/*
Copyright 2017 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 daemon

import (
	"bytes"
	"context"
	"fmt"
	"reflect"
	"sort"

	"k8s.io/klog"

	apps "k8s.io/api/apps/v1"
	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	intstrutil "k8s.io/apimachinery/pkg/util/intstr"
	"k8s.io/apimachinery/pkg/util/json"
	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
	"k8s.io/kubernetes/pkg/controller"
	"k8s.io/kubernetes/pkg/controller/daemon/util"
	labelsutil "k8s.io/kubernetes/pkg/util/labels"
)

// rollingUpdate deletes old daemon set pods making sure that no more than
// ds.Spec.UpdateStrategy.RollingUpdate.MaxUnavailable pods are unavailable
func (dsc *DaemonSetsController) rollingUpdate(ds *apps.DaemonSet, nodeList []*v1.Node, hash string) error {
	nodeToDaemonPods, err := dsc.getNodesToDaemonPods(ds)
	if err != nil {
		return fmt.Errorf("couldn't get node to daemon pod mapping for daemon set %q: %v", ds.Name, err)
	}

	_, oldPods := dsc.getAllDaemonSetPods(ds, nodeToDaemonPods, hash)
	maxUnavailable, numUnavailable, err := dsc.getUnavailableNumbers(ds, nodeList, nodeToDaemonPods)
	if err != nil {
		return fmt.Errorf("couldn't get unavailable numbers: %v", err)
	}
	oldAvailablePods, oldUnavailablePods := util.SplitByAvailablePods(ds.Spec.MinReadySeconds, oldPods)

	// for oldPods delete all not running pods
	var oldPodsToDelete []string
	klog.V(4).Infof("Marking all unavailable old pods for deletion")
	for _, pod := range oldUnavailablePods {
		// Skip terminating pods. We won't delete them again
		if pod.DeletionTimestamp != nil {
			continue
		}
		klog.V(4).Infof("Marking pod %s/%s for deletion", ds.Name, pod.Name)
		oldPodsToDelete = append(oldPodsToDelete, pod.Name)
	}

	klog.V(4).Infof("Marking old pods for deletion")
	for _, pod := range oldAvailablePods {
		if numUnavailable >= maxUnavailable {
			klog.V(4).Infof("Number of unavailable DaemonSet pods: %d, is equal to or exceeds allowed maximum: %d", numUnavailable, maxUnavailable)
			break
		}
		klog.V(4).Infof("Marking pod %s/%s for deletion", ds.Name, pod.Name)
		oldPodsToDelete = append(oldPodsToDelete, pod.Name)
		numUnavailable++
	}
	return dsc.syncNodes(ds, oldPodsToDelete, []string{}, hash)
}

// constructHistory finds all histories controlled by the given DaemonSet, and
// update current history revision number, or create current history if need to.
// It also deduplicates current history, and adds missing unique labels to existing histories.
func (dsc *DaemonSetsController) constructHistory(ds *apps.DaemonSet) (cur *apps.ControllerRevision, old []*apps.ControllerRevision, err error) {
	var histories []*apps.ControllerRevision
	var currentHistories []*apps.ControllerRevision
	histories, err = dsc.controlledHistories(ds)
	if err != nil {
		return nil, nil, err
	}
	for _, history := range histories {
		// Add the unique label if it's not already added to the history
		// We use history name instead of computing hash, so that we don't need to worry about hash collision
		if _, ok := history.Labels[apps.DefaultDaemonSetUniqueLabelKey]; !ok {
			toUpdate := history.DeepCopy()
			toUpdate.Labels[apps.DefaultDaemonSetUniqueLabelKey] = toUpdate.Name
			history, err = dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Update(context.TODO(), toUpdate, metav1.UpdateOptions{})
			if err != nil {
				return nil, nil, err
			}
		}
		// Compare histories with ds to separate cur and old history
		found := false
		found, err = Match(ds, history)
		if err != nil {
			return nil, nil, err
		}
		if found {
			currentHistories = append(currentHistories, history)
		} else {
			old = append(old, history)
		}
	}

