/*
Copyright 2017 the Velero contributors.

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 backup

import (
	"archive/tar"
	"encoding/json"
	"fmt"
	"path/filepath"
	"time"

	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	corev1api "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	kubeerrs "k8s.io/apimachinery/pkg/util/errors"

	api "github.com/vmware-tanzu/velero/pkg/apis/velero/v1"
	velerov1api "github.com/vmware-tanzu/velero/pkg/apis/velero/v1"
	"github.com/vmware-tanzu/velero/pkg/client"
	"github.com/vmware-tanzu/velero/pkg/discovery"
	"github.com/vmware-tanzu/velero/pkg/kuberesource"
	"github.com/vmware-tanzu/velero/pkg/plugin/velero"
	"github.com/vmware-tanzu/velero/pkg/podexec"
	"github.com/vmware-tanzu/velero/pkg/restic"
	"github.com/vmware-tanzu/velero/pkg/volume"
)

type itemBackupperFactory interface {
	newItemBackupper(
		backup *Request,
		podCommandExecutor podexec.PodCommandExecutor,
		tarWriter tarWriter,
		dynamicFactory client.DynamicFactory,
		discoveryHelper discovery.Helper,
		resticBackupper restic.Backupper,
		resticSnapshotTracker *pvcSnapshotTracker,
		volumeSnapshotterGetter VolumeSnapshotterGetter,
	) ItemBackupper
}

type defaultItemBackupperFactory struct{}

func (f *defaultItemBackupperFactory) newItemBackupper(
	backupRequest *Request,
	podCommandExecutor podexec.PodCommandExecutor,
	tarWriter tarWriter,
	dynamicFactory client.DynamicFactory,
	discoveryHelper discovery.Helper,
	resticBackupper restic.Backupper,
	resticSnapshotTracker *pvcSnapshotTracker,
	volumeSnapshotterGetter VolumeSnapshotterGetter,
) ItemBackupper {
	ib := &defaultItemBackupper{
		backupRequest:           backupRequest,
		tarWriter:               tarWriter,
		dynamicFactory:          dynamicFactory,
		discoveryHelper:         discoveryHelper,
		resticBackupper:         resticBackupper,
		resticSnapshotTracker:   resticSnapshotTracker,
		volumeSnapshotterGetter: volumeSnapshotterGetter,

		itemHookHandler: &defaultItemHookHandler{
			podCommandExecutor: podCommandExecutor,
		},
	}

	// this is for testing purposes
	ib.additionalItemBackupper = ib

	return ib
}

type ItemBackupper interface {
	backupItem(logger logrus.FieldLogger, obj runtime.Unstructured, groupResource schema.GroupResource) (bool, error)
}

type defaultItemBackupper struct {
	backupRequest           *Request
	tarWriter               tarWriter
	dynamicFactory          client.DynamicFactory
	discoveryHelper         discovery.Helper
	resticBackupper         restic.Backupper
	resticSnapshotTracker   *pvcSnapshotTracker
	volumeSnapshotterGetter VolumeSnapshotterGetter

	itemHookHandler                    itemHookHandler
	additionalItemBackupper            ItemBackupper
	snapshotLocationVolumeSnapshotters map[string]velero.VolumeSnapshotter
}

// backupItem backs up an individual item to tarWriter. The item may be excluded based on the
// namespaces IncludesExcludes list.
// In addition to the error return, backupItem also returns a bool indicating whether the item
// was actually backed up.
func (ib *defaultItemBackupper) backupItem(logger logrus.FieldLogger, obj runtime.Unstructured, groupResource schema.GroupResource) (bool, error) {
	metadata, err := meta.Accessor(obj)
	if err != nil {
		return false, err
	}

	namespace := metadata.GetNamespace()
	name := metadata.GetName()

	log := logger.WithField("name", name)
	log = log.WithField("resource", groupResource)
	log = log.WithField("namespace", namespace)

	if metadata.GetLabels()["velero.io/exclude-from-backup"] == "true" {
		log.Info("Excluding item because it has label velero.io/exclude-from-backup=true")
		return false, nil
	}

	// NOTE: we have to re-check namespace & resource includes/excludes because it's possible that
	// backupItem can be invoked by a custom action.
	if namespace != "" && !ib.backupRequest.NamespaceIncludesExcludes.ShouldInclude(namespace) {
		log.Info("Excluding item because namespace is excluded")
		return false, nil
	}

