You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: reconciler.go
    path of file: ./repos/gardener/pkg/controllermanager/controller/shoot/quota
    
    the code of the file until where you have to start completion: // Copyright 2018 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 quota

import (
	"context"
	"fmt"
	"time"

	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/utils/clock"
	"sigs.k8s.io/controller-runtime/pkg/client"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	gardencorev1beta1 "github.com/gardener/gardener/pkg/apis/core/v1beta1"
	v1beta1constants "github.com/gardener/gardener/pkg/apis/core/v1beta1/constants"
	"github.com/gardener/gardener/pkg/controllermanager/apis/config"
	"github.com/gardener/gardener/pkg/controllerutils"
	gardenerutils "github.com/gardener/gardener/pkg/utils/gardener"
	kubernetesutils "github.com/gardener/gardener/pkg/utils/kubernetes"
)

// Reconciler reconciles Shoots and auto-deletes them if they are bound to a Quota with a configured cluster lifetime.
type Reconciler struct {
	Client client.Client
	Config config.ShootQuotaControllerConfiguration
	Clock  clock.Clock
}

// Reconcile reconciles Shoots and auto-d
    
func (r *Reconciler) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) {
	log := logf.FromContext(ctx)

	ctx, cancel := controllerutils.GetMainReconciliationContext(ctx, r.Config.SyncPeriod.Duration)
	defer cancel()

	shoot := &gardencorev1beta1.Shoot{}
	if err := r.Client.Get(ctx, request.NamespacedName, shoot); err != nil {
		if apierrors.IsNotFound(err) {
			log.V(1).Info("Object is gone, stop reconciling")
			return reconcile.Result{}, nil
		}
		return reconcile.Result{}, fmt.Errorf("error retrieving object from store: %w", err)
	}

	var (
		secretBinding   = &gardencorev1beta1.SecretBinding{}
		clusterLifeTime *int32
	)

	if shoot.Spec.SecretBindingName != nil {
		if err := r.Client.Get(ctx, kubernetesutils.Key(shoot.Namespace, *shoot.Spec.SecretBindingName), secretBinding); err != nil {
			return reconcile.Result{}, err
		}
	}

	for _, quotaRef := range secretBinding.Quotas {
		quota := &gardencorev1beta1.Quota{}
		if err := r.Client.Get(ctx, kubernetesutils.Key(quotaRef.Namespace, quotaRef.Name), quota); err != nil {
			return reconcile.Result{}, err
		}

		if quota.Spec.ClusterLifetimeDays == nil {
			continue
		}
		if clusterLifeTime == nil || *quota.Spec.ClusterLifetimeDays < *clusterLifeTime {
			clusterLifeTime = quota.Spec.ClusterLifetimeDays
		}
	}

	// If the Shoot has no Quotas referenced (anymore) or if the referenced Quotas does not have a clusterLifetime,
	// then we will not check for cluster lifetime expiration, even if the Shoot has a clusterLifetime timestamp already
	// annotated.
	if clusterLifeTime == nil {
		if metav1.HasAnnotation(shoot.ObjectMeta, v1beta1constants.ShootExpirationTimestamp) {
			log.Info("Removing expiration timestamp annotation")

			patch := client.MergeFrom(shoot.DeepCopy())
			delete(shoot.Annotations, v1beta1constants.ShootExpirationTimestamp)
			if err := r.Client.Patch(ctx, shoot, patch); err != nil {
				return reconcile.Result{}, err
			}
		}
		return reconcile.Result{RequeueAfter: r.Config.SyncPeriod.Duration}, nil
	}

	expirationTime, exist := shoot.Annotations[v1beta1constants.ShootExpirationTimestamp]
	if !exist {
		expirationTime = shoot.CreationTimestamp.Add(time.Duration(*clusterLifeTime*24) * time.Hour).Format(time.RFC3339)
		log.Info("Setting expiration timestamp annotation", "expirationTime", expirationTime)

		patch := client.MergeFrom(shoot.DeepCopy())
		metav1.SetMetaDataAnnotation(&shoot.ObjectMeta, v1beta1constants.ShootExpirationTimestamp, expirationTime)
		if err := r.Client.Patch(ctx, shoot, patch); err != nil {
			return reconcile.Result{}, err
		}
	}

	expirationTimeParsed, err := time.Parse(time.RFC3339, expirationTime)
	if err != nil {
		return reconcile.Result{}, err
	}

	if r.Clock.Now().UTC().After(expirationTimeParsed.UTC()) {
		log.Info("Shoot cluster lifetime expired, deleting Shoot", "expirationTime", expirationTime)

		// We have to annotate the Shoot to confirm the deletion.
		if err := gardenerutils.ConfirmDeletion(ctx, r.Client, shoot); err != nil {
			if apierrors.IsNotFound(err) {
				return reconcile.Result{}, nil
			}
			return reconcile.Result{}, err
		}

		// Now we are allowed to delete the Shoot (to set the deletionTimestamp).
		return reconcile.Result{}, client.IgnoreNotFound(r.Client.Delete(ctx, shoot))
	}

	return reconcile.Result{RequeueAfter: r.Config.SyncPeriod.Duration}, nil
}