// Copyright 2024 Universidad Carlos III de Madrid
//
// 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 controller

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	l2smv1 "github.com/Networks-it-uc3m/L2S-M/api/v1"
	"github.com/Networks-it-uc3m/L2S-M/internal/utils"
	nettypes "github.com/k8snetworkplumbingwg/network-attachment-definition-client/pkg/apis/k8s.cni.cncf.io/v1"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/log"

	switchv1 "github.com/Networks-it-uc3m/l2sm-switch/api/v1"
)

// OverlayReconciler reconciles a Overlay object
type OverlayReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

var replicaSetOwnerKeyOverlay = ".metadata.controller.overlay"

// +kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=configmaps,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=services,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=replicasets,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=apps,resources=replicasets,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=overlays,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=overlays/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=l2sm.l2sm.k8s.local,resources=overlays/finalizers,verbs=update

// Reconcile is part of the main kubernetes reconciliation loop which aims to
// move the current state of the cluster closer to the desired state.
// TODO(user): Modify the Reconcile function to compare the state specified by
// the Overlay object against the actual cluster state, and then
// perform operations to make the cluster state reflect the state specified by
// the user.
//
// For more details, check Reconcile and its Result here:
// - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.17.0/pkg/reconcile
func (r *OverlayReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {

	log := log.FromContext(ctx)

	overlay := &l2smv1.Overlay{}

	if err := r.Get(ctx, req.NamespacedName, overlay); err != nil {
		// we'll ignore not-found errors, since they can't be fixed by an immediate
		// requeue (we'll need to wait for a new notification), and we can get them
		// on deleted requests.
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	// name of our custom finalizer

	// examine DeletionTimestamp to determine if object is under deletion
	if overlay.ObjectMeta.DeletionTimestamp.IsZero() {
		// The object is not being deleted, so if it does not have our finalizer,
		// then lets add the finalizer and update the object. This is equivalent
		// to registering our finalizer.
		if !controllerutil.ContainsFinalizer(overlay, l2smFinalizer) {
			controllerutil.AddFinalizer(overlay, l2smFinalizer)
			if err := r.Update(ctx, overlay); err != nil {
				return ctrl.Result{}, err
			}
			log.Info("Overlay created", "Overlay", overlay.Name)

		}
	} else {
		// The object is being deleted
		if controllerutil.ContainsFinalizer(overlay, l2smFinalizer) {
			// our finalizer is present, so lets handle any external dependency
			// if err := r.deleteExternalResources(ctx, overlay); err != nil {
			// 	// if fail to delete the external dependency here, return with error
			// 	// so that it can be retried.
			// 	return ctrl.Result{}, err
			// }

			// remove our finalizer from the list and update it.
			controllerutil.RemoveFinalizer(overlay, l2smFinalizer)
			if err := r.Update(ctx, overlay); err != nil {
				return ctrl.Result{}, err
			}

		}
		log.Info("Overlay deleted", "Overlay", overlay.Name)
		// Stop reconciliation as the item is being deleted
		return ctrl.Result{}, nil
	}

	var switchReplicaSets appsv1.ReplicaSetList
	if err := r.List(ctx, &switchReplicaSets, client.InNamespace(req.Namespace), client.MatchingFields{replicaSetOwnerKeyOverlay: req.Name}); err != nil {
		log.Error(err, "unable to list child ReplicaSets")
		return ctrl.Result{}, err
	}

	if len(switchReplicaSets.Items) == 0 {
		if err := r.createExternalResources(ctx, overlay); err != nil {
			log.Error(err, "unable to create ReplicaSet")
			return ctrl.Result{}, err
		}
		log.Info("Overlay Launched")
		return ctrl.Result{RequeueAfter: time.Second * 20}, nil
	}
	// else {

	// 	//b, _ := json.Marshal(netEdgeDevice.Spec.Neighbors)

	// }

	return ctrl.Result{}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *OverlayReconciler) SetupWithManager(mgr ctrl.Manager) error {
	if err := mgr.GetFieldIndexer().IndexField(context.Background(), &appsv1.ReplicaSet{}, replicaSetOwnerKeyOverlay, func(rawObj client.Object) []string {
		// grab the replica set object, extract the owner...
		replicaSet := rawObj.(*appsv1.ReplicaSet)
		owner := metav1.GetControllerOf(replicaSet)
		if owner == nil {
			return nil
		}
		// ...make sure it's a ReplicaSet...
		if owner.APIVersion != apiGVStr || owner.Kind != "Overlay" {
			return nil
		}

