/*
Copyright The Helm 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 action

import (
	"bytes"
	"fmt"
	"strings"
	"time"

	"github.com/pkg/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/cli-runtime/pkg/resource"

	"helm.sh/helm/v3/pkg/chart"
	"helm.sh/helm/v3/pkg/chartutil"
	"helm.sh/helm/v3/pkg/kube"
	"helm.sh/helm/v3/pkg/release"
	"helm.sh/helm/v3/pkg/releaseutil"
)

// Upgrade is the action for upgrading releases.
//
// It provides the implementation of 'helm upgrade'.
type Upgrade struct {
	cfg *Configuration

	ChartPathOptions

	Install      bool
	Devel        bool
	Namespace    string
	Timeout      time.Duration
	Wait         bool
	DisableHooks bool
	DryRun       bool
	Force        bool
	ResetValues  bool
	ReuseValues  bool
	// Recreate will (if true) recreate pods after a rollback.
	Recreate bool
	// MaxHistory limits the maximum number of revisions saved per release
	MaxHistory    int
	Atomic        bool
	CleanupOnFail bool
	SubNotes      bool
}

// NewUpgrade creates a new Upgrade object with the given configuration.
func NewUpgrade(cfg *Configuration) *Upgrade {
	return &Upgrade{
		cfg: cfg,
	}
}

// Run executes the upgrade on the given release.
func (u *Upgrade) Run(name string, chart *chart.Chart, vals map[string]interface{}) (*release.Release, error) {
	// Make sure if Atomic is set, that wait is set as well. This makes it so
	// the user doesn't have to specify both
	u.Wait = u.Wait || u.Atomic

	if err := validateReleaseName(name); err != nil {
		return nil, errors.Errorf("release name is invalid: %s", name)
	}
	u.cfg.Log("preparing upgrade for %s", name)
	currentRelease, upgradedRelease, err := u.prepareUpgrade(name, chart, vals)
	if err != nil {
		return nil, err
	}

	u.cfg.Releases.MaxHistory = u.MaxHistory

	u.cfg.Log("performing update for %s", name)
	res, err := u.performUpgrade(currentRelease, upgradedRelease)
	if err != nil {
		return res, err
	}

	if !u.DryRun {
		u.cfg.Log("updating status for upgraded release for %s", name)
		if err := u.cfg.Releases.Update(upgradedRelease); err != nil {
			return res, err
		}
	}

	return res, nil
}

func validateReleaseName(releaseName string) error {
	if releaseName == "" {
		return errMissingRelease
	}

	if !ValidName.MatchString(releaseName) || (len(releaseName) > releaseNameMaxLen) {
		return errInvalidName
	}

	return nil
}

// prepareUpgrade builds an upgraded release for an upgrade operation.
func (u *Upgrade) prepareUpgrade(name string, chart *chart.Chart, vals map[string]interface{}) (*release.Release, *release.Release, error) {
	if chart == nil {
		return nil, nil, errMissingChart
	}

	// finds the deployed release with the given name
	currentRelease, err := u.cfg.Releases.Deployed(name)
	if err != nil {
		return nil, nil, err
	}

	// determine if values will be reused
	vals, err = u.reuseValues(chart, currentRelease, vals)
	if err != nil {
		return nil, nil, err
	}

	if err := chartutil.ProcessDependencies(chart, vals); err != nil {
		return nil, nil, err
	}

	// finds the non-deleted release with the given name
	lastRelease, err := u.cfg.Releases.Last(name)
	if err != nil {
		return nil, nil, err
	}

	// Increment revision count. This is passed to templates, and also stored on
	// the release object.
	revision := lastRelease.Version + 1

	options := chartutil.ReleaseOptions{
		Name:      name,
		Namespace: currentRelease.Namespace,
		Revision:  revision,
		IsUpgrade: true,
	}

	caps, err := u.cfg.getCapabilities()
	if err != nil {
		return nil, nil, err
	}
	valuesToRender, err := chartutil.ToRenderValues(chart, vals, options, caps)
	if err != nil {
		return nil, nil, err
	}

	hooks, manifestDoc, notesTxt, err := u.cfg.renderResources(chart, valuesToRender, "", u.SubNotes)
	if err != nil {
		return nil, nil, err
	}

