/*
Copyright 2019 Intel Corporation.
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 collectdplugin

import (
	"context"
	"fmt"
	"reflect"
	"strings"

	"github.com/go-logr/logr"
	"github.com/operator-framework/operator-sdk/pkg/predicate"

	onapv1alpha1 "collectd-operator/pkg/apis/onap/v1alpha1"
	collectdutils "collectd-operator/pkg/controller/utils"
	dspredicate "collectd-operator/pkg/controller/utils"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/util/retry"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

var log = logf.Log.WithName("controller_collectdplugin")

// Add creates a new CollectdPlugin Controller and adds it to the Manager. The Manager will set fields on the Controller
// and Start it when the Manager is Started.
func Add(mgr manager.Manager) error {
	return add(mgr, newReconciler(mgr))
}

// newReconciler returns a new reconcile.Reconciler
func newReconciler(mgr manager.Manager) reconcile.Reconciler {
	return &ReconcileCollectdPlugin{client: mgr.GetClient(), scheme: mgr.GetScheme()}
}

// add adds a new Controller to mgr with r as the reconcile.Reconciler
func add(mgr manager.Manager, r reconcile.Reconciler) error {
	// Create a new controller
	log.V(1).Info("Creating a new controller for CollectdPlugin")
	c, err := controller.New("collectdplugin-controller", mgr, controller.Options{Reconciler: r})
	if err != nil {
		return err
	}

	// Watch for changes to primary resource CollectdPlugin
	log.V(1).Info("Add watcher for primary resource CollectdPlugin")
	err = c.Watch(&source.Kind{Type: &onapv1alpha1.CollectdPlugin{}}, &handler.EnqueueRequestForObject{}, predicate.GenerationChangedPredicate{})
	if err != nil {
		return err
	}

	log.V(1).Info("Add watcher for secondary resource Collectd Daemonset")
	err = c.Watch(
		&source.Kind{Type: &appsv1.DaemonSet{}},
		&handler.EnqueueRequestsFromMapFunc{
			ToRequests: handler.ToRequestsFunc(func(a handler.MapObject) []reconcile.Request {
				labelSelector, err := collectdutils.GetWatchLabels()
				labels := strings.Split(labelSelector, "=")
				if err != nil {
					log.Error(err, "Failed to get watch labels, continuing with default label")
				}
				rcp := r.(*ReconcileCollectdPlugin)
				// Select the Daemonset with labelSelector (Default  is app=collectd)
				if a.Meta.GetLabels()[labels[0]] == labels[1] {
					var requests []reconcile.Request
					cpList, err := collectdutils.GetCollectdPluginList(rcp.client, a.Meta.GetNamespace())
					if err != nil || cpList == nil || cpList.Items == nil || len(cpList.Items) == 0 {
						log.V(1).Info("No CollectdPlugin CR instance Exist")
						return nil
					}
					for _, cp := range cpList.Items {
						requests = append(requests, reconcile.Request{
							NamespacedName: client.ObjectKey{Namespace: cp.Namespace, Name: cp.Name}})
					}
					return requests
				}
				return nil
			}),
		}, dspredicate.DaemonSetStatusChangedPredicate{})

	return nil
}

// blank assignment to verify that ReconcileCollectdPlugin implements reconcile.Reconciler
var _ reconcile.Reconciler = &ReconcileCollectdPlugin{}

// ReconcileCollectdPlugin reconciles a CollectdPlugin object
type ReconcileCollectdPlugin struct {
	// This client, initialized using mgr.Client() above, is a split client
	// that reads objects from the cache and writes to the apiserver
	client client.Client
	scheme *runtime.Scheme
}

// Reconcile reads that state of the cluster for a CollectdPlugin object and makes changes based on the state read
// and what is in the CollectdPlugin.Spec
// TODO(user): Modify this Reconcile function to implement your Controller logic.  This example creates
// a Pod as an example
// Note:
// The Controller will requeue the Request to be processed again if the returned error is non-nil or
// Result.Requeue is true, otherwise upon completion it will remove the work from the queue.
func (r *ReconcileCollectdPlugin) Reconcile(request reconcile.Request) (reconcile.Result, error) {
	reqLogger := log.WithValues("Request.Namespace", request.Namespace, "Request.Name", request.Name)
	reqLogger.Info("Reconciling CollectdPlugin")

