/*
Copyright 2015 The Kubernetes Authors All rights reserved.

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

import (
	"fmt"
	"strconv"
	"time"

	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/unversioned"
	"k8s.io/kubernetes/pkg/apis/extensions"
	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
	unversionedcore "k8s.io/kubernetes/pkg/client/typed/generated/core/unversioned"
	unversionedextensions "k8s.io/kubernetes/pkg/client/typed/generated/extensions/unversioned"
	"k8s.io/kubernetes/pkg/labels"
	"k8s.io/kubernetes/pkg/util/integer"
	intstrutil "k8s.io/kubernetes/pkg/util/intstr"
	labelsutil "k8s.io/kubernetes/pkg/util/labels"
	podutil "k8s.io/kubernetes/pkg/util/pod"
	"k8s.io/kubernetes/pkg/util/wait"
)

const (
	// The revision annotation of a deployment's replica sets which records its rollout sequence
	RevisionAnnotation = "deployment.kubernetes.io/revision"

	// Here are the possible rollback event reasons
	RollbackRevisionNotFound  = "DeploymentRollbackRevisionNotFound"
	RollbackTemplateUnchanged = "DeploymentRollbackTemplateUnchanged"
	RollbackDone              = "DeploymentRollback"
)

// GetOldReplicaSets returns the old replica sets targeted by the given Deployment; get PodList and ReplicaSetList from client interface.
// Note that the first set of old replica sets doesn't include the ones with no pods, and the second set of old replica sets include all old replica sets.
func GetOldReplicaSets(deployment extensions.Deployment, c clientset.Interface) ([]*extensions.ReplicaSet, []*extensions.ReplicaSet, error) {
	return GetOldReplicaSetsFromLists(deployment, c,
		func(namespace string, options api.ListOptions) (*api.PodList, error) {
			return c.Core().Pods(namespace).List(options)
		},
		func(namespace string, options api.ListOptions) ([]extensions.ReplicaSet, error) {
			rsList, err := c.Extensions().ReplicaSets(namespace).List(options)
			return rsList.Items, err
		})
}

// TODO: switch this to full namespacers
type rsListFunc func(string, api.ListOptions) ([]extensions.ReplicaSet, error)
type podListFunc func(string, api.ListOptions) (*api.PodList, error)

// GetOldReplicaSetsFromLists returns two sets of old replica sets targeted by the given Deployment; get PodList and ReplicaSetList with input functions.
// Note that the first set of old replica sets doesn't include the ones with no pods, and the second set of old replica sets include all old replica sets.
func GetOldReplicaSetsFromLists(deployment extensions.Deployment, c clientset.Interface, getPodList podListFunc, getRSList rsListFunc) ([]*extensions.ReplicaSet, []*extensions.ReplicaSet, error) {
	// Find all pods whose labels match deployment.Spec.Selector, and corresponding replica sets for pods in podList.
	// All pods and replica sets are labeled with pod-template-hash to prevent overlapping
	// TODO: Right now we list all replica sets and then filter. We should add an API for this.
	oldRSs := map[string]extensions.ReplicaSet{}
	allOldRSs := map[string]extensions.ReplicaSet{}
	rsList, podList, err := rsAndPodsWithHashKeySynced(deployment, c, getRSList, getPodList)
	if err != nil {
		return nil, nil, fmt.Errorf("error labeling replica sets and pods with pod-template-hash: %v", err)
	}
	newRSTemplate := GetNewReplicaSetTemplate(deployment)
	for _, pod := range podList.Items {
		podLabelsSelector := labels.Set(pod.ObjectMeta.Labels)
		for _, rs := range rsList {
			rsLabelsSelector, err := unversioned.LabelSelectorAsSelector(rs.Spec.Selector)
			if err != nil {
				return nil, nil, fmt.Errorf("invalid label selector: %v", err)
			}
			// Filter out replica set that has the same pod template spec as the deployment - that is the new replica set.
			if api.Semantic.DeepEqual(rs.Spec.Template, &newRSTemplate) {
				continue
			}
			allOldRSs[rs.ObjectMeta.Name] = rs
			if rsLabelsSelector.Matches(podLabelsSelector) {
				oldRSs[rs.ObjectMeta.Name] = rs
			}
		}
	}
	requiredRSs := []*extensions.ReplicaSet{}
	for key := range oldRSs {
		value := oldRSs[key]
		requiredRSs = append(requiredRSs, &value)
	}
	allRSs := []*extensions.ReplicaSet{}
	for key := range allOldRSs {
		value := allOldRSs[key]
		allRSs = append(allRSs, &value)
	}
	return requiredRSs, allRSs, nil
}

