/*
Copyright 2015 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 deployment contains all the logic for handling Kubernetes Deployments.
// It implements a set of strategies (rolling, recreate) for deploying an application,
// the means to rollback to previous versions, proportional scaling for mitigating
// risk, cleanup policy, and other useful features of Deployments.
package deployment

import (
	"fmt"
	"reflect"
	"sort"
	"time"

	"github.com/golang/glog"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/unversioned"
	"k8s.io/kubernetes/pkg/apis/extensions"
	"k8s.io/kubernetes/pkg/client/cache"
	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
	unversionedcore "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset/typed/core/unversioned"
	"k8s.io/kubernetes/pkg/client/record"
	"k8s.io/kubernetes/pkg/controller"
	"k8s.io/kubernetes/pkg/controller/deployment/util"
	"k8s.io/kubernetes/pkg/controller/informers"
	"k8s.io/kubernetes/pkg/labels"
	"k8s.io/kubernetes/pkg/util/metrics"
	utilruntime "k8s.io/kubernetes/pkg/util/runtime"
	"k8s.io/kubernetes/pkg/util/wait"
	"k8s.io/kubernetes/pkg/util/workqueue"
)

const (
	// FullDeploymentResyncPeriod means we'll attempt to recompute the required replicas
	// of all deployments.
	// This recomputation happens based on contents in the local caches.
	FullDeploymentResyncPeriod = 30 * time.Second
	// We must avoid creating new replica set / counting pods until the replica set / pods store has synced.
	// If it hasn't synced, to avoid a hot loop, we'll wait this long between checks.
	StoreSyncedPollPeriod = 100 * time.Millisecond
	// MaxRetries is the number of times a deployment will be retried before it is dropped out of the queue.
	MaxRetries = 5
)

// DeploymentController is responsible for synchronizing Deployment objects stored
// in the system with actual running replica sets and pods.
type DeploymentController struct {
	client        clientset.Interface
	eventRecorder record.EventRecorder

	// To allow injection of syncDeployment for testing.
	syncHandler func(dKey string) error

	// A store of deployments, populated by the dController
	dLister *cache.StoreToDeploymentLister
	// A store of ReplicaSets, populated by the rsController
	rsLister *cache.StoreToReplicaSetLister
	// A store of pods, populated by the podController
	podLister *cache.StoreToPodLister

	// dListerSynced returns true if the Deployment store has been synced at least once.
	// Added as a member to the struct to allow injection for testing.
	dListerSynced cache.InformerSynced
	// rsListerSynced returns true if the ReplicaSet store has been synced at least once.
	// Added as a member to the struct to allow injection for testing.
	rsListerSynced cache.InformerSynced
	// podListerSynced returns true if the pod store has been synced at least once.
	// Added as a member to the struct to allow injection for testing.
	podListerSynced cache.InformerSynced

	// Deployments that need to be synced
	queue workqueue.RateLimitingInterface
}

// NewDeploymentController creates a new DeploymentController.
func NewDeploymentController(dInformer informers.DeploymentInformer, rsInformer informers.ReplicaSetInformer, podInformer informers.PodInformer, client clientset.Interface) *DeploymentController {
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartLogging(glog.Infof)
	// TODO: remove the wrapper when every clients have moved to use the clientset.
	eventBroadcaster.StartRecordingToSink(&unversionedcore.EventSinkImpl{Interface: client.Core().Events("")})

	if client != nil && client.Core().RESTClient().GetRateLimiter() != nil {
		metrics.RegisterMetricAndTrackRateLimiterUsage("deployment_controller", client.Core().RESTClient().GetRateLimiter())
	}
	dc := &DeploymentController{
		client:        client,
		eventRecorder: eventBroadcaster.NewRecorder(api.EventSource{Component: "deployment-controller"}),
		queue:         workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "deployment"),
	}

	dInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    dc.addDeploymentNotification,
		UpdateFunc: dc.updateDeploymentNotification,
		// This will enter the sync loop and no-op, because the deployment has been deleted from the store.
		DeleteFunc: dc.deleteDeploymentNotification,
	})
	rsInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    dc.addReplicaSet,
		UpdateFunc: dc.updateReplicaSet,
		DeleteFunc: dc.deleteReplicaSet,
	})

	dc.syncHandler = dc.syncDeployment
	dc.dLister = dInformer.Lister()
	dc.rsLister = rsInformer.Lister()
	dc.podLister = podInformer.Lister()
	dc.dListerSynced = dInformer.Informer().HasSynced
	dc.rsListerSynced = dInformer.Informer().HasSynced
	dc.podListerSynced = dInformer.Informer().HasSynced
	return dc
}