	// NOTE: we specifically allow namespaces to be backed up even if IncludeClusterResources is
	// false.
	if namespace == "" && groupResource != kuberesource.Namespaces && ib.backupRequest.Spec.IncludeClusterResources != nil && !*ib.backupRequest.Spec.IncludeClusterResources {
		log.Info("Excluding item because resource is cluster-scoped and backup.spec.includeClusterResources is false")
		return false, nil
	}

	if !ib.backupRequest.ResourceIncludesExcludes.ShouldInclude(groupResource.String()) {
		log.Info("Excluding item because resource is excluded")
		return false, nil
	}

	if metadata.GetDeletionTimestamp() != nil {
		log.Info("Skipping item because it's being deleted.")
		return false, nil
	}

	key := itemKey{
		resource:  resourceKey(obj),
		namespace: namespace,
		name:      name,
	}

	if _, exists := ib.backupRequest.BackedUpItems[key]; exists {
		log.Info("Skipping item because it's already been backed up.")
		// returning true since this item *is* in the backup, even though we're not backing it up here
		return true, nil
	}
	ib.backupRequest.BackedUpItems[key] = struct{}{}

	log.Info("Backing up item")

	log.Debug("Executing pre hooks")
	if err := ib.itemHookHandler.handleHooks(log, groupResource, obj, ib.backupRequest.ResourceHooks, hookPhasePre); err != nil {
		return false, err
	}

	var (
		backupErrs            []error
		pod                   *corev1api.Pod
		resticVolumesToBackup []string
	)

	if groupResource == kuberesource.Pods {
		// pod needs to be initialized for the unstructured converter
		pod = new(corev1api.Pod)
		if err := runtime.DefaultUnstructuredConverter.FromUnstructured(obj.UnstructuredContent(), pod); err != nil {
			backupErrs = append(backupErrs, errors.WithStack(err))
			// nil it on error since it's not valid
			pod = nil
		} else {
			// Get the list of volumes to back up using restic from the pod's annotations. Remove from this list
			// any volumes that use a PVC that we've already backed up (this would be in a read-write-many scenario,
			// where it's been backed up from another pod), since we don't need >1 backup per PVC.
			for _, volume := range restic.GetVolumesToBackup(pod) {
				if found, pvcName := ib.resticSnapshotTracker.HasPVCForPodVolume(pod, volume); found {
					log.WithFields(map[string]interface{}{
						"podVolume": volume,
						"pvcName":   pvcName,
					}).Info("Pod volume uses a persistent volume claim which has already been backed up with restic from another pod, skipping.")
					continue
				}

				resticVolumesToBackup = append(resticVolumesToBackup, volume)
			}

			// track the volumes that are PVCs using the PVC snapshot tracker, so that when we backup PVCs/PVs
			// via an item action in the next step, we don't snapshot PVs that will have their data backed up
			// with restic.
			ib.resticSnapshotTracker.Track(pod, resticVolumesToBackup)
		}
	}

	updatedObj, err := ib.executeActions(log, obj, groupResource, name, namespace, metadata)
	if err != nil {
		backupErrs = append(backupErrs, err)

		// if there was an error running actions, execute post hooks and return
		log.Debug("Executing post hooks")
		if err := ib.itemHookHandler.handleHooks(log, groupResource, obj, ib.backupRequest.ResourceHooks, hookPhasePost); err != nil {
			backupErrs = append(backupErrs, err)
		}

		return false, kubeerrs.NewAggregate(backupErrs)
	}
	obj = updatedObj
	if metadata, err = meta.Accessor(obj); err != nil {
		return false, errors.WithStack(err)
	}
	// update name and namespace in case they were modified in an action
	name = metadata.GetName()
	namespace = metadata.GetNamespace()

	if groupResource == kuberesource.PersistentVolumes {
		if err := ib.takePVSnapshot(obj, log); err != nil {
			backupErrs = append(backupErrs, err)
		}
	}

	if groupResource == kuberesource.Pods && pod != nil {
		// this function will return partial results, so process podVolumeBackups
		// even if there are errors.
		podVolumeBackups, errs := ib.backupPodVolumes(log, pod, resticVolumesToBackup)

		ib.backupRequest.PodVolumeBackups = append(ib.backupRequest.PodVolumeBackups, podVolumeBackups...)
		backupErrs = append(backupErrs, errs...)
	}

	log.Debug("Executing post hooks")
	if err := ib.itemHookHandler.handleHooks(log, groupResource, obj, ib.backupRequest.ResourceHooks, hookPhasePost); err != nil {
		backupErrs = append(backupErrs, err)
	}

	if len(backupErrs) != 0 {
		return false, kubeerrs.NewAggregate(backupErrs)
	}

	var filePath string
	if namespace != "" {
		filePath = filepath.Join(api.ResourcesDir, groupResource.String(), api.NamespaceScopedDir, namespace, name+".json")
	} else {
		filePath = filepath.Join(api.ResourcesDir, groupResource.String(), api.ClusterScopedDir, name+".json")
	}

	itemBytes, err := json.Marshal(obj.UnstructuredContent())
	if err != nil {
		return false, errors.WithStack(err)
	}

