/*
Copyright 2018 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 podvolume

import (
	"context"
	"sync"

	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	corev1api "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/tools/cache"

	velerov1api "github.com/vmware-tanzu/velero/pkg/apis/velero/v1"
	clientset "github.com/vmware-tanzu/velero/pkg/generated/clientset/versioned"
	"github.com/vmware-tanzu/velero/pkg/label"
	"github.com/vmware-tanzu/velero/pkg/repository"
	"github.com/vmware-tanzu/velero/pkg/util/boolptr"
)

type RestoreData struct {
	Restore                         *velerov1api.Restore
	Pod                             *corev1api.Pod
	PodVolumeBackups                []*velerov1api.PodVolumeBackup
	SourceNamespace, BackupLocation string
}

// Restorer can execute restic restores of volumes in a pod.
type Restorer interface {
	// RestorePodVolumes restores all annotated volumes in a pod.
	RestorePodVolumes(RestoreData) []error
}

type restorer struct {
	ctx          context.Context
	repoLocker   *repository.RepoLocker
	repoEnsurer  *repository.RepositoryEnsurer
	veleroClient clientset.Interface
	pvcClient    corev1client.PersistentVolumeClaimsGetter

	resultsLock sync.Mutex
	results     map[string]chan *velerov1api.PodVolumeRestore
	log         logrus.FieldLogger
}

func newRestorer(
	ctx context.Context,
	repoLocker *repository.RepoLocker,
	repoEnsurer *repository.RepositoryEnsurer,
	podVolumeRestoreInformer cache.SharedIndexInformer,
	veleroClient clientset.Interface,
	pvcClient corev1client.PersistentVolumeClaimsGetter,
	log logrus.FieldLogger,
) *restorer {
	r := &restorer{
		ctx:          ctx,
		repoLocker:   repoLocker,
		repoEnsurer:  repoEnsurer,
		veleroClient: veleroClient,
		pvcClient:    pvcClient,

		results: make(map[string]chan *velerov1api.PodVolumeRestore),
		log:     log,
	}

	podVolumeRestoreInformer.AddEventHandler(
		cache.ResourceEventHandlerFuncs{
			UpdateFunc: func(_, obj interface{}) {
				pvr := obj.(*velerov1api.PodVolumeRestore)

				if pvr.Status.Phase == velerov1api.PodVolumeRestorePhaseCompleted || pvr.Status.Phase == velerov1api.PodVolumeRestorePhaseFailed {
					r.resultsLock.Lock()
					defer r.resultsLock.Unlock()

					resChan, ok := r.results[resultsKey(pvr.Spec.Pod.Namespace, pvr.Spec.Pod.Name)]
					if !ok {
						log.Errorf("No results channel found for pod %s/%s to send pod volume restore %s/%s on", pvr.Spec.Pod.Namespace, pvr.Spec.Pod.Name, pvr.Namespace, pvr.Name)
						return
					}
					resChan <- pvr
				}
			},
		},
	)

	return r
}

func (r *restorer) RestorePodVolumes(data RestoreData) []error {
	volumesToRestore := getVolumeBackupInfoForPod(data.PodVolumeBackups, data.Pod, data.SourceNamespace)
	if len(volumesToRestore) == 0 {
		return nil
	}

	repositoryType, err := getVolumesRepositoryType(volumesToRestore)
	if err != nil {
		return []error{err}
	}

	repo, err := r.repoEnsurer.EnsureRepo(r.ctx, data.Restore.Namespace, data.SourceNamespace, data.BackupLocation, repositoryType)
	if err != nil {
		return []error{err}
	}

	// get a single non-exclusive lock since we'll wait for all individual
	// restores to be complete before releasing it.
	r.repoLocker.Lock(repo.Name)
	defer r.repoLocker.Unlock(repo.Name)

	resultsChan := make(chan *velerov1api.PodVolumeRestore)

	r.resultsLock.Lock()
	r.results[resultsKey(data.Pod.Namespace, data.Pod.Name)] = resultsChan
	r.resultsLock.Unlock()

	var (
		errs        []error
		numRestores int
		podVolumes  = make(map[string]corev1api.Volume)
	)

