/*
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 replicaset

import (
	"bytes"
	"encoding/json"
	"fmt"
	"reflect"
	"sort"
	"time"

	"github.com/golang/glog"

	fed "k8s.io/kubernetes/federation/apis/federation"
	fedv1 "k8s.io/kubernetes/federation/apis/federation/v1beta1"
	fedclientset "k8s.io/kubernetes/federation/client/clientset_generated/federation_release_1_4"
	planner "k8s.io/kubernetes/federation/pkg/federation-controller/replicaset/planner"
	fedutil "k8s.io/kubernetes/federation/pkg/federation-controller/util"
	"k8s.io/kubernetes/pkg/api"
	apiv1 "k8s.io/kubernetes/pkg/api/v1"
	extensionsv1 "k8s.io/kubernetes/pkg/apis/extensions/v1beta1"
	"k8s.io/kubernetes/pkg/client/cache"
	kubeclientset "k8s.io/kubernetes/pkg/client/clientset_generated/release_1_4"
	"k8s.io/kubernetes/pkg/controller"
	"k8s.io/kubernetes/pkg/controller/framework"
	"k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/util/flowcontrol"
	"k8s.io/kubernetes/pkg/util/wait"
	"k8s.io/kubernetes/pkg/util/workqueue"
	"k8s.io/kubernetes/pkg/watch"
)

const (
	FedReplicaSetPreferencesAnnotation = "federation.kubernetes.io/replica-set-preferences"
	allClustersKey                     = "THE_ALL_CLUSTER_KEY"
	UserAgentName                      = "Federation-replicaset-Controller"
)

var (
	replicaSetReviewDelay    = 10 * time.Second
	clusterAvailableDelay    = 20 * time.Second
	clusterUnavailableDelay  = 60 * time.Second
	allReplicaSetReviewDealy = 2 * time.Minute
	updateTimeout            = 30 * time.Second
)

func parseFederationReplicaSetReference(frs *extensionsv1.ReplicaSet) (*fed.FederatedReplicaSetPreferences, error) {
	if frs.Annotations == nil {
		return nil, nil
	}
	frsPrefString, found := frs.Annotations[FedReplicaSetPreferencesAnnotation]
	if !found {
		return nil, nil
	}
	var frsPref fed.FederatedReplicaSetPreferences
	if err := json.Unmarshal([]byte(frsPrefString), &frsPref); err != nil {
		return nil, err
	}
	return &frsPref, nil
}

type ReplicaSetController struct {
	fedClient fedclientset.Interface

	replicaSetController *framework.Controller
	replicaSetStore      cache.StoreToReplicaSetLister

	fedReplicaSetInformer fedutil.FederatedInformer
	fedPodInformer        fedutil.FederatedInformer

	replicasetDeliverer *fedutil.DelayingDeliverer
	clusterDeliverer    *fedutil.DelayingDeliverer
	replicasetWorkQueue workqueue.Interface
	// For updating members of federation.
	fedUpdater fedutil.FederatedUpdater

	replicaSetBackoff *flowcontrol.Backoff

	defaultPlanner *planner.Planner
}

// NewclusterController returns a new cluster controller
func NewReplicaSetController(federationClient fedclientset.Interface) *ReplicaSetController {
	frsc := &ReplicaSetController{
		fedClient:           federationClient,
		replicasetDeliverer: fedutil.NewDelayingDeliverer(),
		clusterDeliverer:    fedutil.NewDelayingDeliverer(),
		replicasetWorkQueue: workqueue.New(),
		replicaSetBackoff:   flowcontrol.NewBackOff(5*time.Second, time.Minute),
		defaultPlanner: planner.NewPlanner(&fed.FederatedReplicaSetPreferences{
			Clusters: map[string]fed.ClusterReplicaSetPreferences{
				"*": {Weight: 1},
			},
		}),
	}

