/*
Copyright 2019-2021 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 nfdmaster

import (
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"net"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/google/uuid"
	"golang.org/x/net/context"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/health"
	"google.golang.org/grpc/health/grpc_health_v1"
	"google.golang.org/grpc/peer"
	corev1 "k8s.io/api/core/v1"
	k8sQuantity "k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	k8sLabels "k8s.io/apimachinery/pkg/labels"
	k8svalidation "k8s.io/apimachinery/pkg/util/validation"
	"k8s.io/client-go/kubernetes"
	restclient "k8s.io/client-go/rest"
	"k8s.io/client-go/tools/leaderelection"
	"k8s.io/client-go/tools/leaderelection/resourcelock"
	"k8s.io/klog/v2"
	controller "k8s.io/kubernetes/pkg/controller"
	taintutils "k8s.io/kubernetes/pkg/util/taints"
	"sigs.k8s.io/yaml"

	"sigs.k8s.io/node-feature-discovery/pkg/apihelper"
	nfdv1alpha1 "sigs.k8s.io/node-feature-discovery/pkg/apis/nfd/v1alpha1"
	pb "sigs.k8s.io/node-feature-discovery/pkg/labeler"
	"sigs.k8s.io/node-feature-discovery/pkg/utils"
	"sigs.k8s.io/node-feature-discovery/pkg/version"
)

// Labels are a Kubernetes representation of discovered features.
type Labels map[string]string

// ExtendedResources are k8s extended resources which are created from discovered features.
type ExtendedResources map[string]string

// Annotations are used for NFD-related node metadata
type Annotations map[string]string

// NFDConfig contains the configuration settings of NfdMaster.
type NFDConfig struct {
	DenyLabelNs       utils.StringSetVal
	ExtraLabelNs      utils.StringSetVal
	LabelWhiteList    utils.RegexpVal
	NoPublish         bool
	ResourceLabels    utils.StringSetVal
	EnableTaints      bool
	ResyncPeriod      utils.DurationVal
	LeaderElection    LeaderElectionConfig
	NfdApiParallelism int
}

// LeaderElectionConfig contains the configuration for leader election
type LeaderElectionConfig struct {
	LeaseDuration utils.DurationVal
	RenewDeadline utils.DurationVal
	RetryPeriod   utils.DurationVal
}

// ConfigOverrideArgs are args that override config file options
type ConfigOverrideArgs struct {
	DenyLabelNs       *utils.StringSetVal
	ExtraLabelNs      *utils.StringSetVal
	LabelWhiteList    *utils.RegexpVal
	ResourceLabels    *utils.StringSetVal
	EnableTaints      *bool
	NoPublish         *bool
	ResyncPeriod      *utils.DurationVal
	NfdApiParallelism *int
}

// Args holds command line arguments
type Args struct {
	CaFile               string
	CertFile             string
	ConfigFile           string
	Instance             string
	KeyFile              string
	Kubeconfig           string
	CrdController        bool
	EnableNodeFeatureApi bool
	Port                 int
	Prune                bool
	VerifyNodeName       bool
	Options              string
	EnableLeaderElection bool
	MetricsPort          int

	Overrides ConfigOverrideArgs
}

type deniedNs struct {
	normal   utils.StringSetVal
	wildcard utils.StringSetVal
}

type NfdMaster interface {
	Run() error
	Stop()
	WaitForReady(time.Duration) bool
}

type nfdMaster struct {
	*nfdController

	args            Args
	namespace       string
	nodeName        string
	configFilePath  string
	server          *grpc.Server
	stop            chan struct{}
	ready           chan bool
	apihelper       apihelper.APIHelpers
	kubeconfig      *restclient.Config
	nodeUpdaterPool *nodeUpdaterPool
	deniedNs
	config *NFDConfig
}

// NewNfdMaster creates a new NfdMaster server instance.
func NewNfdMaster(args *Args) (NfdMaster, error) {
	nfd := &nfdMaster{args: *args,
		nodeName:  utils.NodeName(),
		namespace: utils.GetKubernetesNamespace(),
		ready:     make(chan bool, 1),
		stop:      make(chan struct{}, 1),
	}

	if args.Instance != "" {
		if ok, _ := regexp.MatchString(`^([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]$`, args.Instance); !ok {
			return nfd, fmt.Errorf("invalid -instance %q: instance name "+
				"must start and end with an alphanumeric character and may only contain "+
				"alphanumerics, `-`, `_` or `.`", args.Instance)
		}
	}

	// Check TLS related args
	if args.CertFile != "" || args.KeyFile != "" || args.CaFile != "" {
		if args.CertFile == "" {
			return nfd, fmt.Errorf("-cert-file needs to be specified alongside -key-file and -ca-file")
		}
		if args.KeyFile == "" {
			return nfd, fmt.Errorf("-key-file needs to be specified alongside -cert-file and -ca-file")
		}
		if args.CaFile == "" {
			return nfd, fmt.Errorf("-ca-file needs to be specified alongside -cert-file and -key-file")
		}
	}

	if args.ConfigFile != "" {
		nfd.configFilePath = filepath.Clean(args.ConfigFile)
	}

	nfd.nodeUpdaterPool = newNodeUpdaterPool(nfd)

	return nfd, nil
}

func newDefaultConfig() *NFDConfig {
	return &NFDConfig{
		LabelWhiteList:    utils.RegexpVal{Regexp: *regexp.MustCompile("")},
		DenyLabelNs:       utils.StringSetVal{},
		ExtraLabelNs:      utils.StringSetVal{},
		NoPublish:         false,
		NfdApiParallelism: 10,
		ResourceLabels:    utils.StringSetVal{},
		EnableTaints:      false,
		ResyncPeriod:      utils.DurationVal{Duration: time.Duration(1) * time.Hour},
		LeaderElection: LeaderElectionConfig{
			LeaseDuration: utils.DurationVal{Duration: time.Duration(15) * time.Second},
			RetryPeriod:   utils.DurationVal{Duration: time.Duration(2) * time.Second},
			RenewDeadline: utils.DurationVal{Duration: time.Duration(10) * time.Second},
		},
	}
}

