/*
Copyright 2017 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 node

import (
	"time"

	"k8s.io/klog/v2"

	corev1 "k8s.io/api/core/v1"
	resourcev1alpha2 "k8s.io/api/resource/v1alpha2"
	storagev1 "k8s.io/api/storage/v1"
	"k8s.io/apimachinery/pkg/util/wait"
	corev1informers "k8s.io/client-go/informers/core/v1"
	resourcev1alpha2informers "k8s.io/client-go/informers/resource/v1alpha2"
	storageinformers "k8s.io/client-go/informers/storage/v1"
	"k8s.io/client-go/tools/cache"
)

type graphPopulator struct {
	graph *Graph
}

func AddGraphEventHandlers(
	graph *Graph,
	nodes corev1informers.NodeInformer,
	pods corev1informers.PodInformer,
	pvs corev1informers.PersistentVolumeInformer,
	attachments storageinformers.VolumeAttachmentInformer,
	slices resourcev1alpha2informers.ResourceSliceInformer,
) {
	g := &graphPopulator{
		graph: graph,
	}

	podHandler, _ := pods.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    g.addPod,
		UpdateFunc: g.updatePod,
		DeleteFunc: g.deletePod,
	})

	pvsHandler, _ := pvs.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    g.addPV,
		UpdateFunc: g.updatePV,
		DeleteFunc: g.deletePV,
	})

	attachHandler, _ := attachments.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    g.addVolumeAttachment,
		UpdateFunc: g.updateVolumeAttachment,
		DeleteFunc: g.deleteVolumeAttachment,
	})

	synced := []cache.InformerSynced{
		podHandler.HasSynced, pvsHandler.HasSynced, attachHandler.HasSynced,
	}

	if slices != nil {
		sliceHandler, _ := slices.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
			AddFunc:    g.addResourceSlice,
			UpdateFunc: nil, // Not needed, NodeName is immutable.
			DeleteFunc: g.deleteResourceSlice,
		})
		synced = append(synced, sliceHandler.HasSynced)
	}

	go cache.WaitForNamedCacheSync("node_authorizer", wait.NeverStop, synced...)
}

func (g *graphPopulator) addPod(obj interface{}) {
	g.updatePod(nil, obj)
}

func (g *graphPopulator) updatePod(oldObj, obj interface{}) {
	pod := obj.(*corev1.Pod)
	if len(pod.Spec.NodeName) == 0 {
		// No node assigned
		klog.V(5).Infof("updatePod %s/%s, no node", pod.Namespace, pod.Name)
		return
	}
	if oldPod, ok := oldObj.(*corev1.Pod); ok && oldPod != nil {
		if (pod.Spec.NodeName == oldPod.Spec.NodeName) && (pod.UID == oldPod.UID) &&
			resourceClaimStatusesEqual(oldPod.Status.ResourceClaimStatuses, pod.Status.ResourceClaimStatuses) {
			// Node and uid are unchanged, all object references in the pod spec are immutable respectively unmodified (claim statuses).
			klog.V(5).Infof("updatePod %s/%s, node unchanged", pod.Namespace, pod.Name)
			return
		}
	}

	klog.V(4).Infof("updatePod %s/%s for node %s", pod.Namespace, pod.Name, pod.Spec.NodeName)
	startTime := time.Now()
	g.graph.AddPod(pod)
	klog.V(5).Infof("updatePod %s/%s for node %s completed in %v", pod.Namespace, pod.Name, pod.Spec.NodeName, time.Since(startTime))
}

func resourceClaimStatusesEqual(statusA, statusB []corev1.PodResourceClaimStatus) bool {
	if len(statusA) != len(statusB) {
		return false
	}
	// In most cases, status entries only get added once and not modified.
	// But this cannot be guaranteed, so for the sake of correctness in all
	// cases this code here has to check.
	for i := range statusA {
		if statusA[i].Name != statusB[i].Name {
			return false
		}
		claimNameA := statusA[i].ResourceClaimName
		claimNameB := statusB[i].ResourceClaimName
		if (claimNameA == nil) != (claimNameB == nil) {
			return false
		}
		if claimNameA != nil && *claimNameA != *claimNameB {
			return false
		}
	}
	return true
}

func (g *graphPopulator) deletePod(obj interface{}) {
	if tombstone, ok := obj.(cache.DeletedFinalStateUnknown); ok {
		obj = tombstone.Obj
	}
	pod, ok := obj.(*corev1.Pod)
	if !ok {
		klog.Infof("unexpected type %T", obj)
		return
	}
	if len(pod.Spec.NodeName) == 0 {
		klog.V(5).Infof("deletePod %s/%s, no node", pod.Namespace, pod.Name)
		return
	}

	klog.V(4).Infof("deletePod %s/%s for node %s", pod.Namespace, pod.Name, pod.Spec.NodeName)
	startTime := time.Now()
	g.graph.DeletePod(pod.Name, pod.Namespace)
	klog.V(5).Infof("deletePod %s/%s for node %s completed in %v", pod.Namespace, pod.Name, pod.Spec.NodeName, time.Since(startTime))
}

func (g *graphPopulator) addPV(obj interface{}) {
	g.updatePV(nil, obj)
}

func (g *graphPopulator) updatePV(oldObj, obj interface{}) {
	pv := obj.(*corev1.PersistentVolume)
	// TODO: skip add if uid, pvc, and secrets are all identical between old and new
	g.graph.AddPV(pv)
}

func (g *graphPopulator) deletePV(obj interface{}) {
	if tombstone, ok := obj.(cache.DeletedFinalStateUnknown); ok {
		obj = tombstone.Obj
	}
	pv, ok := obj.(*corev1.PersistentVolume)
	if !ok {
		klog.Infof("unexpected type %T", obj)
		return
	}
	g.graph.DeletePV(pv.Name)
}

func (g *graphPopulator) addVolumeAttachment(obj interface{}) {
	g.updateVolumeAttachment(nil, obj)
}

func (g *graphPopulator) updateVolumeAttachment(oldObj, obj interface{}) {
	attachment := obj.(*storagev1.VolumeAttachment)
	if oldObj != nil {
		// skip add if node name is identical
		oldAttachment := oldObj.(*storagev1.VolumeAttachment)
		if oldAttachment.Spec.NodeName == attachment.Spec.NodeName {
			return
		}
	}
	g.graph.AddVolumeAttachment(attachment.Name, attachment.Spec.NodeName)
}

func (g *graphPopulator) deleteVolumeAttachment(obj interface{}) {
	if tombstone, ok := obj.(cache.DeletedFinalStateUnknown); ok {
		obj = tombstone.Obj
	}
	attachment, ok := obj.(*storagev1.VolumeAttachment)
	if !ok {
		klog.Infof("unexpected type %T", obj)
		return
	}
	g.graph.DeleteVolumeAttachment(attachment.Name)
}

func (g *graphPopulator) addResourceSlice(obj interface{}) {
	slice, ok := obj.(*resourcev1alpha2.ResourceSlice)
	if !ok {
		klog.Infof("unexpected type %T", obj)
		return
	}
	g.graph.AddResourceSlice(slice.Name, slice.NodeName)
}

func (g *graphPopulator) deleteResourceSlice(obj interface{}) {
	if tombstone, ok := obj.(cache.DeletedFinalStateUnknown); ok {
		obj = tombstone.Obj
	}
	slice, ok := obj.(*resourcev1alpha2.ResourceSlice)
	if !ok {
		klog.Infof("unexpected type %T", obj)
		return
	}
	g.graph.DeleteResourceSlice(slice.Name)
}