/*
Copyright 2015 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 framework

import (
	"bytes"
	"fmt"
	"math"
	"sort"
	"strconv"
	"strings"
	"sync"
	"text/tabwriter"
	"time"

	"k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	clientset "k8s.io/client-go/kubernetes"
	"k8s.io/kubernetes/pkg/util/system"
)

type ResourceConstraint struct {
	CPUConstraint    float64
	MemoryConstraint uint64
}

type SingleContainerSummary struct {
	Name string
	Cpu  float64
	Mem  uint64
}

// we can't have int here, as JSON does not accept integer keys.
type ResourceUsageSummary map[string][]SingleContainerSummary

func (s *ResourceUsageSummary) PrintHumanReadable() string {
	buf := &bytes.Buffer{}
	w := tabwriter.NewWriter(buf, 1, 0, 1, ' ', 0)
	for perc, summaries := range *s {
		buf.WriteString(fmt.Sprintf("%v percentile:\n", perc))
		fmt.Fprintf(w, "container\tcpu(cores)\tmemory(MB)\n")
		for _, summary := range summaries {
			fmt.Fprintf(w, "%q\t%.3f\t%.2f\n", summary.Name, summary.Cpu, float64(summary.Mem)/(1024*1024))
		}
		w.Flush()
	}
	return buf.String()
}

func (s *ResourceUsageSummary) PrintJSON() string {
	return PrettyPrintJSON(*s)
}

func (s *ResourceUsageSummary) SummaryKind() string {
	return "ResourceUsageSummary"
}

func computePercentiles(timeSeries []ResourceUsagePerContainer, percentilesToCompute []int) map[int]ResourceUsagePerContainer {
	if len(timeSeries) == 0 {
		return make(map[int]ResourceUsagePerContainer)
	}
	dataMap := make(map[string]*usageDataPerContainer)
	for i := range timeSeries {
		for name, data := range timeSeries[i] {
			if dataMap[name] == nil {
				dataMap[name] = &usageDataPerContainer{
					cpuData:        make([]float64, 0, len(timeSeries)),
					memUseData:     make([]uint64, 0, len(timeSeries)),
					memWorkSetData: make([]uint64, 0, len(timeSeries)),
				}
			}
			dataMap[name].cpuData = append(dataMap[name].cpuData, data.CPUUsageInCores)
			dataMap[name].memUseData = append(dataMap[name].memUseData, data.MemoryUsageInBytes)
			dataMap[name].memWorkSetData = append(dataMap[name].memWorkSetData, data.MemoryWorkingSetInBytes)
		}
	}
	for _, v := range dataMap {
		sort.Float64s(v.cpuData)
		sort.Sort(uint64arr(v.memUseData))
		sort.Sort(uint64arr(v.memWorkSetData))
	}

	result := make(map[int]ResourceUsagePerContainer)
	for _, perc := range percentilesToCompute {
		data := make(ResourceUsagePerContainer)
		for k, v := range dataMap {
			percentileIndex := int(math.Ceil(float64(len(v.cpuData)*perc)/100)) - 1
			data[k] = &ContainerResourceUsage{
				Name:                    k,
				CPUUsageInCores:         v.cpuData[percentileIndex],
				MemoryUsageInBytes:      v.memUseData[percentileIndex],
				MemoryWorkingSetInBytes: v.memWorkSetData[percentileIndex],
			}
		}
		result[perc] = data
	}
	return result
}

func leftMergeData(left, right map[int]ResourceUsagePerContainer) map[int]ResourceUsagePerContainer {
	result := make(map[int]ResourceUsagePerContainer)
	for percentile, data := range left {
		result[percentile] = data
		if _, ok := right[percentile]; !ok {
			continue
		}
		for k, v := range right[percentile] {
			result[percentile][k] = v
		}
	}
	return result
}

type resourceGatherWorker struct {
	c                           clientset.Interface
	nodeName                    string
	wg                          *sync.WaitGroup
	containerIDs                []string
	stopCh                      chan struct{}
	dataSeries                  []ResourceUsagePerContainer
	finished                    bool
	inKubemark                  bool
	resourceDataGatheringPeriod time.Duration
	probeDuration               time.Duration
	printVerboseLogs            bool
}

