/*
Copyright 2023 The Karmada 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 top

import (
	"fmt"
	"io"
	"sort"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/resource"
	"k8s.io/cli-runtime/pkg/printers"
	"k8s.io/kubectl/pkg/metricsutil"
	metricsapi "k8s.io/metrics/pkg/apis/metrics"

	autoscalingv1alpha1 "github.com/karmada-io/karmada/pkg/apis/autoscaling/v1alpha1"
)

var (
	// MeasuredResources is the list of resources that are measured by the top command.
	MeasuredResources = []corev1.ResourceName{
		corev1.ResourceCPU,
		corev1.ResourceMemory,
	}
	// PodColumns is the list of columns used in the top pod command.
	PodColumns = []string{"NAME", "CLUSTER", "CPU(cores)", "MEMORY(bytes)"}
	// NamespaceColumn is the column name for namespace.
	NamespaceColumn = "NAMESPACE"
	// PodColumn is the column name for pod.
	PodColumn = "POD"
)

// ResourceMetricsInfo contains the information of a resource metric.
type ResourceMetricsInfo struct {
	Cluster   string
	Name      string
	Metrics   corev1.ResourceList
	Available corev1.ResourceList
}

// CmdPrinter is an implementation of TopPrinter which prints the metrics to the given writer.
type CmdPrinter struct {
	out io.Writer
}

// NewTopCmdPrinter creates a new TopCmdPrinter.
func NewTopCmdPrinter(out io.Writer) *CmdPrinter {
	return &CmdPrinter{out: out}
}

// PrintPodMetrics prints the given metrics to the given writer.
func (printer *CmdPrinter) PrintPodMetrics(metrics []metricsapi.PodMetrics, printContainers, withNamespace, noHeaders bool, sortBy string, sum bool) error {
	if len(metrics) == 0 {
		return nil
	}
	w := printers.GetNewTabWriter(printer.out)
	defer w.Flush()

	columnWidth := len(PodColumns)
	if !noHeaders {
		if withNamespace {
			printValue(w, NamespaceColumn)
			columnWidth++
		}
		if printContainers {
			printValue(w, PodColumn)
			columnWidth++
		}
		printColumnNames(w, PodColumns)
	}

	sort.Sort(NewPodMetricsSorter(metrics, withNamespace, sortBy))

	for i := range metrics {
		if printContainers {
			sort.Sort(metricsutil.NewContainerMetricsSorter(metrics[i].Containers, sortBy))
			printSinglePodContainerMetrics(w, &metrics[i], withNamespace)
		} else {
			printSinglePodMetrics(w, &metrics[i], withNamespace)
		}
	}

	if sum {
		adder := NewResourceAdder(MeasuredResources)
		for i := range metrics {
			adder.AddPodMetrics(&metrics[i])
		}
		printPodResourcesSum(w, adder.total, columnWidth)
	}

	return nil
}

func printColumnNames(out io.Writer, names []string) {
	for _, name := range names {
		printValue(out, name)
	}
	fmt.Fprint(out, "\n")
}

func printSinglePodMetrics(out io.Writer, m *metricsapi.PodMetrics, withNamespace bool) {
	podMetrics := getPodMetrics(m)
	if withNamespace {
		printValue(out, m.Namespace)
	}
	printMetricsLine(out, &ResourceMetricsInfo{
		Name:      m.Name,
		Cluster:   m.Annotations[autoscalingv1alpha1.QuerySourceAnnotationKey],
		Metrics:   podMetrics,
		Available: corev1.ResourceList{},
	})
}

func printSinglePodContainerMetrics(out io.Writer, m *metricsapi.PodMetrics, withNamespace bool) {
	for _, c := range m.Containers {
		if withNamespace {
			printValue(out, m.Namespace)
		}
		printValue(out, m.Name)
		printMetricsLine(out, &ResourceMetricsInfo{
			Name:      c.Name,
			Cluster:   m.Annotations[autoscalingv1alpha1.QuerySourceAnnotationKey],
			Metrics:   c.Usage,
			Available: corev1.ResourceList{},
		})
	}
}

func getPodMetrics(m *metricsapi.PodMetrics) corev1.ResourceList {
	podMetrics := make(corev1.ResourceList)
	for _, res := range MeasuredResources {
		podMetrics[res], _ = resource.ParseQuantity("0")
	}

	for _, c := range m.Containers {
		for _, res := range MeasuredResources {
			quantity := podMetrics[res]
			quantity.Add(c.Usage[res])
			podMetrics[res] = quantity
		}
	}
	return podMetrics
}

func printMetricsLine(out io.Writer, metrics *ResourceMetricsInfo) {
	printValue(out, metrics.Name)
	printValue(out, metrics.Cluster)
	printAllResourceUsages(out, metrics)
	fmt.Fprint(out, "\n")
}

func printValue(out io.Writer, value interface{}) {
	fmt.Fprintf(out, "%v\t", value)
}

func printAllResourceUsages(out io.Writer, metrics *ResourceMetricsInfo) {
	for _, res := range MeasuredResources {
		quantity := metrics.Metrics[res]
		printSingleResourceUsage(out, res, quantity)
		fmt.Fprint(out, "\t")
		if available, found := metrics.Available[res]; found {
			fraction := float64(quantity.MilliValue()) / float64(available.MilliValue()) * 100
			fmt.Fprintf(out, "%d%%\t", int64(fraction))
		}
	}
}

func printSingleResourceUsage(out io.Writer, resourceType corev1.ResourceName, quantity resource.Quantity) {
	switch resourceType {
	case corev1.ResourceCPU:
		fmt.Fprintf(out, "%vm", quantity.MilliValue())
	case corev1.ResourceMemory:
		fmt.Fprintf(out, "%vMi", quantity.Value()/(1024*1024))
	default:
		fmt.Fprintf(out, "%v", quantity.Value())
	}
}

func printPodResourcesSum(out io.Writer, total corev1.ResourceList, columnWidth int) {
	for i := 0; i < columnWidth-2; i++ {
		printValue(out, "")
	}
	printValue(out, "________")
	printValue(out, "________")
	fmt.Fprintf(out, "\n")
	for i := 0; i < columnWidth-4; i++ {
		printValue(out, "")
	}
	printMetricsLine(out, &ResourceMetricsInfo{
		Name:      "",
		Metrics:   total,
		Available: corev1.ResourceList{},
	})
}

// ResourceAdder adds pod metrics to a total
type ResourceAdder struct {
	resources []corev1.ResourceName
	total     corev1.ResourceList
}

// NewResourceAdder returns a new ResourceAdder
func NewResourceAdder(resources []corev1.ResourceName) *ResourceAdder {
	return &ResourceAdder{
		resources: resources,
		total:     make(corev1.ResourceList),
	}
}

// AddPodMetrics adds each pod metric to the total
func (adder *ResourceAdder) AddPodMetrics(m *metricsapi.PodMetrics) {
	for _, c := range m.Containers {
		for _, res := range adder.resources {
			total := adder.total[res]
			total.Add(c.Usage[res])
			adder.total[res] = total
		}
	}
}