	currRevision := maxRevision(old) + 1
	switch len(currentHistories) {
	case 0:
		// Create a new history if the current one isn't found
		cur, err = dsc.snapshot(ds, currRevision)
		if err != nil {
			return nil, nil, err
		}
	default:
		cur, err = dsc.dedupCurHistories(ds, currentHistories)
		if err != nil {
			return nil, nil, err
		}
		// Update revision number if necessary
		if cur.Revision < currRevision {
			toUpdate := cur.DeepCopy()
			toUpdate.Revision = currRevision
			_, err = dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Update(context.TODO(), toUpdate, metav1.UpdateOptions{})
			if err != nil {
				return nil, nil, err
			}
		}
	}
	return cur, old, err
}

func (dsc *DaemonSetsController) cleanupHistory(ds *apps.DaemonSet, old []*apps.ControllerRevision) error {
	nodesToDaemonPods, err := dsc.getNodesToDaemonPods(ds)
	if err != nil {
		return fmt.Errorf("couldn't get node to daemon pod mapping for daemon set %q: %v", ds.Name, err)
	}

	toKeep := int(*ds.Spec.RevisionHistoryLimit)
	toKill := len(old) - toKeep
	if toKill <= 0 {
		return nil
	}

	// Find all hashes of live pods
	liveHashes := make(map[string]bool)
	for _, pods := range nodesToDaemonPods {
		for _, pod := range pods {
			if hash := pod.Labels[apps.DefaultDaemonSetUniqueLabelKey]; len(hash) > 0 {
				liveHashes[hash] = true
			}
		}
	}

	// Clean up old history from smallest to highest revision (from oldest to newest)
	sort.Sort(historiesByRevision(old))
	for _, history := range old {
		if toKill <= 0 {
			break
		}
		if hash := history.Labels[apps.DefaultDaemonSetUniqueLabelKey]; liveHashes[hash] {
			continue
		}
		// Clean up
		err := dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Delete(context.TODO(), history.Name, metav1.DeleteOptions{})
		if err != nil {
			return err
		}
		toKill--
	}
	return nil
}

// maxRevision returns the max revision number of the given list of histories
func maxRevision(histories []*apps.ControllerRevision) int64 {
	max := int64(0)
	for _, history := range histories {
		if history.Revision > max {
			max = history.Revision
		}
	}
	return max
}

func (dsc *DaemonSetsController) dedupCurHistories(ds *apps.DaemonSet, curHistories []*apps.ControllerRevision) (*apps.ControllerRevision, error) {
	if len(curHistories) == 1 {
		return curHistories[0], nil
	}
	var maxRevision int64
	var keepCur *apps.ControllerRevision
	for _, cur := range curHistories {
		if cur.Revision >= maxRevision {
			keepCur = cur
			maxRevision = cur.Revision
		}
	}
	// Clean up duplicates and relabel pods
	for _, cur := range curHistories {
		if cur.Name == keepCur.Name {
			continue
		}
		// Relabel pods before dedup
		pods, err := dsc.getDaemonPods(ds)
		if err != nil {
			return nil, err
		}
		for _, pod := range pods {
			if pod.Labels[apps.DefaultDaemonSetUniqueLabelKey] != keepCur.Labels[apps.DefaultDaemonSetUniqueLabelKey] {
				toUpdate := pod.DeepCopy()
				if toUpdate.Labels == nil {
					toUpdate.Labels = make(map[string]string)
				}
				toUpdate.Labels[apps.DefaultDaemonSetUniqueLabelKey] = keepCur.Labels[apps.DefaultDaemonSetUniqueLabelKey]
				_, err = dsc.kubeClient.CoreV1().Pods(ds.Namespace).Update(context.TODO(), toUpdate, metav1.UpdateOptions{})
				if err != nil {
					return nil, err
				}
			}
		}
		// Remove duplicates
		err = dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Delete(context.TODO(), cur.Name, metav1.DeleteOptions{})
		if err != nil {
			return nil, err
		}
	}
	return keepCur, nil
}