func (w *resourceGatherWorker) singleProbe() {
	data := make(ResourceUsagePerContainer)
	if w.inKubemark {
		kubemarkData := GetKubemarkMasterComponentsResourceUsage()
		if data == nil {
			return
		}
		for k, v := range kubemarkData {
			data[k] = &ContainerResourceUsage{
				Name: v.Name,
				MemoryWorkingSetInBytes: v.MemoryWorkingSetInBytes,
				CPUUsageInCores:         v.CPUUsageInCores,
			}
		}
	} else {
		nodeUsage, err := getOneTimeResourceUsageOnNode(w.c, w.nodeName, w.probeDuration, func() []string { return w.containerIDs })
		if err != nil {
			Logf("Error while reading data from %v: %v", w.nodeName, err)
			return
		}
		for k, v := range nodeUsage {
			data[k] = v
			if w.printVerboseLogs {
				Logf("Get container %v usage on node %v. CPUUsageInCores: %v, MemoryUsageInBytes: %v, MemoryWorkingSetInBytes: %v", k, w.nodeName, v.CPUUsageInCores, v.MemoryUsageInBytes, v.MemoryWorkingSetInBytes)
			}
		}
	}
	w.dataSeries = append(w.dataSeries, data)
}

func (w *resourceGatherWorker) gather(initialSleep time.Duration) {
	defer utilruntime.HandleCrash()
	defer w.wg.Done()
	defer Logf("Closing worker for %v", w.nodeName)
	defer func() { w.finished = true }()
	select {
	case <-time.After(initialSleep):
		w.singleProbe()
		for {
			select {
			case <-time.After(w.resourceDataGatheringPeriod):
				w.singleProbe()
			case <-w.stopCh:
				return
			}
		}
	case <-w.stopCh:
		return
	}
}

type ContainerResourceGatherer struct {
	client       clientset.Interface
	stopCh       chan struct{}
	workers      []resourceGatherWorker
	workerWg     sync.WaitGroup
	containerIDs []string
	options      ResourceGathererOptions
}

type ResourceGathererOptions struct {
	InKubemark                  bool
	MasterOnly                  bool
	ResourceDataGatheringPeriod time.Duration
	ProbeDuration               time.Duration
	PrintVerboseLogs            bool
}

func NewResourceUsageGatherer(c clientset.Interface, options ResourceGathererOptions, pods *v1.PodList) (*ContainerResourceGatherer, error) {
	g := ContainerResourceGatherer{
		client:       c,
		stopCh:       make(chan struct{}),
		containerIDs: make([]string, 0),
		options:      options,
	}

	if options.InKubemark {
		g.workerWg.Add(1)
		g.workers = append(g.workers, resourceGatherWorker{
			inKubemark:                  true,
			stopCh:                      g.stopCh,
			wg:                          &g.workerWg,
			finished:                    false,
			resourceDataGatheringPeriod: options.ResourceDataGatheringPeriod,
			probeDuration:               options.ProbeDuration,
			printVerboseLogs:            options.PrintVerboseLogs,
		})
	} else {
		// Tracks kube-system pods if no valid PodList is passed in.
		var err error
		if pods == nil {
			pods, err = c.CoreV1().Pods("kube-system").List(metav1.ListOptions{})
			if err != nil {
				Logf("Error while listing Pods: %v", err)
				return nil, err
			}
		}
		for _, pod := range pods.Items {
			for _, container := range pod.Status.InitContainerStatuses {
				g.containerIDs = append(g.containerIDs, container.Name)
			}
			for _, container := range pod.Status.ContainerStatuses {
				g.containerIDs = append(g.containerIDs, container.Name)
			}
		}
		nodeList, err := c.CoreV1().Nodes().List(metav1.ListOptions{})
		if err != nil {
			Logf("Error while listing Nodes: %v", err)
			return nil, err
		}

		for _, node := range nodeList.Items {
			if !options.MasterOnly || system.IsMasterNode(node.Name) {
				g.workerWg.Add(1)
				g.workers = append(g.workers, resourceGatherWorker{
					c:                           c,
					nodeName:                    node.Name,
					wg:                          &g.workerWg,
					containerIDs:                g.containerIDs,
					stopCh:                      g.stopCh,
					finished:                    false,
					inKubemark:                  false,
					resourceDataGatheringPeriod: options.ResourceDataGatheringPeriod,
					probeDuration:               options.ProbeDuration,
					printVerboseLogs:            options.PrintVerboseLogs,
				})
				if options.MasterOnly {
					break
				}
			}
		}
	}
	return &g, nil
}