// GetNewReplicaSet returns a replica set that matches the intent of the given deployment; get ReplicaSetList from client interface.
// Returns nil if the new replica set doesn't exist yet.
func GetNewReplicaSet(deployment extensions.Deployment, c clientset.Interface) (*extensions.ReplicaSet, error) {
	return GetNewReplicaSetFromList(deployment, c,
		func(namespace string, options api.ListOptions) (*api.PodList, error) {
			return c.Core().Pods(namespace).List(options)
		},
		func(namespace string, options api.ListOptions) ([]extensions.ReplicaSet, error) {
			rsList, err := c.Extensions().ReplicaSets(namespace).List(options)
			return rsList.Items, err
		})
}

// GetNewReplicaSetFromList returns a replica set that matches the intent of the given deployment; get ReplicaSetList with the input function.
// Returns nil if the new replica set doesn't exist yet.
func GetNewReplicaSetFromList(deployment extensions.Deployment, c clientset.Interface, getPodList podListFunc, getRSList rsListFunc) (*extensions.ReplicaSet, error) {
	rsList, _, err := rsAndPodsWithHashKeySynced(deployment, c, getRSList, getPodList)
	if err != nil {
		return nil, fmt.Errorf("error listing ReplicaSets: %v", err)
	}
	newRSTemplate := GetNewReplicaSetTemplate(deployment)

	for i := range rsList {
		if api.Semantic.DeepEqual(rsList[i].Spec.Template, &newRSTemplate) {
			// This is the new ReplicaSet.
			return &rsList[i], nil
		}
	}
	// new ReplicaSet does not exist.
	return nil, nil
}

// rsAndPodsWithHashKeySynced returns the RSs and pods the given deployment targets, with pod-template-hash information synced.
func rsAndPodsWithHashKeySynced(deployment extensions.Deployment, c clientset.Interface, getRSList rsListFunc, getPodList podListFunc) ([]extensions.ReplicaSet, *api.PodList, error) {
	namespace := deployment.Namespace
	selector, err := unversioned.LabelSelectorAsSelector(deployment.Spec.Selector)
	if err != nil {
		return nil, nil, err
	}
	options := api.ListOptions{LabelSelector: selector}
	rsList, err := getRSList(namespace, options)
	if err != nil {
		return nil, nil, err
	}
	syncedRSList := []extensions.ReplicaSet{}
	for _, rs := range rsList {
		// Add pod-template-hash information if it's not in the RS.
		// Otherwise, new RS produced by Deployment will overlap with pre-existing ones
		// that aren't constrained by the pod-template-hash.
		syncedRS, err := addHashKeyToRSAndPods(deployment, c, rs, getPodList)
		if err != nil {
			return nil, nil, err
		}
		syncedRSList = append(syncedRSList, *syncedRS)
	}
	syncedPodList, err := getPodList(namespace, options)
	if err != nil {
		return nil, nil, err
	}
	return syncedRSList, syncedPodList, nil
}

