/*
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 noderesources

import (
	"context"
	"fmt"
	"math"
	"strconv"
	"strings"

	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/sets"
	v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
	"k8s.io/kubernetes/pkg/scheduler/apis/config"
	"k8s.io/kubernetes/pkg/scheduler/apis/config/validation"
	"k8s.io/kubernetes/pkg/scheduler/framework"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/feature"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/names"
)

var _ framework.PreFilterPlugin = &Fit{}
var _ framework.FilterPlugin = &Fit{}
var _ framework.EnqueueExtensions = &Fit{}
var _ framework.ScorePlugin = &Fit{}

const (
	// FitName is the name of the plugin used in the plugin registry and configurations.
	FitName = names.NodeResourcesFit

	// preFilterStateKey is the key in CycleState to NodeResourcesFit pre-computed data.
	// Using the name of the plugin will likely help us avoid collisions with other plugins.
	preFilterStateKey = "PreFilter" + FitName
)

// nodeResourceStrategyTypeMap maps strategy to scorer implementation
var nodeResourceStrategyTypeMap = map[config.ScoringStrategyType]scorer{
	config.LeastAllocated: func(args *config.NodeResourcesFitArgs) *resourceAllocationScorer {
		resToWeightMap := resourcesToWeightMap(args.ScoringStrategy.Resources)
		return &resourceAllocationScorer{
			Name:                LeastAllocatedName,
			scorer:              leastResourceScorer(resToWeightMap),
			resourceToWeightMap: resToWeightMap,
		}
	},
	config.MostAllocated: func(args *config.NodeResourcesFitArgs) *resourceAllocationScorer {
		resToWeightMap := resourcesToWeightMap(args.ScoringStrategy.Resources)
		return &resourceAllocationScorer{
			Name:                MostAllocatedName,
			scorer:              mostResourceScorer(resToWeightMap),
			resourceToWeightMap: resToWeightMap,
		}
	},
	config.RequestedToCapacityRatio: func(args *config.NodeResourcesFitArgs) *resourceAllocationScorer {
		resToWeightMap := resourcesToWeightMap(args.ScoringStrategy.Resources)
		return &resourceAllocationScorer{
			Name:                RequestedToCapacityRatioName,
			scorer:              requestedToCapacityRatioScorer(resToWeightMap, args.ScoringStrategy.RequestedToCapacityRatio.Shape),
			resourceToWeightMap: resToWeightMap,
		}
	},
}

// Fit is a plugin that checks if a node has sufficient resources.
type Fit struct {
	ignoredResources      sets.String
	ignoredResourceGroups sets.String
	enablePodOverhead     bool
	handle                framework.Handle
	resourceAllocationScorer
}

// ScoreExtensions of the Score plugin.
func (f *Fit) ScoreExtensions() framework.ScoreExtensions {
	return nil
}

// preFilterState computed at PreFilter and used at Filter.
type preFilterState struct {
	framework.Resource
}

// Clone the prefilter state.
func (s *preFilterState) Clone() framework.StateData {
	return s
}

// Name returns name of the plugin. It is used in logs, etc.
func (f *Fit) Name() string {
	return FitName
}

// NewFit initializes a new plugin and returns it.
func NewFit(plArgs runtime.Object, h framework.Handle, fts feature.Features) (framework.Plugin, error) {
	args, ok := plArgs.(*config.NodeResourcesFitArgs)
	if !ok {
		return nil, fmt.Errorf("want args to be of type NodeResourcesFitArgs, got %T", plArgs)
	}
	if err := validation.ValidateNodeResourcesFitArgs(nil, args); err != nil {
		return nil, err
	}

	if args.ScoringStrategy == nil {
		return nil, fmt.Errorf("scoring strategy not specified")
	}

	strategy := args.ScoringStrategy.Type
	scorePlugin, ok := nodeResourceStrategyTypeMap[strategy]
	if !ok {
		return nil, fmt.Errorf("scoring strategy %s is not supported", strategy)
	}

	return &Fit{
		ignoredResources:         sets.NewString(args.IgnoredResources...),
		ignoredResourceGroups:    sets.NewString(args.IgnoredResourceGroups...),
		enablePodOverhead:        fts.EnablePodOverhead,
		handle:                   h,
		resourceAllocationScorer: *scorePlugin(args),
	}, nil
}