// Run begins watching and syncing.
func (dc *DeploymentController) Run(workers int, stopCh <-chan struct{}) {
	defer utilruntime.HandleCrash()
	defer dc.queue.ShutDown()

	glog.Infof("Starting deployment controller")

	if !cache.WaitForCacheSync(stopCh, dc.dListerSynced, dc.rsListerSynced, dc.podListerSynced) {
		return
	}

	for i := 0; i < workers; i++ {
		go wait.Until(dc.worker, time.Second, stopCh)
	}

	<-stopCh
	glog.Infof("Shutting down deployment controller")
}

func (dc *DeploymentController) addDeploymentNotification(obj interface{}) {
	d := obj.(*extensions.Deployment)
	glog.V(4).Infof("Adding deployment %s", d.Name)
	dc.enqueueDeployment(d)
}

func (dc *DeploymentController) updateDeploymentNotification(old, cur interface{}) {
	oldD := old.(*extensions.Deployment)
	glog.V(4).Infof("Updating deployment %s", oldD.Name)
	// Resync on deployment object relist.
	dc.enqueueDeployment(cur.(*extensions.Deployment))
}

func (dc *DeploymentController) deleteDeploymentNotification(obj interface{}) {
	d, ok := obj.(*extensions.Deployment)
	if !ok {
		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
		if !ok {
			glog.Errorf("Couldn't get object from tombstone %#v", obj)
			return
		}
		d, ok = tombstone.Obj.(*extensions.Deployment)
		if !ok {
			glog.Errorf("Tombstone contained object that is not a Deployment %#v", obj)
			return
		}
	}
	glog.V(4).Infof("Deleting deployment %s", d.Name)
	dc.enqueueDeployment(d)
}

// addReplicaSet enqueues the deployment that manages a ReplicaSet when the ReplicaSet is created.
func (dc *DeploymentController) addReplicaSet(obj interface{}) {
	rs := obj.(*extensions.ReplicaSet)
	glog.V(4).Infof("ReplicaSet %s added.", rs.Name)
	if d := dc.getDeploymentForReplicaSet(rs); d != nil {
		dc.enqueueDeployment(d)
	}
}

// getDeploymentForReplicaSet returns the deployment managing the given ReplicaSet.
func (dc *DeploymentController) getDeploymentForReplicaSet(rs *extensions.ReplicaSet) *extensions.Deployment {
	deployments, err := dc.dLister.GetDeploymentsForReplicaSet(rs)
	if err != nil || len(deployments) == 0 {
		glog.V(4).Infof("Error: %v. No deployment found for ReplicaSet %v, deployment controller will avoid syncing.", err, rs.Name)
		return nil
	}
	// Because all ReplicaSet's belonging to a deployment should have a unique label key,
	// there should never be more than one deployment returned by the above method.
	// If that happens we should probably dynamically repair the situation by ultimately
	// trying to clean up one of the controllers, for now we just return the older one
	if len(deployments) > 1 {
		sort.Sort(util.BySelectorLastUpdateTime(deployments))
		glog.Errorf("user error! more than one deployment is selecting replica set %s/%s with labels: %#v, returning %s/%s", rs.Namespace, rs.Name, rs.Labels, deployments[0].Namespace, deployments[0].Name)
	}
	return deployments[0]
}

