/*
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 namespace

import (
	"fmt"
	"reflect"
	"time"

	federation_api "k8s.io/kubernetes/federation/apis/federation/v1beta1"
	federation_release_1_4 "k8s.io/kubernetes/federation/client/clientset_generated/federation_release_1_4"
	"k8s.io/kubernetes/federation/pkg/federation-controller/util"
	"k8s.io/kubernetes/federation/pkg/federation-controller/util/eventsink"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/errors"
	api_v1 "k8s.io/kubernetes/pkg/api/v1"
	"k8s.io/kubernetes/pkg/client/cache"
	kube_release_1_4 "k8s.io/kubernetes/pkg/client/clientset_generated/release_1_4"
	"k8s.io/kubernetes/pkg/client/record"
	"k8s.io/kubernetes/pkg/controller"
	pkg_runtime "k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/util/flowcontrol"
	"k8s.io/kubernetes/pkg/util/sets"
	"k8s.io/kubernetes/pkg/watch"

	"github.com/golang/glog"
)

const (
	allClustersKey = "ALL_CLUSTERS"
)

type NamespaceController struct {
	// For triggering single namespace reconcilation. This is used when there is an
	// add/update/delete operation on a namespace in either federated API server or
	// in some member of the federation.
	namespaceDeliverer *util.DelayingDeliverer

	// For triggering all namespaces reconcilation. This is used when
	// a new cluster becomes available.
	clusterDeliverer *util.DelayingDeliverer

	// Contains namespaces present in members of federation.
	namespaceFederatedInformer util.FederatedInformer
	// For updating members of federation.
	federatedUpdater util.FederatedUpdater
	// Definitions of namespaces that should be federated.
	namespaceInformerStore cache.Store
	// Informer controller for namespaces that should be federated.
	namespaceInformerController cache.ControllerInterface

	// Client to federated api server.
	federatedApiClient federation_release_1_4.Interface

	// Backoff manager for namespaces
	namespaceBackoff *flowcontrol.Backoff

	// For events
	eventRecorder record.EventRecorder

	namespaceReviewDelay  time.Duration
	clusterAvailableDelay time.Duration
	smallDelay            time.Duration
	updateTimeout         time.Duration
}

// NewNamespaceController returns a new namespace controller
func NewNamespaceController(client federation_release_1_4.Interface) *NamespaceController {
	broadcaster := record.NewBroadcaster()
	broadcaster.StartRecordingToSink(eventsink.NewFederatedEventSink(client))
	recorder := broadcaster.NewRecorder(api.EventSource{Component: "federated-namespace-controller"})

	nc := &NamespaceController{
		federatedApiClient:    client,
		namespaceReviewDelay:  time.Second * 10,
		clusterAvailableDelay: time.Second * 20,
		smallDelay:            time.Second * 3,
		updateTimeout:         time.Second * 30,
		namespaceBackoff:      flowcontrol.NewBackOff(5*time.Second, time.Minute),
		eventRecorder:         recorder,
	}

	// Build delivereres for triggering reconcilations.
	nc.namespaceDeliverer = util.NewDelayingDeliverer()
	nc.clusterDeliverer = util.NewDelayingDeliverer()

	// Start informer in federated API servers on namespaces that should be federated.
	nc.namespaceInformerStore, nc.namespaceInformerController = cache.NewInformer(
		&cache.ListWatch{
			ListFunc: func(options api.ListOptions) (pkg_runtime.Object, error) {
				return client.Core().Namespaces().List(options)
			},
			WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
				return client.Core().Namespaces().Watch(options)
			},
		},
		&api_v1.Namespace{},
		controller.NoResyncPeriodFunc(),
		util.NewTriggerOnAllChanges(func(obj pkg_runtime.Object) { nc.deliverNamespaceObj(obj, 0, false) }))

	// Federated informer on namespaces in members of federation.
	nc.namespaceFederatedInformer = util.NewFederatedInformer(
		client,
		func(cluster *federation_api.Cluster, targetClient kube_release_1_4.Interface) (cache.Store, cache.ControllerInterface) {
			return cache.NewInformer(
				&cache.ListWatch{
					ListFunc: func(options api.ListOptions) (pkg_runtime.Object, error) {
						return targetClient.Core().Namespaces().List(options)
					},
					WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
						return targetClient.Core().Namespaces().Watch(options)
					},
				},
				&api_v1.Namespace{},
				controller.NoResyncPeriodFunc(),
				// Trigger reconcilation whenever something in federated cluster is changed. In most cases it
				// would be just confirmation that some namespace opration suceeded.
				util.NewTriggerOnMetaAndSpecChanges(
					func(obj pkg_runtime.Object) { nc.deliverNamespaceObj(obj, nc.namespaceReviewDelay, false) },
				))
		},

