExternalSecrets based on the target secret name,
	// this lets us quickly find all ExternalSecrets which target a specific Secret
	if err := mgr.GetFieldIndexer().IndexField(context.Background(), &esv1beta1.ExternalSecret{}, indexESTargetSecretNameField, func(obj client.Object) []string {
		es := obj.(*esv1beta1.ExternalSecret)
		// if the target name is set, use that as the index
		if es.Spec.Target.Name != "" {
			return []string{es.Spec.Target.Name}
		}
		// otherwise, use the ExternalSecret name
		return []string{es.Name}
	}); err != nil {
		return err
	}

	// predicate function to ignore secret events unless they have the "managed" label
	secretHasESLabel := predicate.NewPredicateFuncs(func(object client.Object) bool {
		value, hasLabel := object.GetLabels()[esv1beta1.LabelManaged]
		return hasLabel && value == esv1beta1.LabelManagedValue
	})

	return ctrl.NewControllerManagedBy(mgr).
		WithOptions(opts).
		For(&esv1beta1.ExternalSecret{}).
		// we cant use Owns(), as we don't set ownerReferences when the creationPolicy is not Owner.
		// we use WatchesMetadata() to reduce memory usage, as otherwise we have to process full secret objects.
		WatchesMetadata(
			&v1.Secret{},
			handler.EnqueueRequestsFromMapFunc(r.findObjectsForSecret),
			builder.WithPredicates(predicate.ResourceVersionChangedPredicate{}, secretHasESLabel),
		).
		Complete(r)
}

func (r *Reconciler) findObjectsForSecret(ctx context.Context, secret client.Object) []reconcile.Request {
	externalSecretsList := &esv1beta1.ExternalSecretList{}
	listOps := &client.ListOptions{
		FieldSelector: fields.OneTermEqualSelector(indexESTargetSecretNameField, secret.GetName()),
		Namespace:     secret.GetNamespace(),
	}
	err := r.List(ctx, externalSecretsList, listOps)
	if err != nil {
		return []reconcile.Request{}
	}

	requests := make([]reconcile.Request, len(externalSecretsList.Items))
	for i, item := range externalSecretsList.Items {
		requests[i] = reconcile.Request{
			NamespacedName: types.NamespacedName{
				Name:      item.GetName(),
				Namespace: item.GetNamespace(),
			},
		}
	}
	return requests
}

func BuildManagedSecretClient(mgr ctrl.Manager) (client.Client, error) {
	// secrets we manage will have the `reconcile.external-secrets.io/managed=true` label
	managedLabelReq, _ := labels.NewRequirement(esv1beta1.LabelManaged, selection.Equals, []string{esv1beta1.LabelManagedValue})
	managedLabelSelector := labels.NewSelector().Add(*managedLabelReq)

	// create a new cache with a label selector for managed secrets
	// NOTE: this means that the cache/client will be unable to see secrets without the "managed" label
	secretCacheOpts := cache.Options{
		HTTPClient: mgr.GetHTTPClient(),
		Scheme:     mgr.GetScheme(),
		Mapper:     mgr.GetRESTMapper(),
		ByObject: map[client.Object]cache.ByObject{
			&v1.Secret{}: {
				Label: managedLabelSelector,
			},
		},
		// this requires us to explicitly start an informer for each object type
		// and helps avoid people mistakenly using the secret client for other resources
		ReaderFailOnMissingInformer: true,
	}
	secretCache, err := cache.New(mgr.GetConfig(), secretCacheOpts)
	if err != nil {
		return nil, err
	}

	// start an informer for secrets
	// this is required because we set ReaderFailOnMissingInformer to true
	_, err = secretCache.GetInformer(context.Background(), &v1.Secret{})
	if err != nil {
		return nil, err
	}

	// add the secret cache to the manager, so that it starts at the same time
	err = mgr.Add(secretCache)
	if err != nil {
		return nil, err
	}

	// create a new client that uses the secret cache
	secretClient, err := client.New(mgr.GetConfig(), client.Options{
		HTTPClient: mgr.GetHTTPClient(),
		Scheme:     mgr.GetScheme(),
		Mapper:     mgr.GetRESTMapper(),
		Cache: &client.CacheOptions{
			Reader: secretCache,
		},
	})
	if err != nil {
		return nil, err
	}

	return secretClient, nil
}