// Run NfdMaster server. The method returns in case of fatal errors or if Stop()
// is called.
func (m *nfdMaster) Run() error {
	klog.InfoS("Node Feature Discovery Master", "version", version.Get(), "nodeName", m.nodeName, "namespace", m.namespace)
	if m.args.Instance != "" {
		klog.InfoS("Master instance", "instance", m.args.Instance)
	}

	// Read initial configuration
	if err := m.configure(m.configFilePath, m.args.Options); err != nil {
		return err
	}

	if m.args.Prune {
		return m.prune()
	}

	if m.args.CrdController {
		err := m.startNfdApiController()
		if err != nil {
			return err
		}
	}

	m.nodeUpdaterPool.start(m.config.NfdApiParallelism)

	// Create watcher for config file
	configWatch, err := utils.CreateFsWatcher(time.Second, m.configFilePath)
	if err != nil {
		return err
	}

	if !m.config.NoPublish {
		err := m.updateMasterNode()
		if err != nil {
			return fmt.Errorf("failed to update master node: %v", err)
		}
	}

	// Register to metrics server
	if m.args.MetricsPort > 0 {
		go runMetricsServer(m.args.MetricsPort)
		registerVersion(version.Get())
		defer stopMetricsServer()
	}

	// Run gRPC server
	grpcErr := make(chan error, 1)
	go m.runGrpcServer(grpcErr)

	// Run updater that handles events from the nfd CRD API.
	if m.nfdController != nil {
		if m.args.EnableLeaderElection {
			go m.nfdAPIUpdateHandlerWithLeaderElection()
		} else {
			go m.nfdAPIUpdateHandler()
		}
	}

	// Notify that we're ready to accept connections
	m.ready <- true
	close(m.ready)

	// NFD-Master main event loop
	for {
		select {
		case err := <-grpcErr:
			return fmt.Errorf("error in serving gRPC: %w", err)

		case <-configWatch.Events:
			klog.InfoS("reloading configuration")
			if err := m.configure(m.configFilePath, m.args.Options); err != nil {
				return err
			}

			// restart NFD API controller
			if m.nfdController != nil {
				klog.InfoS("stopping the nfd api controller")
				m.nfdController.stop()
			}
			if m.args.CrdController {
				err := m.startNfdApiController()
				if err != nil {
					return nil
				}
			}
			// Update all nodes when the configuration changes
			if m.nfdController != nil && m.args.EnableNodeFeatureApi {
				m.nfdController.updateAllNodesChan <- struct{}{}
			}
			// Restart the node updater pool
			m.nodeUpdaterPool.stop()
			m.nodeUpdaterPool.start(m.config.NfdApiParallelism)

		case <-m.stop:
			klog.InfoS("shutting down nfd-master")
			return nil
		}
	}
}

func (m *nfdMaster) runGrpcServer(errChan chan<- error) {
	// Create server listening for TCP connections
	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", m.args.Port))
	if err != nil {
		errChan <- fmt.Errorf("failed to listen: %v", err)
		return
	}

	serverOpts := []grpc.ServerOption{}
	tlsConfig := utils.TlsConfig{}
	// Create watcher for TLS cert files
	certWatch, err := utils.CreateFsWatcher(time.Second, m.args.CertFile, m.args.KeyFile, m.args.CaFile)
	if err != nil {
		errChan <- err
		return
	}
	// Enable mutual TLS authentication if -cert-file, -key-file or -ca-file
	// is defined
	if m.args.CertFile != "" || m.args.KeyFile != "" || m.args.CaFile != "" {
		if err := tlsConfig.UpdateConfig(m.args.CertFile, m.args.KeyFile, m.args.CaFile); err != nil {
			errChan <- err
			return
		}

		tlsConfig := &tls.Config{GetConfigForClient: tlsConfig.GetConfig}
		serverOpts = append(serverOpts, grpc.Creds(credentials.NewTLS(tlsConfig)))
	}
	m.server = grpc.NewServer(serverOpts...)

	// If the NodeFeature API is enabled, don'tregister the labeler API
	// server. Otherwise, register the labeler server.
	if !m.args.EnableNodeFeatureApi {
		pb.RegisterLabelerServer(m.server, m)
	}

	grpc_health_v1.RegisterHealthServer(m.server, health.NewServer())
	klog.InfoS("gRPC server serving", "port", m.args.Port)

	// Run gRPC server
	grpcErr := make(chan error, 1)
	go func() {
		defer lis.Close()
		grpcErr <- m.server.Serve(lis)
	}()

	for {
		select {
		case <-certWatch.Events:
			klog.InfoS("reloading TLS certificates")
			if err := tlsConfig.UpdateConfig(m.args.CertFile, m.args.KeyFile, m.args.CaFile); err != nil {
				errChan <- err
			}

		case err := <-grpcErr:
			if err != nil {
				errChan <- fmt.Errorf("gRPC server exited with an error: %v", err)
			}
			klog.InfoS("gRPC server stopped")
		}
	}
}

// nfdAPIUpdateHandler handles events from the nfd API controller.
func (m *nfdMaster) nfdAPIUpdateHandler() {
	// We want to unconditionally update all nodes at startup if gRPC is
	// disabled (i.e. NodeFeature API is enabled)
	updateAll := m.args.EnableNodeFeatureApi
	updateNodes := make(map[string]struct{})
	rateLimit := time.After(time.Second)
	for {
		select {
		case <-m.nfdController.updateAllNodesChan:
			updateAll = true
		case nodeName := <-m.nfdController.updateOneNodeChan:
			updateNodes[nodeName] = struct{}{}
		case <-rateLimit:
			errUpdateAll := false
			if updateAll {
				if err := m.nfdAPIUpdateAllNodes(); err != nil {
					klog.ErrorS(err, "failed to update nodes")
					errUpdateAll = true
				}
			} else {
				for nodeName := range updateNodes {
					m.nodeUpdaterPool.queue.Add(nodeName)
				}
			}