// controlledHistories returns all ControllerRevisions controlled by the given DaemonSet.
// This also reconciles ControllerRef by adopting/orphaning.
// Note that returned histories are pointers to objects in the cache.
// If you want to modify one, you need to deep-copy it first.
func (dsc *DaemonSetsController) controlledHistories(ds *apps.DaemonSet) ([]*apps.ControllerRevision, error) {
	selector, err := metav1.LabelSelectorAsSelector(ds.Spec.Selector)
	if err != nil {
		return nil, err
	}

	// List all histories to include those that don't match the selector anymore
	// but have a ControllerRef pointing to the controller.
	histories, err := dsc.historyLister.List(labels.Everything())
	if err != nil {
		return nil, err
	}
	// If any adoptions are attempted, we should first recheck for deletion with
	// an uncached quorum read sometime after listing Pods (see #42639).
	canAdoptFunc := controller.RecheckDeletionTimestamp(func() (metav1.Object, error) {
		fresh, err := dsc.kubeClient.AppsV1().DaemonSets(ds.Namespace).Get(context.TODO(), ds.Name, metav1.GetOptions{})
		if err != nil {
			return nil, err
		}
		if fresh.UID != ds.UID {
			return nil, fmt.Errorf("original DaemonSet %v/%v is gone: got uid %v, wanted %v", ds.Namespace, ds.Name, fresh.UID, ds.UID)
		}
		return fresh, nil
	})
	// Use ControllerRefManager to adopt/orphan as needed.
	cm := controller.NewControllerRevisionControllerRefManager(dsc.crControl, ds, selector, controllerKind, canAdoptFunc)
	return cm.ClaimControllerRevisions(histories)
}

// Match check if the given DaemonSet's template matches the template stored in the given history.
func Match(ds *apps.DaemonSet, history *apps.ControllerRevision) (bool, error) {
	patch, err := getPatch(ds)
	if err != nil {
		return false, err
	}
	return bytes.Equal(patch, history.Data.Raw), nil
}

// getPatch returns a strategic merge patch that can be applied to restore a Daemonset to a
// previous version. If the returned error is nil the patch is valid. The current state that we save is just the
// PodSpecTemplate. We can modify this later to encompass more state (or less) and remain compatible with previously
// recorded patches.
func getPatch(ds *apps.DaemonSet) ([]byte, error) {
	dsBytes, err := json.Marshal(ds)
	if err != nil {
		return nil, err
	}
	var raw map[string]interface{}
	err = json.Unmarshal(dsBytes, &raw)
	if err != nil {
		return nil, err
	}
	objCopy := make(map[string]interface{})
	specCopy := make(map[string]interface{})

	// Create a patch of the DaemonSet that replaces spec.template
	spec := raw["spec"].(map[string]interface{})
	template := spec["template"].(map[string]interface{})
	specCopy["template"] = template
	template["$patch"] = "replace"
	objCopy["spec"] = specCopy
	patch, err := json.Marshal(objCopy)
	return patch, err
}

func (dsc *DaemonSetsController) snapshot(ds *apps.DaemonSet, revision int64) (*apps.ControllerRevision, error) {
	patch, err := getPatch(ds)
	if err != nil {
		return nil, err
	}
	hash := controller.ComputeHash(&ds.Spec.Template, ds.Status.CollisionCount)
	name := ds.Name + "-" + hash
	history := &apps.ControllerRevision{
		ObjectMeta: metav1.ObjectMeta{
			Name:            name,
			Namespace:       ds.Namespace,
			Labels:          labelsutil.CloneAndAddLabel(ds.Spec.Template.Labels, apps.DefaultDaemonSetUniqueLabelKey, hash),
			Annotations:     ds.Annotations,
			OwnerReferences: []metav1.OwnerReference{*metav1.NewControllerRef(ds, controllerKind)},
		},
		Data:     runtime.RawExtension{Raw: patch},
		Revision: revision,
	}

	history, err = dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Create(context.TODO(), history, metav1.CreateOptions{})
	if outerErr := err; errors.IsAlreadyExists(outerErr) {
		// TODO: Is it okay to get from historyLister?
		existedHistory, getErr := dsc.kubeClient.AppsV1().ControllerRevisions(ds.Namespace).Get(context.TODO(), name, metav1.GetOptions{})
		if getErr != nil {
			return nil, getErr
		}
		// Check if we already created it
		done, matchErr := Match(ds, existedHistory)
		if matchErr != nil {
			return nil, matchErr
		}
		if done {
			return existedHistory, nil
		}

