/*
Copyright 2022 The KubeSphere Authors.

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"
	"net"
	"time"

	"github.com/go-logr/logr"
	"github.com/google/go-cmp/cmp"
	"github.com/pkg/errors"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/tools/record"
	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
	"sigs.k8s.io/cluster-api/util"
	"sigs.k8s.io/cluster-api/util/annotations"
	"sigs.k8s.io/cluster-api/util/conditions"
	"sigs.k8s.io/cluster-api/util/patch"
	"sigs.k8s.io/cluster-api/util/predicates"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/event"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"

	infrav1 "github.com/kubesphere/kubekey/api/v1beta1"
	"github.com/kubesphere/kubekey/pkg/scope"
)

// KKClusterReconciler reconciles a KKCluster object
type KKClusterReconciler struct {
	client.Client
	Recorder         record.EventRecorder
	Scheme           *runtime.Scheme
	WatchFilterValue string
	DataDir          string
}

// SetupWithManager sets up the controller with the Manager.
func (r *KKClusterReconciler) SetupWithManager(ctx context.Context, mgr ctrl.Manager, options controller.Options) error {
	log := ctrl.LoggerFrom(ctx)
	c, err := ctrl.NewControllerManagedBy(mgr).
		WithOptions(options).
		For(&infrav1.KKCluster{}).
		WithEventFilter(predicates.ResourceNotPausedAndHasFilterLabel(log, r.WatchFilterValue)).
		WithEventFilter(
			predicate.Funcs{
				// Avoid reconciling if the event triggering the reconciliation is related to incremental status updates
				// for KKCluster resources only
				UpdateFunc: func(e event.UpdateEvent) bool {
					if _, ok := e.ObjectOld.(*infrav1.KKCluster); !ok {
						return true
					}

					oldCluster := e.ObjectOld.(*infrav1.KKCluster).DeepCopy()
					newCluster := e.ObjectNew.(*infrav1.KKCluster).DeepCopy()

					oldCluster.Status = infrav1.KKClusterStatus{}
					newCluster.Status = infrav1.KKClusterStatus{}

					oldCluster.ObjectMeta.ResourceVersion = ""
					newCluster.ObjectMeta.ResourceVersion = ""

					return !cmp.Equal(oldCluster, newCluster)
				},
			},
		).
		WithEventFilter(predicates.ResourceIsNotExternallyManaged(log)).
		Build(r)
	if err != nil {
		return errors.Wrap(err, "error creating controller")
	}

	return c.Watch(
		&source.Kind{Type: &clusterv1.Cluster{}},
		handler.EnqueueRequestsFromMapFunc(r.requeueKKClusterForUnpausedCluster(ctx, log)),
		predicates.ClusterUnpaused(log),
	)
}

//+kubebuilder:rbac:groups=infrastructure.cluster.x-k8s.io,resources=kkclusters,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=infrastructure.cluster.x-k8s.io,resources=kkclusters/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=cluster.x-k8s.io,resources=clusters;clusters/status,verbs=get;list;watch

func (r *KKClusterReconciler) Reconcile(ctx context.Context, req ctrl.Request) (_ ctrl.Result, retErr error) {
	log := ctrl.LoggerFrom(ctx)

	kkCluster := &infrav1.KKCluster{}
	err := r.Get(ctx, req.NamespacedName, kkCluster)
	if err != nil {
		if apierrors.IsNotFound(err) {
			return reconcile.Result{}, nil
		}
		return reconcile.Result{}, err
	}

	// Fetch the Cluster.
	cluster, err := util.GetOwnerCluster(ctx, r.Client, kkCluster.ObjectMeta)
	if err != nil {
		return reconcile.Result{}, err
	}

	if cluster == nil {
		log.Info("Cluster Controller has not yet set OwnerRef")
		return reconcile.Result{}, nil
	}

	if annotations.IsPaused(cluster, kkCluster) {
		log.Info("KKCluster or linked Cluster is marked as paused. Won't reconcile")
		return reconcile.Result{}, nil
	}

	log = log.WithValues("cluster", cluster.Name)
	helper, err := patch.NewHelper(kkCluster, r.Client)
	if err != nil {
		return reconcile.Result{}, errors.Wrap(err, "failed to init patch helper")
	}

	defer func() {
		e := helper.Patch(
			context.TODO(),
			kkCluster,
			patch.WithOwnedConditions{Conditions: []clusterv1.ConditionType{
				infrav1.PrincipalPreparedCondition,
			}})
		if e != nil {
			fmt.Println(e.Error())
		}
	}()

