/*
Copyright 2016 The Kubernetes Authors.

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 persistentvolume

import (
	"fmt"
	"strconv"
	"time"

	"k8s.io/api/core/v1"
	storage "k8s.io/api/storage/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	coreinformers "k8s.io/client-go/informers/core/v1"
	storageinformers "k8s.io/client-go/informers/storage/v1"
	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	v1core "k8s.io/client-go/kubernetes/typed/core/v1"
	corelisters "k8s.io/client-go/listers/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"
	"k8s.io/kubernetes/pkg/cloudprovider"
	"k8s.io/kubernetes/pkg/controller"
	"k8s.io/kubernetes/pkg/util/goroutinemap"
	vol "k8s.io/kubernetes/pkg/volume"

	"github.com/golang/glog"
)

// This file contains the controller base functionality, i.e. framework to
// process PV/PVC added/updated/deleted events. The real binding, provisioning,
// recycling and deleting is done in pv_controller.go

// ControllerParameters contains arguments for creation of a new
// PersistentVolume controller.
type ControllerParameters struct {
	KubeClient                clientset.Interface
	SyncPeriod                time.Duration
	VolumePlugins             []vol.VolumePlugin
	Cloud                     cloudprovider.Interface
	ClusterName               string
	VolumeInformer            coreinformers.PersistentVolumeInformer
	ClaimInformer             coreinformers.PersistentVolumeClaimInformer
	ClassInformer             storageinformers.StorageClassInformer
	EventRecorder             record.EventRecorder
	EnableDynamicProvisioning bool
}

// NewController creates a new PersistentVolume controller
func NewController(p ControllerParameters) (*PersistentVolumeController, error) {
	eventRecorder := p.EventRecorder
	if eventRecorder == nil {
		broadcaster := record.NewBroadcaster()
		broadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: v1core.New(p.KubeClient.Core().RESTClient()).Events("")})
		eventRecorder = broadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "persistentvolume-controller"})
	}

	controller := &PersistentVolumeController{
		volumes:           newPersistentVolumeOrderedIndex(),
		claims:            cache.NewStore(cache.DeletionHandlingMetaNamespaceKeyFunc),
		kubeClient:        p.KubeClient,
		eventRecorder:     eventRecorder,
		runningOperations: goroutinemap.NewGoRoutineMap(true /* exponentialBackOffOnError */),
		cloud:             p.Cloud,
		enableDynamicProvisioning:     p.EnableDynamicProvisioning,
		clusterName:                   p.ClusterName,
		createProvisionedPVRetryCount: createProvisionedPVRetryCount,
		createProvisionedPVInterval:   createProvisionedPVInterval,
		claimQueue:                    workqueue.NewNamed("claims"),
		volumeQueue:                   workqueue.NewNamed("volumes"),
		resyncPeriod:                  p.SyncPeriod,
	}

	if err := controller.volumePluginMgr.InitPlugins(p.VolumePlugins, controller); err != nil {
		return nil, fmt.Errorf("Could not initialize volume plugins for PersistentVolume Controller: %v", err)
	}

	p.VolumeInformer.Informer().AddEventHandler(
		cache.ResourceEventHandlerFuncs{
			AddFunc:    func(obj interface{}) { controller.enqueueWork(controller.volumeQueue, obj) },
			UpdateFunc: func(oldObj, newObj interface{}) { controller.enqueueWork(controller.volumeQueue, newObj) },
			DeleteFunc: func(obj interface{}) { controller.enqueueWork(controller.volumeQueue, obj) },
		},
	)
	controller.volumeLister = p.VolumeInformer.Lister()
	controller.volumeListerSynced = p.VolumeInformer.Informer().HasSynced

	p.ClaimInformer.Informer().AddEventHandler(
		cache.ResourceEventHandlerFuncs{
			AddFunc:    func(obj interface{}) { controller.enqueueWork(controller.claimQueue, obj) },
			UpdateFunc: func(oldObj, newObj interface{}) { controller.enqueueWork(controller.claimQueue, newObj) },
			DeleteFunc: func(obj interface{}) { controller.enqueueWork(controller.claimQueue, obj) },
		},
	)
	controller.claimLister = p.ClaimInformer.Lister()
	controller.claimListerSynced = p.ClaimInformer.Informer().HasSynced

	controller.classLister = p.ClassInformer.Lister()
	controller.classListerSynced = p.ClassInformer.Informer().HasSynced
	return controller, nil
}