			// Reset "work queue" and timer
			updateAll = errUpdateAll
			updateNodes = map[string]struct{}{}
			rateLimit = time.After(time.Second)
		}
	}
}

// Stop NfdMaster
func (m *nfdMaster) Stop() {
	m.server.GracefulStop()

	if m.nfdController != nil {
		m.nfdController.stop()
	}

	m.nodeUpdaterPool.stop()

	close(m.stop)
}

// Wait until NfdMaster is able able to accept connections.
func (m *nfdMaster) WaitForReady(timeout time.Duration) bool {
	select {
	case ready, ok := <-m.ready:
		// Ready if the flag is true or the channel has been closed
		if ready || !ok {
			return true
		}
	case <-time.After(timeout):
		return false
	}
	// We should never end-up here
	return false
}

// Prune erases all NFD related properties from the node objects of the cluster.
func (m *nfdMaster) prune() error {
	if m.config.NoPublish {
		klog.InfoS("skipping pruning of nodes as noPublish config option is set")
		return nil
	}

	cli, err := m.apihelper.GetClient()
	if err != nil {
		return err
	}

	nodes, err := m.apihelper.GetNodes(cli)
	if err != nil {
		return err
	}

	for _, node := range nodes.Items {
		klog.InfoS("pruning node...", "nodeName", node.Name)

		// Prune labels and extended resources
		err := m.updateNodeObject(cli, node.Name, Labels{}, Annotations{}, ExtendedResources{}, []corev1.Taint{})
		if err != nil {
			return fmt.Errorf("failed to prune node %q: %v", node.Name, err)
		}

		// Prune annotations
		node, err := m.apihelper.GetNode(cli, node.Name)
		if err != nil {
			return err
		}
		for a := range node.Annotations {
			if strings.HasPrefix(a, m.instanceAnnotation(nfdv1alpha1.AnnotationNs)) {
				delete(node.Annotations, a)
			}
		}
		err = m.apihelper.UpdateNode(cli, node)
		if err != nil {
			return fmt.Errorf("failed to prune annotations from node %q: %v", node.Name, err)
		}
	}
	return nil
}

// Advertise NFD master information
func (m *nfdMaster) updateMasterNode() error {
	cli, err := m.apihelper.GetClient()
	if err != nil {
		return err
	}
	node, err := m.apihelper.GetNode(cli, m.nodeName)
	if err != nil {
		return err
	}

	// Advertise NFD version as an annotation
	p := createPatches(nil,
		node.Annotations,
		Annotations{m.instanceAnnotation(nfdv1alpha1.MasterVersionAnnotation): version.Get()},
		"/metadata/annotations")
	err = m.apihelper.PatchNode(cli, node.Name, p)
	if err != nil {
		return fmt.Errorf("failed to patch node annotations: %v", err)
	}

	return nil
}

// Filter labels by namespace and name whitelist, and, turn selected labels
// into extended resources. This function also handles proper namespacing of
// labels and ERs, i.e. adds the possibly missing default namespace for labels
// arriving through the gRPC API.
func (m *nfdMaster) filterFeatureLabels(labels Labels, features *nfdv1alpha1.Features) (Labels, ExtendedResources) {
	outLabels := Labels{}
	for name, value := range labels {
		// Add possibly missing default ns
		name := addNs(name, nfdv1alpha1.FeatureLabelNs)

		if value, err := m.filterFeatureLabel(name, value, features); err != nil {
			klog.ErrorS(err, "ignoring label", "labelKey", name, "labelValue", value)
		} else {
			outLabels[name] = value
		}
	}

	// Remove labels which are intended to be extended resources
	extendedResources := ExtendedResources{}
	for extendedResourceName := range m.config.ResourceLabels {
		// Add possibly missing default ns
		extendedResourceName = addNs(extendedResourceName, nfdv1alpha1.FeatureLabelNs)
		if value, ok := outLabels[extendedResourceName]; ok {
			if _, err := strconv.Atoi(value); err != nil {
				klog.ErrorS(err, "bad label value encountered for extended resource", "labelKey", extendedResourceName, "labelValue", value)
				continue // non-numeric label can't be used
			}

			extendedResources[extendedResourceName] = value
			delete(outLabels, extendedResourceName)
		}
	}

	return outLabels, extendedResources
}

func (m *nfdMaster) filterFeatureLabel(name, value string, features *nfdv1alpha1.Features) (string, error) {

	//Validate label name
	if errs := k8svalidation.IsQualifiedName(name); len(errs) > 0 {
		return "", fmt.Errorf("invalid name %q: %s", name, strings.Join(errs, "; "))
	}

	// Check label namespace, filter out if ns is not whitelisted
	ns, base := splitNs(name)
	if ns != nfdv1alpha1.FeatureLabelNs && ns != nfdv1alpha1.ProfileLabelNs &&
		!strings.HasSuffix(ns, nfdv1alpha1.FeatureLabelSubNsSuffix) && !strings.HasSuffix(ns, nfdv1alpha1.ProfileLabelSubNsSuffix) {
		// If the namespace is denied, and not present in the extraLabelNs, label will be ignored
		if isNamespaceDenied(ns, m.deniedNs.wildcard, m.deniedNs.normal) {
			if _, ok := m.config.ExtraLabelNs[ns]; !ok {
				return "", fmt.Errorf("namespace %q is not allowed", ns)
			}
		}
	}

	// Skip if label doesn't match labelWhiteList
	if !m.config.LabelWhiteList.Regexp.MatchString(base) {
		return "", fmt.Errorf("%s (%s) does not match the whitelist (%s)", base, name, m.config.LabelWhiteList.Regexp.String())
	}

	var filteredLabel string

	// Dynamic Value
	if strings.HasPrefix(value, "@") {
		dynamicValue, err := getDynamicValue(value, features)
		if err != nil {
			return "", err
		}
		filteredLabel = dynamicValue
	} else {
		filteredLabel = value
	}