// computePodResourceRequest returns a framework.Resource that covers the largest
// width in each resource dimension. Because init-containers run sequentially, we collect
// the max in each dimension iteratively. In contrast, we sum the resource vectors for
// regular containers since they run simultaneously.
//
// If Pod Overhead is specified and the feature gate is set, the resources defined for Overhead
// are added to the calculated Resource request sum
//
// Example:
//
// Pod:
//   InitContainers
//     IC1:
//       CPU: 2
//       Memory: 1G
//     IC2:
//       CPU: 2
//       Memory: 3G
//   Containers
//     C1:
//       CPU: 2
//       Memory: 1G
//     C2:
//       CPU: 1
//       Memory: 1G
//
// Result: CPU: 3, Memory: 3G
func computePodResourceRequest(pod *v1.Pod, enablePodOverhead bool) *preFilterState {
	result := &preFilterState{}
	for _, container := range pod.Spec.Containers {
		result.Add(container.Resources.Requests)
	}

	// take max_resource(sum_pod, any_init_container)
	for _, container := range pod.Spec.InitContainers {
		result.SetMaxResource(container.Resources.Requests)
	}

	// If Overhead is being utilized, add to the total requests for the pod
	if pod.Spec.Overhead != nil && enablePodOverhead {
		result.Add(pod.Spec.Overhead)
	}

	return result
}

// PreFilter invoked at the prefilter extension point.
func (f *Fit) PreFilter(ctx context.Context, cycleState *framework.CycleState, pod *v1.Pod) *framework.Status {
	cycleState.Write(preFilterStateKey, computePodResourceRequest(pod, f.enablePodOverhead))
	return nil
}

// PreFilterExtensions returns prefilter extensions, pod add and remove.
func (f *Fit) PreFilterExtensions() framework.PreFilterExtensions {
	return nil
}

func getPreFilterState(cycleState *framework.CycleState) (*preFilterState, error) {
	c, err := cycleState.Read(preFilterStateKey)
	if err != nil {
		// preFilterState doesn't exist, likely PreFilter wasn't invoked.
		return nil, fmt.Errorf("error reading %q from cycleState: %w", preFilterStateKey, err)
	}

	s, ok := c.(*preFilterState)
	if !ok {
		return nil, fmt.Errorf("%+v  convert to NodeResourcesFit.preFilterState error", c)
	}
	return s, nil
}

// EventsToRegister returns the possible events that may make a Pod
// failed by this plugin schedulable.
// NOTE: if in-place-update (KEP 1287) gets implemented, then PodUpdate event
// should be registered for this plugin since a Pod update may free up resources
// that make other Pods schedulable.
func (f *Fit) EventsToRegister() []framework.ClusterEvent {
	return []framework.ClusterEvent{
		{Resource: framework.Pod, ActionType: framework.Delete},
		{Resource: framework.Node, ActionType: framework.Add | framework.UpdateNodeAllocatable},
	}
}

// Filter invoked at the filter extension point.
// Checks if a node has sufficient resources, such as cpu, memory, gpu, opaque int resources etc to run a pod.
// It returns a list of insufficient resources, if empty, then the node has all the resources requested by the pod.
func (f *Fit) Filter(ctx context.Context, cycleState *framework.CycleState, pod *v1.Pod, nodeInfo *framework.NodeInfo) *framework.Status {
	s, err := getPreFilterState(cycleState)
	if err != nil {
		return framework.AsStatus(err)
	}

	insufficientResources := fitsRequest(s, nodeInfo, f.ignoredResources, f.ignoredResourceGroups)

	if len(insufficientResources) != 0 {
		// We will keep all failure reasons.
		failureReasons := make([]string, 0, len(insufficientResources))
		for _, r := range insufficientResources {
			failureReasons = append(failureReasons, r.Reason)
		}
		return framework.NewStatus(framework.Unschedulable, failureReasons...)
	}
	return nil
}

// InsufficientResource describes what kind of resource limit is hit and caused the pod to not fit the node.
type InsufficientResource struct {
	ResourceName v1.ResourceName
	// We explicitly have a parameter for reason to avoid formatting a message on the fly
	// for common resources, which is expensive for cluster autoscaler simulations.
	Reason    string
	Requested int64
	Used      int64
	Capacity  int64
}

// Fits checks if node have enough resources to host the pod.
func Fits(pod *v1.Pod, nodeInfo *framework.NodeInfo, enablePodOverhead bool) []InsufficientResource {
	return fitsRequest(computePodResourceRequest(pod, enablePodOverhead), nodeInfo, nil, nil)
}
func RTmilliCPU(ni *framework.NodeInfo) int64 {
	var sum int64
	sum = 0
	fmt.Println("RTMilliCPU check!!")
	for p := range ni.Pods {
		value, exists := ni.Pods[p].Pod.Annotations["RTbandwidth"]
		if exists {
			fmt.Println("Found RT pod on the node!!", value)
			intval, _ := strconv.Atoi(value)
			sum += int64(intval)
		}
	}
	return sum * 10
}

