// When a pod is deleted, enqueue the controller that manages the pod and update its expectations.
// obj could be an *api.Pod, or a DeletionFinalStateUnknown marker item.
func (rm *ReplicationManager) deletePod(obj interface{}) {
	pod, ok := obj.(*api.Pod)

	// 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 pod
	// changed labels the new rc 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 controller recreates a replica", obj, controller.ExpectationsTimeout)
			return
		}
		pod, ok = tombstone.Obj.(*api.Pod)
		if !ok {
			glog.Errorf("Tombstone contained object that is not a pod %+v, could take up to %v before controller recreates a replica", obj, controller.ExpectationsTimeout)
			return
		}
	}
	if rc := rm.getPodController(pod); rc != nil {
		rcKey, err := controller.KeyFunc(rc)
		if err != nil {
			glog.Errorf("Couldn't get key for replication controller %#v: %v", rc, err)
			return
		}
		rm.expectations.DeletionObserved(rcKey)
		rm.enqueueController(rc)
	}
}

func getKey(rc *api.ReplicationController, t *testing.T) string {
	if key, err := controller.KeyFunc(rc); err != nil {
		t.Errorf("Unexpected error getting key for rc %v: %v", rc.Name, err)
		return ""
	} else {
		return key
	}
}

// syncReplicationController will sync the rc with the given key if it has had its expectations fulfilled, meaning
// it did not expect to see any more of its pods created or deleted. This function is not meant to be invoked
// concurrently with the same key.
func (rm *ReplicationManager) syncReplicationController(key string) error {
	startTime := time.Now()
	defer func() {
		glog.V(4).Infof("Finished syncing controller %q (%v)", key, time.Now().Sub(startTime))
	}()

	obj, exists, err := rm.rcStore.Store.GetByKey(key)
	if !exists {
		glog.Infof("Replication Controller has been deleted %v", key)
		rm.expectations.DeleteExpectations(key)
		return nil
	}
	if err != nil {
		glog.Infof("Unable to retrieve rc %v from store: %v", key, err)
		rm.queue.Add(key)
		return err
	}
	rc := *obj.(*api.ReplicationController)
	if !rm.podStoreSynced() {
		// Sleep so we give the pod reflector goroutine a chance to run.
		time.Sleep(PodStoreSyncedPollPeriod)
		glog.Infof("Waiting for pods controller to sync, requeuing rc %v", rc.Name)
		rm.enqueueController(&rc)
		return nil
	}

	// Check the expectations of the rc before counting active pods, otherwise a new pod can sneak in
	// and update the expectations after we've retrieved active pods from the store. If a new pod enters
	// the store after we've checked the expectation, the rc sync is just deferred till the next relist.
	rcKey, err := controller.KeyFunc(&rc)
	if err != nil {
		glog.Errorf("Couldn't get key for replication controller %#v: %v", rc, err)
		return err
	}
	rcNeedsSync := rm.expectations.SatisfiedExpectations(rcKey)
	podList, err := rm.podStore.Pods(rc.Namespace).List(labels.Set(rc.Spec.Selector).AsSelector())
	if err != nil {
		glog.Errorf("Error getting pods for rc %q: %v", key, err)
		rm.queue.Add(key)
		return err
	}

	// TODO: Do this in a single pass, or use an index.
	filteredPods := controller.FilterActivePods(podList.Items)
	if rcNeedsSync {
		rm.manageReplicas(filteredPods, &rc)
	}

	// Always updates status as pods come up or die.
	if err := updateReplicaCount(rm.kubeClient.ReplicationControllers(rc.Namespace), rc, len(filteredPods)); err != nil {
		// Multiple things could lead to this update failing. Requeuing the controller ensures
		// we retry with some fairness.
		glog.V(2).Infof("Failed to update replica count for controller %v, requeuing", rc.Name)
		rm.enqueueController(&rc)
	}
	return nil
}