	// Validate the label value
	if errs := k8svalidation.IsValidLabelValue(filteredLabel); len(errs) > 0 {
		return "", fmt.Errorf("invalid value %q: %s", filteredLabel, strings.Join(errs, "; "))
	}
	return filteredLabel, nil
}

func getDynamicValue(value string, features *nfdv1alpha1.Features) (string, error) {
	// value is a string in the form of attribute.featureset.elements
	split := strings.SplitN(value[1:], ".", 3)
	if len(split) != 3 {
		return "", fmt.Errorf("value %s is not in the form of '@domain.feature.element'", value)
	}
	featureName := split[0] + "." + split[1]
	elementName := split[2]
	attrFeatureSet, ok := features.Attributes[featureName]
	if !ok {
		return "", fmt.Errorf("feature %s not found", featureName)
	}
	element, ok := attrFeatureSet.Elements[elementName]
	if !ok {
		return "", fmt.Errorf("element %s not found on feature %s", elementName, featureName)
	}
	return element, nil
}

func filterTaints(taints []corev1.Taint) []corev1.Taint {
	outTaints := []corev1.Taint{}

	for _, taint := range taints {
		if err := filterTaint(&taint); err != nil {
			klog.ErrorS(err, "ignoring taint", "taint", taint)
		} else {
			outTaints = append(outTaints, taint)
		}
	}
	return outTaints
}

func filterTaint(taint *corev1.Taint) error {
	// Check prefix of the key, filter out disallowed ones
	ns, _ := splitNs(taint.Key)
	if ns == "" {
		return fmt.Errorf("taint keys without namespace (prefix/) are not allowed")
	}
	if ns != nfdv1alpha1.TaintNs && !strings.HasSuffix(ns, nfdv1alpha1.TaintSubNsSuffix) &&
		(ns == "kubernetes.io" || strings.HasSuffix(ns, ".kubernetes.io")) {
		return fmt.Errorf("prefix %q is not allowed for taint key", ns)
	}
	return nil
}

func verifyNodeName(cert *x509.Certificate, nodeName string) error {
	if cert.Subject.CommonName == nodeName {
		return nil
	}

	err := cert.VerifyHostname(nodeName)
	if err != nil {
		return fmt.Errorf("certificate %q not valid for node %q: %v", cert.Subject.CommonName, nodeName, err)
	}
	return nil
}

func isNamespaceDenied(labelNs string, wildcardDeniedNs map[string]struct{}, normalDeniedNs map[string]struct{}) bool {
	for deniedNs := range normalDeniedNs {
		if labelNs == deniedNs {
			return true
		}
	}
	for deniedNs := range wildcardDeniedNs {
		if strings.HasSuffix(labelNs, deniedNs) {
			return true
		}
	}
	return false
}

// SetLabels implements LabelerServer
func (m *nfdMaster) SetLabels(c context.Context, r *pb.SetLabelsRequest) (*pb.SetLabelsReply, error) {
	err := authorizeClient(c, m.args.VerifyNodeName, r.NodeName)
	if err != nil {
		klog.ErrorS(err, "gRPC client authorization failed", "nodeName", r.NodeName)
		return &pb.SetLabelsReply{}, err
	}

	switch {
	case klog.V(4).Enabled():
		klog.InfoS("gRPC SetLabels request received", "setLabelsRequest", utils.DelayedDumper(r))
	case klog.V(1).Enabled():
		klog.InfoS("gRPC SetLabels request received", "nodeName", r.NodeName, "nfdVersion", r.NfdVersion, "labels", r.Labels)
	default:
		klog.InfoS("gRPC SetLabels request received", "nodeName", r.NodeName)
	}
	if !m.config.NoPublish {
		cli, err := m.apihelper.GetClient()
		if err != nil {
			return &pb.SetLabelsReply{}, err
		}

		// Advertise NFD worker version as an annotation
		annotations := Annotations{m.instanceAnnotation(nfdv1alpha1.WorkerVersionAnnotation): r.NfdVersion}

		// Create labels et al
		if err := m.refreshNodeFeatures(cli, r.NodeName, annotations, r.GetLabels(), r.GetFeatures()); err != nil {
			return &pb.SetLabelsReply{}, err
		}
	}
	return &pb.SetLabelsReply{}, nil
}

func (m *nfdMaster) nfdAPIUpdateAllNodes() error {
	klog.InfoS("will process all nodes in the cluster")

	cli, err := m.apihelper.GetClient()
	if err != nil {
		return err
	}

	nodes, err := m.apihelper.GetNodes(cli)
	if err != nil {
		return err
	}

	for _, node := range nodes.Items {
		m.nodeUpdaterPool.queue.Add(node.Name)
	}

	return nil
}

func (m *nfdMaster) nfdAPIUpdateOneNode(nodeName string) error {
	if m.nfdController == nil || m.nfdController.featureLister == nil {
		return nil
	}

	sel := k8sLabels.SelectorFromSet(k8sLabels.Set{nfdv1alpha1.NodeFeatureObjNodeNameLabel: nodeName})
	objs, err := m.nfdController.featureLister.List(sel)
	if err != nil {
		return fmt.Errorf("failed to get NodeFeature resources for node %q: %w", nodeName, err)
	}