	// put the pod's volumes in a map for efficient lookup below
	for _, podVolume := range data.Pod.Spec.Volumes {
		podVolumes[podVolume.Name] = podVolume
	}
	for volume, backupInfo := range volumesToRestore {
		volumeObj, ok := podVolumes[volume]
		var pvc *corev1api.PersistentVolumeClaim
		if ok {
			if volumeObj.PersistentVolumeClaim != nil {
				pvc, err = r.pvcClient.PersistentVolumeClaims(data.Pod.Namespace).Get(context.TODO(), volumeObj.PersistentVolumeClaim.ClaimName, metav1.GetOptions{})
				if err != nil {
					errs = append(errs, errors.Wrap(err, "error getting persistent volume claim for volume"))
					continue
				}
			}
		}

		volumeRestore := newPodVolumeRestore(data.Restore, data.Pod, data.BackupLocation, volume, backupInfo.snapshotID, repo.Spec.ResticIdentifier, backupInfo.uploaderType, pvc)

		if err := errorOnly(r.veleroClient.VeleroV1().PodVolumeRestores(volumeRestore.Namespace).Create(context.TODO(), volumeRestore, metav1.CreateOptions{})); err != nil {
			errs = append(errs, errors.WithStack(err))
			continue
		}
		numRestores++
	}

ForEachVolume:
	for i := 0; i < numRestores; i++ {
		select {
		case <-r.ctx.Done():
			errs = append(errs, errors.New("timed out waiting for all PodVolumeRestores to complete"))
			break ForEachVolume
		case res := <-resultsChan:
			if res.Status.Phase == velerov1api.PodVolumeRestorePhaseFailed {
				errs = append(errs, errors.Errorf("pod volume restore failed: %s", res.Status.Message))
			}
		}
	}

	r.resultsLock.Lock()
	delete(r.results, resultsKey(data.Pod.Namespace, data.Pod.Name))
	r.resultsLock.Unlock()

	return errs
}

func newPodVolumeRestore(restore *velerov1api.Restore, pod *corev1api.Pod, backupLocation, volume, snapshot, repoIdentifier, uploaderType string, pvc *corev1api.PersistentVolumeClaim) *velerov1api.PodVolumeRestore {
	pvr := &velerov1api.PodVolumeRestore{
		ObjectMeta: metav1.ObjectMeta{
			Namespace:    restore.Namespace,
			GenerateName: restore.Name + "-",
			OwnerReferences: []metav1.OwnerReference{
				{
					APIVersion: velerov1api.SchemeGroupVersion.String(),
					Kind:       "Restore",
					Name:       restore.Name,
					UID:        restore.UID,
					Controller: boolptr.True(),
				},
			},
			Labels: map[string]string{
				velerov1api.RestoreNameLabel: label.GetValidName(restore.Name),
				velerov1api.RestoreUIDLabel:  string(restore.UID),
				velerov1api.PodUIDLabel:      string(pod.UID),
			},
		},
		Spec: velerov1api.PodVolumeRestoreSpec{
			Pod: corev1api.ObjectReference{
				Kind:      "Pod",
				Namespace: pod.Namespace,
				Name:      pod.Name,
				UID:       pod.UID,
			},
			Volume:                volume,
			SnapshotID:            snapshot,
			BackupStorageLocation: backupLocation,
			RepoIdentifier:        repoIdentifier,
		},
	}
	if pvc != nil {
		// this label is not used by velero, but useful for debugging.
		pvr.Labels[velerov1api.PVCUIDLabel] = string(pvc.UID)
	}
	return pvr
}

func getVolumesRepositoryType(volumes map[string]volumeBackupInfo) (string, error) {
	if len(volumes) == 0 {
		return "", errors.New("empty volume list")
	}

	// the podVolumeBackups list come from one backup. In one backup, it is impossible that volumes are
	// backed up by different uploaders or to different repositories. Asserting this ensures one repo only,
	// which will simplify the following logics
	repositoryType := ""
	for _, backupInfo := range volumes {
		if backupInfo.repositoryType == "" {
			return "", errors.Errorf("empty repository type found among volume snapshots, snapshot ID %s, uploader %s",
				backupInfo.snapshotID, backupInfo.uploaderType)
		}

		if repositoryType == "" {
			repositoryType = backupInfo.repositoryType
		} else if repositoryType != backupInfo.repositoryType {
			return "", errors.Errorf("multiple repository type in one backup, current type %s, differential one [type %s, snapshot ID %s, uploader %s]",
				repositoryType, backupInfo.repositoryType, backupInfo.snapshotID, backupInfo.uploaderType)
		}
	}

	return repositoryType, nil
}