	replicaSetFedInformerFactory := func(cluster *fedv1.Cluster, clientset kubeclientset.Interface) (cache.Store, framework.ControllerInterface) {
		return framework.NewInformer(
			&cache.ListWatch{
				ListFunc: func(options api.ListOptions) (runtime.Object, error) {
					return clientset.Extensions().ReplicaSets(apiv1.NamespaceAll).List(options)
				},
				WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
					return clientset.Extensions().ReplicaSets(apiv1.NamespaceAll).Watch(options)
				},
			},
			&extensionsv1.ReplicaSet{},
			controller.NoResyncPeriodFunc(),
			fedutil.NewTriggerOnAllChanges(
				func(obj runtime.Object) { frsc.deliverLocalReplicaSet(obj, allReplicaSetReviewDealy) },
			),
		)
	}
	clusterLifecycle := fedutil.ClusterLifecycleHandlerFuncs{
		ClusterAvailable: func(cluster *fedv1.Cluster) {
			frsc.clusterDeliverer.DeliverAfter(allClustersKey, nil, clusterUnavailableDelay)
		},
		ClusterUnavailable: func(cluster *fedv1.Cluster, _ []interface{}) {
			frsc.clusterDeliverer.DeliverAfter(allClustersKey, nil, clusterUnavailableDelay)
		},
	}
	frsc.fedReplicaSetInformer = fedutil.NewFederatedInformer(federationClient, replicaSetFedInformerFactory, &clusterLifecycle)

	podFedInformerFactory := func(cluster *fedv1.Cluster, clientset kubeclientset.Interface) (cache.Store, framework.ControllerInterface) {
		return framework.NewInformer(
			&cache.ListWatch{
				ListFunc: func(options api.ListOptions) (runtime.Object, error) {
					return clientset.Core().Pods(apiv1.NamespaceAll).List(options)
				},
				WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
					return clientset.Core().Pods(apiv1.NamespaceAll).Watch(options)
				},
			},
			&apiv1.Pod{},
			controller.NoResyncPeriodFunc(),
			fedutil.NewTriggerOnAllChanges(
				func(obj runtime.Object) {
					frsc.clusterDeliverer.DeliverAfter(allClustersKey, nil, clusterUnavailableDelay)
				},
			),
		)
	}
	frsc.fedPodInformer = fedutil.NewFederatedInformer(federationClient, podFedInformerFactory, &fedutil.ClusterLifecycleHandlerFuncs{})

	frsc.replicaSetStore.Store, frsc.replicaSetController = framework.NewInformer(
		&cache.ListWatch{
			ListFunc: func(options api.ListOptions) (runtime.Object, error) {
				return frsc.fedClient.Extensions().ReplicaSets(apiv1.NamespaceAll).List(options)
			},
			WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
				return frsc.fedClient.Extensions().ReplicaSets(apiv1.NamespaceAll).Watch(options)
			},
		},
		&extensionsv1.ReplicaSet{},
		controller.NoResyncPeriodFunc(),
		fedutil.NewTriggerOnMetaAndSpecChanges(
			func(obj runtime.Object) { frsc.deliverFedReplicaSetObj(obj, replicaSetReviewDelay) },
		),
	)

	frsc.fedUpdater = fedutil.NewFederatedUpdater(frsc.fedReplicaSetInformer,
		func(client kubeclientset.Interface, obj runtime.Object) error {
			rs := obj.(*extensionsv1.ReplicaSet)
			_, err := client.Extensions().ReplicaSets(rs.Namespace).Create(rs)
			return err
		},
		func(client kubeclientset.Interface, obj runtime.Object) error {
			rs := obj.(*extensionsv1.ReplicaSet)
			_, err := client.Extensions().ReplicaSets(rs.Namespace).Update(rs)
			return err
		},
		func(client kubeclientset.Interface, obj runtime.Object) error {
			rs := obj.(*extensionsv1.ReplicaSet)
			err := client.Extensions().ReplicaSets(rs.Namespace).Delete(rs.Name, &api.DeleteOptions{})
			return err
		})