// initializeCaches fills all controller caches with initial data from etcd in
// order to have the caches already filled when first addClaim/addVolume to
// perform initial synchronization of the controller.
func (ctrl *PersistentVolumeController) initializeCaches(volumeLister corelisters.PersistentVolumeLister, claimLister corelisters.PersistentVolumeClaimLister) {
	volumeList, err := volumeLister.List(labels.Everything())
	if err != nil {
		glog.Errorf("PersistentVolumeController can't initialize caches: %v", err)
		return
	}
	for _, volume := range volumeList {
		clone, err := scheme.Scheme.DeepCopy(volume)
		if err != nil {
			glog.Errorf("error cloning volume %q: %v", volume.Name, err)
			continue
		}
		volumeClone := clone.(*v1.PersistentVolume)
		if _, err = ctrl.storeVolumeUpdate(volumeClone); err != nil {
			glog.Errorf("error updating volume cache: %v", err)
		}
	}

	claimList, err := claimLister.List(labels.Everything())
	if err != nil {
		glog.Errorf("PersistentVolumeController can't initialize caches: %v", err)
		return
	}
	for _, claim := range claimList {
		clone, err := scheme.Scheme.DeepCopy(claim)
		if err != nil {
			glog.Errorf("error cloning claim %q: %v", claimToClaimKey(claim), err)
			continue
		}
		claimClone := clone.(*v1.PersistentVolumeClaim)
		if _, err = ctrl.storeClaimUpdate(claimClone); err != nil {
			glog.Errorf("error updating claim cache: %v", err)
		}
	}
	glog.V(4).Infof("controller initialized")
}

// enqueueWork adds volume or claim to given work queue.
func (ctrl *PersistentVolumeController) enqueueWork(queue workqueue.Interface, obj interface{}) {
	// Beware of "xxx deleted" events
	if unknown, ok := obj.(cache.DeletedFinalStateUnknown); ok && unknown.Obj != nil {
		obj = unknown.Obj
	}
	objName, err := controller.KeyFunc(obj)
	if err != nil {
		glog.Errorf("failed to get key from object: %v", err)
		return
	}
	glog.V(5).Infof("enqueued %q for sync", objName)
	queue.Add(objName)
}

func (ctrl *PersistentVolumeController) storeVolumeUpdate(volume interface{}) (bool, error) {
	return storeObjectUpdate(ctrl.volumes.store, volume, "volume")
}

func (ctrl *PersistentVolumeController) storeClaimUpdate(claim interface{}) (bool, error) {
	return storeObjectUpdate(ctrl.claims, claim, "claim")
}

// updateVolume runs in worker thread and handles "volume added",
// "volume updated" and "periodic sync" events.
func (ctrl *PersistentVolumeController) updateVolume(volume *v1.PersistentVolume) {
	// Store the new volume version in the cache and do not process it if this
	// is an old version.
	new, err := ctrl.storeVolumeUpdate(volume)
	if err != nil {
		glog.Errorf("%v", err)
	}
	if !new {
		return
	}

	err = ctrl.syncVolume(volume)
	if err != nil {
		if errors.IsConflict(err) {
			// Version conflict error happens quite often and the controller
			// recovers from it easily.
			glog.V(3).Infof("could not sync volume %q: %+v", volume.Name, err)
		} else {
			glog.Errorf("could not sync volume %q: %+v", volume.Name, err)
		}
	}
}

// deleteVolume runs in worker thread and handles "volume deleted" event.
func (ctrl *PersistentVolumeController) deleteVolume(volume *v1.PersistentVolume) {
	_ = ctrl.volumes.store.Delete(volume)
	glog.V(4).Infof("volume %q deleted", volume.Name)

	if volume.Spec.ClaimRef == nil {
		return
	}
	// sync the claim when its volume is deleted. Explicitly syncing the
	// claim here in response to volume deletion prevents the claim from
	// waiting until the next sync period for its Lost status.
	claimKey := claimrefToClaimKey(volume.Spec.ClaimRef)
	glog.V(5).Infof("deleteVolume[%s]: scheduling sync of claim %q", volume.Name, claimKey)
	ctrl.claimQueue.Add(claimKey)
}