		&util.ClusterLifecycleHandlerFuncs{
			ClusterAvailable: func(cluster *federation_api.Cluster) {
				// When new cluster becomes available process all the namespaces again.
				nc.clusterDeliverer.DeliverAfter(allClustersKey, nil, nc.clusterAvailableDelay)
			},
		},
	)

	// Federated updeater along with Create/Update/Delete operations.
	nc.federatedUpdater = util.NewFederatedUpdater(nc.namespaceFederatedInformer,
		func(client kube_release_1_4.Interface, obj pkg_runtime.Object) error {
			namespace := obj.(*api_v1.Namespace)
			_, err := client.Core().Namespaces().Create(namespace)
			return err
		},
		func(client kube_release_1_4.Interface, obj pkg_runtime.Object) error {
			namespace := obj.(*api_v1.Namespace)
			_, err := client.Core().Namespaces().Update(namespace)
			return err
		},
		func(client kube_release_1_4.Interface, obj pkg_runtime.Object) error {
			namespace := obj.(*api_v1.Namespace)
			err := client.Core().Namespaces().Delete(namespace.Name, &api.DeleteOptions{})
			return err
		})
	return nc
}

func (nc *NamespaceController) Run(stopChan <-chan struct{}) {
	go nc.namespaceInformerController.Run(stopChan)
	nc.namespaceFederatedInformer.Start()
	go func() {
		<-stopChan
		nc.namespaceFederatedInformer.Stop()
	}()
	nc.namespaceDeliverer.StartWithHandler(func(item *util.DelayingDelivererItem) {
		namespace := item.Value.(string)
		nc.reconcileNamespace(namespace)
	})
	nc.clusterDeliverer.StartWithHandler(func(_ *util.DelayingDelivererItem) {
		nc.reconcileNamespacesOnClusterChange()
	})
	go func() {
		select {
		case <-time.After(time.Minute):
			nc.namespaceBackoff.GC()
		case <-stopChan:
			return
		}
	}()
}

func (nc *NamespaceController) deliverNamespaceObj(obj interface{}, delay time.Duration, failed bool) {
	namespace := obj.(*api_v1.Namespace)
	nc.deliverNamespace(namespace.Name, delay, failed)
}

// Adds backoff to delay if this delivery is related to some failure. Resets backoff if there was no failure.
func (nc *NamespaceController) deliverNamespace(namespace string, delay time.Duration, failed bool) {
	if failed {
		nc.namespaceBackoff.Next(namespace, time.Now())
		delay = delay + nc.namespaceBackoff.Get(namespace)
	} else {
		nc.namespaceBackoff.Reset(namespace)
	}
	nc.namespaceDeliverer.DeliverAfter(namespace, namespace, delay)
}

// Check whether all data stores are in sync. False is returned if any of the informer/stores is not yet
// synced with the coresponding api server.
func (nc *NamespaceController) isSynced() bool {
	if !nc.namespaceFederatedInformer.ClustersSynced() {
		glog.V(2).Infof("Cluster list not synced")
		return false
	}
	clusters, err := nc.namespaceFederatedInformer.GetReadyClusters()
	if err != nil {
		glog.Errorf("Failed to get ready clusters: %v", err)
		return false
	}
	if !nc.namespaceFederatedInformer.GetTargetStore().ClustersSynced(clusters) {
		return false
	}
	return true
}

// The function triggers reconcilation of all federated namespaces.
func (nc *NamespaceController) reconcileNamespacesOnClusterChange() {
	if !nc.isSynced() {
		nc.clusterDeliverer.DeliverAfter(allClustersKey, nil, nc.clusterAvailableDelay)
	}
	for _, obj := range nc.namespaceInformerStore.List() {
		namespace := obj.(*api_v1.Namespace)
		nc.deliverNamespace(namespace.Name, nc.smallDelay, false)
	}
}

func (nc *NamespaceController) reconcileNamespace(namespace string) {
	if !nc.isSynced() {
		nc.deliverNamespace(namespace, nc.clusterAvailableDelay, false)
		return
	}

	baseNamespaceObj, exist, err := nc.namespaceInformerStore.GetByKey(namespace)
	if err != nil {
		glog.Errorf("Failed to query main namespace store for %v: %v", namespace, err)
		nc.deliverNamespace(namespace, 0, true)
		return
	}

	if !exist {
		// Not federated namespace, ignoring.
		return
	}
	baseNamespace := baseNamespaceObj.(*api_v1.Namespace)
	if baseNamespace.DeletionTimestamp != nil {
		nc.delete(baseNamespace)
		return
	}

	clusters, err := nc.namespaceFederatedInformer.GetReadyClusters()
	if err != nil {
		glog.Errorf("Failed to get cluster list: %v", err)
		nc.deliverNamespace(namespace, nc.clusterAvailableDelay, false)
		return
	}