	// Sort our objects
	sort.Slice(objs, func(i, j int) bool {
		// Objects in our nfd namespace gets into the beginning of the list
		if objs[i].Namespace == m.namespace && objs[j].Namespace != m.namespace {
			return true
		}
		if objs[i].Namespace != m.namespace && objs[j].Namespace == m.namespace {
			return false
		}
		// After the nfd namespace, sort objects by their name
		if objs[i].Name != objs[j].Name {
			return objs[i].Name < objs[j].Name
		}
		// Objects with the same name are sorted by their namespace
		return objs[i].Namespace < objs[j].Namespace
	})

	if m.config.NoPublish {
		return nil
	}

	klog.V(1).InfoS("processing of node initiated by NodeFeature API", "nodeName", nodeName)

	features := nfdv1alpha1.NewNodeFeatureSpec()

	annotations := Annotations{}

	if len(objs) > 0 {
		// Merge in features
		//
		// NOTE: changing the rule api to support handle multiple objects instead
		// of merging would probably perform better with lot less data to copy.
		features = objs[0].Spec.DeepCopy()
		for _, o := range objs[1:] {
			o.Spec.MergeInto(features)
		}

		klog.V(4).InfoS("merged nodeFeatureSpecs", "newNodeFeatureSpec", utils.DelayedDumper(features))

		if objs[0].Namespace == m.namespace && objs[0].Name == nodeName {
			// This is the one created by nfd-worker
			if v := objs[0].Annotations[nfdv1alpha1.WorkerVersionAnnotation]; v != "" {
				annotations[nfdv1alpha1.WorkerVersionAnnotation] = v
			}
		}
	}

	// Update node labels et al. This may also mean removing all NFD-owned
	// labels (et al.), for example  in the case no NodeFeature objects are
	// present.
	cli, err := m.apihelper.GetClient()
	if err != nil {
		return err
	}
	if err := m.refreshNodeFeatures(cli, nodeName, annotations, features.Labels, &features.Features); err != nil {
		return err
	}

	return nil
}

// filterExtendedResources filters extended resources and returns a map
// of valid extended resources.
func filterExtendedResources(features *nfdv1alpha1.Features, extendedResources ExtendedResources) ExtendedResources {
	outExtendedResources := ExtendedResources{}
	for name, value := range extendedResources {
		// Add possibly missing default ns
		name = addNs(name, nfdv1alpha1.ExtendedResourceNs)

		capacity, err := filterExtendedResource(name, value, features)
		if err != nil {
			klog.ErrorS(err, "failed to create extended resources", "extendedResourceName", name, "extendedResourceValue", value)
		} else {
			outExtendedResources[name] = capacity
		}
	}
	return outExtendedResources
}

func filterExtendedResource(name, value string, features *nfdv1alpha1.Features) (string, error) {
	// Check if given NS is allowed
	ns, _ := splitNs(name)
	if ns != nfdv1alpha1.ExtendedResourceNs && !strings.HasPrefix(ns, nfdv1alpha1.ExtendedResourceSubNsSuffix) {
		if ns == "kubernetes.io" || strings.HasSuffix(ns, ".kubernetes.io") {
			return "", fmt.Errorf("namespace %q is not allowed", ns)
		}
	}

	// Dynamic Value
	if strings.HasPrefix(value, "@") {
		if element, err := getDynamicValue(value, features); err != nil {
			return "", err
		} else {
			q, err := k8sQuantity.ParseQuantity(element)
			if err != nil {
				return "", fmt.Errorf("invalid value %s (from %s): %w", element, value, err)
			}
			return q.String(), nil
		}
	}
	// Static Value (Pre-Defined at the NodeFeatureRule)
	q, err := k8sQuantity.ParseQuantity(value)
	if err != nil {
		return "", fmt.Errorf("invalid value %s: %w", value, err)
	}
	return q.String(), nil
}

func (m *nfdMaster) refreshNodeFeatures(cli *kubernetes.Clientset, nodeName string, annotations Annotations, labels map[string]string, features *nfdv1alpha1.Features) error {
	if labels == nil {
		labels = make(map[string]string)
	}

	crLabels, crExtendedResources, crTaints := m.processNodeFeatureRule(nodeName, features)

	// Mix in CR-originated labels
	for k, v := range crLabels {
		labels[k] = v
	}

	// Remove labels which are intended to be extended resources via
	// -resource-labels or their NS is not whitelisted
	labels, extendedResources := m.filterFeatureLabels(labels, features)

	// Mix in CR-originated extended resources with -resource-labels
	for k, v := range crExtendedResources {
		extendedResources[k] = v
	}
	extendedResources = filterExtendedResources(features, extendedResources)

	var taints []corev1.Taint
	if m.config.EnableTaints {
		taints = filterTaints(crTaints)
	}

	err := m.updateNodeObject(cli, nodeName, labels, annotations, extendedResources, taints)
	if err != nil {
		klog.ErrorS(err, "failed to update node", "nodeName", nodeName)
		return err
	}

	return nil
}

// setTaints sets node taints and annotations based on the taints passed via
// nodeFeatureRule custom resorce. If empty list of taints is passed, currently
// NFD owned taints and annotations are removed from the node.
func (m *nfdMaster) setTaints(cli *kubernetes.Clientset, taints []corev1.Taint, nodeName string) error {
	// Fetch the node object.
	node, err := m.apihelper.GetNode(cli, nodeName)
	if err != nil {
		return err
	}

	// De-serialize the taints annotation into corev1.Taint type for comparision below.
	oldTaints := []corev1.Taint{}
	if val, ok := node.Annotations[nfdv1alpha1.NodeTaintsAnnotation]; ok {
		sts := strings.Split(val, ",")
		oldTaints, _, err = taintutils.ParseTaints(sts)
		if err != nil {
			return err
		}
	}

	// Delete old nfd-managed taints that are not found in the set of new taints.
	taintsUpdated := false
	newNode := node.DeepCopy()
	for _, taintToRemove := range oldTaints {
		if taintutils.TaintExists(taints, &taintToRemove) {
			continue
		}

		newTaints, removed := taintutils.DeleteTaint(newNode.Spec.Taints, &taintToRemove)
		if !removed {
			klog.V(1).InfoS("taint already deleted from node", "taint", taintToRemove)
		}
		taintsUpdated = taintsUpdated || removed
		newNode.Spec.Taints = newTaints
	}