// updateClaim runs in worker thread and handles "claim added",
// "claim updated" and "periodic sync" events.
func (ctrl *PersistentVolumeController) updateClaim(claim *v1.PersistentVolumeClaim) {
	// Store the new claim version in the cache and do not process it if this is
	// an old version.
	new, err := ctrl.storeClaimUpdate(claim)
	if err != nil {
		glog.Errorf("%v", err)
	}
	if !new {
		return
	}
	err = ctrl.syncClaim(claim)
	if err != nil {
		if errors.IsConflict(err) {
			// Version conflict error happens quite often and the controller
			// recovers from it easily.
			glog.V(3).Infof("could not sync claim %q: %+v", claimToClaimKey(claim), err)
		} else {
			glog.Errorf("could not sync volume %q: %+v", claimToClaimKey(claim), err)
		}
	}
}

// deleteClaim runs in worker thread and handles "claim deleted" event.
func (ctrl *PersistentVolumeController) deleteClaim(claim *v1.PersistentVolumeClaim) {
	_ = ctrl.claims.Delete(claim)
	glog.V(4).Infof("claim %q deleted", claimToClaimKey(claim))

	// sync the volume when its claim is deleted.  Explicitly sync'ing the
	// volume here in response to claim deletion prevents the volume from
	// waiting until the next sync period for its Release.
	volumeName := claim.Spec.VolumeName
	glog.V(5).Infof("deleteClaim[%s]: scheduling sync of volume %q", claimToClaimKey(claim), volumeName)
	ctrl.volumeQueue.Add(volumeName)
}

// Run starts all of this controller's control loops
func (ctrl *PersistentVolumeController) Run(stopCh <-chan struct{}) {
	defer utilruntime.HandleCrash()
	defer ctrl.claimQueue.ShutDown()
	defer ctrl.volumeQueue.ShutDown()

	glog.Infof("Starting persistent volume controller")
	defer glog.Infof("Shutting down peristent volume controller")

	if !controller.WaitForCacheSync("persistent volume", stopCh, ctrl.volumeListerSynced, ctrl.claimListerSynced, ctrl.classListerSynced) {
		return
	}

	ctrl.initializeCaches(ctrl.volumeLister, ctrl.claimLister)

	go wait.Until(ctrl.resync, ctrl.resyncPeriod, stopCh)
	go wait.Until(ctrl.volumeWorker, time.Second, stopCh)
	go wait.Until(ctrl.claimWorker, time.Second, stopCh)

	<-stopCh
}

// volumeWorker processes items from volumeQueue. It must run only once,
// syncVolume is not assured to be reentrant.
func (ctrl *PersistentVolumeController) volumeWorker() {
	workFunc := func() bool {
		keyObj, quit := ctrl.volumeQueue.Get()
		if quit {
			return true
		}
		defer ctrl.volumeQueue.Done(keyObj)
		key := keyObj.(string)
		glog.V(5).Infof("volumeWorker[%s]", key)

		_, name, err := cache.SplitMetaNamespaceKey(key)
		if err != nil {
			glog.V(4).Infof("error getting name of volume %q to get volume from informer: %v", key, err)
			return false
		}
		volume, err := ctrl.volumeLister.Get(name)
		if err == nil {
			// The volume still exists in informer cache, the event must have
			// been add/update/sync
			ctrl.updateVolume(volume)
			return false
		}
		if !errors.IsNotFound(err) {
			glog.V(2).Infof("error getting volume %q from informer: %v", key, err)
			return false
		}

		// The volume is not in informer cache, the event must have been
		// "delete"
		volumeObj, found, err := ctrl.volumes.store.GetByKey(key)
		if err != nil {
			glog.V(2).Infof("error getting volume %q from cache: %v", key, err)
			return false
		}
		if !found {
			// The controller has already processed the delete event and
			// deleted the volume from its cache
			glog.V(2).Infof("deletion of volume %q was already processed", key)
			return false
		}
		volume, ok := volumeObj.(*v1.PersistentVolume)
		if !ok {
			glog.Errorf("expected volume, got %+v", volumeObj)
			return false
		}
		ctrl.deleteVolume(volume)
		return false
	}
	for {
		if quit := workFunc(); quit {
			glog.Infof("volume worker queue shutting down")
			return
		}
	}
}