	hdr := &tar.Header{
		Name:     filePath,
		Size:     int64(len(itemBytes)),
		Typeflag: tar.TypeReg,
		Mode:     0755,
		ModTime:  time.Now(),
	}

	if err := ib.tarWriter.WriteHeader(hdr); err != nil {
		return false, errors.WithStack(err)
	}

	if _, err := ib.tarWriter.Write(itemBytes); err != nil {
		return false, errors.WithStack(err)
	}

	return true, nil
}

// backupPodVolumes triggers restic backups of the specified pod volumes, and returns a list of PodVolumeBackups
// for volumes that were successfully backed up, and a slice of any errors that were encountered.
func (ib *defaultItemBackupper) backupPodVolumes(log logrus.FieldLogger, pod *corev1api.Pod, volumes []string) ([]*velerov1api.PodVolumeBackup, []error) {
	if len(volumes) == 0 {
		return nil, nil
	}

	if ib.resticBackupper == nil {
		log.Warn("No restic backupper, not backing up pod's volumes")
		return nil, nil
	}

	return ib.resticBackupper.BackupPodVolumes(ib.backupRequest.Backup, pod, volumes, log)
}

func (ib *defaultItemBackupper) executeActions(
	log logrus.FieldLogger,
	obj runtime.Unstructured,
	groupResource schema.GroupResource,
	name, namespace string,
	metadata metav1.Object,
) (runtime.Unstructured, error) {
	for _, action := range ib.backupRequest.ResolvedActions {
		if !action.resourceIncludesExcludes.ShouldInclude(groupResource.String()) {
			log.Debug("Skipping action because it does not apply to this resource")
			continue
		}

		if namespace != "" && !action.namespaceIncludesExcludes.ShouldInclude(namespace) {
			log.Debug("Skipping action because it does not apply to this namespace")
			continue
		}

		if namespace == "" && !action.namespaceIncludesExcludes.IncludeEverything() {
			log.Debug("Skipping action because resource is cluster-scoped and action only applies to specific namespaces")
			continue
		}

		if !action.selector.Matches(labels.Set(metadata.GetLabels())) {
			log.Debug("Skipping action because label selector does not match")
			continue
		}

		log.Info("Executing custom action")

		updatedItem, additionalItemIdentifiers, err := action.Execute(obj, ib.backupRequest.Backup)
		if err != nil {
			return nil, errors.Wrapf(err, "error executing custom action (groupResource=%s, namespace=%s, name=%s)", groupResource.String(), namespace, name)
		}
		obj = updatedItem

		for _, additionalItem := range additionalItemIdentifiers {
			gvr, resource, err := ib.discoveryHelper.ResourceFor(additionalItem.GroupResource.WithVersion(""))
			if err != nil {
				return nil, err
			}

			client, err := ib.dynamicFactory.ClientForGroupVersionResource(gvr.GroupVersion(), resource, additionalItem.Namespace)
			if err != nil {
				return nil, err
			}

			additionalItem, err := client.Get(additionalItem.Name, metav1.GetOptions{})
			if err != nil {
				return nil, errors.WithStack(err)
			}

			if _, err = ib.additionalItemBackupper.backupItem(log, additionalItem, gvr.GroupResource()); err != nil {
				return nil, err
			}
		}
	}

	return obj, nil
}

// volumeSnapshotter instantiates and initializes a VolumeSnapshotter given a VolumeSnapshotLocation,
// or returns an existing one if one's already been initialized for the location.
func (ib *defaultItemBackupper) volumeSnapshotter(snapshotLocation *api.VolumeSnapshotLocation) (velero.VolumeSnapshotter, error) {
	if bs, ok := ib.snapshotLocationVolumeSnapshotters[snapshotLocation.Name]; ok {
		return bs, nil
	}

	bs, err := ib.volumeSnapshotterGetter.GetVolumeSnapshotter(snapshotLocation.Spec.Provider)
	if err != nil {
		return nil, err
	}

	if err := bs.Init(snapshotLocation.Spec.Config); err != nil {
		return nil, err
	}

	if ib.snapshotLocationVolumeSnapshotters == nil {
		ib.snapshotLocationVolumeSnapshotters = make(map[string]velero.VolumeSnapshotter)
	}
	ib.snapshotLocationVolumeSnapshotters[snapshotLocation.Name] = bs

	return bs, nil
}

// zoneLabel is the label that stores availability-zone info
// on PVs
const zoneLabel = "failure-domain.beta.kubernetes.io/zone"