	// Add new taints found in the set of new taints.
	for _, taint := range taints {
		var updated bool
		newNode, updated, err = taintutils.AddOrUpdateTaint(newNode, &taint)
		if err != nil {
			return fmt.Errorf("failed to add %q taint on node %v", taint, node.Name)
		}
		taintsUpdated = taintsUpdated || updated
	}

	if taintsUpdated {
		err = controller.PatchNodeTaints(context.TODO(), cli, nodeName, node, newNode)
		if err != nil {
			return fmt.Errorf("failed to patch the node %v", node.Name)
		}
		klog.InfoS("updated node taints", "nodeName", nodeName)
	}

	// Update node annotation that holds the taints managed by us
	newAnnotations := map[string]string{}
	if len(taints) > 0 {
		// Serialize the new taints into string and update the annotation
		// with that string.
		taintStrs := make([]string, 0, len(taints))
		for _, taint := range taints {
			taintStrs = append(taintStrs, taint.ToString())
		}
		newAnnotations[nfdv1alpha1.NodeTaintsAnnotation] = strings.Join(taintStrs, ",")
	}

	patches := createPatches([]string{nfdv1alpha1.NodeTaintsAnnotation}, node.Annotations, newAnnotations, "/metadata/annotations")
	if len(patches) > 0 {
		err = m.apihelper.PatchNode(cli, node.Name, patches)
		if err != nil {
			return fmt.Errorf("error while patching node object: %v", err)
		}
		klog.V(1).InfoS("patched node annotations for taints", "nodeName", nodeName)
	}
	return nil
}

func authorizeClient(c context.Context, checkNodeName bool, nodeName string) error {
	if checkNodeName {
		// Client authorization.
		// Check that the node name matches the CN from the TLS cert
		client, ok := peer.FromContext(c)
		if !ok {
			return fmt.Errorf("failed to get peer (client)")
		}
		tlsAuth, ok := client.AuthInfo.(credentials.TLSInfo)
		if !ok {
			return fmt.Errorf("incorrect client credentials")
		}
		if len(tlsAuth.State.VerifiedChains) == 0 || len(tlsAuth.State.VerifiedChains[0]) == 0 {
			return fmt.Errorf("client certificate verification failed")
		}

		err := verifyNodeName(tlsAuth.State.VerifiedChains[0][0], nodeName)
		if err != nil {
			return err
		}
	}
	return nil
}

func (m *nfdMaster) processNodeFeatureRule(nodeName string, features *nfdv1alpha1.Features) (Labels, ExtendedResources, []corev1.Taint) {
	if m.nfdController == nil {
		return nil, nil, nil
	}

	extendedResources := ExtendedResources{}
	labels := make(map[string]string)
	var taints []corev1.Taint
	ruleSpecs, err := m.nfdController.ruleLister.List(k8sLabels.Everything())
	sort.Slice(ruleSpecs, func(i, j int) bool {
		return ruleSpecs[i].Name < ruleSpecs[j].Name
	})

	if err != nil {
		klog.ErrorS(err, "failed to list NodeFeatureRule resources")
		return nil, nil, nil
	}

	// Process all rule CRs
	processStart := time.Now()
	for _, spec := range ruleSpecs {
		t := time.Now()
		switch {
		case klog.V(3).Enabled():
			klog.InfoS("executing NodeFeatureRule", "nodefeaturerule", klog.KObj(spec), "nodeName", nodeName, "nodeFeatureRuleSpec", utils.DelayedDumper(spec.Spec))
		case klog.V(1).Enabled():
			klog.InfoS("executing NodeFeatureRule", "nodefeaturerule", klog.KObj(spec), "nodeName", nodeName)
		}
		for _, rule := range spec.Spec.Rules {
			ruleOut, err := rule.Execute(features)
			if err != nil {
				klog.ErrorS(err, "failed to process rule", "ruleName", rule.Name, "nodefeaturerule", klog.KObj(spec), "nodeName", nodeName)
				continue
			}
			taints = append(taints, ruleOut.Taints...)
			for k, v := range ruleOut.Labels {
				labels[k] = v
			}
			for k, v := range ruleOut.ExtendedResources {
				extendedResources[k] = v
			}

			// Feed back rule output to features map for subsequent rules to match
			features.InsertAttributeFeatures(nfdv1alpha1.RuleBackrefDomain, nfdv1alpha1.RuleBackrefFeature, ruleOut.Labels)
			features.InsertAttributeFeatures(nfdv1alpha1.RuleBackrefDomain, nfdv1alpha1.RuleBackrefFeature, ruleOut.Vars)
		}
		nfrProcessingTime.WithLabelValues(spec.Name, nodeName).Observe(time.Since(t).Seconds())
	}
	processingTime := time.Since(processStart)
	klog.V(2).InfoS("processed NodeFeatureRule objects", "nodeName", nodeName, "objectCount", len(ruleSpecs), "duration", processingTime)

	return labels, extendedResources, taints
}

// updateNodeObject ensures the Kubernetes node object is up to date,
// creating new labels and extended resources where necessary and removing
// outdated ones. Also updates the corresponding annotations.
func (m *nfdMaster) updateNodeObject(cli *kubernetes.Clientset, nodeName string, labels Labels, annotations Annotations, extendedResources ExtendedResources, taints []corev1.Taint) error {
	if cli == nil {
		return fmt.Errorf("no client is passed, client:  %v", cli)
	}

	// Get the worker node object
	node, err := m.apihelper.GetNode(cli, nodeName)
	if err != nil {
		return err
	}

	// Store names of labels in an annotation
	if len(labels) > 0 {
		labelKeys := make([]string, 0, len(labels))
		for key := range labels {
			// Drop the ns part for labels in the default ns
			labelKeys = append(labelKeys, strings.TrimPrefix(key, nfdv1alpha1.FeatureLabelNs+"/"))
		}
		sort.Strings(labelKeys)
		annotations[m.instanceAnnotation(nfdv1alpha1.FeatureLabelsAnnotation)] = strings.Join(labelKeys, ",")
	}