	operations := make([]util.FederatedOperation, 0)
	for _, cluster := range clusters {
		clusterNamespaceObj, found, err := nc.namespaceFederatedInformer.GetTargetStore().GetByKey(cluster.Name, namespace)
		if err != nil {
			glog.Errorf("Failed to get %s from %s: %v", namespace, cluster.Name, err)
			nc.deliverNamespace(namespace, 0, true)
			return
		}
		desiredNamespace := &api_v1.Namespace{
			ObjectMeta: util.CopyObjectMeta(baseNamespace.ObjectMeta),
			Spec:       baseNamespace.Spec,
		}

		if !found {
			nc.eventRecorder.Eventf(baseNamespace, api.EventTypeNormal, "CreateInCluster",
				"Creating namespace in cluster %s", cluster.Name)

			operations = append(operations, util.FederatedOperation{
				Type:        util.OperationTypeAdd,
				Obj:         desiredNamespace,
				ClusterName: cluster.Name,
			})
		} else {
			clusterNamespace := clusterNamespaceObj.(*api_v1.Namespace)

			// Update existing namespace, if needed.
			if !util.ObjectMetaEquivalent(desiredNamespace.ObjectMeta, clusterNamespace.ObjectMeta) ||
				!reflect.DeepEqual(desiredNamespace.Spec, clusterNamespace.Spec) {
				nc.eventRecorder.Eventf(baseNamespace, api.EventTypeNormal, "UpdateInCluster",
					"Updating namespace in cluster %s", cluster.Name)

				operations = append(operations, util.FederatedOperation{
					Type:        util.OperationTypeUpdate,
					Obj:         desiredNamespace,
					ClusterName: cluster.Name,
				})
			}
		}
	}

	if len(operations) == 0 {
		// Everything is in order
		return
	}
	err = nc.federatedUpdater.UpdateWithOnError(operations, nc.updateTimeout, func(op util.FederatedOperation, operror error) {
		nc.eventRecorder.Eventf(baseNamespace, api.EventTypeNormal, "UpdateInClusterFailed",
			"Namespace update in cluster %s failed: %v", op.ClusterName, operror)
	})
	if err != nil {
		glog.Errorf("Failed to execute updates for %s: %v", namespace, err)
		nc.deliverNamespace(namespace, 0, true)
		return
	}

	// Evertyhing is in order but lets be double sure
	nc.deliverNamespace(namespace, nc.namespaceReviewDelay, false)
}

func (nc *NamespaceController) delete(namespace *api_v1.Namespace) {
	// Set Terminating status.
	updatedNamespace := &api_v1.Namespace{
		ObjectMeta: namespace.ObjectMeta,
		Spec:       namespace.Spec,
		Status: api_v1.NamespaceStatus{
			Phase: api_v1.NamespaceTerminating,
		},
	}
	if namespace.Status.Phase != api_v1.NamespaceTerminating {
		nc.eventRecorder.Event(namespace, api.EventTypeNormal, "DeleteNamespace", fmt.Sprintf("Marking for deletion"))
		_, err := nc.federatedApiClient.Core().Namespaces().Update(updatedNamespace)
		if err != nil {
			glog.Errorf("Failed to update namespace %s: %v", updatedNamespace.Name, err)
			nc.deliverNamespace(namespace.Name, 0, true)
			return
		}
	}

	// TODO: delete all namespace content.

	// Remove kube_api.FinalzerKubernetes
	if len(updatedNamespace.Spec.Finalizers) != 0 {
		finalizerSet := sets.NewString()
		for i := range namespace.Spec.Finalizers {
			if namespace.Spec.Finalizers[i] != api_v1.FinalizerKubernetes {
				finalizerSet.Insert(string(namespace.Spec.Finalizers[i]))
			}
		}
		updatedNamespace.Spec.Finalizers = make([]api_v1.FinalizerName, 0, len(finalizerSet))
		for _, value := range finalizerSet.List() {
			updatedNamespace.Spec.Finalizers = append(updatedNamespace.Spec.Finalizers, api_v1.FinalizerName(value))
		}
		_, err := nc.federatedApiClient.Core().Namespaces().Finalize(updatedNamespace)
		if err != nil {
			glog.Errorf("Failed to update namespace %s: %v", updatedNamespace.Name, err)
			nc.deliverNamespace(namespace.Name, 0, true)
			return
		}
	}

	// TODO: What about namespaces in subclusters ???
	err := nc.federatedApiClient.Core().Namespaces().Delete(updatedNamespace.Name, &api.DeleteOptions{})
	if err != nil {
		// Its all good if the error is not found error. That means it is deleted already and we do not have to do anything.
		// This is expected when we are processing an update as a result of namespace finalizer deletion.
		// The process that deleted the last finalizer is also going to delete the namespace and we do not have to do anything.
		if !errors.IsNotFound(err) {
			glog.Errorf("Failed to delete namespace %s: %v", namespace.Name, err)
			nc.deliverNamespace(namespace.Name, 0, true)
		}
	}
}