/*
Copyright 2024.

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"
	"github.com/apache/iotdb-operator/internal/controller/strutil"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/intstr"
	"k8s.io/client-go/util/retry"
	"reflect"
	. "sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"

	"k8s.io/apimachinery/pkg/runtime"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"

	iotdbv1 "github.com/apache/iotdb-operator/api/v1"
)

// ConfigNodeReconciler reconciles a ConfigNode object
type ConfigNodeReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=iotdb.apache.org,resources=confignodes,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=iotdb.apache.org,resources=confignodes/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=iotdb.apache.org,resources=confignodes/finalizers,verbs=update
// +kubebuilder:rbac:groups="",resources=services,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups="",resources=persistentvolumeclaims,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=apps,resources=statefulsets,verbs=get;list;watch;create;update;patch;delete

// Reconcile function compares the state specified by the ConfigNode object against the actual cluster state.
func (r *ConfigNodeReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	logger := log.FromContext(ctx)

	var configNode iotdbv1.ConfigNode
	if err := r.Get(ctx, req.NamespacedName, &configNode); err != nil {
		if errors.IsNotFound(err) {
			logger.Info("ConfigNode resource not found. May have been deleted.")
			return ctrl.Result{}, nil
		}
		logger.Error(err, "Failed to get IoTDB ConfigNode")
		return ctrl.Result{}, err
	}

	// Ensure the service exists
	services, err := r.constructServicesForConfigNode(&configNode)
	if err != nil {
		return ctrl.Result{}, err
	}
	for _, service := range services {
		existingService := &corev1.Service{}
		err := r.Get(ctx, types.NamespacedName{Name: service.Name, Namespace: service.Namespace}, existingService)
		if err != nil && errors.IsNotFound(err) {
			if err := r.Create(ctx, &service); err != nil {
				return ctrl.Result{}, err
			}
		} else if err != nil {
			return ctrl.Result{}, err
		} else {
			// Ensure the service is up-to-date
			if !reflect.DeepEqual(existingService.Spec, service.Spec) {
				service.ResourceVersion = existingService.ResourceVersion
				if err := r.Update(ctx, &service); err != nil {
					return ctrl.Result{}, err
				}
			}
		}
	}

	// Ensure StatefulSet exists and is up-to-date
	err = retry.RetryOnConflict(retry.DefaultRetry, func() error {
		current := &appsv1.StatefulSet{}
		err := r.Get(ctx, types.NamespacedName{Name: configNode.Name, Namespace: configNode.Namespace}, current)
		if err != nil && errors.IsNotFound(err) {
			stateFulSet := r.constructStateFulSetForConfigNode(&configNode)
			if err := r.Create(ctx, stateFulSet); err != nil {
				return err
			}
			return nil
		} else if err != nil {
			return err
		}

		updatedStateFulSet := r.constructStateFulSetForConfigNode(&configNode)
		if !reflect.DeepEqual(current.Spec, updatedStateFulSet.Spec) {
			updatedStateFulSet.ResourceVersion = current.ResourceVersion
			return r.Update(ctx, updatedStateFulSet)
		}
		return nil
	})

	if err != nil {
		logger.Error(err, "Failed to update StateFulSet for IoTDB ConfigNode")
		return ctrl.Result{}, err
	}

	return ctrl.Result{}, nil
}

func (r *ConfigNodeReconciler) constructStateFulSetForConfigNode(configNode *iotdbv1.ConfigNode) *appsv1.StatefulSet {
	labels := map[string]string{"app": ConfigNodeName}
	replicas := int32(configNode.Spec.Replicas)
	envVars := make([]corev1.EnvVar, 3)
	envNum := 0
	if configNode.Spec.Envs != nil {
		envNum = len(configNode.Spec.Envs)
		envVars = make([]corev1.EnvVar, len(configNode.Spec.Envs)+3)
		i := 0
		for key, value := range configNode.Spec.Envs {
			if key == "cn_internal_port" {
				value = "10710"
			} else if key == "cn_consensus_port" {
				value = "10720"
			} else if key == "cn_metric_prometheus_reporter_port" {
				value = "9091"
			}
			envVars[i] = corev1.EnvVar{Name: key, Value: value}
			i++
		}
	}

	envVars[envNum] = corev1.EnvVar{
		Name: "POD_NAME",
		ValueFrom: &corev1.EnvVarSource{
			FieldRef: &corev1.ObjectFieldSelector{
				FieldPath: "metadata.name",
			},
		},
	}
	val1 := ConfigNodeName + "-0." + ConfigNodeName + "-headless." + configNode.Namespace + ".svc.cluster.local:10710"
	val2 := "$(POD_NAME)." + ConfigNodeName + "-headless." + configNode.Namespace + ".svc.cluster.local"
	envVars[envNum+1] = corev1.EnvVar{Name: "cn_seed_config_node", Value: val1}
	envVars[envNum+2] = corev1.EnvVar{Name: "cn_internal_address", Value: val2}