	// Store names of extended resources in an annotation
	if len(extendedResources) > 0 {
		extendedResourceKeys := make([]string, 0, len(extendedResources))
		for key := range extendedResources {
			// Drop the ns part if in the default ns
			extendedResourceKeys = append(extendedResourceKeys, strings.TrimPrefix(key, nfdv1alpha1.FeatureLabelNs+"/"))
		}
		sort.Strings(extendedResourceKeys)
		annotations[m.instanceAnnotation(nfdv1alpha1.ExtendedResourceAnnotation)] = strings.Join(extendedResourceKeys, ",")
	}

	// Create JSON patches for changes in labels and annotations
	oldLabels := stringToNsNames(node.Annotations[m.instanceAnnotation(nfdv1alpha1.FeatureLabelsAnnotation)], nfdv1alpha1.FeatureLabelNs)
	patches := createPatches(oldLabels, node.Labels, labels, "/metadata/labels")
	patches = append(patches,
		createPatches(
			[]string{nfdv1alpha1.FeatureLabelsAnnotation, nfdv1alpha1.ExtendedResourceAnnotation},
			node.Annotations,
			annotations,
			"/metadata/annotations")...)

	// patch node status with extended resource changes
	statusPatches := m.createExtendedResourcePatches(node, extendedResources)
	err = m.apihelper.PatchNodeStatus(cli, node.Name, statusPatches)
	if err != nil {
		return fmt.Errorf("error while patching extended resources: %v", err)
	}

	// Patch the node object in the apiserver
	err = m.apihelper.PatchNode(cli, node.Name, patches)
	if err != nil {
		return fmt.Errorf("error while patching node object: %v", err)
	}

	if len(patches) > 0 || len(statusPatches) > 0 {
		nodeUpdates.Inc()
		klog.InfoS("node updated", "nodeName", nodeName)
	} else {
		klog.V(1).InfoS("no updates to node", "nodeName", nodeName)
	}

	// Set taints
	err = m.setTaints(cli, taints, node.Name)
	if err != nil {
		return err
	}

	return err
}

func (m *nfdMaster) getKubeconfig() (*restclient.Config, error) {
	var err error
	if m.kubeconfig == nil {
		m.kubeconfig, err = apihelper.GetKubeconfig(m.args.Kubeconfig)
	}
	return m.kubeconfig, err
}

// createPatches is a generic helper that returns json patch operations to perform
func createPatches(removeKeys []string, oldItems map[string]string, newItems map[string]string, jsonPath string) []apihelper.JsonPatch {
	patches := []apihelper.JsonPatch{}

	// Determine items to remove
	for _, key := range removeKeys {
		if _, ok := oldItems[key]; ok {
			if _, ok := newItems[key]; !ok {
				patches = append(patches, apihelper.NewJsonPatch("remove", jsonPath, key, ""))
			}
		}
	}

	// Determine items to add or replace
	for key, newVal := range newItems {
		if oldVal, ok := oldItems[key]; ok {
			if newVal != oldVal {
				patches = append(patches, apihelper.NewJsonPatch("replace", jsonPath, key, newVal))
			}
		} else {
			patches = append(patches, apihelper.NewJsonPatch("add", jsonPath, key, newVal))
		}
	}

	return patches
}

// createExtendedResourcePatches returns a slice of operations to perform on
// the node status
func (m *nfdMaster) createExtendedResourcePatches(n *corev1.Node, extendedResources ExtendedResources) []apihelper.JsonPatch {
	patches := []apihelper.JsonPatch{}

	// Form a list of namespaced resource names managed by us
	oldResources := stringToNsNames(n.Annotations[m.instanceAnnotation(nfdv1alpha1.ExtendedResourceAnnotation)], nfdv1alpha1.FeatureLabelNs)

	// figure out which resources to remove
	for _, resource := range oldResources {
		if _, ok := n.Status.Capacity[corev1.ResourceName(resource)]; ok {
			// check if the ext resource is still needed
			if _, extResNeeded := extendedResources[resource]; !extResNeeded {
				patches = append(patches, apihelper.NewJsonPatch("remove", "/status/capacity", resource, ""))
				patches = append(patches, apihelper.NewJsonPatch("remove", "/status/allocatable", resource, ""))
			}
		}
	}

	// figure out which resources to replace and which to add
	for resource, value := range extendedResources {
		// check if the extended resource already exists with the same capacity in the node
		if quantity, ok := n.Status.Capacity[corev1.ResourceName(resource)]; ok {
			val, _ := quantity.AsInt64()
			if strconv.FormatInt(val, 10) != value {
				patches = append(patches, apihelper.NewJsonPatch("replace", "/status/capacity", resource, value))
				patches = append(patches, apihelper.NewJsonPatch("replace", "/status/allocatable", resource, value))
			}
		} else {
			patches = append(patches, apihelper.NewJsonPatch("add", "/status/capacity", resource, value))
			// "allocatable" gets added implicitly after adding to capacity
		}
	}

	return patches
}

// Parse configuration options
func (m *nfdMaster) configure(filepath string, overrides string) error {
	// Create a new default config
	c := newDefaultConfig()