// updateReplicaSet figures out what deployment(s) manage a ReplicaSet when the ReplicaSet
// is updated and wake them up. If the anything of the ReplicaSets have changed, we need to
// awaken both the old and new deployments. old and cur must be *extensions.ReplicaSet
// types.
func (dc *DeploymentController) updateReplicaSet(old, cur interface{}) {
	curRS := cur.(*extensions.ReplicaSet)
	oldRS := old.(*extensions.ReplicaSet)
	if curRS.ResourceVersion == oldRS.ResourceVersion {
		// Periodic resync will send update events for all known replica sets.
		// Two different versions of the same replica set will always have different RVs.
		return
	}
	// TODO: Write a unittest for this case
	glog.V(4).Infof("ReplicaSet %s updated.", curRS.Name)
	if d := dc.getDeploymentForReplicaSet(curRS); d != nil {
		dc.enqueueDeployment(d)
	}
	// A number of things could affect the old deployment: labels changing,
	// pod template changing, etc.
	if !api.Semantic.DeepEqual(oldRS, curRS) {
		if oldD := dc.getDeploymentForReplicaSet(oldRS); oldD != nil {
			dc.enqueueDeployment(oldD)
		}
	}
}

// deleteReplicaSet enqueues the deployment that manages a ReplicaSet when
// the ReplicaSet is deleted. obj could be an *extensions.ReplicaSet, or
// a DeletionFinalStateUnknown marker item.
func (dc *DeploymentController) deleteReplicaSet(obj interface{}) {
	rs, ok := obj.(*extensions.ReplicaSet)

	// When a delete is dropped, the relist will notice a pod in the store not
	// in the list, leading to the insertion of a tombstone object which contains
	// the deleted key/value. Note that this value might be stale. If the ReplicaSet
	// changed labels the new deployment will not be woken up till the periodic resync.
	if !ok {
		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
		if !ok {
			glog.Errorf("Couldn't get object from tombstone %#v, could take up to %v before a deployment recreates/updates replicasets", obj, FullDeploymentResyncPeriod)
			return
		}
		rs, ok = tombstone.Obj.(*extensions.ReplicaSet)
		if !ok {
			glog.Errorf("Tombstone contained object that is not a ReplicaSet %#v, could take up to %v before a deployment recreates/updates replicasets", obj, FullDeploymentResyncPeriod)
			return
		}
	}
	glog.V(4).Infof("ReplicaSet %s deleted.", rs.Name)
	if d := dc.getDeploymentForReplicaSet(rs); d != nil {
		dc.enqueueDeployment(d)
	}
}

func (dc *DeploymentController) enqueueDeployment(deployment *extensions.Deployment) {
	key, err := controller.KeyFunc(deployment)
	if err != nil {
		glog.Errorf("Couldn't get key for object %#v: %v", deployment, err)
		return
	}

	dc.queue.Add(key)
}

func (dc *DeploymentController) markDeploymentOverlap(deployment *extensions.Deployment, withDeployment string) (*extensions.Deployment, error) {
	if deployment.Annotations[util.OverlapAnnotation] == withDeployment {
		return deployment, nil
	}
	if deployment.Annotations == nil {
		deployment.Annotations = make(map[string]string)
	}
	deployment.Annotations[util.OverlapAnnotation] = withDeployment
	return dc.client.Extensions().Deployments(deployment.Namespace).Update(deployment)
}

func (dc *DeploymentController) clearDeploymentOverlap(deployment *extensions.Deployment) (*extensions.Deployment, error) {
	if len(deployment.Annotations[util.OverlapAnnotation]) == 0 {
		return deployment, nil
	}
	delete(deployment.Annotations, util.OverlapAnnotation)
	return dc.client.Extensions().Deployments(deployment.Namespace).Update(deployment)
}

// worker runs a worker thread that just dequeues items, processes them, and marks them done.
// It enforces that the syncHandler is never invoked concurrently with the same key.
func (dc *DeploymentController) worker() {
	work := func() bool {
		key, quit := dc.queue.Get()
		if quit {
			return true
		}
		defer dc.queue.Done(key)

		err := dc.syncHandler(key.(string))
		dc.handleErr(err, key)

		return false
	}

	for {
		if quit := work(); quit {
			return
		}
	}
}

func (dc *DeploymentController) handleErr(err error, key interface{}) {
	if err == nil {
		dc.queue.Forget(key)
		return
	}

	if dc.queue.NumRequeues(key) < MaxRetries {
		glog.V(2).Infof("Error syncing deployment %v: %v", key, err)
		dc.queue.AddRateLimited(key)
		return
	}