		// ...and if so, return it
		return []string{owner.Name}
	}); err != nil {
		return err
	}
	return ctrl.NewControllerManagedBy(mgr).
		For(&l2smv1.Overlay{}).
		Owns(&appsv1.ReplicaSet{}).
		Complete(r)
}

// func (r *OverlayReconciler) deleteExternalResources(ctx context.Context, overlay *l2smv1.Overlay) error {

// 	return nil
// }

type OverlayConfigJson struct {
	ControllerIp string `json:"ControllerIp"`
}

type TopologySwitchJson struct {
	Nodes []NodeJson    `json:"Nodes"`
	Links []l2smv1.Link `json:"Links"`
}

type NodeJson struct {
	Name   string `json:"name"`
	NodeIP string `json:"nodeIP"`
}

func (r *OverlayReconciler) createExternalResources(ctx context.Context, overlay *l2smv1.Overlay) error {

	// Create a ConfigMap to store the topology JSON
	constructConfigMapForOverlay := func(overlay *l2smv1.Overlay) (*corev1.ConfigMap, error) {

		// Construct the TopologySwitchJson
		topologySwitch := switchv1.Topology{}

		overlayConfig := switchv1.OverlaySettings{ControllerIp: overlay.Spec.NetworkController.Domain,
			InterfacesNumber: overlay.Spec.InterfaceNumber,
			OverlayName:      overlay.Name}

		overlayName := overlay.ObjectMeta.Name

		// Populate Nodes
		for _, nodeName := range overlay.Spec.Topology.Nodes {
			node := switchv1.Node{
				Name:   nodeName,
				NodeIP: fmt.Sprintf("l2sm-switch-%s-%s", overlayName, nodeName),
			}
			topologySwitch.Nodes = append(topologySwitch.Nodes, node)
		}

		// Populate Links
		for _, overlayLink := range overlay.Spec.Topology.Links {
			link := switchv1.Link{
				EndpointNodeA: overlayLink.EndpointA,
				EndpointNodeB: overlayLink.EndpointB,
			}
			topologySwitch.Links = append(topologySwitch.Links, link)
		}

		// Convert TopologySwitchJson to JSON
		topologyJSON, err := json.Marshal(topologySwitch)
		if err != nil {
			return nil, err
		}

		configJSON, err := json.Marshal(overlayConfig)
		if err != nil {
			return nil, err
		}
		configMap := &corev1.ConfigMap{
			ObjectMeta: metav1.ObjectMeta{
				Name:      fmt.Sprintf("%s-topology", overlay.Name),
				Namespace: overlay.Namespace,
			},
			Data: map[string]string{
				"topology.json": string(topologyJSON),
				"config.json":   string(configJSON),
			},
		}
		if err := controllerutil.SetControllerReference(overlay, configMap, r.Scheme); err != nil {
			return nil, err
		}
		return configMap, nil
	}

	configMap, _ := constructConfigMapForOverlay(overlay)

	// Create the ConfigMap in Kubernetes
	if err := r.Client.Create(ctx, configMap); err != nil {
		return err
	}

	constructNodeResourcesForOverlay := func(overlay *l2smv1.Overlay) ([]*appsv1.ReplicaSet, []*corev1.Service, []*nettypes.NetworkAttachmentDefinition, error) {

		// Define volume mounts to be added to each container
		volumeMounts := []corev1.VolumeMount{
			{
				Name:      "topology",
				MountPath: "/etc/l2sm/",
				ReadOnly:  true,
			},
			{
				Name:      "configuration",
				MountPath: "/etc/l2sm/",
				ReadOnly:  true,
			},
		}

		// Update containers to include the volume mount
		containers := make([]corev1.Container, len(overlay.Spec.SwitchTemplate.Spec.Containers))
		for i, container := range overlay.Spec.SwitchTemplate.Spec.Containers {
			container.VolumeMounts = append(container.VolumeMounts, volumeMounts...)
			containers[i] = container
		}

