/*
Copyright 2019 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 main

import (
	"context"
	"fmt"
	"os"

	"github.com/blang/semver/v4"
	"github.com/spf13/cobra"
	"k8s.io/klog/v2"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/kops"
	kopsapi "k8s.io/kops/pkg/apis/kops"
	"k8s.io/kops/pkg/apis/kops/util"
	"k8s.io/kops/pkg/commands"
	"k8s.io/kops/upup/pkg/fi"
	"k8s.io/kops/upup/pkg/fi/cloudup"
	"k8s.io/kops/util/pkg/tables"
)

type UpgradeClusterCmd struct {
	Yes bool

	Channel string
}

var upgradeCluster UpgradeClusterCmd

func init() {
	cmd := &cobra.Command{
		Use:     "cluster",
		Short:   upgradeShort,
		Long:    upgradeLong,
		Example: upgradeExample,
		Run: func(cmd *cobra.Command, args []string) {
			ctx := context.TODO()

			err := upgradeCluster.Run(ctx, args)
			if err != nil {
				exitWithError(err)
			}
		},
	}

	cmd.Flags().BoolVarP(&upgradeCluster.Yes, "yes", "y", false, "Apply update")
	cmd.Flags().StringVar(&upgradeCluster.Channel, "channel", "", "Channel to use for upgrade")

	upgradeCmd.AddCommand(cmd)
}

type upgradeAction struct {
	Item     string
	Property string
	Old      string
	New      string

	apply func()
}

func (c *UpgradeClusterCmd) Run(ctx context.Context, args []string) error {
	err := rootCommand.ProcessArgs(args)
	if err != nil {
		return err
	}

	cluster, err := rootCommand.Cluster(ctx)
	if err != nil {
		return err
	}

	clientset, err := rootCommand.Clientset()
	if err != nil {
		return err
	}

	instanceGroups, err := commands.ReadAllInstanceGroups(ctx, clientset, cluster)
	if err != nil {
		return err
	}

	if cluster.ObjectMeta.Annotations[kopsapi.AnnotationNameManagement] == kopsapi.AnnotationValueManagementImported {
		return fmt.Errorf("upgrade is not for use with imported clusters (did you mean `kops toolbox convert-imported`?)")
	}

	channelLocation := c.Channel
	if channelLocation == "" {
		channelLocation = cluster.Spec.Channel
	}
	if channelLocation == "" {
		channelLocation = kopsapi.DefaultChannel
	}

	var actions []*upgradeAction
	if channelLocation != cluster.Spec.Channel {
		actions = append(actions, &upgradeAction{
			Item:     "Cluster",
			Property: "Channel",
			Old:      cluster.Spec.Channel,
			New:      channelLocation,
			apply: func() {
				cluster.Spec.Channel = channelLocation
			},
		})
	}

	channel, err := kopsapi.LoadChannel(channelLocation)
	if err != nil {
		return fmt.Errorf("error loading channel %q: %v", channelLocation, err)
	}

	channelClusterSpec := channel.Spec.Cluster
	if channelClusterSpec == nil {
		// Just to prevent too much nil handling
		channelClusterSpec = &kopsapi.ClusterSpec{}
	}

	var currentKubernetesVersion *semver.Version
	{
		sv, err := util.ParseKubernetesVersion(cluster.Spec.KubernetesVersion)
		if err != nil {
			klog.Warningf("error parsing KubernetesVersion %q", cluster.Spec.KubernetesVersion)
		} else {
			currentKubernetesVersion = sv
		}
	}

	proposedKubernetesVersion := kopsapi.RecommendedKubernetesVersion(channel, kops.Version)

	// We won't propose a downgrade
	// TODO: What if a kubernetes version is bad?
	if currentKubernetesVersion != nil && proposedKubernetesVersion != nil && currentKubernetesVersion.GT(*proposedKubernetesVersion) {
		klog.Warningf("cluster version %q is greater than recommended version %q", *currentKubernetesVersion, *proposedKubernetesVersion)
		proposedKubernetesVersion = currentKubernetesVersion
	}

	if proposedKubernetesVersion != nil && currentKubernetesVersion != nil && currentKubernetesVersion.NE(*proposedKubernetesVersion) {
		actions = append(actions, &upgradeAction{
			Item:     "Cluster",
			Property: "KubernetesVersion",
			Old:      cluster.Spec.KubernetesVersion,
			New:      proposedKubernetesVersion.String(),
			apply: func() {
				cluster.Spec.KubernetesVersion = proposedKubernetesVersion.String()
			},
		})
	}