// claimWorker processes items from claimQueue. It must run only once,
// syncClaim is not reentrant.
func (ctrl *PersistentVolumeController) claimWorker() {
	workFunc := func() bool {
		keyObj, quit := ctrl.claimQueue.Get()
		if quit {
			return true
		}
		defer ctrl.claimQueue.Done(keyObj)
		key := keyObj.(string)
		glog.V(5).Infof("claimWorker[%s]", key)

		namespace, name, err := cache.SplitMetaNamespaceKey(key)
		if err != nil {
			glog.V(4).Infof("error getting namespace & name of claim %q to get claim from informer: %v", key, err)
			return false
		}
		claim, err := ctrl.claimLister.PersistentVolumeClaims(namespace).Get(name)
		if err == nil {
			// The claim still exists in informer cache, the event must have
			// been add/update/sync
			ctrl.updateClaim(claim)
			return false
		}
		if !errors.IsNotFound(err) {
			glog.V(2).Infof("error getting claim %q from informer: %v", key, err)
			return false
		}

		// The claim is not in informer cache, the event must have been "delete"
		claimObj, found, err := ctrl.claims.GetByKey(key)
		if err != nil {
			glog.V(2).Infof("error getting claim %q from cache: %v", key, err)
			return false
		}
		if !found {
			// The controller has already processed the delete event and
			// deleted the claim from its cache
			glog.V(2).Infof("deletion of claim %q was already processed", key)
			return false
		}
		claim, ok := claimObj.(*v1.PersistentVolumeClaim)
		if !ok {
			glog.Errorf("expected claim, got %+v", claimObj)
			return false
		}
		ctrl.deleteClaim(claim)
		return false
	}
	for {
		if quit := workFunc(); quit {
			glog.Infof("claim worker queue shutting down")
			return
		}
	}
}

// resync supplements short resync period of shared informers - we don't want
// all consumers of PV/PVC shared informer to have a short resync period,
// therefore we do our own.
func (ctrl *PersistentVolumeController) resync() {
	glog.V(4).Infof("resyncing PV controller")

	pvcs, err := ctrl.claimLister.List(labels.NewSelector())
	if err != nil {
		glog.Warningf("cannot list claims: %s", err)
		return
	}
	for _, pvc := range pvcs {
		ctrl.enqueueWork(ctrl.claimQueue, pvc)
	}

	pvs, err := ctrl.volumeLister.List(labels.NewSelector())
	if err != nil {
		glog.Warningf("cannot list persistent volumes: %s", err)
		return
	}
	for _, pv := range pvs {
		ctrl.enqueueWork(ctrl.volumeQueue, pv)
	}
}

// setClaimProvisioner saves
// claim.Annotations[annStorageProvisioner] = class.Provisioner
func (ctrl *PersistentVolumeController) setClaimProvisioner(claim *v1.PersistentVolumeClaim, class *storage.StorageClass) (*v1.PersistentVolumeClaim, error) {
	if val, ok := claim.Annotations[annStorageProvisioner]; ok && val == class.Provisioner {
		// annotation is already set, nothing to do
		return claim, nil
	}

	// The volume from method args can be pointing to watcher cache. We must not
	// modify these, therefore create a copy.
	clone, err := scheme.Scheme.DeepCopy(claim)
	if err != nil {
		return nil, fmt.Errorf("Error cloning pv: %v", err)
	}
	claimClone, ok := clone.(*v1.PersistentVolumeClaim)
	if !ok {
		return nil, fmt.Errorf("Unexpected claim cast error : %v", claimClone)
	}
	metav1.SetMetaDataAnnotation(&claimClone.ObjectMeta, annStorageProvisioner, class.Provisioner)
	newClaim, err := ctrl.kubeClient.Core().PersistentVolumeClaims(claim.Namespace).Update(claimClone)
	if err != nil {
		return newClaim, err
	}
	_, err = ctrl.storeClaimUpdate(newClaim)
	if err != nil {
		return newClaim, err
	}
	return newClaim, nil
}