		// Define the volume using the created ConfigMap
		volumes := []corev1.Volume{
			{
				Name: "topology",
				VolumeSource: corev1.VolumeSource{
					ConfigMap: &corev1.ConfigMapVolumeSource{
						LocalObjectReference: corev1.LocalObjectReference{
							Name: configMap.Name,
						},
						Items: []corev1.KeyToPath{
							{
								Key:  "topology.json",
								Path: "topology.json",
							},
						},
					},
				},
			},
			{
				Name: "configuration",
				VolumeSource: corev1.VolumeSource{
					ConfigMap: &corev1.ConfigMapVolumeSource{
						LocalObjectReference: corev1.LocalObjectReference{
							Name: configMap.Name,
						},
						Items: []corev1.KeyToPath{
							{
								Key:  "config.json",
								Path: "config.json",
							},
						},
					},
				},
			},
		}

		switchInterfacesAnnotations := GenerateAnnotations(overlay.Name, overlay.Spec.InterfaceNumber)

		var networkAttachmentDefinitions []*nettypes.NetworkAttachmentDefinition
		var auxNetAttachDef *nettypes.NetworkAttachmentDefinition

		for i := 1; i <= overlay.Spec.InterfaceNumber; i++ {
			auxNetAttachDef = &nettypes.NetworkAttachmentDefinition{
				ObjectMeta: metav1.ObjectMeta{
					Name:      fmt.Sprintf("%s-veth%d", overlay.Name, i),
					Namespace: overlay.Namespace,
					Labels:    map[string]string{"app": "l2sm"},
				},
				Spec: nettypes.NetworkAttachmentDefinitionSpec{
					Config: fmt.Sprintf(`{
						"cniVersion": "0.3.0",
						"type": "bridge",
						"bridge": "%s-br%d",
						"mtu": 1400,
						"device": "%s-veth%d",
						  "ipam": {
							"type":"static"
						  }
					  }`, overlay.Name, i, overlay.Name, i),
				},
			}
			networkAttachmentDefinitions = append(networkAttachmentDefinitions, auxNetAttachDef)
		}

		var replicaSets []*appsv1.ReplicaSet
		var services []*corev1.Service
		for _, node := range overlay.Spec.Topology.Nodes {

			name := fmt.Sprintf("%s-%s-%s", "l2sm-switch", node, utils.GenerateHash(overlay))

			replicaSet := &appsv1.ReplicaSet{
				ObjectMeta: metav1.ObjectMeta{
					Labels:      make(map[string]string),
					Annotations: make(map[string]string),
					Name:        name,
					Namespace:   overlay.Namespace,
				},
				Spec: appsv1.ReplicaSetSpec{
					Replicas: utils.Int32Ptr(1),
					Selector: &metav1.LabelSelector{
						MatchLabels: map[string]string{
							"app": name,
						},
					},
					Template: corev1.PodTemplateSpec{
						ObjectMeta: metav1.ObjectMeta{
							Labels: map[string]string{
								"app": name,
							},
							Annotations: map[string]string{
								MULTUS_ANNOTATION_KEY: switchInterfacesAnnotations,
							},
						},
						Spec: corev1.PodSpec{
							InitContainers: overlay.Spec.SwitchTemplate.Spec.InitContainers,
							Containers:     containers,
							Volumes:        volumes,
							HostNetwork:    overlay.Spec.SwitchTemplate.Spec.HostNetwork,
							NodeName:       node,
						},
					},
				},
			}

			for k, v := range overlay.Spec.SwitchTemplate.Annotations {
				replicaSet.Annotations[k] = v
			}
			for k, v := range overlay.Spec.SwitchTemplate.Labels {
				replicaSet.Labels[k] = v
			}
			if err := controllerutil.SetControllerReference(overlay, replicaSet, r.Scheme); err != nil {
				return nil, nil, nil, err
			}

			replicaSets = append(replicaSets, replicaSet)

			// Create a headless service for the ReplicaSet
			service := &corev1.Service{
				ObjectMeta: metav1.ObjectMeta{
					Name:      fmt.Sprintf("l2sm-switch-%s-%s", overlay.Name, node),
					Namespace: overlay.Namespace,
					Labels:    map[string]string{"app": name},
				},
				Spec: corev1.ServiceSpec{
					ClusterIP: "None",
					Selector:  map[string]string{"app": name},
					Ports: []corev1.ServicePort{
						{
							Name: "http",
							Port: 80,
						},
					},
				},
			}

			if err := controllerutil.SetControllerReference(overlay, service, r.Scheme); err != nil {
				return nil, nil, nil, err
			}

			services = append(services, service)
		}

		return replicaSets, services, networkAttachmentDefinitions, nil
	}

	replicaSets, services, netAttachDefs, err := constructNodeResourcesForOverlay(overlay)
	if err != nil {
		return err
	}
	for _, netAttachDef := range netAttachDefs {
		if err = r.Client.Create(ctx, netAttachDef); err != nil {
			return err
		}
	}
	for _, replicaSet := range replicaSets {
		if err = r.Client.Create(ctx, replicaSet); err != nil {
			return err
		}
	}
	for _, service := range services {
		if err = r.Client.Create(ctx, service); err != nil {
			return err
		}
	}

	return nil
}