// addHashKeyToRSAndPods adds pod-template-hash information to the given rs, if it's not already there, with the following steps:
// 1. Add hash label to the rs's pod template, and make sure the controller sees this update so that no orphaned pods will be created
// 2. Add hash label to all pods this rs owns
// 3. Add hash label to the rs's label and selector
func addHashKeyToRSAndPods(deployment extensions.Deployment, c clientset.Interface, rs extensions.ReplicaSet, getPodList podListFunc) (updatedRS *extensions.ReplicaSet, err error) {
	// If the rs already has the new hash label in its selector, it's done syncing
	namespace := deployment.Namespace
	hash := fmt.Sprintf("%d", podutil.GetPodTemplateSpecHash(api.PodTemplateSpec{
		ObjectMeta: rs.Spec.Template.ObjectMeta,
		Spec:       rs.Spec.Template.Spec,
	}))
	if labelsutil.SelectorHasLabel(rs.Spec.Selector, extensions.DefaultDeploymentUniqueLabelKey) {
		return &rs, nil
	}
	// 1. Add hash template label to the rs. This ensures that any newly created pods will have the new label.
	if len(rs.Spec.Template.Labels[extensions.DefaultDeploymentUniqueLabelKey]) == 0 {
		updatedRS, err = updateRSWithRetries(c.Extensions().ReplicaSets(namespace), &rs, func(updated *extensions.ReplicaSet) {
			updated.Spec.Template.Labels = labelsutil.AddLabel(updated.Spec.Template.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
		})
		if err != nil {
			return nil, err
		}
	}
	// Make sure rs pod template is updated so that it won't create pods without the new label (orphaned pods).
	if updatedRS.Generation > updatedRS.Status.ObservedGeneration {
		if err = waitForReplicaSetUpdated(c, updatedRS.Generation, namespace, rs.Name); err != nil {
			return nil, err
		}
	}

	// 2. Update all pods managed by the rs to have the new hash label, so they will be correctly adopted.
	selector, err := unversioned.LabelSelectorAsSelector(rs.Spec.Selector)
	if err != nil {
		return nil, err
	}
	options := api.ListOptions{LabelSelector: selector}
	podList, err := getPodList(namespace, options)
	if err != nil {
		return nil, err
	}
	if err = labelPodsWithHash(podList, c, namespace, hash); err != nil {
		return nil, err
	}

	// 3. Update rs label and selector to include the new hash label
	// Copy the old selector, so that we can scrub out any orphaned pods
	if updatedRS, err = updateRSWithRetries(c.Extensions().ReplicaSets(namespace), &rs, func(updated *extensions.ReplicaSet) {
		updated.Labels = labelsutil.AddLabel(updated.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
		updated.Spec.Selector = labelsutil.AddLabelToSelector(updated.Spec.Selector, extensions.DefaultDeploymentUniqueLabelKey, hash)
	}); err != nil {
		return nil, err
	}

	// TODO: look for orphaned pods and label them in the background somewhere else periodically

	return updatedRS, nil
}

func waitForReplicaSetUpdated(c clientset.Interface, desiredGeneration int64, namespace, name string) error {
	return wait.Poll(10*time.Millisecond, 1*time.Minute, func() (bool, error) {
		rs, err := c.Extensions().ReplicaSets(namespace).Get(name)
		if err != nil {
			return false, err
		}
		return rs.Status.ObservedGeneration >= desiredGeneration, nil
	})
}

// labelPodsWithHash labels all pods in the given podList with the new hash label.
func labelPodsWithHash(podList *api.PodList, c clientset.Interface, namespace, hash string) error {
	for _, pod := range podList.Items {
		// Only label the pod that doesn't already have the new hash
		if pod.Labels[extensions.DefaultDeploymentUniqueLabelKey] != hash {
			if _, err := updatePodWithRetries(c.Core().Pods(namespace), &pod, func(updated *api.Pod) {
				pod.Labels = labelsutil.AddLabel(pod.Labels, extensions.DefaultDeploymentUniqueLabelKey, hash)
			}); err != nil {
				return err
			}
		}
	}
	return nil
}

