// Copyright © 2019 The Knative 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 revision

import (
	"fmt"
	"sort"
	"strconv"
	"strings"

	"knative.dev/serving/pkg/apis/serving"

	"github.com/spf13/cobra"
	"knative.dev/serving/pkg/apis/serving/v1alpha1"

	"knative.dev/client/pkg/kn/commands"
	v1alpha12 "knative.dev/client/pkg/serving/v1alpha1"
)

// NewRevisionListCommand represents 'kn revision list' command
func NewRevisionListCommand(p *commands.KnParams) *cobra.Command {
	revisionListFlags := NewRevisionListFlags()

	revisionListCommand := &cobra.Command{
		Use:   "list [name]",
		Short: "List available revisions.",
		Long:  "List revisions for a given service.",
		Example: `
  # List all revisions
  kn revision list

  # List revisions for a service 'svc1' in namespace 'myapp'
  kn revision list -s svc1 -n myapp

  # List all revisions in JSON output format
  kn revision list -o json
  
  # List revision 'web'
  kn revision list web`,
		RunE: func(cmd *cobra.Command, args []string) error {
			namespace, err := p.GetNamespace(cmd)
			if err != nil {
				return err
			}
			client, err := p.NewServingClient(namespace)
			if err != nil {
				return err
			}
			var revisionList *v1alpha1.RevisionList
			if cmd.Flags().Changed("service") {
				serviceName := cmd.Flag("service").Value.String()

				// Verify that service exists
				_, err := client.GetService(serviceName)
				if err != nil {
					return err
				}
				revisionList, err = client.ListRevisions(v1alpha12.WithService(serviceName))
				if err != nil {
					return err
				}
				if len(revisionList.Items) == 0 {
					fmt.Fprintf(cmd.OutOrStdout(), "No revisions found for service '%s'.\n", serviceName)
					return nil
				}
			} else {
				revisionList, err = getRevisionInfo(args, client)
				if err != nil {
					return err
				}
				if len(revisionList.Items) == 0 {
					fmt.Fprintf(cmd.OutOrStdout(), "No revisions found.\n")
					return nil
				}
			}

			// Add revision/service info as annotations: traffic and tags
			var service *v1alpha1.Service
			var serviceName string
			for _, revision := range revisionList.Items {
				if serviceName == "" || revision.Labels[serving.ServiceLabelKey] != serviceName {
					serviceName = revision.Labels[serving.ServiceLabelKey]
					service, err = client.GetService(serviceName)
					if err != nil {
						return err
					}
				}

				traffic, tags := trafficForRevision(revision.Name, service)
				revision.Annotations[RevisionTrafficAnnotation] = fmt.Sprintf("%d%%", traffic)
				revision.Annotations[RevisionTagsAnnotation] = strings.Join(tags, ",")
			}

			// sort revisionList by configuration generation key
			sort.SliceStable(revisionList.Items, func(i, j int) bool {
				a := revisionList.Items[i]
				b := revisionList.Items[j]

				// Convert configuration generation key from string to int for avoiding string comparison.
				agen, err := strconv.Atoi(a.Labels[serving.ConfigurationGenerationLabelKey])
				if err != nil {
					return a.Name < b.Name
				}
				bgen, err := strconv.Atoi(b.Labels[serving.ConfigurationGenerationLabelKey])
				if err != nil {
					return a.Name < b.Name
				}

				if agen != bgen {
					return agen > bgen
				}
				return a.Name < b.Name
			})

			printer, err := revisionListFlags.ToPrinter()
			if err != nil {
				return err
			}

			err = printer.PrintObj(revisionList, cmd.OutOrStdout())
			if err != nil {
				return err
			}
			return nil
		},
	}
	commands.AddNamespaceFlags(revisionListCommand.Flags(), true)
	revisionListFlags.AddFlags(revisionListCommand)
	return revisionListCommand
}

func getRevisionInfo(args []string, client v1alpha12.KnServingClient) (*v1alpha1.RevisionList, error) {
	var (
		revisionList *v1alpha1.RevisionList
		err          error
	)
	switch len(args) {
	case 0:
		revisionList, err = client.ListRevisions()
	case 1:
		revisionList, err = client.ListRevisions(v1alpha12.WithName(args[0]))
	default:
		return nil, fmt.Errorf("'kn revision list' accepts maximum 1 argument")
	}
	return revisionList, err
}