// manageReplicas checks and updates replicas for the given replication controller.
func (rm *ReplicationManager) manageReplicas(filteredPods []*api.Pod, rc *api.ReplicationController) {
	diff := len(filteredPods) - rc.Spec.Replicas
	rcKey, err := controller.KeyFunc(rc)
	if err != nil {
		glog.Errorf("Couldn't get key for replication controller %#v: %v", rc, err)
		return
	}
	if diff < 0 {
		diff *= -1
		if diff > rm.burstReplicas {
			diff = rm.burstReplicas
		}
		rm.expectations.ExpectCreations(rcKey, diff)
		wait := sync.WaitGroup{}
		wait.Add(diff)
		glog.V(2).Infof("Too few %q/%q replicas, need %d, creating %d", rc.Namespace, rc.Name, rc.Spec.Replicas, diff)
		for i := 0; i < diff; i++ {
			go func() {
				defer wait.Done()
				if err := rm.podControl.CreateReplica(rc.Namespace, rc); err != nil {
					// Decrement the expected number of creates because the informer won't observe this pod
					glog.V(2).Infof("Failed creation, decrementing expectations for controller %q/%q", rc.Namespace, rc.Name)
					rm.expectations.CreationObserved(rcKey)
					util.HandleError(err)
				}
			}()
		}
		wait.Wait()
	} else if diff > 0 {
		if diff > rm.burstReplicas {
			diff = rm.burstReplicas
		}
		rm.expectations.ExpectDeletions(rcKey, diff)
		glog.V(2).Infof("Too many %q/%q replicas, need %d, deleting %d", rc.Namespace, rc.Name, rc.Spec.Replicas, diff)
		// No need to sort pods if we are about to delete all of them
		if rc.Spec.Replicas != 0 {
			// Sort the pods in the order such that not-ready < ready, unscheduled
			// < scheduled, and pending < running. This ensures that we delete pods
			// in the earlier stages whenever possible.
			sort.Sort(controller.ActivePods(filteredPods))
		}

		wait := sync.WaitGroup{}
		wait.Add(diff)
		for i := 0; i < diff; i++ {
			go func(ix int) {
				defer wait.Done()
				if err := rm.podControl.DeletePod(rc.Namespace, filteredPods[ix].Name); err != nil {
					// Decrement the expected number of deletes because the informer won't observe this deletion
					glog.V(2).Infof("Failed deletion, decrementing expectations for controller %q/%q", rc.Namespace, rc.Name)
					rm.expectations.DeletionObserved(rcKey)
				}
			}(i)
		}
		wait.Wait()
	}
}

func TestSyncReplicationControllerDormancy(t *testing.T) {
	// Setup a test server so we can lie about the current state of pods
	fakeHandler := util.FakeHandler{
		StatusCode:   200,
		ResponseBody: "",
	}
	testServer := httptest.NewServer(&fakeHandler)
	defer testServer.Close()
	client := client.NewOrDie(&client.Config{Host: testServer.URL, Version: testapi.Version()})

	fakePodControl := FakePodControl{}
	manager := NewReplicationManager(client, BurstReplicas)
	manager.podStoreSynced = alwaysReady
	manager.podControl = &fakePodControl

	controllerSpec := newReplicationController(2)
	manager.rcStore.Store.Add(controllerSpec)
	newPodList(manager.podStore.Store, 1, api.PodRunning, controllerSpec)

	// Creates a replica and sets expectations
	controllerSpec.Status.Replicas = 1
	manager.syncReplicationController(getKey(controllerSpec, t))
	validateSyncReplication(t, &fakePodControl, 1, 0)

	// Expectations prevents replicas but not an update on status
	controllerSpec.Status.Replicas = 0
	fakePodControl.clear()
	manager.syncReplicationController(getKey(controllerSpec, t))
	validateSyncReplication(t, &fakePodControl, 0, 0)

	// Get the key for the controller
	rcKey, err := controller.KeyFunc(controllerSpec)
	if err != nil {
		t.Errorf("Couldn't get key for object %+v: %v", controllerSpec, err)
	}