// TODO: use client library instead when it starts to support update retries
//       see https://github.com/kubernetes/kubernetes/issues/21479
type updateRSFunc func(rs *extensions.ReplicaSet)

func updateRSWithRetries(rsClient unversionedextensions.ReplicaSetInterface, rs *extensions.ReplicaSet, applyUpdate updateRSFunc) (*extensions.ReplicaSet, error) {
	var err error
	oldRs := rs
	err = wait.Poll(10*time.Millisecond, 1*time.Minute, func() (bool, error) {
		// Apply the update, then attempt to push it to the apiserver.
		applyUpdate(rs)
		if rs, err = rsClient.Update(rs); err == nil {
			// rs contains the latest controller post update
			return true, nil
		}
		// Update the controller with the latest resource version, if the update failed we
		// can't trust rs so use oldRs.Name.
		if rs, err = rsClient.Get(oldRs.Name); err != nil {
			// The Get failed: Value in rs cannot be trusted.
			rs = oldRs
		}
		// The Get passed: rs contains the latest controller, expect a poll for the update.
		return false, nil
	})
	// If the error is non-nil the returned controller cannot be trusted, if it is nil, the returned
	// controller contains the applied update.
	return rs, err
}

type updatePodFunc func(pod *api.Pod)

func updatePodWithRetries(podClient unversionedcore.PodInterface, pod *api.Pod, applyUpdate updatePodFunc) (*api.Pod, error) {
	var err error
	oldPod := pod
	err = wait.Poll(10*time.Millisecond, 1*time.Minute, func() (bool, error) {
		// Apply the update, then attempt to push it to the apiserver.
		applyUpdate(pod)
		if pod, err = podClient.Update(pod); err == nil {
			return true, nil
		}
		if pod, err = podClient.Get(oldPod.Name); err != nil {
			pod = oldPod
		}
		return false, nil
	})
	return pod, err
}

// Returns the desired PodTemplateSpec for the new ReplicaSet corresponding to the given ReplicaSet.
func GetNewReplicaSetTemplate(deployment extensions.Deployment) api.PodTemplateSpec {
	// newRS will have the same template as in deployment spec, plus a unique label in some cases.
	newRSTemplate := api.PodTemplateSpec{
		ObjectMeta: deployment.Spec.Template.ObjectMeta,
		Spec:       deployment.Spec.Template.Spec,
	}
	newRSTemplate.ObjectMeta.Labels = labelsutil.CloneAndAddLabel(
		deployment.Spec.Template.ObjectMeta.Labels,
		extensions.DefaultDeploymentUniqueLabelKey,
		podutil.GetPodTemplateSpecHash(newRSTemplate))
	return newRSTemplate
}

// SetFromReplicaSetTemplate sets the desired PodTemplateSpec from a replica set template to the given deployment.
func SetFromReplicaSetTemplate(deployment *extensions.Deployment, template api.PodTemplateSpec) *extensions.Deployment {
	deployment.Spec.Template.ObjectMeta = template.ObjectMeta
	deployment.Spec.Template.Spec = template.Spec
	deployment.Spec.Template.ObjectMeta.Labels = labelsutil.CloneAndRemoveLabel(
		deployment.Spec.Template.ObjectMeta.Labels,
		extensions.DefaultDeploymentUniqueLabelKey)
	return deployment
}

// Returns the sum of Replicas of the given replica sets.
func GetReplicaCountForReplicaSets(replicaSets []*extensions.ReplicaSet) int {
	totalReplicaCount := 0
	for _, rs := range replicaSets {
		totalReplicaCount += rs.Spec.Replicas
	}
	return totalReplicaCount
}

