/*
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 main

import (
	"context"
	"fmt"
	"sort"
	"time"

	"github.com/docker/go-units"
	"github.com/sirupsen/logrus"
	"github.com/urfave/cli/v2"
	internalapi "k8s.io/cri-api/pkg/apis"
	pb "k8s.io/cri-api/pkg/apis/runtime/v1"
)

type statsOptions struct {
	// all containers
	all bool
	// id of container
	id string
	// podID of container
	podID string
	// sample is the duration for sampling cpu usage.
	sample time.Duration
	// labels are selectors for the sandbox
	labels map[string]string
	// output format
	output string
	// live watch
	watch bool
}

var statsCommand = &cli.Command{
	Name:                   "stats",
	Usage:                  "List container(s) resource usage statistics",
	UseShortOptionHandling: true,
	ArgsUsage:              "[ID]",
	Flags: []cli.Flag{
		&cli.BoolFlag{
			Name:    "all",
			Aliases: []string{"a"},
			Usage:   "Show all containers (default shows just running)",
		},
		&cli.StringFlag{
			Name:  "id",
			Value: "",
			Usage: "Filter by container id",
		},
		&cli.StringFlag{
			Name:    "pod",
			Aliases: []string{"p"},
			Value:   "",
			Usage:   "Filter by pod id",
		},
		&cli.StringSliceFlag{
			Name:  "label",
			Usage: "Filter by key=value label",
		},
		&cli.StringFlag{
			Name:    "output",
			Aliases: []string{"o"},
			Usage:   "Output format, One of: json|yaml|table",
		},
		&cli.IntFlag{
			Name:    "seconds",
			Aliases: []string{"s"},
			Value:   1,
			Usage:   "Sample duration for CPU usage in seconds",
		},
		&cli.BoolFlag{
			Name:    "watch",
			Aliases: []string{"w"},
			Usage:   "Watch pod resources",
		},
	},
	Action: func(context *cli.Context) error {
		runtimeClient, err := getRuntimeService(context, 0)
		if err != nil {
			return err
		}

		id := context.String("id")
		if id == "" && context.NArg() > 0 {
			id = context.Args().Get(0)
		}

		opts := statsOptions{
			all:    context.Bool("all"),
			id:     id,
			podID:  context.String("pod"),
			sample: time.Duration(context.Int("seconds")) * time.Second,
			output: context.String("output"),
			watch:  context.Bool("watch"),
		}
		opts.labels, err = parseLabelStringSlice(context.StringSlice("label"))
		if err != nil {
			return err
		}

		if err = ContainerStats(runtimeClient, opts); err != nil {
			return fmt.Errorf("get container stats: %w", err)
		}
		return nil
	},
}

type containerStatsByID []*pb.ContainerStats

func (c containerStatsByID) Len() int      { return len(c) }
func (c containerStatsByID) Swap(i, j int) { c[i], c[j] = c[j], c[i] }
func (c containerStatsByID) Less(i, j int) bool {
	return c[i].Attributes.Id < c[j].Attributes.Id
}

// ContainerStats sends a ListContainerStatsRequest to the server, and
// parses the returned ListContainerStatsResponse.
func ContainerStats(client internalapi.RuntimeService, opts statsOptions) error {
	filter := &pb.ContainerStatsFilter{}
	if opts.id != "" {
		filter.Id = opts.id
	}
	if opts.podID != "" {
		filter.PodSandboxId = opts.podID
	}
	if opts.labels != nil {
		filter.LabelSelector = opts.labels
	}
	request := &pb.ListContainerStatsRequest{
		Filter: filter,
	}

	display := newTableDisplay(20, 1, 3, ' ', 0)
	if !opts.watch {
		if err := displayStats(context.TODO(), client, request, display, opts); err != nil {
			return err
		}
	} else {
		displayErrCh := make(chan error, 1)
		ticker := time.NewTicker(500 * time.Millisecond)
		defer ticker.Stop()
		watchCtx, cancelFn := context.WithCancel(context.Background())
		defer cancelFn()
		// Put the displayStats in another goroutine.
		// because it might be time consuming with lots of containers.
		// and we want to cancel it ASAP when user hit CtrlC
		go func() {
			for range ticker.C {
				if err := displayStats(watchCtx, client, request, display, opts); err != nil {
					displayErrCh <- err
					break
				}
			}
		}()
		// listen for CtrlC or error
		select {
		case <-SetupInterruptSignalHandler():
			cancelFn()
			return nil
		case err := <-displayErrCh:
			return err
		}
	}

	return nil
}

func getContainerStats(ctx context.Context, client internalapi.RuntimeService, request *pb.ListContainerStatsRequest) (*pb.ListContainerStatsResponse, error) {
	logrus.Debugf("ListContainerStatsRequest: %v", request)
	r, err := client.ListContainerStats(context.TODO(), request.Filter)
	logrus.Debugf("ListContainerResponse: %v", r)
	if err != nil {
		return nil, err
	}
	sort.Sort(containerStatsByID(r))
	return &pb.ListContainerStatsResponse{Stats: r}, nil
}

func displayStats(ctx context.Context, client internalapi.RuntimeService, request *pb.ListContainerStatsRequest, display *display, opts statsOptions) error {
	r, err := getContainerStats(ctx, client, request)
	if err != nil {
		return err
	}
	switch opts.output {
	case "json":
		return outputProtobufObjAsJSON(r)
	case "yaml":
		return outputProtobufObjAsYAML(r)
	}
	oldStats := make(map[string]*pb.ContainerStats)
	for _, s := range r.GetStats() {
		if ctx.Err() != nil {
			return ctx.Err()
		}
		oldStats[s.Attributes.Id] = s
	}

	time.Sleep(opts.sample)

	r, err = getContainerStats(ctx, client, request)
	if err != nil {
		return err
	}

	display.AddRow([]string{columnContainer, columnCPU, columnMemory, columnDisk, columnInodes})
	for _, s := range r.GetStats() {
		if ctx.Err() != nil {
			return ctx.Err()
		}
		id := getTruncatedID(s.Attributes.Id, "")
		cpu := s.GetCpu().GetUsageCoreNanoSeconds().GetValue()
		mem := s.GetMemory().GetWorkingSetBytes().GetValue()
		disk := s.GetWritableLayer().GetUsedBytes().GetValue()
		inodes := s.GetWritableLayer().GetInodesUsed().GetValue()
		if !opts.all && cpu == 0 && mem == 0 {
			// Skip non-running container
			continue
		}
		old, ok := oldStats[s.Attributes.Id]
		if !ok {
			// Skip new container
			continue
		}
		var cpuPerc float64
		if cpu != 0 {
			// Only generate cpuPerc for running container
			duration := s.GetCpu().GetTimestamp() - old.GetCpu().GetTimestamp()
			if duration == 0 {
				return fmt.Errorf("cpu stat is not updated during sample")
			}
			cpuPerc = float64(cpu-old.GetCpu().GetUsageCoreNanoSeconds().GetValue()) / float64(duration) * 100
		}
		display.AddRow([]string{id, fmt.Sprintf("%.2f", cpuPerc), units.HumanSize(float64(mem)),
			units.HumanSize(float64(disk)), fmt.Sprintf("%d", inodes)})

	}
	display.ClearScreen()
	display.Flush()

	return nil
}