	pvcTemplate := *r.constructPVCForConfigNode(configNode)
	pvcName := pvcTemplate.Name
	statefulset := &appsv1.StatefulSet{
		ObjectMeta: metav1.ObjectMeta{
			Name:      ConfigNodeName,
			Namespace: configNode.Namespace,
			Labels:    labels,
		},
		Spec: appsv1.StatefulSetSpec{
			Replicas: &replicas,
			Selector: &metav1.LabelSelector{
				MatchLabels: labels,
			},
			ServiceName: ConfigNodeName + "-headless",
			Template: corev1.PodTemplateSpec{
				ObjectMeta: metav1.ObjectMeta{
					Labels: labels,
				},
				Spec: corev1.PodSpec{
					Affinity: &corev1.Affinity{
						PodAntiAffinity: &corev1.PodAntiAffinity{
							RequiredDuringSchedulingIgnoredDuringExecution: []corev1.PodAffinityTerm{
								{
									LabelSelector: &metav1.LabelSelector{
										MatchLabels: labels,
									},
									TopologyKey: "kubernetes.io/hostname",
								},
							},
						},
					},
					Containers: []corev1.Container{
						{
							Name:            ConfigNodeName,
							Image:           configNode.Spec.Image,
							ImagePullPolicy: corev1.PullIfNotPresent,
							Ports: []corev1.ContainerPort{
								{Name: "internal", ContainerPort: 10710},
								{Name: "consensus", ContainerPort: 10720},
							},
							Resources: corev1.ResourceRequirements{
								Limits: corev1.ResourceList{
									corev1.ResourceCPU:    *configNode.Spec.Resources.Limits.Cpu(),
									corev1.ResourceMemory: *configNode.Spec.Resources.Limits.Memory(),
								},
								Requests: corev1.ResourceList{
									corev1.ResourceCPU:    *configNode.Spec.Resources.Limits.Cpu(),
									corev1.ResourceMemory: *configNode.Spec.Resources.Limits.Memory(),
								},
							},
							Env: envVars,
							VolumeMounts: []corev1.VolumeMount{
								{Name: pvcName, MountPath: "/iotdb/data", SubPath: "data"},
								{Name: pvcName, MountPath: "/iotdb/logs", SubPath: "logs"},
								{Name: pvcName, MountPath: "/iotdb/ext", SubPath: "ext"},
								{Name: pvcName, MountPath: "/iotdb/.env", SubPath: ".env"},
								{Name: pvcName, MountPath: "/iotdb/activation", SubPath: "activation"},
							},
						},
					},
				},
			},
			VolumeClaimTemplates: []corev1.PersistentVolumeClaim{pvcTemplate},
		},
	}
	err := SetControllerReference(configNode, statefulset, r.Scheme)
	if err != nil {
		return nil
	}
	return statefulset
}

func (r *ConfigNodeReconciler) constructServicesForConfigNode(configNode *iotdbv1.ConfigNode) ([]corev1.Service, error) {
	headlessService := &corev1.Service{
		ObjectMeta: metav1.ObjectMeta{
			Name:      ConfigNodeName + "-headless",
			Namespace: configNode.Namespace,
			Labels:    map[string]string{"app": ConfigNodeName},
		},
		Spec: corev1.ServiceSpec{
			ClusterIP: "None",
			Ports: []corev1.ServicePort{
				{
					Name:       "cn-internal-port",
					Port:       10710,
					TargetPort: intstr.FromInt32(10710),
				},
				{
					Name:       "cn-consensus-port",
					Port:       10720,
					TargetPort: intstr.FromInt32(10720),
				},
			},
			Selector: map[string]string{
				"app": ConfigNodeName,
			},
		},
	}
	err := SetControllerReference(configNode, headlessService, r.Scheme)
	if err != nil {
		return nil, err
	}

	services := []corev1.Service{*headlessService}
	if configNode.Spec.Service != nil && len(configNode.Spec.Service.Ports) > 0 {
		for key, value := range configNode.Spec.Service.Ports {
			if key == "cn_metric_prometheus_reporter_port" {
				nodePortService := &corev1.Service{
					ObjectMeta: metav1.ObjectMeta{
						Name:      ConfigNodeName,
						Namespace: configNode.Namespace,
						Labels:    map[string]string{"app": ConfigNodeName},
					},
					Spec: corev1.ServiceSpec{
						Type: corev1.ServiceTypeNodePort,
						Ports: []corev1.ServicePort{
							{
								Name:       strutil.ToKebabCase(key),
								Port:       9091,
								NodePort:   value,
								TargetPort: intstr.FromInt32(9091),
							},
						},
						Selector: map[string]string{
							"app": ConfigNodeName,
						},
					},
				}
				err := SetControllerReference(configNode, nodePortService, r.Scheme)
				if err != nil {
					return nil, err
				}
				services = append(services, *nodePortService)
			}
		}
	}
	return services, nil
}

func (r *ConfigNodeReconciler) constructPVCForConfigNode(configNode *iotdbv1.ConfigNode) *corev1.PersistentVolumeClaim {
	pvc := &corev1.PersistentVolumeClaim{
		ObjectMeta: metav1.ObjectMeta{
			Name:      ConfigNodeName,
			Namespace: configNode.Namespace,
			Labels:    map[string]string{"app": ConfigNodeName},
		},
		Spec: configNode.Spec.VolumeClaimTemplate,
	}
	err := SetControllerReference(configNode, pvc, r.Scheme)
	if err != nil {
		return nil
	}
	return pvc
}

// SetupWithManager sets up the controller with the Manager.
func (r *ConfigNodeReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&iotdbv1.ConfigNode{}).
		Owns(&corev1.Service{}).
		Owns(&corev1.PersistentVolumeClaim{}).
		Complete(r)
}