	return frsc
}

func (frsc *ReplicaSetController) Run(workers int, stopCh <-chan struct{}) {
	go frsc.replicaSetController.Run(stopCh)
	frsc.fedReplicaSetInformer.Start()
	frsc.fedPodInformer.Start()

	frsc.replicasetDeliverer.StartWithHandler(func(item *fedutil.DelayingDelivererItem) {
		frsc.replicasetWorkQueue.Add(item.Key)
	})
	frsc.clusterDeliverer.StartWithHandler(func(_ *fedutil.DelayingDelivererItem) {
		frsc.reconcileReplicaSetsOnClusterChange()
	})

	for !frsc.isSynced() {
		time.Sleep(5 * time.Millisecond)
	}

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

	go func() {
		select {
		case <-time.After(time.Minute):
			frsc.replicaSetBackoff.GC()
		case <-stopCh:
			return
		}
	}()

	<-stopCh
	glog.Infof("Shutting down ReplicaSetController")
	frsc.replicasetDeliverer.Stop()
	frsc.clusterDeliverer.Stop()
	frsc.replicasetWorkQueue.ShutDown()
	frsc.fedReplicaSetInformer.Stop()
	frsc.fedPodInformer.Stop()
}

func (frsc *ReplicaSetController) isSynced() bool {
	if !frsc.fedReplicaSetInformer.ClustersSynced() {
		glog.V(2).Infof("Cluster list not synced")
		return false
	}
	clusters, err := frsc.fedReplicaSetInformer.GetReadyClusters()
	if err != nil {
		glog.Errorf("Failed to get ready clusters: %v", err)
		return false
	}
	if !frsc.fedReplicaSetInformer.GetTargetStore().ClustersSynced(clusters) {
		return false
	}

	if !frsc.fedPodInformer.ClustersSynced() {
		glog.V(2).Infof("Cluster list not synced")
		return false
	}
	clusters2, err := frsc.fedPodInformer.GetReadyClusters()
	if err != nil {
		glog.Errorf("Failed to get ready clusters: %v", err)
		return false
	}

	// This also checks whether podInformer and replicaSetInformer have the
	// same cluster lists.
	if !frsc.fedPodInformer.GetTargetStore().ClustersSynced(clusters) {
		return false
	}
	if !frsc.fedPodInformer.GetTargetStore().ClustersSynced(clusters2) {
		return false
	}

	if !frsc.replicaSetController.HasSynced() {
		glog.V(2).Infof("federation replicaset list not synced")
		return false
	}
	return true
}

func (frsc *ReplicaSetController) deliverLocalReplicaSet(obj interface{}, duration time.Duration) {
	key, err := controller.KeyFunc(obj)
	if err != nil {
		glog.Errorf("Couldn't get key for object %v: %v", obj, err)
		return
	}
	_, exists, err := frsc.replicaSetStore.Store.GetByKey(key)
	if err != nil {
		glog.Errorf("Couldn't get federation replicaset %v: %v", key, err)
		return
	}
	if exists { // ignore replicasets exists only in local k8s
		frsc.deliverReplicaSetByKey(key, duration, false)
	}
}

func (frsc *ReplicaSetController) deliverFedReplicaSetObj(obj interface{}, delay time.Duration) {
	key, err := controller.KeyFunc(obj)
	if err != nil {
		glog.Errorf("Couldn't get key for object %+v: %v", obj, err)
		return
	}
	frsc.deliverReplicaSetByKey(key, delay, false)
}

func (frsc *ReplicaSetController) deliverReplicaSetByKey(key string, delay time.Duration, failed bool) {
	if failed {
		frsc.replicaSetBackoff.Next(key, time.Now())
		delay = delay + frsc.replicaSetBackoff.Get(key)
	} else {
		frsc.replicaSetBackoff.Reset(key)
	}
	frsc.replicasetDeliverer.DeliverAfter(key, nil, delay)
}

