/*
Copyright 2014 The Kubernetes Authors.
Copyright 2020 Authors of Arktos - file modified.

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.
*/

// File modified by backporting scheduler 1.18.5 from kubernetes on 05/04/2021
package algorithmprovider

import (
	"sort"
	"strings"

	utilfeature "k8s.io/apiserver/pkg/util/feature"
	"k8s.io/klog"
	"k8s.io/kubernetes/pkg/features"
	schedulerapi "k8s.io/kubernetes/pkg/scheduler/apis/config"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/defaultbinder"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/defaultpodtopologyspread"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/imagelocality"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/interpodaffinity"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodeaffinity"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodename"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodeports"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodepreferavoidpods"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/noderesources"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/noderuntimenotready"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodeunschedulable"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/nodevolumelimits"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/podtopologyspread"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/queuesort"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/tainttoleration"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/volumebinding"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/volumerestrictions"
	"k8s.io/kubernetes/pkg/scheduler/framework/plugins/volumezone"
)

// ClusterAutoscalerProvider defines the default autoscaler provider
const ClusterAutoscalerProvider = "ClusterAutoscalerProvider"

// Registry is a collection of all available algorithm providers.
type Registry map[string]*schedulerapi.Plugins

// NewRegistry returns an algorithm provider registry instance.
func NewRegistry() Registry {
	defaultConfig := getDefaultConfig()
	applyFeatureGates(defaultConfig)

	caConfig := getClusterAutoscalerConfig()
	applyFeatureGates(caConfig)

	return Registry{
		schedulerapi.SchedulerDefaultProviderName: defaultConfig,
		ClusterAutoscalerProvider:                 caConfig,
	}
}

// ListAlgorithmProviders lists registered algorithm providers.
func ListAlgorithmProviders() string {
	r := NewRegistry()
	var providers []string
	for k := range r {
		providers = append(providers, k)
	}
	sort.Strings(providers)
	return strings.Join(providers, " | ")
}

func getDefaultConfig() *schedulerapi.Plugins {
	return &schedulerapi.Plugins{
		QueueSort: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: queuesort.Name},
			},
		},
		PreFilter: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: noderesources.FitName},
				{Name: nodeports.Name},
				{Name: interpodaffinity.Name},
			},
		},
		Filter: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: noderuntimenotready.Name},
				{Name: nodeunschedulable.Name},
				{Name: noderesources.FitName},
				{Name: nodename.Name},
				{Name: nodeports.Name},
				{Name: nodeaffinity.Name},
				{Name: volumerestrictions.Name},
				{Name: tainttoleration.Name},
				{Name: nodevolumelimits.EBSName},
				{Name: nodevolumelimits.GCEPDName},
				{Name: nodevolumelimits.CSIName},
				{Name: nodevolumelimits.AzureDiskName},
				{Name: volumebinding.Name},
				{Name: volumezone.Name},
				{Name: interpodaffinity.Name},
			},
		},
		PreScore: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: interpodaffinity.Name},
				{Name: defaultpodtopologyspread.Name},
				{Name: tainttoleration.Name},
			},
		},
		Score: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: noderesources.BalancedAllocationName, Weight: 1},
				{Name: imagelocality.Name, Weight: 1},
				{Name: interpodaffinity.Name, Weight: 1},
				{Name: noderesources.LeastAllocatedName, Weight: 1},
				{Name: nodeaffinity.Name, Weight: 1},
				{Name: nodepreferavoidpods.Name, Weight: 10000},
				{Name: defaultpodtopologyspread.Name, Weight: 1},
				{Name: tainttoleration.Name, Weight: 1},
			},
		},
		Bind: &schedulerapi.PluginSet{
			Enabled: []schedulerapi.Plugin{
				{Name: defaultbinder.Name},
			},
		},
	}
}

func getClusterAutoscalerConfig() *schedulerapi.Plugins {
	caConfig := getDefaultConfig()
	// Replace least with most requested.
	for i := range caConfig.Score.Enabled {
		if caConfig.Score.Enabled[i].Name == noderesources.LeastAllocatedName {
			caConfig.Score.Enabled[i].Name = noderesources.MostAllocatedName
		}
	}
	return caConfig
}

func applyFeatureGates(config *schedulerapi.Plugins) {
	// Only add EvenPodsSpread if the feature is enabled.
	if utilfeature.DefaultFeatureGate.Enabled(features.EvenPodsSpread) {
		klog.Infof("Registering EvenPodsSpread predicate and priority function")
		f := schedulerapi.Plugin{Name: podtopologyspread.Name}
		config.PreFilter.Enabled = append(config.PreFilter.Enabled, f)
		config.Filter.Enabled = append(config.Filter.Enabled, f)
		config.PreScore.Enabled = append(config.PreScore.Enabled, f)
		s := schedulerapi.Plugin{Name: podtopologyspread.Name, Weight: 1}
		config.Score.Enabled = append(config.Score.Enabled, s)
	}

	// Prioritizes nodes that satisfy pod's resource limits
	if utilfeature.DefaultFeatureGate.Enabled(features.ResourceLimitsPriorityFunction) {
		klog.Infof("Registering resourcelimits priority function")
		s := schedulerapi.Plugin{Name: noderesources.ResourceLimitsName}
		config.PreScore.Enabled = append(config.PreScore.Enabled, s)
		s = schedulerapi.Plugin{Name: noderesources.ResourceLimitsName, Weight: 1}
		config.Score.Enabled = append(config.Score.Enabled, s)
	}
}