// Stateless functions

func getClaimStatusForLogging(claim *v1.PersistentVolumeClaim) string {
	bound := metav1.HasAnnotation(claim.ObjectMeta, annBindCompleted)
	boundByController := metav1.HasAnnotation(claim.ObjectMeta, annBoundByController)

	return fmt.Sprintf("phase: %s, bound to: %q, bindCompleted: %v, boundByController: %v", claim.Status.Phase, claim.Spec.VolumeName, bound, boundByController)
}

func getVolumeStatusForLogging(volume *v1.PersistentVolume) string {
	boundByController := metav1.HasAnnotation(volume.ObjectMeta, annBoundByController)
	claimName := ""
	if volume.Spec.ClaimRef != nil {
		claimName = fmt.Sprintf("%s/%s (uid: %s)", volume.Spec.ClaimRef.Namespace, volume.Spec.ClaimRef.Name, volume.Spec.ClaimRef.UID)
	}
	return fmt.Sprintf("phase: %s, bound to: %q, boundByController: %v", volume.Status.Phase, claimName, boundByController)
}

// isVolumeBoundToClaim returns true, if given volume is pre-bound or bound
// to specific claim. Both claim.Name and claim.Namespace must be equal.
// If claim.UID is present in volume.Spec.ClaimRef, it must be equal too.
func isVolumeBoundToClaim(volume *v1.PersistentVolume, claim *v1.PersistentVolumeClaim) bool {
	if volume.Spec.ClaimRef == nil {
		return false
	}
	if claim.Name != volume.Spec.ClaimRef.Name || claim.Namespace != volume.Spec.ClaimRef.Namespace {
		return false
	}
	if volume.Spec.ClaimRef.UID != "" && claim.UID != volume.Spec.ClaimRef.UID {
		return false
	}
	return true
}

// storeObjectUpdate updates given cache with a new object version from Informer
// callback (i.e. with events from etcd) or with an object modified by the
// controller itself. Returns "true", if the cache was updated, false if the
// object is an old version and should be ignored.
func storeObjectUpdate(store cache.Store, obj interface{}, className string) (bool, error) {
	objName, err := controller.KeyFunc(obj)
	if err != nil {
		return false, fmt.Errorf("Couldn't get key for object %+v: %v", obj, err)
	}
	oldObj, found, err := store.Get(obj)
	if err != nil {
		return false, fmt.Errorf("Error finding %s %q in controller cache: %v", className, objName, err)
	}

	objAccessor, err := meta.Accessor(obj)
	if err != nil {
		return false, err
	}

	if !found {
		// This is a new object
		glog.V(4).Infof("storeObjectUpdate: adding %s %q, version %s", className, objName, objAccessor.GetResourceVersion())
		if err = store.Add(obj); err != nil {
			return false, fmt.Errorf("Error adding %s %q to controller cache: %v", className, objName, err)
		}
		return true, nil
	}

	oldObjAccessor, err := meta.Accessor(oldObj)
	if err != nil {
		return false, err
	}

	objResourceVersion, err := strconv.ParseInt(objAccessor.GetResourceVersion(), 10, 64)
	if err != nil {
		return false, fmt.Errorf("Error parsing ResourceVersion %q of %s %q: %s", objAccessor.GetResourceVersion(), className, objName, err)
	}
	oldObjResourceVersion, err := strconv.ParseInt(oldObjAccessor.GetResourceVersion(), 10, 64)
	if err != nil {
		return false, fmt.Errorf("Error parsing old ResourceVersion %q of %s %q: %s", oldObjAccessor.GetResourceVersion(), className, objName, err)
	}

	// Throw away only older version, let the same version pass - we do want to
	// get periodic sync events.
	if oldObjResourceVersion > objResourceVersion {
		glog.V(4).Infof("storeObjectUpdate: ignoring %s %q version %s", className, objName, objAccessor.GetResourceVersion())
		return false, nil
	}

	glog.V(4).Infof("storeObjectUpdate updating %s %q with version %s", className, objName, objAccessor.GetResourceVersion())
	if err = store.Update(obj); err != nil {
		return false, fmt.Errorf("Error updating %s %q in controller cache: %v", className, objName, err)
	}
	return true, nil
}