	// For further calculations, default to the current kubernetes version
	if proposedKubernetesVersion == nil {
		proposedKubernetesVersion = currentKubernetesVersion
	}

	cloud, err := cloudup.BuildCloud(cluster)
	if err != nil {
		return err
	}

	// Prompt to upgrade image
	if proposedKubernetesVersion != nil {
		image := channel.FindImage(cloud.ProviderID(), *proposedKubernetesVersion)

		if image == nil {
			klog.Warningf("No matching images specified in channel; cannot prompt for upgrade")
		} else {
			for _, ig := range instanceGroups {
				if channel.HasUpstreamImagePrefix(ig.Spec.Image) {
					if ig.Spec.Image != image.Name {
						target := ig
						actions = append(actions, &upgradeAction{
							Item:     "InstanceGroup/" + target.ObjectMeta.Name,
							Property: "Image",
							Old:      target.Spec.Image,
							New:      image.Name,
							apply: func() {
								target.Spec.Image = image.Name
							},
						})
					}
				} else {
					klog.Infof("Custom image (%s) has been provided for Instance Group %q; not updating image", ig.Spec.Image, ig.GetName())
				}
			}
		}
	}

	// Prompt to upgrade to overlayfs
	if channelClusterSpec.Docker != nil {
		if cluster.Spec.Docker == nil {
			cluster.Spec.Docker = &kopsapi.DockerConfig{}
		}
		// TODO: make less hard-coded
		if channelClusterSpec.Docker.Storage != nil {
			dockerStorage := fi.StringValue(cluster.Spec.Docker.Storage)
			if dockerStorage != fi.StringValue(channelClusterSpec.Docker.Storage) {
				actions = append(actions, &upgradeAction{
					Item:     "Cluster",
					Property: "Docker.Storage",
					Old:      dockerStorage,
					New:      fi.StringValue(channelClusterSpec.Docker.Storage),
					apply: func() {
						cluster.Spec.Docker.Storage = channelClusterSpec.Docker.Storage
					},
				})
			}
		}
	}

	if len(actions) == 0 {
		// TODO: Allow --force option to force even if not needed?
		// Note stderr - we try not to print to stdout if no update is needed
		fmt.Fprintf(os.Stderr, "\nNo upgrade required\n")
		return nil
	}

	{
		t := &tables.Table{}
		t.AddColumn("ITEM", func(a *upgradeAction) string {
			return a.Item
		})
		t.AddColumn("PROPERTY", func(a *upgradeAction) string {
			return a.Property
		})
		t.AddColumn("OLD", func(a *upgradeAction) string {
			return a.Old
		})
		t.AddColumn("NEW", func(a *upgradeAction) string {
			return a.New
		})

		err := t.Render(actions, os.Stdout, "ITEM", "PROPERTY", "OLD", "NEW")
		if err != nil {
			return err
		}
	}

	if !c.Yes {
		fmt.Printf("\nMust specify --yes to perform upgrade\n")
		return nil
	}
	for _, action := range actions {
		action.apply()
	}

	if err := commands.UpdateCluster(ctx, clientset, cluster, instanceGroups); err != nil {
		return err
	}

	for _, g := range instanceGroups {
		_, err := clientset.InstanceGroupsFor(cluster).Update(ctx, g, metav1.UpdateOptions{})
		if err != nil {
			return fmt.Errorf("error writing InstanceGroup %q: %v", g.ObjectMeta.Name, err)
		}
	}

	fmt.Printf("\nUpdates applied to configuration.\n")

	// TODO: automate this step
	fmt.Printf("You can now apply these changes, using `kops update cluster %s`\n", cluster.ObjectMeta.Name)

	return nil
}