func (frsc *ReplicaSetController) worker() {
	for {
		item, quit := frsc.replicasetWorkQueue.Get()
		if quit {
			return
		}
		key := item.(string)
		status, err := frsc.reconcileReplicaSet(key)
		frsc.replicasetWorkQueue.Done(item)
		if err != nil {
			glog.Errorf("Error syncing cluster controller: %v", err)
			frsc.deliverReplicaSetByKey(key, 0, true)
		} else {
			switch status {
			case statusAllOk:
				break
			case statusError:
				frsc.deliverReplicaSetByKey(key, 0, true)
			case statusNeedRecheck:
				frsc.deliverReplicaSetByKey(key, replicaSetReviewDelay, false)
			case statusNotSynced:
				frsc.deliverReplicaSetByKey(key, clusterAvailableDelay, false)
			default:
				glog.Errorf("Unhandled reconciliation status: %s", status)
				frsc.deliverReplicaSetByKey(key, replicaSetReviewDelay, false)
			}
		}
	}
}

func (frsc *ReplicaSetController) schedule(frs *extensionsv1.ReplicaSet, clusters []*fedv1.Cluster,
	current map[string]int64, estimatedCapacity map[string]int64) map[string]int64 {
	// TODO: integrate real scheduler

	plnr := frsc.defaultPlanner
	frsPref, err := parseFederationReplicaSetReference(frs)
	if err != nil {
		glog.Info("Invalid ReplicaSet specific preference, use default. rs: %v, err: %v", frs, err)
	}
	if frsPref != nil { // create a new planner if user specified a preference
		plnr = planner.NewPlanner(frsPref)
	}

	replicas := int64(*frs.Spec.Replicas)
	var clusterNames []string
	for _, cluster := range clusters {
		clusterNames = append(clusterNames, cluster.Name)
	}
	scheduleResult, overflow := plnr.Plan(replicas, clusterNames, current, estimatedCapacity,
		frs.Namespace+"/"+frs.Name)
	// make sure the return contains clusters need to zero the replicas
	result := make(map[string]int64)
	for clusterName := range current {
		result[clusterName] = 0
	}
	for clusterName, replicas := range scheduleResult {
		result[clusterName] = replicas
	}
	for clusterName, replicas := range overflow {
		result[clusterName] += replicas
	}
	if glog.V(4) {
		buf := bytes.NewBufferString(fmt.Sprintf("Schedule - ReplicaSet: %s/%s\n", frs.Namespace, frs.Name))
		sort.Strings(clusterNames)
		for _, clusterName := range clusterNames {
			cur := current[clusterName]
			target := scheduleResult[clusterName]
			fmt.Fprintf(buf, "%s: current: %d target: %d", clusterName, cur, target)
			if over, found := overflow[clusterName]; found {
				fmt.Fprintf(buf, " overflow: %d", over)
			}
			if capacity, found := estimatedCapacity[clusterName]; found {
				fmt.Fprintf(buf, " capacity: %d", capacity)
			}
			fmt.Fprintf(buf, "\n")
		}
		glog.V(4).Infof(buf.String())
	}
	return result
}

type reconciliationStatus string

const (
	statusAllOk       = reconciliationStatus("ALL_OK")
	statusNeedRecheck = reconciliationStatus("RECHECK")
	statusError       = reconciliationStatus("ERROR")
	statusNotSynced   = reconciliationStatus("NOSYNC")
)

func (frsc *ReplicaSetController) reconcileReplicaSet(key string) (reconciliationStatus, error) {
	if !frsc.isSynced() {
		return statusNotSynced, nil
	}

	glog.V(4).Infof("Start reconcile replicaset %q", key)
	startTime := time.Now()
	defer glog.V(4).Infof("Finished reconcile replicaset %q (%v)", key, time.Now().Sub(startTime))

	obj, exists, err := frsc.replicaSetStore.Store.GetByKey(key)
	if err != nil {
		return statusError, err
	}
	if !exists {
		// don't delete local replicasets for now. Do not reconcile it anymore.
		return statusAllOk, nil
	}
	frs := obj.(*extensionsv1.ReplicaSet)

	clusters, err := frsc.fedReplicaSetInformer.GetReadyClusters()
	if err != nil {
		return statusError, err
	}