// Returns the number of available pods corresponding to the given replica sets.
func GetAvailablePodsForReplicaSets(c clientset.Interface, rss []*extensions.ReplicaSet, minReadySeconds int) (int, error) {
	allPods, err := GetPodsForReplicaSets(c, rss)
	if err != nil {
		return 0, err
	}
	return getReadyPodsCount(allPods, minReadySeconds), nil
}

func getReadyPodsCount(pods []api.Pod, minReadySeconds int) int {
	readyPodCount := 0
	for _, pod := range pods {
		if IsPodAvailable(&pod, minReadySeconds) {
			readyPodCount++
		}
	}
	return readyPodCount
}

func IsPodAvailable(pod *api.Pod, minReadySeconds int) bool {
	// Check if we've passed minReadySeconds since LastTransitionTime
	// If so, this pod is ready
	for _, c := range pod.Status.Conditions {
		// we only care about pod ready conditions
		if c.Type == api.PodReady && c.Status == api.ConditionTrue {
			// 2 cases that this ready condition is valid (passed minReadySeconds, i.e. the pod is ready):
			// 1. minReadySeconds <= 0
			// 2. LastTransitionTime (is set) + minReadySeconds (>0) < current time
			minReadySecondsDuration := time.Duration(minReadySeconds) * time.Second
			if minReadySeconds <= 0 || !c.LastTransitionTime.IsZero() && c.LastTransitionTime.Add(minReadySecondsDuration).Before(time.Now()) {
				return true
			}
		}
	}
	return false
}

func GetPodsForReplicaSets(c clientset.Interface, replicaSets []*extensions.ReplicaSet) ([]api.Pod, error) {
	allPods := []api.Pod{}
	for _, rs := range replicaSets {
		selector, err := unversioned.LabelSelectorAsSelector(rs.Spec.Selector)
		if err != nil {
			return nil, fmt.Errorf("invalid label selector: %v", err)
		}
		options := api.ListOptions{LabelSelector: selector}
		podList, err := c.Core().Pods(rs.ObjectMeta.Namespace).List(options)
		if err != nil {
			return allPods, fmt.Errorf("error listing pods: %v", err)
		}
		allPods = append(allPods, podList.Items...)
	}
	return allPods, nil
}

// Revision returns the revision number of the input replica set
func Revision(rs *extensions.ReplicaSet) (int64, error) {
	v, ok := rs.Annotations[RevisionAnnotation]
	if !ok {
		return 0, nil
	}
	return strconv.ParseInt(v, 10, 64)
}

func IsRollingUpdate(deployment *extensions.Deployment) bool {
	return deployment.Spec.Strategy.Type == extensions.RollingUpdateDeploymentStrategyType
}

// NewRSNewReplicas calculates the number of replicas a deployment's new RS should have.
// When one of the followings is true, we're rolling out the deployment; otherwise, we're scaling it.
// 1) The new RS is saturated: newRS's replicas == deployment's replicas
// 2) Max number of pods allowed is reached: deployment's replicas + maxSurge == all RSs' replicas
func NewRSNewReplicas(deployment *extensions.Deployment, allRSs []*extensions.ReplicaSet, newRS *extensions.ReplicaSet) (int, error) {
	switch deployment.Spec.Strategy.Type {
	case extensions.RollingUpdateDeploymentStrategyType:
		// Check if we can scale up.
		maxSurge, err := intstrutil.GetValueFromIntOrPercent(&deployment.Spec.Strategy.RollingUpdate.MaxSurge, deployment.Spec.Replicas)
		if err != nil {
			return 0, err
		}
		// Find the total number of pods
		currentPodCount := GetReplicaCountForReplicaSets(allRSs)
		maxTotalPods := deployment.Spec.Replicas + maxSurge
		if currentPodCount >= maxTotalPods {
			// Cannot scale up.
			return newRS.Spec.Replicas, nil
		}
		// Scale up.
		scaleUpCount := maxTotalPods - currentPodCount
		// Do not exceed the number of desired replicas.
		scaleUpCount = integer.IntMin(scaleUpCount, deployment.Spec.Replicas-newRS.Spec.Replicas)
		return newRS.Spec.Replicas + scaleUpCount, nil
	case extensions.RecreateDeploymentStrategyType:
		return deployment.Spec.Replicas, nil
	default:
		return 0, fmt.Errorf("deployment type %v isn't supported", deployment.Spec.Strategy.Type)
	}
}