	// Create the scope.
	clusterScope, err := scope.NewClusterScope(scope.ClusterScopeParams{
		Client:         r.Client,
		Logger:         &log,
		Cluster:        cluster,
		KKCluster:      kkCluster,
		ControllerName: "kkcluster",
		RootFsBasePath: r.DataDir,
	})
	if err != nil {
		return reconcile.Result{}, errors.Errorf("failed to create scope: %+v", err)
	}

	// Always close the scope when exiting this function, so we can persist any KKCluster changes.
	defer func() {
		if err := clusterScope.Close(); err != nil && retErr == nil {
			log.Error(err, "failed to patch object")
			retErr = err
		}
	}()

	// Handle deleted clusters
	if !kkCluster.DeletionTimestamp.IsZero() {
		return r.reconcileDelete(ctx, clusterScope)
	}

	// Handle non-deleted clusters
	return r.reconcileNormal(ctx, clusterScope)
}

func (r *KKClusterReconciler) reconcileDelete(ctx context.Context, clusterScope *scope.ClusterScope) (ctrl.Result, error) { //nolint:unparam
	log := ctrl.LoggerFrom(ctx)
	log.V(4).Info("Reconcile KKCluster delete")

	// Cluster is deleted so remove the finalizer.
	controllerutil.RemoveFinalizer(clusterScope.KKCluster, infrav1.ClusterFinalizer)
	return ctrl.Result{}, nil
}

func (r *KKClusterReconciler) reconcileNormal(ctx context.Context, clusterScope *scope.ClusterScope) (reconcile.Result, error) {
	log := ctrl.LoggerFrom(ctx)
	log.V(4).Info("Reconcile KKCluster normal")

	kkCluster := clusterScope.KKCluster

	// If the KKCluster doesn't have our finalizer, add it.
	controllerutil.AddFinalizer(kkCluster, infrav1.ClusterFinalizer)
	// Register the finalizer immediately to avoid orphaning KK resources on delete
	if err := clusterScope.PatchObject(); err != nil {
		return reconcile.Result{}, err
	}

	if _, err := net.LookupIP(kkCluster.Spec.ControlPlaneLoadBalancer.Host); err != nil {
		conditions.MarkFalse(kkCluster, infrav1.ExternalLoadBalancerReadyCondition, infrav1.WaitForDNSNameResolveReason, clusterv1.ConditionSeverityInfo, "")
		clusterScope.Info("Waiting on API server DNS name to resolve")
		return reconcile.Result{RequeueAfter: 15 * time.Second}, nil //nolint:nilerr
	}
	conditions.MarkTrue(kkCluster, infrav1.ExternalLoadBalancerReadyCondition)

	kkCluster.Spec.ControlPlaneEndpoint = clusterv1.APIEndpoint{
		Host: clusterScope.ControlPlaneLoadBalancer().Host,
		Port: clusterScope.APIServerPort(),
	}

	kkCluster.Status.Ready = true
	return ctrl.Result{}, nil
}

func (r *KKClusterReconciler) requeueKKClusterForUnpausedCluster(ctx context.Context, log logr.Logger) handler.MapFunc {
	return func(o client.Object) []ctrl.Request {
		c, ok := o.(*clusterv1.Cluster)
		if !ok {
			panic(fmt.Sprintf("Expected a Cluster but got a %T", o))
		}

		log := log.WithValues("objectMapper", "clusterToKKCluster", "namespace", c.Namespace, "cluster", c.Name)

		// Don't handle deleted clusters
		if !c.ObjectMeta.DeletionTimestamp.IsZero() {
			log.V(4).Info("Cluster has a deletion timestamp, skipping mapping.")
			return nil
		}

		// Make sure the ref is set
		if c.Spec.InfrastructureRef == nil {
			log.V(4).Info("Cluster does not have an InfrastructureRef, skipping mapping.")
			return nil
		}

		if c.Spec.InfrastructureRef.GroupVersionKind().Kind != "KKCluster" {
			log.V(4).Info("Cluster has an InfrastructureRef for a different type, skipping mapping.")
			return nil
		}

		kkCluster := &infrav1.KKCluster{}
		key := types.NamespacedName{Namespace: c.Spec.InfrastructureRef.Namespace, Name: c.Spec.InfrastructureRef.Name}

		if err := r.Get(ctx, key, kkCluster); err != nil {
			log.V(4).Error(err, "Failed to get KubeKey cluster")
			return nil
		}

		if annotations.IsExternallyManaged(kkCluster) {
			log.V(4).Info("KKCluster is externally managed, skipping mapping.")
			return nil
		}

		log.V(4).Info("Adding request.", "kkCluster", c.Spec.InfrastructureRef.Name)
		return []ctrl.Request{
			{
				NamespacedName: client.ObjectKey{Namespace: c.Namespace, Name: c.Spec.InfrastructureRef.Name},
			},
		}
	}
}