// takePVSnapshot triggers a snapshot for the volume/disk underlying a PersistentVolume if the provided
// backup has volume snapshots enabled and the PV is of a compatible type. Also records cloud
// disk type and IOPS (if applicable) to be able to restore to current state later.
func (ib *defaultItemBackupper) takePVSnapshot(obj runtime.Unstructured, log logrus.FieldLogger) error {
	log.Info("Executing takePVSnapshot")

	if ib.backupRequest.Spec.SnapshotVolumes != nil && !*ib.backupRequest.Spec.SnapshotVolumes {
		log.Info("Backup has volume snapshots disabled; skipping volume snapshot action.")
		return nil
	}

	pv := new(corev1api.PersistentVolume)
	if err := runtime.DefaultUnstructuredConverter.FromUnstructured(obj.UnstructuredContent(), pv); err != nil {
		return errors.WithStack(err)
	}

	log = log.WithField("persistentVolume", pv.Name)

	// If this PV is claimed, see if we've already taken a (restic) snapshot of the contents
	// of this PV. If so, don't take a snapshot.
	if pv.Spec.ClaimRef != nil {
		if ib.resticSnapshotTracker.Has(pv.Spec.ClaimRef.Namespace, pv.Spec.ClaimRef.Name) {
			log.Info("Skipping snapshot of persistent volume because volume is being backed up with restic.")
			return nil
		}
	}

	pvFailureDomainZone := pv.Labels[zoneLabel]
	if pvFailureDomainZone == "" {
		log.Infof("label %q is not present on PersistentVolume", zoneLabel)
	}

	var (
		volumeID, location string
		volumeSnapshotter  velero.VolumeSnapshotter
	)

	for _, snapshotLocation := range ib.backupRequest.SnapshotLocations {
		log := log.WithField("volumeSnapshotLocation", snapshotLocation.Name)

		bs, err := ib.volumeSnapshotter(snapshotLocation)
		if err != nil {
			log.WithError(err).Error("Error getting volume snapshotter for volume snapshot location")
			continue
		}

		if volumeID, err = bs.GetVolumeID(obj); err != nil {
			log.WithError(err).Errorf("Error attempting to get volume ID for persistent volume")
			continue
		}
		if volumeID == "" {
			log.Infof("No volume ID returned by volume snapshotter for persistent volume")
			continue
		}

		log.Infof("Got volume ID for persistent volume")
		volumeSnapshotter = bs
		location = snapshotLocation.Name
		break
	}

	if volumeSnapshotter == nil {
		log.Info("Persistent volume is not a supported volume type for snapshots, skipping.")
		return nil
	}

	log = log.WithField("volumeID", volumeID)

	tags := ib.backupRequest.GetLabels()
	if tags == nil {
		tags = map[string]string{}
	}
	tags["velero.io/backup"] = ib.backupRequest.Name
	tags["velero.io/pv"] = pv.Name

	log.Info("Getting volume information")
	volumeType, iops, err := volumeSnapshotter.GetVolumeInfo(volumeID, pvFailureDomainZone)
	if err != nil {
		return errors.WithMessage(err, "error getting volume info")
	}

	log.Info("Snapshotting persistent volume")
	snapshot := volumeSnapshot(ib.backupRequest.Backup, pv.Name, volumeID, volumeType, pvFailureDomainZone, location, iops)

	var errs []error
	snapshotID, err := volumeSnapshotter.CreateSnapshot(snapshot.Spec.ProviderVolumeID, snapshot.Spec.VolumeAZ, tags)
	if err != nil {
		errs = append(errs, errors.Wrap(err, "error taking snapshot of volume"))
		snapshot.Status.Phase = volume.SnapshotPhaseFailed
	} else {
		snapshot.Status.Phase = volume.SnapshotPhaseCompleted
		snapshot.Status.ProviderSnapshotID = snapshotID
	}
	ib.backupRequest.VolumeSnapshots = append(ib.backupRequest.VolumeSnapshots, snapshot)

	// nil errors are automatically removed
	return kubeerrs.NewAggregate(errs)
}

func volumeSnapshot(backup *api.Backup, volumeName, volumeID, volumeType, az, location string, iops *int64) *volume.Snapshot {
	return &volume.Snapshot{
		Spec: volume.SnapshotSpec{
			BackupName:           backup.Name,
			BackupUID:            string(backup.UID),
			Location:             location,
			PersistentVolumeName: volumeName,
			ProviderVolumeID:     volumeID,
			VolumeType:           volumeType,
			VolumeAZ:             az,
			VolumeIOPS:           iops,
		},
		Status: volume.SnapshotStatus{
			Phase: volume.SnapshotPhaseNew,
		},
	}
}

// resourceKey returns a string representing the object's GroupVersionKind (e.g.
// apps/v1/Deployment).
func resourceKey(obj runtime.Unstructured) string {
	gvk := obj.GetObjectKind().GroupVersionKind()
	return fmt.Sprintf("%s/%s", gvk.GroupVersion().String(), gvk.Kind)
}