// Copyright 2020 VEXXHOST, Inc.
//
// 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 controllers

import (
	"context"
	"fmt"
	"sort"
	"strconv"

	"github.com/go-logr/logr"
	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"

	infrastructurev1alpha1 "opendev.org/vexxhost/openstack-operator/api/v1alpha1"

	monitoringv1 "opendev.org/vexxhost/openstack-operator/api/monitoring/v1"
	"opendev.org/vexxhost/openstack-operator/builders"
	"opendev.org/vexxhost/openstack-operator/utils/baseutils"
	"opendev.org/vexxhost/openstack-operator/utils/k8sutils"
)

// MemcachedReconciler reconciles a Memcached object
type MemcachedReconciler struct {
	client.Client
	Log    logr.Logger
	Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=infrastructure.vexxhost.cloud,resources=memcacheds,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=infrastructure.vexxhost.cloud,resources=memcacheds/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=monitoring.coreos.com,resources=prometheusrules,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=monitoring.coreos.com,resources=podmonitors,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete

// Reconcile does the reconcilication of Memcached instances
func (r *MemcachedReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
	ctx := context.Background()
	log := r.Log.WithValues("memcached", req.NamespacedName)

	var memcached infrastructurev1alpha1.Memcached
	if err := r.Get(ctx, req.NamespacedName, &memcached); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	// Labels
	typeLabels := baseutils.MergeMapsWithoutOverwrite(map[string]string{
		"app.kubernetes.io/name":       "memcached",
		"app.kubernetes.io/managed-by": "openstack-operator",
	}, memcached.Labels)

	labels := map[string]string{
		"app.kubernetes.io/name":       "memcached",
		"app.kubernetes.io/managed-by": "openstack-operator",
		"app.kubernetes.io/instance":   req.Name,
	}
	mcrouterLabels := baseutils.MergeMapsWithoutOverwrite(map[string]string{
		"app.kubernetes.io/name":       "memcached",
		"app.kubernetes.io/managed-by": "openstack-operator",
		"app.kubernetes.io/instance":   req.Name,
	}, memcached.Labels)

	// Deployment
	if res, err := r.ReconcileDeployment(ctx, req, &memcached, log, labels); err != nil || res != (ctrl.Result{}) {
		return res, err
	}

	// PodMonitor
	if res, err := r.ReconcilePodMonitor(ctx, req, &memcached, log, typeLabels); err != nil || res != (ctrl.Result{}) {
		return res, err
	}

	// Alertrule
	if res, err := r.ReconcilePrometheusRule(ctx, req, &memcached, log, typeLabels); err != nil || res != (ctrl.Result{}) {
		return res, err
	}

	// Mcrouter
	if res, err := r.ReconcileMcrouter(ctx, req, &memcached, log, labels, mcrouterLabels); err != nil || res != (ctrl.Result{}) {
		return res, err
	}

	return ctrl.Result{}, nil
}

// SetupWithManager initializes the controller with primary manager
func (r *MemcachedReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&infrastructurev1alpha1.Memcached{}).
		Owns(&appsv1.Deployment{}).
		Owns(&infrastructurev1alpha1.Mcrouter{}).
		Owns(&monitoringv1.PodMonitor{}).
		Owns(&monitoringv1.PrometheusRule{}).
		Complete(r)
}

// ReconcilePodMonitor reconciles the podMonitor
func (r *MemcachedReconciler) ReconcilePodMonitor(ctx context.Context, req ctrl.Request, memcached *infrastructurev1alpha1.Memcached, log logr.Logger, labels map[string]string) (ctrl.Result, error) {
	podMonitor := &monitoringv1.PodMonitor{
		TypeMeta: metav1.TypeMeta{
			APIVersion: "monitoring.coreos.com/v1",
			Kind:       "PodMonitor",
		},
		ObjectMeta: metav1.ObjectMeta{
			Namespace: req.Namespace,
			Name:      "memcached-podmonitor",
		},
	}
	op, err := k8sutils.CreateOrUpdate(ctx, r, podMonitor, func() error {
		return builders.PodMonitor(podMonitor, memcached, r.Scheme).
			Labels(labels).
			Selector(map[string]string{
				"app.kubernetes.io/name": "memcached",
			}).
			PodMetricsEndpoints(
				builders.PodMetricsEndpoint().
					Port("metrics").
					Path("/metrics").
					Interval("15s"),
			).Build()

	})
	if err != nil {
		return ctrl.Result{}, err
	}
	log.WithValues("resource", "podmonitor").WithValues("op", op).Info("Reconciled")
	return ctrl.Result{}, nil
}