	// Lowering expectations should lead to a sync that creates a replica, however the
	// fakePodControl error will prevent this, leaving expectations at 0, 0
	manager.expectations.CreationObserved(rcKey)
	controllerSpec.Status.Replicas = 1
	fakePodControl.clear()
	fakePodControl.err = fmt.Errorf("Fake Error")

	manager.syncReplicationController(getKey(controllerSpec, t))
	validateSyncReplication(t, &fakePodControl, 0, 0)

	// This replica should not need a Lowering of expectations, since the previous create failed
	fakePodControl.err = nil
	manager.syncReplicationController(getKey(controllerSpec, t))
	validateSyncReplication(t, &fakePodControl, 1, 0)

	// 1 PUT for the rc status during dormancy window.
	// Note that the pod creates go through pod control so they're not recorded.
	fakeHandler.ValidateRequestCount(t, 1)
}

// When a pod is created, enqueue the controller that manages it and update it's expectations.
func (rm *ReplicationManager) addPod(obj interface{}) {
	pod := obj.(*api.Pod)
	if rc := rm.getPodController(pod); rc != nil {
		rcKey, err := controller.KeyFunc(rc)
		if err != nil {
			glog.Errorf("Couldn't get key for replication controller %#v: %v", rc, err)
			return
		}
		rm.expectations.CreationObserved(rcKey)
		rm.enqueueController(rc)
	}
}

// obj could be an *api.ReplicationController, or a DeletionFinalStateUnknown marker item.
func (rm *ReplicationManager) enqueueController(obj interface{}) {
	key, err := controller.KeyFunc(obj)
	if err != nil {
		glog.Errorf("Couldn't get key for object %+v: %v", obj, err)
		return
	}

	// TODO: Handle overlapping controllers better. Either disallow them at admission time or
	// deterministically avoid syncing controllers that fight over pods. Currently, we only
	// ensure that the same controller is synced for a given pod. When we periodically relist
	// all controllers there will still be some replica instability. One way to handle this is
	// by querying the store for all controllers that this rc overlaps, as well as all
	// controllers that overlap this rc, and sorting them.
	rm.queue.Add(key)
}

func TestDeleteControllerAndExpectations(t *testing.T) {
	client := client.NewOrDie(&client.Config{Host: "", Version: testapi.Version()})
	manager := NewReplicationManager(client, 10)
	manager.podStoreSynced = alwaysReady

	rc := newReplicationController(1)
	manager.rcStore.Store.Add(rc)

	fakePodControl := FakePodControl{}
	manager.podControl = &fakePodControl

	// This should set expectations for the rc
	manager.syncReplicationController(getKey(rc, t))
	validateSyncReplication(t, &fakePodControl, 1, 0)
	fakePodControl.clear()

	// Get the RC key
	rcKey, err := controller.KeyFunc(rc)
	if err != nil {
		t.Errorf("Couldn't get key for object %+v: %v", rc, err)
	}

	// This is to simulate a concurrent addPod, that has a handle on the expectations
	// as the controller deletes it.
	podExp, exists, err := manager.expectations.GetExpectations(rcKey)
	if !exists || err != nil {
		t.Errorf("No expectations found for rc")
	}
	manager.rcStore.Delete(rc)
	manager.syncReplicationController(getKey(rc, t))

	if _, exists, err = manager.expectations.GetExpectations(rcKey); exists {
		t.Errorf("Found expectaions, expected none since the rc has been deleted.")
	}

