/*
Copyright 2019 The Rook Authors. All rights reserved.

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 crash

import (
	"reflect"
	"strings"

	"github.com/pkg/errors"
	"github.com/rook/rook/pkg/operator/k8sutil"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/event"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

const (
	controllerName = "ceph-crashcollector-controller"
	// AppName is the value to the "app" label for the ceph-crash pods
	AppName = "rook-ceph-crashcollector"
	// NodeNameLabel is a node name label
	NodeNameLabel = "node_name"
)

// Add adds a new Controller based on nodedrain.ReconcileNode and registers the relevant watches and handlers
func Add(mgr manager.Manager) error {
	reconcileNode := &ReconcileNode{
		client: mgr.GetClient(),
		scheme: mgr.GetScheme(),
	}
	reconciler := reconcile.Reconciler(reconcileNode)

	// Create a new controller
	c, err := controller.New(controllerName, mgr, controller.Options{Reconciler: reconciler})
	if err != nil {
		return errors.Wrapf(err, "failed to create a new %q", controllerName)
	}

	// Watch for changes to the nodes
	specChangePredicate := predicate.Funcs{
		UpdateFunc: func(e event.UpdateEvent) bool {
			nodeOld := e.ObjectOld.DeepCopyObject().(*corev1.Node)
			nodeNew := e.ObjectNew.DeepCopyObject().(*corev1.Node)
			return !reflect.DeepEqual(nodeOld.Spec, nodeNew.Spec)
		},
	}
	logger.Debugf("watch for changes to the nodes")
	err = c.Watch(&source.Kind{Type: &corev1.Node{}}, &handler.EnqueueRequestForObject{}, specChangePredicate)
	if err != nil {
		return errors.Wrapf(err, "failed to watch for node changes")
	}

	// Watch for changes to the ceph-crash deployments
	logger.Debugf("watch for changes to the ceph-crash deployments")
	err = c.Watch(
		&source.Kind{Type: &appsv1.Deployment{}},
		&handler.EnqueueRequestsFromMapFunc{
			ToRequests: handler.ToRequestsFunc(func(obj handler.MapObject) []reconcile.Request {
				deployment, ok := obj.Object.(*appsv1.Deployment)
				if !ok {
					return []reconcile.Request{}
				}
				labels := deployment.GetLabels()
				appName, ok := labels[k8sutil.AppAttr]
				if !ok || appName != AppName {
					return []reconcile.Request{}
				}
				nodeName, ok := deployment.Spec.Template.ObjectMeta.Labels[NodeNameLabel]
				if !ok {
					return []reconcile.Request{}
				}
				req := reconcile.Request{NamespacedName: types.NamespacedName{Name: nodeName}}
				return []reconcile.Request{req}
			}),
		},
	)
	if err != nil {
		return errors.Wrapf(err, "failed to watch for changes on the ceph-crash deployment")
	}

	// Watch for changes to the ceph pod nodename and enqueue their nodes
	logger.Debugf("watch for changes to the ceph pod nodename and enqueue their nodes")
	err = c.Watch(
		&source.Kind{Type: &corev1.Pod{}},
		&handler.EnqueueRequestsFromMapFunc{
			ToRequests: handler.ToRequestsFunc(func(obj handler.MapObject) []reconcile.Request {
				pod, ok := obj.Object.(*corev1.Pod)
				if !ok {
					return []reconcile.Request{}
				}
				nodeName := pod.Spec.NodeName
				if nodeName == "" {
					return []reconcile.Request{}
				}
				if isCephPod(pod.Labels, pod.Name) {
					req := reconcile.Request{NamespacedName: types.NamespacedName{Name: nodeName}}
					return []reconcile.Request{req}
				}
				logger.Debugf("%q is not a ceph pod", pod.Name)
				return []reconcile.Request{}
			}),
		},
		// only enqueue the update event if the pod moved nodes
		predicate.Funcs{
			UpdateFunc: func(event event.UpdateEvent) bool {
				oldPod, ok := event.ObjectOld.(*corev1.Pod)
				if !ok {
					return false
				}
				newPod, ok := event.ObjectNew.(*corev1.Pod)
				if !ok {
					return false
				}
				// only enqueue if the nodename has changed
				if oldPod.Spec.NodeName == newPod.Spec.NodeName {
					return false
				}
				return true
			},
		},
	)
	if err != nil {
		return errors.Wrapf(err, "failed to watch for changes on the ceph pod nodename and enqueue their nodes")
	}

	return nil
}

func isCephPod(labels map[string]string, podName string) bool {
	_, ok := labels["rook_cluster"]
	// canary pods for monitors might stick around during startup
	// at that time, the initial monitors haven't been deployed yet.
	// If we don't invalidate canary pods,
	// the crash collector pod will start and environment variable like 'ROOK_CEPH_MON_HOST'
	// will be empty since the monitors don't exist yet
	isCanaryPod := strings.Contains(podName, "-canary-")
	if ok && !isCanaryPod {
		logger.Debugf("%q is a ceph pod!", podName)
		return true
	}

	return false
}