	// Store an upgraded release.
	upgradedRelease := &release.Release{
		Name:      name,
		Namespace: currentRelease.Namespace,
		Chart:     chart,
		Config:    vals,
		Info: &release.Info{
			FirstDeployed: currentRelease.Info.FirstDeployed,
			LastDeployed:  Timestamper(),
			Status:        release.StatusPendingUpgrade,
			Description:   "Preparing upgrade", // This should be overwritten later.
		},
		Version:  revision,
		Manifest: manifestDoc.String(),
		Hooks:    hooks,
	}

	if len(notesTxt) > 0 {
		upgradedRelease.Info.Notes = notesTxt
	}
	err = validateManifest(u.cfg.KubeClient, manifestDoc.Bytes())
	return currentRelease, upgradedRelease, err
}

func (u *Upgrade) performUpgrade(originalRelease, upgradedRelease *release.Release) (*release.Release, error) {
	current, err := u.cfg.KubeClient.Build(bytes.NewBufferString(originalRelease.Manifest), false)
	if err != nil {
		return upgradedRelease, errors.Wrap(err, "unable to build kubernetes objects from current release manifest")
	}
	target, err := u.cfg.KubeClient.Build(bytes.NewBufferString(upgradedRelease.Manifest), true)
	if err != nil {
		return upgradedRelease, errors.Wrap(err, "unable to build kubernetes objects from new release manifest")
	}

	// Do a basic diff using gvk + name to figure out what new resources are being created so we can validate they don't already exist
	existingResources := make(map[string]bool)
	for _, r := range current {
		existingResources[objectKey(r)] = true
	}

	var toBeCreated kube.ResourceList
	for _, r := range target {
		if !existingResources[objectKey(r)] {
			toBeCreated = append(toBeCreated, r)
		}
	}

	if err := existingResourceConflict(toBeCreated); err != nil {
		return nil, errors.Wrap(err, "rendered manifests contain a new resource that already exists. Unable to continue with update")
	}

	if u.DryRun {
		u.cfg.Log("dry run for %s", upgradedRelease.Name)
		upgradedRelease.Info.Description = "Dry run complete"
		return upgradedRelease, nil
	}

	u.cfg.Log("creating upgraded release for %s", upgradedRelease.Name)
	if err := u.cfg.Releases.Create(upgradedRelease); err != nil {
		return nil, err
	}

	// pre-upgrade hooks
	if !u.DisableHooks {
		if err := u.cfg.execHook(upgradedRelease, release.HookPreUpgrade, u.Timeout); err != nil {
			return u.failRelease(upgradedRelease, kube.ResourceList{}, fmt.Errorf("pre-upgrade hooks failed: %s", err))
		}
	} else {
		u.cfg.Log("upgrade hooks disabled for %s", upgradedRelease.Name)
	}

	results, err := u.cfg.KubeClient.Update(current, target, u.Force)
	if err != nil {
		u.cfg.recordRelease(originalRelease)
		return u.failRelease(upgradedRelease, results.Created, err)
	}

	if u.Recreate {
		// NOTE: Because this is not critical for a release to succeed, we just
		// log if an error occurs and continue onward. If we ever introduce log
		// levels, we should make these error level logs so users are notified
		// that they'll need to go do the cleanup on their own
		if err := recreate(u.cfg, results.Updated); err != nil {
			u.cfg.Log(err.Error())
		}
	}

	if u.Wait {
		if err := u.cfg.KubeClient.Wait(target, u.Timeout); err != nil {
			u.cfg.recordRelease(originalRelease)
			return u.failRelease(upgradedRelease, results.Created, err)
		}
	}

	// post-upgrade hooks
	if !u.DisableHooks {
		if err := u.cfg.execHook(upgradedRelease, release.HookPostUpgrade, u.Timeout); err != nil {
			return u.failRelease(upgradedRelease, results.Created, fmt.Errorf("post-upgrade hooks failed: %s", err))
		}
	}

	originalRelease.Info.Status = release.StatusSuperseded
	u.cfg.recordRelease(originalRelease)

	upgradedRelease.Info.Status = release.StatusDeployed
	upgradedRelease.Info.Description = "Upgrade complete"

	return upgradedRelease, nil
}

func (u *Upgrade) failRelease(rel *release.Release, created kube.ResourceList, err error) (*release.Release, error) {
	msg := fmt.Sprintf("Upgrade %q failed: %s", rel.Name, err)
	u.cfg.Log("warning: %s", msg)

	rel.Info.Status = release.StatusFailed
	rel.Info.Description = msg
	u.cfg.recordRelease(rel)
	if u.CleanupOnFail {
		u.cfg.Log("Cleanup on fail set, cleaning up %d resources", len(created))
		_, errs := u.cfg.KubeClient.Delete(created)
		if errs != nil {
			var errorList []string
			for _, e := range errs {
				errorList = append(errorList, e.Error())
			}
			return rel, errors.Wrapf(fmt.Errorf("unable to cleanup resources: %s", strings.Join(errorList, ", ")), "an error occurred while cleaning up resources. original upgrade error: %s", err)
		}
		u.cfg.Log("Resource cleanup complete")
	}
	if u.Atomic {
		u.cfg.Log("Upgrade failed and atomic is set, rolling back to last successful release")