	// Fetch the CollectdPlugin instance
	instance := &onapv1alpha1.CollectdPlugin{}
	err := r.client.Get(context.TODO(), request.NamespacedName, instance)
	if err != nil {
		if errors.IsNotFound(err) {
			// Request object not found, could have been deleted after reconcile request.
			// Owned objects are automatically garbage collected. For additional cleanup logic use finalizers.
			// Return and don't requeue
			reqLogger.V(1).Info("CollectdPlugin object Not found")
			return reconcile.Result{}, nil
		}
		// Error reading the object - requeue the request.
		reqLogger.V(1).Info("Error reading the CollectdPlugin object, Requeuing")
		return reconcile.Result{}, err
	}

	// Handle Delete CR for additional cleanup
	isDelete, err := r.handleDelete(reqLogger, instance)
	if isDelete {
		return reconcile.Result{}, err
	}

	// Add finalizer for this CR
	if !collectdutils.Contains(instance.GetFinalizers(), collectdutils.CollectdFinalizer) {
		if err := r.addFinalizer(reqLogger, instance); err != nil {
			return reconcile.Result{}, err
		}
		//return reconcile.Result{}, nil
	}
	// Handle the reconciliation for CollectdPlugin.
	// At this stage the Status of the CollectdPlugin should NOT be ""
	err = r.handleCollectdPlugin(reqLogger, instance, false)
	return reconcile.Result{}, err
}

// handleCollectdPlugin regenerates the collectd conf on CR Create, Update, Delete events
func (r *ReconcileCollectdPlugin) handleCollectdPlugin(reqLogger logr.Logger, cr *onapv1alpha1.CollectdPlugin, isDelete bool) error {
	collectdutils.ReconcileLock.Lock()
	defer collectdutils.ReconcileLock.Unlock()
	retryErr := retry.RetryOnConflict(retry.DefaultRetry, func() error {
		cm, err := collectdutils.GetConfigMap(r.client, reqLogger, cr.Namespace)
		if err != nil {
			reqLogger.Error(err, "Skip reconcile: ConfigMap not found")
			return err
		}
		reqLogger.V(1).Info(":::: ConfigMap Info ::::", "ConfigMap.Namespace", cm.Namespace, "ConfigMap.Name", cm.Name)

		collectdConf, err := collectdutils.RebuildCollectdConf(r.client, cr.Namespace, isDelete, cr.Spec.PluginName)
		if err != nil {
			reqLogger.Error(err, "Skip reconcile: Rebuild conf failed")
			return err
		}

		cm.SetAnnotations(map[string]string{
			"daaas-random": collectdutils.ComputeSHA256([]byte(collectdConf)),
		})
		cm.Data["collectd.conf"] = collectdConf

		// Update the ConfigMap with new Spec and reload DaemonSets
		reqLogger.Info("Updating the ConfigMap", "ConfigMap.Namespace", cm.Namespace, "ConfigMap.Name", cm.Name)
		updateErr := r.client.Update(context.TODO(), cm)
		if updateErr != nil {
			reqLogger.Error(updateErr, "Update ConfigMap failed")
			return updateErr
		}

		// Retrieve the latest version of Daemonset before attempting update
		// RetryOnConflict uses exponential backoff to avoid exhausting the apiserver
		// Select DaemonSets with label
		dsList := &appsv1.DaemonSetList{}
		opts := &client.ListOptions{}
		labelSelector, err := collectdutils.GetWatchLabels()
		if err != nil {
			reqLogger.Error(err, "Failed to get watch labels, continuing with default label")
		}
		opts.SetLabelSelector(labelSelector)
		opts.InNamespace(cr.Namespace)
		err = r.client.List(context.TODO(), opts, dsList)
		if err != nil {
			panic(fmt.Errorf("Failed to get latest version of DaemonSet: %v", err))
		}

		if dsList.Items == nil || len(dsList.Items) == 0 {
			return errors.NewNotFound(corev1.Resource("daemonset"), "DaemonSet")
		}
		ds := &dsList.Items[0]
		//Restart Collectd Pods
		reqLogger.Info("Reloading the Daemonset", "DaemonSet.Namespace", ds.Namespace, "DaemonSet.Name", ds.Name)
		//Restart only if hash of conf has changed.
		ds.Spec.Template.SetAnnotations(map[string]string{
			"daaas-random": collectdutils.ComputeSHA256([]byte(collectdConf)),
		})
		updateErr = r.client.Update(context.TODO(), ds)
		return updateErr
	})
	if retryErr != nil {
		panic(fmt.Errorf("Update failed: %v", retryErr))
	}

	retryErr = retry.RetryOnConflict(retry.DefaultRetry, func() error {
		err := r.updateStatus(cr)
		return err
	})

	if retryErr != nil {
		panic(fmt.Errorf("Update failed: %v", retryErr))
	}
	// Reconcile success
	reqLogger.Info("Reconcile success!!")
	return nil
}