	utilruntime.HandleError(err)
	dc.queue.Forget(key)
}

// syncDeployment will sync the deployment with the given key.
// This function is not meant to be invoked concurrently with the same key.
func (dc *DeploymentController) syncDeployment(key string) error {
	startTime := time.Now()
	defer func() {
		glog.V(4).Infof("Finished syncing deployment %q (%v)", key, time.Now().Sub(startTime))
	}()

	obj, exists, err := dc.dLister.Indexer.GetByKey(key)
	if err != nil {
		glog.Errorf("Unable to retrieve deployment %v from store: %v", key, err)
		return err
	}
	if !exists {
		glog.Infof("Deployment has been deleted %v", key)
		return nil
	}

	deployment := obj.(*extensions.Deployment)
	everything := unversioned.LabelSelector{}
	if reflect.DeepEqual(deployment.Spec.Selector, &everything) {
		dc.eventRecorder.Eventf(deployment, api.EventTypeWarning, "SelectingAll", "This deployment is selecting all pods. A non-empty selector is required.")
		return nil
	}

	// Deep-copy otherwise we are mutating our cache.
	// TODO: Deep-copy only when needed.
	d, err := util.DeploymentDeepCopy(deployment)
	if err != nil {
		return err
	}

	if d.DeletionTimestamp != nil {
		return dc.syncStatusOnly(d)
	}

	// Handle overlapping deployments by deterministically avoid syncing deployments that fight over ReplicaSets.
	if err = dc.handleOverlap(d); err != nil {
		dc.eventRecorder.Eventf(deployment, api.EventTypeWarning, "SelectorOverlap", err.Error())
		return nil
	}

	if d.Spec.Paused {
		return dc.sync(d)
	}

	if d.Spec.RollbackTo != nil {
		revision := d.Spec.RollbackTo.Revision
		if d, err = dc.rollback(d, &revision); err != nil {
			return err
		}
	}

	scalingEvent, err := dc.isScalingEvent(d)
	if err != nil {
		return err
	}
	if scalingEvent {
		return dc.sync(d)
	}

	switch d.Spec.Strategy.Type {
	case extensions.RecreateDeploymentStrategyType:
		return dc.rolloutRecreate(d)
	case extensions.RollingUpdateDeploymentStrategyType:
		return dc.rolloutRolling(d)
	}
	return fmt.Errorf("unexpected deployment strategy type: %s", d.Spec.Strategy.Type)
}

// handleOverlap relists all deployment in the same namespace for overlaps, and avoid syncing
// the newer overlapping ones (only sync the oldest one). New/old is determined by when the
// deployment's selector is last updated.
func (dc *DeploymentController) handleOverlap(d *extensions.Deployment) error {
	selector, err := unversioned.LabelSelectorAsSelector(d.Spec.Selector)
	if err != nil {
		return fmt.Errorf("deployment %s/%s has invalid label selector: %v", d.Namespace, d.Name, err)
	}
	deployments, err := dc.dLister.Deployments(d.Namespace).List(labels.Everything())
	if err != nil {
		return fmt.Errorf("error listing deployments in namespace %s: %v", d.Namespace, err)
	}
	overlapping := false
	for _, other := range deployments {
		if !selector.Empty() && selector.Matches(labels.Set(other.Spec.Template.Labels)) && d.UID != other.UID {
			deploymentCopy, err := util.DeploymentDeepCopy(other)
			if err != nil {
				return err
			}
			overlapping = true
			// We don't care if the overlapping annotation update failed or not (we don't make decision on it)
			d, _ = dc.markDeploymentOverlap(d, other.Name)
			deploymentCopy, _ = dc.markDeploymentOverlap(deploymentCopy, d.Name)
			// Skip syncing this one if older overlapping one is found
			// TODO: figure out a better way to determine which deployment to skip,
			// either with controller reference, or with validation.
			// Using oldest active replica set to determine which deployment to skip wouldn't make much difference,
			// since new replica set hasn't been created after selector update
			if util.SelectorUpdatedBefore(deploymentCopy, d) {
				return fmt.Errorf("found deployment %s/%s has overlapping selector with an older deployment %s/%s, skip syncing it", d.Namespace, d.Name, other.Namespace, other.Name)
			}
		}
	}
	if !overlapping {
		// We don't care if the overlapping annotation update failed or not (we don't make decision on it)
		d, _ = dc.clearDeploymentOverlap(d)
	}
	return nil
}