func fitsRequest(podRequest *preFilterState, nodeInfo *framework.NodeInfo, ignoredExtendedResources, ignoredResourceGroups sets.String) []InsufficientResource {
	insufficientResources := make([]InsufficientResource, 0, 4)

	allowedPodNumber := nodeInfo.Allocatable.AllowedPodNumber
	if len(nodeInfo.Pods)+1 > allowedPodNumber {
		insufficientResources = append(insufficientResources, InsufficientResource{
			v1.ResourcePods,
			"Too many pods",
			1,
			int64(len(nodeInfo.Pods)),
			int64(allowedPodNumber),
		})
	}

	if podRequest.MilliCPU == 0 &&
		podRequest.Memory == 0 &&
		podRequest.EphemeralStorage == 0 &&
		len(podRequest.ScalarResources) == 0 {
		return insufficientResources
	}

	if podRequest.MilliCPU > (nodeInfo.Allocatable.MilliCPU - nodeInfo.Requested.MilliCPU - RTmilliCPU(nodeInfo)) {
		insufficientResources = append(insufficientResources, InsufficientResource{
			v1.ResourceCPU,
			"Insufficient cpu",
			podRequest.MilliCPU,
			nodeInfo.Requested.MilliCPU,
			nodeInfo.Allocatable.MilliCPU,
		})
	}
	if podRequest.Memory > (nodeInfo.Allocatable.Memory - nodeInfo.Requested.Memory) {
		insufficientResources = append(insufficientResources, InsufficientResource{
			v1.ResourceMemory,
			"Insufficient memory",
			podRequest.Memory,
			nodeInfo.Requested.Memory,
			nodeInfo.Allocatable.Memory,
		})
	}
	if podRequest.EphemeralStorage > (nodeInfo.Allocatable.EphemeralStorage - nodeInfo.Requested.EphemeralStorage) {
		insufficientResources = append(insufficientResources, InsufficientResource{
			v1.ResourceEphemeralStorage,
			"Insufficient ephemeral-storage",
			podRequest.EphemeralStorage,
			nodeInfo.Requested.EphemeralStorage,
			nodeInfo.Allocatable.EphemeralStorage,
		})
	}

	for rName, rQuant := range podRequest.ScalarResources {
		if v1helper.IsExtendedResourceName(rName) {
			// If this resource is one of the extended resources that should be ignored, we will skip checking it.
			// rName is guaranteed to have a slash due to API validation.
			var rNamePrefix string
			if ignoredResourceGroups.Len() > 0 {
				rNamePrefix = strings.Split(string(rName), "/")[0]
			}
			if ignoredExtendedResources.Has(string(rName)) || ignoredResourceGroups.Has(rNamePrefix) {
				continue
			}
		}
		if rQuant > (nodeInfo.Allocatable.ScalarResources[rName] - nodeInfo.Requested.ScalarResources[rName]) {
			insufficientResources = append(insufficientResources, InsufficientResource{
				rName,
				fmt.Sprintf("Insufficient %v", rName),
				podRequest.ScalarResources[rName],
				nodeInfo.Requested.ScalarResources[rName],
				nodeInfo.Allocatable.ScalarResources[rName],
			})
		}
	}

	return insufficientResources
}

// Score invoked at the Score extension point.
func (f *Fit) Score(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (int64, *framework.Status) {
	nodeInfo, err := f.handle.SnapshotSharedLister().NodeInfos().Get(nodeName)
	if err != nil {
		return 0, framework.AsStatus(fmt.Errorf("getting node %q from Snapshot: %w", nodeName, err))
	}

	return f.score(pod, nodeInfo)
}

func (alloc *Fit) NormalizeScore(ctx context.Context, state *framework.CycleState, pod *v1.Pod, scores framework.NodeScoreList) *framework.Status {
	// Find highest and lowest scores.
	var highest int64 = -math.MaxInt64
	var lowest int64 = math.MaxInt64
	for _, nodeScore := range scores {
		if nodeScore.Score > highest {
			highest = nodeScore.Score
		}
		if nodeScore.Score < lowest {
			lowest = nodeScore.Score
		}
	}

	// Transform the highest to lowest score range to fit the framework's min to max node score range.
	oldRange := highest - lowest
	newRange := framework.MaxNodeScore - framework.MinNodeScore
	for i, nodeScore := range scores {
		if oldRange == 0 {
			scores[i].Score = framework.MinNodeScore
		} else {
			scores[i].Score = ((nodeScore.Score - lowest) * newRange / oldRange) + framework.MinNodeScore
		}
	}

	return nil
}