		// Handle name collisions between different history
		// Get the latest DaemonSet from the API server to make sure collision count is only increased when necessary
		currDS, getErr := dsc.kubeClient.AppsV1().DaemonSets(ds.Namespace).Get(context.TODO(), ds.Name, metav1.GetOptions{})
		if getErr != nil {
			return nil, getErr
		}
		// If the collision count used to compute hash was in fact stale, there's no need to bump collision count; retry again
		if !reflect.DeepEqual(currDS.Status.CollisionCount, ds.Status.CollisionCount) {
			return nil, fmt.Errorf("found a stale collision count (%d, expected %d) of DaemonSet %q while processing; will retry until it is updated", ds.Status.CollisionCount, currDS.Status.CollisionCount, ds.Name)
		}
		if currDS.Status.CollisionCount == nil {
			currDS.Status.CollisionCount = new(int32)
		}
		*currDS.Status.CollisionCount++
		_, updateErr := dsc.kubeClient.AppsV1().DaemonSets(ds.Namespace).UpdateStatus(context.TODO(), currDS, metav1.UpdateOptions{})
		if updateErr != nil {
			return nil, updateErr
		}
		klog.V(2).Infof("Found a hash collision for DaemonSet %q - bumping collisionCount to %d to resolve it", ds.Name, *currDS.Status.CollisionCount)
		return nil, outerErr
	}
	return history, err
}

func (dsc *DaemonSetsController) getAllDaemonSetPods(ds *apps.DaemonSet, nodeToDaemonPods map[string][]*v1.Pod, hash string) ([]*v1.Pod, []*v1.Pod) {
	var newPods []*v1.Pod
	var oldPods []*v1.Pod

	for _, pods := range nodeToDaemonPods {
		for _, pod := range pods {
			// If the returned error is not nil we have a parse error.
			// The controller handles this via the hash.
			generation, err := util.GetTemplateGeneration(ds)
			if err != nil {
				generation = nil
			}
			if util.IsPodUpdated(pod, hash, generation) {
				newPods = append(newPods, pod)
			} else {
				oldPods = append(oldPods, pod)
			}
		}
	}
	return newPods, oldPods
}

func (dsc *DaemonSetsController) getUnavailableNumbers(ds *apps.DaemonSet, nodeList []*v1.Node, nodeToDaemonPods map[string][]*v1.Pod) (int, int, error) {
	klog.V(4).Infof("Getting unavailable numbers")
	var numUnavailable, desiredNumberScheduled int
	for i := range nodeList {
		node := nodeList[i]
		wantToRun, _, err := dsc.nodeShouldRunDaemonPod(node, ds)
		if err != nil {
			return -1, -1, err
		}
		if !wantToRun {
			continue
		}
		desiredNumberScheduled++
		daemonPods, exists := nodeToDaemonPods[node.Name]
		if !exists {
			numUnavailable++
			continue
		}
		available := false
		for _, pod := range daemonPods {
			//for the purposes of update we ensure that the Pod is both available and not terminating
			if podutil.IsPodAvailable(pod, ds.Spec.MinReadySeconds, metav1.Now()) && pod.DeletionTimestamp == nil {
				available = true
				break
			}
		}
		if !available {
			numUnavailable++
		}
	}
	maxUnavailable, err := intstrutil.GetValueFromIntOrPercent(ds.Spec.UpdateStrategy.RollingUpdate.MaxUnavailable, desiredNumberScheduled, true)
	if err != nil {
		return -1, -1, fmt.Errorf("invalid value for MaxUnavailable: %v", err)
	}
	klog.V(4).Infof(" DaemonSet %s/%s, maxUnavailable: %d, numUnavailable: %d", ds.Namespace, ds.Name, maxUnavailable, numUnavailable)
	return maxUnavailable, numUnavailable, nil
}

type historiesByRevision []*apps.ControllerRevision

func (h historiesByRevision) Len() int      { return len(h) }
func (h historiesByRevision) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
func (h historiesByRevision) Less(i, j int) bool {
	return h[i].Revision < h[j].Revision
}