// StartGatheringData starts a stat gathering worker blocks for each node to track,
// and blocks until StopAndSummarize is called.
func (g *ContainerResourceGatherer) StartGatheringData() {
	if len(g.workers) == 0 {
		return
	}
	delayPeriod := g.options.ResourceDataGatheringPeriod / time.Duration(len(g.workers))
	delay := time.Duration(0)
	for i := range g.workers {
		go g.workers[i].gather(delay)
		delay += delayPeriod
	}
	g.workerWg.Wait()
}

// StopAndSummarize stops stat gathering workers, processes the collected stats,
// generates resource summary for the passed-in percentiles, and returns the summary.
// It returns an error if the resource usage at any percentile is beyond the
// specified resource constraints.
func (g *ContainerResourceGatherer) StopAndSummarize(percentiles []int, constraints map[string]ResourceConstraint) (*ResourceUsageSummary, error) {
	close(g.stopCh)
	Logf("Closed stop channel. Waiting for %v workers", len(g.workers))
	finished := make(chan struct{})
	go func() {
		g.workerWg.Wait()
		finished <- struct{}{}
	}()
	select {
	case <-finished:
		Logf("Waitgroup finished.")
	case <-time.After(2 * time.Minute):
		unfinished := make([]string, 0)
		for i := range g.workers {
			if !g.workers[i].finished {
				unfinished = append(unfinished, g.workers[i].nodeName)
			}
		}
		Logf("Timed out while waiting for waitgroup, some workers failed to finish: %v", unfinished)
	}

	if len(percentiles) == 0 {
		Logf("Warning! Empty percentile list for stopAndPrintData.")
		return &ResourceUsageSummary{}, fmt.Errorf("Failed to get any resource usage data")
	}
	data := make(map[int]ResourceUsagePerContainer)
	for i := range g.workers {
		if g.workers[i].finished {
			stats := computePercentiles(g.workers[i].dataSeries, percentiles)
			data = leftMergeData(stats, data)
		}
	}

	// Workers has been stopped. We need to gather data stored in them.
	sortedKeys := []string{}
	for name := range data[percentiles[0]] {
		sortedKeys = append(sortedKeys, name)
	}
	sort.Strings(sortedKeys)
	violatedConstraints := make([]string, 0)
	summary := make(ResourceUsageSummary)
	for _, perc := range percentiles {
		for _, name := range sortedKeys {
			usage := data[perc][name]
			summary[strconv.Itoa(perc)] = append(summary[strconv.Itoa(perc)], SingleContainerSummary{
				Name: name,
				Cpu:  usage.CPUUsageInCores,
				Mem:  usage.MemoryWorkingSetInBytes,
			})
			// Verifying 99th percentile of resource usage
			if perc == 99 {
				// Name has a form: <pod_name>/<container_name>
				containerName := strings.Split(name, "/")[1]
				if constraint, ok := constraints[containerName]; ok {
					if usage.CPUUsageInCores > constraint.CPUConstraint {
						violatedConstraints = append(
							violatedConstraints,
							fmt.Sprintf("Container %v is using %v/%v CPU",
								name,
								usage.CPUUsageInCores,
								constraint.CPUConstraint,
							),
						)
					}
					if usage.MemoryWorkingSetInBytes > constraint.MemoryConstraint {
						violatedConstraints = append(
							violatedConstraints,
							fmt.Sprintf("Container %v is using %v/%v MB of memory",
								name,
								float64(usage.MemoryWorkingSetInBytes)/(1024*1024),
								float64(constraint.MemoryConstraint)/(1024*1024),
							),
						)
					}
				}
			}
		}
	}
	if len(violatedConstraints) > 0 {
		return &summary, fmt.Errorf(strings.Join(violatedConstraints, "\n"))
	}
	return &summary, nil
}