		// As a protection, get the last successful release before rollback.
		// If there are no successful releases, bail out
		hist := NewHistory(u.cfg)
		fullHistory, herr := hist.Run(rel.Name)
		if herr != nil {
			return rel, errors.Wrapf(herr, "an error occurred while finding last successful release. original upgrade error: %s", err)
		}

		// There isn't a way to tell if a previous release was successful, but
		// generally failed releases do not get superseded unless the next
		// release is successful, so this should be relatively safe
		filteredHistory := releaseutil.FilterFunc(func(r *release.Release) bool {
			return r.Info.Status == release.StatusSuperseded || r.Info.Status == release.StatusDeployed
		}).Filter(fullHistory)
		if len(filteredHistory) == 0 {
			return rel, errors.Wrap(err, "unable to find a previously successful release when attempting to rollback. original upgrade error")
		}

		releaseutil.Reverse(filteredHistory, releaseutil.SortByRevision)

		rollin := NewRollback(u.cfg)
		rollin.Version = filteredHistory[0].Version
		rollin.Wait = true
		rollin.DisableHooks = u.DisableHooks
		rollin.Recreate = u.Recreate
		rollin.Force = u.Force
		rollin.Timeout = u.Timeout
		if rollErr := rollin.Run(rel.Name); rollErr != nil {
			return rel, errors.Wrapf(rollErr, "an error occurred while rolling back the release. original upgrade error: %s", err)
		}
		return rel, errors.Wrapf(err, "release %s failed, and has been rolled back due to atomic being set", rel.Name)
	}

	return rel, err
}

// reuseValues copies values from the current release to a new release if the
// new release does not have any values.
//
// If the request already has values, or if there are no values in the current
// release, this does nothing.
//
// This is skipped if the u.ResetValues flag is set, in which case the
// request values are not altered.
func (u *Upgrade) reuseValues(chart *chart.Chart, current *release.Release, newVals map[string]interface{}) (map[string]interface{}, error) {
	if u.ResetValues {
		// If ResetValues is set, we completely ignore current.Config.
		u.cfg.Log("resetting values to the chart's original version")
		return newVals, nil
	}

	// If the ReuseValues flag is set, we always copy the old values over the new config's values.
	if u.ReuseValues {
		u.cfg.Log("reusing the old release's values")

		// We have to regenerate the old coalesced values:
		oldVals, err := chartutil.CoalesceValues(current.Chart, current.Config)
		if err != nil {
			return nil, errors.Wrap(err, "failed to rebuild old values")
		}

		newVals = chartutil.CoalesceTables(newVals, current.Config)

		chart.Values = oldVals

		return newVals, nil
	}

	if len(newVals) == 0 && len(current.Config) > 0 {
		u.cfg.Log("copying values from %s (v%d) to new release.", current.Name, current.Version)
		newVals = current.Config
	}
	return newVals, nil
}

func validateManifest(c kube.Interface, manifest []byte) error {
	_, err := c.Build(bytes.NewReader(manifest), true)
	return err
}

// recreate captures all the logic for recreating pods for both upgrade and
// rollback. If we end up refactoring rollback to use upgrade, this can just be
// made an unexported method on the upgrade action.
func recreate(cfg *Configuration, resources kube.ResourceList) error {
	for _, res := range resources {
		versioned := kube.AsVersioned(res)
		selector, err := kube.SelectorsForObject(versioned)
		if err != nil {
			// If no selector is returned, it means this object is
			// definitely not a pod, so continue onward
			continue
		}

		client, err := cfg.KubernetesClientSet()
		if err != nil {
			return errors.Wrapf(err, "unable to recreate pods for object %s/%s because an error occurred", res.Namespace, res.Name)
		}

		pods, err := client.CoreV1().Pods(res.Namespace).List(metav1.ListOptions{
			LabelSelector: selector.String(),
		})
		if err != nil {
			return errors.Wrapf(err, "unable to recreate pods for object %s/%s because an error occurred", res.Namespace, res.Name)
		}

		// Restart pods
		for _, pod := range pods.Items {
			// Delete each pod for get them restarted with changed spec.
			if err := client.CoreV1().Pods(pod.Namespace).Delete(pod.Name, metav1.NewPreconditionDeleteOptions(string(pod.UID))); err != nil {
				return errors.Wrapf(err, "unable to recreate pods for object %s/%s because an error occurred", res.Namespace, res.Name)
			}
		}
	}
	return nil
}

func objectKey(r *resource.Info) string {
	gvk := r.Object.GetObjectKind().GroupVersionKind()
	return fmt.Sprintf("%s/%s/%s", gvk.GroupVersion().String(), gvk.Kind, r.Name)
}