// ReconcilePrometheusRule reconciles the prometheusRule
func (r *MemcachedReconciler) ReconcilePrometheusRule(ctx context.Context, req ctrl.Request, memcached *infrastructurev1alpha1.Memcached, log logr.Logger, labels map[string]string) (ctrl.Result, error) {
	alertRule := &monitoringv1.PrometheusRule{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: req.Namespace,
			Name:      "memcached-alertrule",
		},
	}
	op, err := k8sutils.CreateOrUpdate(ctx, r, alertRule, func() error {

		return builders.PrometheusRule(alertRule, memcached, r.Scheme).
			Labels(labels).
			RuleGroups(builders.RuleGroup().
				Name("memcached-rule").
				Rules(
					builders.Rule().
						Alert("MemcachedDown").
						Priority(3).
						Expr("memcached_up == 0"),

					builders.Rule().
						Alert("MemcachedMaxConnections").
						Priority(3).
						Expr("memcached_current_connections/memcached_max_connections * 100 > 95"),
					builders.Rule().
						Alert("MemcachedMaxConnections").
						Priority(4).
						Expr("memcached_current_connections/memcached_max_connections * 100 > 90"),
				).
				Interval("1m")).
			Build()
	})
	if err != nil {
		return ctrl.Result{}, err
	}
	log.WithValues("resource", "memcached-alertrule").WithValues("op", op).Info("Reconciled")
	return ctrl.Result{}, nil
}

// ReconcileMcrouter reconciles the mcrouter
func (r *MemcachedReconciler) ReconcileMcrouter(ctx context.Context, req ctrl.Request, memcached *infrastructurev1alpha1.Memcached, log logr.Logger, labels map[string]string, mcrouterLabels map[string]string) (ctrl.Result, error) {
	// Get the memcached pod list
	pods := &corev1.PodList{}
	if err := r.List(ctx, pods, client.InNamespace(req.Namespace), client.MatchingLabels(labels)); err != nil {
		return ctrl.Result{}, err
	}
	// Generate list of pod IP addresses
	servers := []string{}
	for _, pod := range pods.Items {
		// NOTE(mnaser): It's not possible that there is no pod IP assiged yet
		if len(pod.Status.PodIP) == 0 {
			continue
		}
		server := fmt.Sprintf("%s:11211", pod.Status.PodIP)
		servers = append(servers, server)
	}
	// If we don't have any servers, requeue.
	if len(servers) == 0 {
		return ctrl.Result{Requeue: true}, nil
	}
	// Make sure that they're sorted so we're idempotent
	sort.Strings(servers)
	mcrouter := &infrastructurev1alpha1.Mcrouter{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: req.Namespace,
			Name:      fmt.Sprintf("memcached-%s", req.Name),
		},
	}
	op, err := k8sutils.CreateOrUpdate(ctx, r, mcrouter, func() error {
		return builders.Mcrouter(mcrouter, memcached, r.Scheme).
			Labels(mcrouterLabels).
			NodeSelector(memcached.Spec.NodeSelector).
			Tolerations(memcached.Spec.Tolerations).
			Route("PoolRoute|default").
			Pool("default", builders.McrouterPoolSpec().Servers(servers)).
			Build()
	})
	if err != nil {
		return ctrl.Result{}, err
	}
	log.WithValues("resource", "Mcrouter").WithValues("op", op).Info("Reconciled")
	return ctrl.Result{}, nil
}

// ReconcileDeployment reconciles the deployment
func (r *MemcachedReconciler) ReconcileDeployment(ctx context.Context, req ctrl.Request, memcached *infrastructurev1alpha1.Memcached, log logr.Logger, labels map[string]string) (ctrl.Result, error) {
	// Calculate size per shared
	size := memcached.Spec.Megabytes / 2
	deployment := &appsv1.Deployment{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: req.Namespace,
			Name:      fmt.Sprintf("memcached-%s", req.Name),
			Labels:    labels,
		},
	}
	op, err := k8sutils.CreateOrUpdate(ctx, r, deployment, func() error {
		return builders.Deployment(deployment, memcached, r.Scheme).
			Labels(labels).
			Replicas(2).
			PodTemplateSpec(
				builders.PodTemplateSpec().
					Labels(labels).
					PodSpec(
						builders.PodSpec().
							NodeSelector(memcached.Spec.NodeSelector).
							Tolerations(memcached.Spec.Tolerations).
							Containers(
								builders.Container("memcached", "vexxhost/memcached:latest").
									Args("-m", strconv.Itoa(size)).
									Port("memcached", 11211).PortProbe("memcached", 10, 30).
									Resources(1000, int64(size), 500, 1.10).
									SecurityContext(
										builders.SecurityContext().
											RunAsUser(1001),
									),
								builders.Container("exporter", "vexxhost/memcached-exporter:latest").
									Port("metrics", 9150).HTTPProbe("metrics", "/metrics", 10, 30).
									Resources(500, 128, 500, 2).
									SecurityContext(
										builders.SecurityContext().
											RunAsUser(1001),
									),
							),
					),
			).
			Build()
	})
	if err != nil {
		return ctrl.Result{}, err
	}
	log.WithValues("resource", "Deployment").WithValues("op", op).Info("Reconciled")
	return ctrl.Result{}, nil
}