	// Try to read and parse config file
	if filepath != "" {
		data, err := os.ReadFile(filepath)
		if err != nil {
			if os.IsNotExist(err) {
				klog.InfoS("config file not found, using defaults", "path", filepath)
			} else {
				return fmt.Errorf("error reading config file: %w", err)
			}
		} else {
			err = yaml.Unmarshal(data, c)
			if err != nil {
				return fmt.Errorf("failed to parse config file: %w", err)
			}

			klog.InfoS("configuration file parsed", "path", filepath)
		}
	}

	// Parse config overrides
	if err := yaml.Unmarshal([]byte(overrides), c); err != nil {
		return fmt.Errorf("failed to parse -options: %s", err)
	}
	if m.args.Overrides.NoPublish != nil {
		c.NoPublish = *m.args.Overrides.NoPublish
	}
	if m.args.Overrides.DenyLabelNs != nil {
		c.DenyLabelNs = *m.args.Overrides.DenyLabelNs
	}
	if m.args.Overrides.ExtraLabelNs != nil {
		c.ExtraLabelNs = *m.args.Overrides.ExtraLabelNs
	}
	if m.args.Overrides.ResourceLabels != nil {
		c.ResourceLabels = *m.args.Overrides.ResourceLabels
	}
	if m.args.Overrides.EnableTaints != nil {
		c.EnableTaints = *m.args.Overrides.EnableTaints
	}
	if m.args.Overrides.LabelWhiteList != nil {
		c.LabelWhiteList = *m.args.Overrides.LabelWhiteList
	}
	if m.args.Overrides.ResyncPeriod != nil {
		c.ResyncPeriod = *m.args.Overrides.ResyncPeriod
	}
	if m.args.Overrides.NfdApiParallelism != nil {
		c.NfdApiParallelism = *m.args.Overrides.NfdApiParallelism
	}

	if c.NfdApiParallelism <= 0 {
		return fmt.Errorf("the maximum number of concurrent labelers should be a non-zero positive number")
	}

	m.config = c
	if !c.NoPublish {
		kubeconfig, err := m.getKubeconfig()
		if err != nil {
			return err
		}
		m.apihelper = apihelper.K8sHelpers{Kubeconfig: kubeconfig}
	}

	// Pre-process DenyLabelNS into 2 lists: one for normal ns, and the other for wildcard ns
	normalDeniedNs, wildcardDeniedNs := preProcessDeniedNamespaces(c.DenyLabelNs)
	m.deniedNs.normal = normalDeniedNs
	m.deniedNs.wildcard = wildcardDeniedNs
	// We forcibly deny kubernetes.io
	m.deniedNs.normal[""] = struct{}{}
	m.deniedNs.normal["kubernetes.io"] = struct{}{}
	m.deniedNs.wildcard[".kubernetes.io"] = struct{}{}

	klog.InfoS("configuration successfully updated", "configuration", utils.DelayedDumper(m.config))

	return nil
}

// addNs adds a namespace if one isn't already found from src string
func addNs(src string, nsToAdd string) string {
	if strings.Contains(src, "/") {
		return src
	}
	return path.Join(nsToAdd, src)
}

// splitNs splits a name into its namespace and name parts
func splitNs(fullname string) (string, string) {
	split := strings.SplitN(fullname, "/", 2)
	if len(split) == 2 {
		return split[0], split[1]
	}
	return "", fullname
}

// stringToNsNames is a helper for converting a string of comma-separated names
// into a slice of fully namespaced names
func stringToNsNames(cslist, ns string) []string {
	var names []string
	if cslist != "" {
		names = strings.Split(cslist, ",")
		for i, name := range names {
			// Expect that names may omit the ns part
			names[i] = addNs(name, ns)
		}
	}
	return names
}

// Seperate denied namespaces into two lists:
// one contains wildcard namespaces the other contains normal namespaces
func preProcessDeniedNamespaces(deniedNs map[string]struct{}) (normalDeniedNs map[string]struct{}, wildcardDeniedNs map[string]struct{}) {
	normalDeniedNs = map[string]struct{}{}
	wildcardDeniedNs = map[string]struct{}{}
	for ns := range deniedNs {
		if strings.HasPrefix(ns, "*") {
			trimedNs := strings.TrimLeft(ns, "*")
			wildcardDeniedNs[trimedNs] = struct{}{}
		} else {
			normalDeniedNs[ns] = struct{}{}
		}
	}
	return
}

func (m *nfdMaster) instanceAnnotation(name string) string {
	if m.args.Instance == "" {
		return name
	}
	return m.args.Instance + "." + name
}

func (m *nfdMaster) startNfdApiController() error {
	kubeconfig, err := m.getKubeconfig()
	if err != nil {
		return err
	}
	klog.InfoS("starting the nfd api controller")
	m.nfdController, err = newNfdController(kubeconfig, nfdApiControllerOptions{
		DisableNodeFeature: !m.args.EnableNodeFeatureApi,
		ResyncPeriod:       m.config.ResyncPeriod.Duration,
	})
	if err != nil {
		return fmt.Errorf("failed to initialize CRD controller: %w", err)
	}
	return nil
}

func (m *nfdMaster) nfdAPIUpdateHandlerWithLeaderElection() {
	ctx := context.Background()
	client, err := m.apihelper.GetClient()
	if err != nil {
		klog.ErrorS(err, "failed to get Kubernetes client")
		m.Stop()
	}
	lock := &resourcelock.LeaseLock{
		LeaseMeta: metav1.ObjectMeta{
			Name:      "nfd-master.nfd.kubernetes.io",
			Namespace: m.namespace,
		},
		Client: client.CoordinationV1(),
		LockConfig: resourcelock.ResourceLockConfig{
			// add uuid to prevent situation where 2 nfd-master nodes run on same node
			Identity: m.nodeName + "_" + uuid.NewString(),
		},
	}
	config := leaderelection.LeaderElectionConfig{
		Lock: lock,
		// make it configurable?
		LeaseDuration: m.config.LeaderElection.LeaseDuration.Duration,
		RetryPeriod:   m.config.LeaderElection.RetryPeriod.Duration,
		RenewDeadline: m.config.LeaderElection.RenewDeadline.Duration,
		Callbacks: leaderelection.LeaderCallbacks{
			OnStartedLeading: func(_ context.Context) {
				m.nfdAPIUpdateHandler()
			},
			OnStoppedLeading: func() {
				// We lost the lock.
				klog.ErrorS(err, "leaderelection lock was lost")
				m.Stop()
			},
		},
	}
	leaderElector, err := leaderelection.NewLeaderElector(config)
	if err != nil {
		klog.ErrorS(err, "couldn't create leader elector")
		m.Stop()
	}

	leaderElector.Run(ctx)
}