/*
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 restic

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"
	"github.com/vmware-tanzu/velero/pkg/label"
	"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
	repoManager *repositoryManager
	repoEnsurer *repositoryEnsurer
	pvcClient   corev1client.PersistentVolumeClaimsGetter

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

func newRestorer(
	ctx context.Context,
	rm *repositoryManager,
	repoEnsurer *repositoryEnsurer,
	podVolumeRestoreInformer cache.SharedIndexInformer,
	pvcClient corev1client.PersistentVolumeClaimsGetter,
	log logrus.FieldLogger,
) *restorer {
	r := &restorer{
		ctx:         ctx,
		repoManager: rm,
		repoEnsurer: repoEnsurer,
		pvcClient:   pvcClient,

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

	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 := GetVolumeBackupsForPod(data.PodVolumeBackups, data.Pod, data.SourceNamespace)
	if len(volumesToRestore) == 0 {
		return nil
	}

	repo, err := r.repoEnsurer.EnsureRepo(r.ctx, data.Restore.Namespace, data.SourceNamespace, data.BackupLocation)
	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.repoManager.repoLocker.Lock(repo.Name)
	defer r.repoManager.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, snapshot := 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, snapshot, repo.Spec.ResticIdentifier, pvc)

		if err := errorOnly(r.repoManager.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 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
}