	// collect current status and do schedule
	allPods, err := frsc.fedPodInformer.GetTargetStore().List()
	if err != nil {
		return statusError, err
	}
	podStatus, err := AnalysePods(frs, allPods, time.Now())
	current := make(map[string]int64)
	estimatedCapacity := make(map[string]int64)
	for _, cluster := range clusters {
		lrsObj, exists, err := frsc.fedReplicaSetInformer.GetTargetStore().GetByKey(cluster.Name, key)
		if err != nil {
			return statusError, err
		}
		if exists {
			lrs := lrsObj.(*extensionsv1.ReplicaSet)
			current[cluster.Name] = int64(podStatus[cluster.Name].RunningAndReady) // include pending as well?
			unschedulable := int64(podStatus[cluster.Name].Unschedulable)
			if unschedulable > 0 {
				estimatedCapacity[cluster.Name] = int64(*lrs.Spec.Replicas) - unschedulable
			}
		}
	}

	scheduleResult := frsc.schedule(frs, clusters, current, estimatedCapacity)

	glog.V(4).Infof("Start syncing local replicaset %s: %v", key, scheduleResult)

	fedStatus := extensionsv1.ReplicaSetStatus{ObservedGeneration: frs.Generation}
	operations := make([]fedutil.FederatedOperation, 0)
	for clusterName, replicas := range scheduleResult {

		lrsObj, exists, err := frsc.fedReplicaSetInformer.GetTargetStore().GetByKey(clusterName, key)
		if err != nil {
			return statusError, err
		}

		lrs := &extensionsv1.ReplicaSet{
			ObjectMeta: fedutil.CopyObjectMeta(frs.ObjectMeta),
			Spec:       frs.Spec,
		}
		specReplicas := int32(replicas)
		lrs.Spec.Replicas = &specReplicas

		if !exists {
			if replicas > 0 {
				operations = append(operations, fedutil.FederatedOperation{
					Type:        fedutil.OperationTypeAdd,
					Obj:         lrs,
					ClusterName: clusterName,
				})
			}
		} else {
			currentLrs := lrsObj.(*extensionsv1.ReplicaSet)
			// Update existing replica set, if needed.
			if !fedutil.ObjectMetaEquivalent(lrs.ObjectMeta, currentLrs.ObjectMeta) ||
				!reflect.DeepEqual(lrs.Spec, currentLrs.Spec) {
				operations = append(operations, fedutil.FederatedOperation{
					Type:        fedutil.OperationTypeUpdate,
					Obj:         lrs,
					ClusterName: clusterName,
				})
			}
			fedStatus.Replicas += currentLrs.Status.Replicas
			fedStatus.FullyLabeledReplicas += currentLrs.Status.FullyLabeledReplicas
			// leave the replicaset even the replicas dropped to 0
		}
	}
	if fedStatus.Replicas != frs.Status.Replicas || fedStatus.FullyLabeledReplicas != frs.Status.FullyLabeledReplicas {
		frs.Status = fedStatus
		_, err = frsc.fedClient.Extensions().ReplicaSets(frs.Namespace).UpdateStatus(frs)
		if err != nil {
			return statusError, err
		}
	}

	if len(operations) == 0 {
		// Everything is in order
		return statusAllOk, nil
	}
	err = frsc.fedUpdater.Update(operations, updateTimeout)
	if err != nil {
		glog.Errorf("Failed to execute updates for %s: %v", key, err)
		return statusError, err
	}

	// Some operations were made, reconcile after a while.
	return statusNeedRecheck, nil
}

func (frsc *ReplicaSetController) reconcileReplicaSetsOnClusterChange() {
	if !frsc.isSynced() {
		frsc.clusterDeliverer.DeliverAfter(allClustersKey, nil, clusterAvailableDelay)
	}
	rss := frsc.replicaSetStore.Store.List()
	for _, rs := range rss {
		key, _ := controller.KeyFunc(rs)
		frsc.deliverReplicaSetByKey(key, 0, false)
	}
}