	// This should have no effect, since we've deleted the rc.
	podExp.Seen(1, 0)
	manager.podStore.Store.Replace(make([]interface{}, 0))
	manager.syncReplicationController(getKey(rc, t))
	validateSyncReplication(t, &fakePodControl, 0, 0)
}

func doTestControllerBurstReplicas(t *testing.T, burstReplicas, numReplicas int) {
	client := client.NewOrDie(&client.Config{Host: "", Version: testapi.Version()})
	fakePodControl := FakePodControl{}
	manager := NewReplicationManager(client, burstReplicas)
	manager.podStoreSynced = alwaysReady
	manager.podControl = &fakePodControl

	controllerSpec := newReplicationController(numReplicas)
	manager.rcStore.Store.Add(controllerSpec)

	expectedPods := 0
	pods := newPodList(nil, numReplicas, api.PodPending, controllerSpec)

	rcKey, err := controller.KeyFunc(controllerSpec)
	if err != nil {
		t.Errorf("Couldn't get key for object %+v: %v", controllerSpec, err)
	}

	// Size up the controller, then size it down, and confirm the expected create/delete pattern
	for _, replicas := range []int{numReplicas, 0} {

		controllerSpec.Spec.Replicas = replicas
		manager.rcStore.Store.Add(controllerSpec)

		for i := 0; i < numReplicas; i += burstReplicas {
			manager.syncReplicationController(getKey(controllerSpec, t))

			// The store accrues active pods. It's also used by the rc to determine how many
			// replicas to create.
			activePods := len(manager.podStore.Store.List())
			if replicas != 0 {
				// This is the number of pods currently "in flight". They were created by the rc manager above,
				// which then puts the rc to sleep till all of them have been observed.
				expectedPods = replicas - activePods
				if expectedPods > burstReplicas {
					expectedPods = burstReplicas
				}
				// This validates the rc manager sync actually created pods
				validateSyncReplication(t, &fakePodControl, expectedPods, 0)

				// This simulates the watch events for all but 1 of the expected pods.
				// None of these should wake the controller because it has expectations==BurstReplicas.
				for i := 0; i < expectedPods-1; i++ {
					manager.podStore.Store.Add(&pods.Items[i])
					manager.addPod(&pods.Items[i])
				}

				podExp, exists, err := manager.expectations.GetExpectations(rcKey)
				if !exists || err != nil {
					t.Fatalf("Did not find expectations for rc.")
				}
				if add, _ := podExp.GetExpectations(); add != 1 {
					t.Fatalf("Expectations are wrong %v", podExp)
				}
			} else {
				expectedPods = (replicas - activePods) * -1
				if expectedPods > burstReplicas {
					expectedPods = burstReplicas
				}
				validateSyncReplication(t, &fakePodControl, 0, expectedPods)
				for i := 0; i < expectedPods-1; i++ {
					manager.podStore.Store.Delete(&pods.Items[i])
					manager.deletePod(&pods.Items[i])
				}
				podExp, exists, err := manager.expectations.GetExpectations(rcKey)
				if !exists || err != nil {
					t.Fatalf("Did not find expectations for rc.")
				}
				if _, del := podExp.GetExpectations(); del != 1 {
					t.Fatalf("Expectations are wrong %v", podExp)
				}
			}

			// Check that the rc didn't take any action for all the above pods
			fakePodControl.clear()
			manager.syncReplicationController(getKey(controllerSpec, t))
			validateSyncReplication(t, &fakePodControl, 0, 0)

			// Create/Delete the last pod
			// The last add pod will decrease the expectation of the rc to 0,
			// which will cause it to create/delete the remaining replicas upto burstReplicas.
			if replicas != 0 {
				manager.podStore.Store.Add(&pods.Items[expectedPods-1])
				manager.addPod(&pods.Items[expectedPods-1])
			} else {
				manager.podStore.Store.Delete(&pods.Items[expectedPods-1])
				manager.deletePod(&pods.Items[expectedPods-1])
			}
			pods.Items = pods.Items[expectedPods:]
		}

		// Confirm that we've created the right number of replicas
		activePods := len(manager.podStore.Store.List())
		if activePods != controllerSpec.Spec.Replicas {
			t.Fatalf("Unexpected number of active pods, expected %d, got %d", controllerSpec.Spec.Replicas, activePods)
		}
		// Replenish the pod list, since we cut it down sizing up
		pods = newPodList(nil, replicas, api.PodRunning, controllerSpec)
	}
}