/*
Copyright 2023.

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"

	databasev1 "github.com/iwanhae/nodb/api/v1"
	"github.com/iwanhae/nodb/internal/templates"
	"github.com/pkg/errors"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/intstr"
	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"
)

// PostgreSQLReconciler reconciles a PostgreSQL object
type PostgreSQLReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

//+kubebuilder:rbac:groups=database.iwanhae.kr,resources=postgresqls,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=database.iwanhae.kr,resources=postgresqls/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=database.iwanhae.kr,resources=postgresqls/finalizers,verbs=update
//+kubebuilder:rbac:groups="",resources=pods,verbs=get;create

// 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 PostgreSQL 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@v0.16.0/pkg/reconcile
func (r *PostgreSQLReconciler) Reconcile(ctx context.Context, req ctrl.Request) (result ctrl.Result, err error) {
	logger := log.FromContext(ctx)

	obj := databasev1.PostgreSQL{}
	if err := r.Get(ctx, req.NamespacedName, &obj); err != nil {
		if client.IgnoreNotFound(err) == nil {
			return ctrl.Result{}, nil
		}
		logger.Error(err, "resource not found")
		return ctrl.Result{}, err
	}
	original := obj.DeepCopy()
	logger.Info("reconcile", "namespace", obj.Namespace, "name", obj.Name)

	defer func() {
		status := databasev1.Status_Ready
		if obj.Status.Conditions.Pod.IsLowerThan(status) {
			status = obj.Status.Conditions.Pod
		}
		if obj.Status.Conditions.Service.IsLowerThan(status) {
			status = obj.Status.Conditions.Service
		}
		obj.Status.Status = status
		err = r.Status().Patch(ctx, &obj, client.MergeFrom(original))
		if err != nil {
			logger.Error(err, "failed to update status")
		}
	}()

	if err := r.createOrUpdatePod(ctx, &obj); err != nil {
		return ctrl.Result{}, err
	}

	if err := r.createOrUpdateService(ctx, &obj); err != nil {
		return ctrl.Result{}, err
	}

	return ctrl.Result{}, nil
}

func (r *PostgreSQLReconciler) createOrUpdateService(ctx context.Context, obj *databasev1.PostgreSQL) error {
	logger := log.FromContext(ctx)

	svc := corev1.Service{
		ObjectMeta: metav1.ObjectMeta{Name: obj.Name, Namespace: obj.Namespace},
	}
	err := r.Client.Get(ctx, types.NamespacedName{
		Namespace: obj.Namespace, Name: obj.Name,
	}, &svc)
	if err != nil && !apierrors.IsNotFound(err) {
		// can't handle other than not found error
		return err
	}

	logger.Info("create or update service")
	if result, err := controllerutil.CreateOrUpdate(ctx, r.Client, &svc, func() error {
		if err := controllerutil.SetOwnerReference(obj, &svc, r.Scheme); err != nil {
			return errors.Wrap(err, "failed to set owner reference")
		}
		svc.ObjectMeta.Labels = map[string]string{
			templates.LabelKeyType: templates.LabelValuePostgreSQL,
			templates.LabelKeyName: obj.Name,
		}
		svc.Spec.Selector = map[string]string{
			templates.LabelKeyType: templates.LabelValuePostgreSQL,
			templates.LabelKeyName: obj.Name,
		}
		svc.Spec.Ports = []corev1.ServicePort{
			{Name: "postgres", Port: 5432, TargetPort: intstr.FromString("postgres"), Protocol: corev1.ProtocolTCP},
		}
		svc.Spec.Type = corev1.ServiceTypeNodePort
		svc.Spec.ExternalTrafficPolicy = corev1.ServiceExternalTrafficPolicyLocal
		return nil
	}); err != nil {
		return err
	} else if result != controllerutil.OperationResultNone {
		logger.Info("service modified", "result", result)
	}

	obj.Status.Conditions.Service = databasev1.Status_Ready
	return nil
}
func (r *PostgreSQLReconciler) createOrUpdatePod(ctx context.Context, obj *databasev1.PostgreSQL) error {
	logger := log.FromContext(ctx)

	pod := corev1.Pod{}
	if err := r.Client.Get(ctx, types.NamespacedName{
		Namespace: obj.Namespace,
		Name:      obj.Name,
	}, &pod); err == nil {
		// if found return
		logger.Info("ignore already existing pod")
		return nil
	} else if !apierrors.IsNotFound(err) {
		// can't handle other than not found error
		return err
	}

	pod = templates.PostgreSQLPod(templates.PostgreSQLOpts{
		Name:      obj.Name,
		Namespace: obj.Namespace,
		Tag:       obj.Spec.Version,

		User:     obj.Spec.User,
		Password: obj.Spec.Password,
		Database: obj.Spec.Database,

		Memory: resource.MustParse("1Gi"),
		Owner:  obj,
	})

	logger.Info("create pod", "namespace", pod.Namespace, "name", pod.Name)
	if err := r.Client.Create(ctx, &pod); err != nil {
		return errors.Wrap(err, "failed to create pod")
	}

	obj.Status.Conditions.Pod = databasev1.Status_Initializing
	return nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *PostgreSQLReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&databasev1.PostgreSQL{}).
		Complete(r)
}