// Handle Delete CR event for additional cleanup
func (r *ReconcileCollectdPlugin) handleDelete(reqLogger logr.Logger, cr *onapv1alpha1.CollectdPlugin) (bool, error) {
	// Check if the CollectdPlugin instance is marked to be deleted, which is
	// indicated by the deletion timestamp being set.
	isMarkedToBeDeleted := cr.GetDeletionTimestamp() != nil
	if isMarkedToBeDeleted {
		// Update status to Deleting state
		cr.Status.Status = onapv1alpha1.Deleting
		cr.Status.CollectdAgents = nil
		_ = r.client.Status().Update(context.TODO(), cr)

		if collectdutils.Contains(cr.GetFinalizers(), collectdutils.CollectdFinalizer) {
			// Run finalization logic for collectdPluginFinalizer. If the
			// finalization logic fails, don't remove the finalizer so
			// that we can retry during the next reconciliation.
			if err := r.finalizeCollectdPlugin(reqLogger, cr); err != nil {
				return isMarkedToBeDeleted, err
			}

			// Remove collectdPluginFinalizer. Once all finalizers have been
			// removed, the object will be deleted.
			cr.SetFinalizers(collectdutils.Remove(cr.GetFinalizers(), collectdutils.CollectdFinalizer))
			err := r.client.Update(context.TODO(), cr)
			if err != nil {
				return isMarkedToBeDeleted, err
			}
		}
	}
	return isMarkedToBeDeleted, nil
}

func (r *ReconcileCollectdPlugin) updateStatus(cr *onapv1alpha1.CollectdPlugin) error {
	// Fetch the CollectdPlugin instance
	instance := &onapv1alpha1.CollectdPlugin{}
	key := types.NamespacedName{Namespace: cr.Namespace, Name: cr.Name}
	err := r.client.Get(context.TODO(), key, instance)
	if err != nil {
		return err
	}
	switch instance.Status.Status {
	case onapv1alpha1.Initial:
		instance.Status.Status = onapv1alpha1.Created
	case onapv1alpha1.Created, onapv1alpha1.Enabled:
		pods, err := collectdutils.GetPodList(r.client, instance.Namespace)
		if err != nil {
			return err
		}
		if !reflect.DeepEqual(pods, instance.Status.CollectdAgents) {
			instance.Status.CollectdAgents = pods
			instance.Status.Status = onapv1alpha1.Enabled
		}
	case onapv1alpha1.Deleting, onapv1alpha1.Deprecated:
		return nil
	}
	err = r.client.Status().Update(context.TODO(), instance)
	return err
}

func (r *ReconcileCollectdPlugin) finalizeCollectdPlugin(reqLogger logr.Logger, cr *onapv1alpha1.CollectdPlugin) error {
	// Cleanup by regenerating new collectd conf and rolling update of DaemonSet
	if err := r.handleCollectdPlugin(reqLogger, cr, true); err != nil {
		reqLogger.Error(err, "Finalize CollectdPlugin failed!!")
		return err
	}
	reqLogger.Info("Successfully finalized CollectdPlugin!!")
	return nil
}

func (r *ReconcileCollectdPlugin) addFinalizer(reqLogger logr.Logger, cr *onapv1alpha1.CollectdPlugin) error {
	reqLogger.Info("Adding Finalizer for the CollectdPlugin")
	cr.SetFinalizers(append(cr.GetFinalizers(), collectdutils.CollectdFinalizer))
	// Update status from Initial to Created
	// Since addFinalizer will be executed only once,
	// the status will be changed from Initial state to Created
	// updateErr := r.updateStatus(cr)
	// if updateErr != nil {
	// 	reqLogger.Error(updateErr, "Failed to update status from Initial state")
	// }
	// Update CR
	cr.Status.Status = onapv1alpha1.Created
	err := r.client.Update(context.TODO(), cr)
	if err != nil {
		reqLogger.Error(err, "Failed to update CollectdPlugin with finalizer")
		return err
	}
	return nil
}