// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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"
	"time"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/tools/record"
	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/reconcile"

	dsv1alpha1 "dolphinscheduler-operator/api/v1alpha1"
)

// DSWorkerReconciler reconciles a DSWorker object
type DSWorkerReconciler struct {
	client.Client
	Scheme   *runtime.Scheme
	recorder record.EventRecorder
}

var (
	workerLogger = ctrl.Log.WithName("DSWorker-controller")
)

//+kubebuilder:rbac:groups=ds.apache.dolphinscheduler.dev,resources=dsworkers,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=ds.apache.dolphinscheduler.dev,resources=dsworkers/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=ds.apache.dolphinscheduler.dev,resources=dsworkers/finalizers,verbs=update
//+kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups="",resources=persistentvolumeclaims,verbs=get;create;delete;list;watch
//+kubebuilder:rbac:groups="",resources=pods,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups="",resources=services,verbs=get;list;watch;create;update;patch;delete

// Reconcile is part of the main kubernetes reconciliation loop which aims to
// move the current state of the cluster closer to the desired state.
// the DSWorker 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@v0.11.0/pkg/reconcile
func (r *DSWorkerReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	workerLogger.Info("dmWorker start reconcile logic")
	defer workerLogger.Info("dmWorker Reconcile end ---------------------------------------------")

	cluster := &dsv1alpha1.DSWorker{}

	if err := r.Client.Get(ctx, req.NamespacedName, cluster); err != nil {
		if errors.IsNotFound(err) {
			r.recorder.Event(cluster, corev1.EventTypeWarning, "dmWorker is not Found", "dmWorker is not Found")
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}
	desired := cluster.DeepCopy()

	// Handler finalizer
	// examine DeletionTimestamp to determine if object is under deletion
	if cluster.ObjectMeta.DeletionTimestamp.IsZero() {
		// The object is not being deleted, so if it does not have our finalizer,
		// then lets add the finalizer and update the object. This is equivalent
		// registering our finalizer.
		if !controllerutil.ContainsFinalizer(desired, dsv1alpha1.FinalizerName) {
			controllerutil.AddFinalizer(desired, dsv1alpha1.FinalizerName)
			if err := r.Update(ctx, desired); err != nil {
				return ctrl.Result{}, err
			}
		}
	} else {
		// The object is being deleted
		if controllerutil.ContainsFinalizer(desired, dsv1alpha1.FinalizerName) {
			// our finalizer is present, so lets handle any external dependency
			if err := r.ensureDSWorkerDeleted(ctx, cluster); err != nil {
				return ctrl.Result{}, err
			}
			// remove our finalizer from the list and update it.
			controllerutil.RemoveFinalizer(desired, dsv1alpha1.FinalizerName)
			if err := r.Update(ctx, desired); err != nil {
				return ctrl.Result{}, err
			}
		}
		return ctrl.Result{}, nil
	}

	// If dsworker-cluster is paused, we do nothing on things changed.
	// Until dsworker-cluster is un-paused, we will reconcile to the dsworker state of that point.
	if cluster.Spec.Paused {
		workerLogger.Info("ds-worker control has been paused: ", "ds-worker-name", cluster.Name)
		desired.Status.ControlPaused = true
		if err := r.Status().Patch(ctx, desired, client.MergeFrom(cluster)); err != nil {
			if apierrors.IsConflict(err) {
				return ctrl.Result{Requeue: true}, nil
			} else {
				masterLogger.Error(err, "unexpected error when worker update status in paused")
				return ctrl.Result{}, err
			}
		}
		r.recorder.Event(cluster, corev1.EventTypeNormal, "the spec status is paused", "do nothing")
		return ctrl.Result{}, nil
	}

	// 1. First time we see the ds-worker-cluster, initialize it
	if cluster.Status.Phase == dsv1alpha1.DsPhaseNone {
		if desired.Status.Selector == "" {
			selector, err := metav1.LabelSelectorAsSelector(&metav1.LabelSelector{MatchLabels: LabelForWorkerPod()})
			if err != nil {
				masterLogger.Error(err, "Error retrieving selector labels")
				return reconcile.Result{}, err
			}
			desired.Status.Selector = selector.String()
		}
		desired.Status.Phase = dsv1alpha1.DsPhaseCreating
		workerLogger.Info("phase had been changed from  none ---> creating")
		if err := r.Client.Status().Patch(ctx, desired, client.MergeFrom(cluster)); err != nil {
			if apierrors.IsConflict(err) {
				return ctrl.Result{RequeueAfter: 100 * time.Millisecond}, err
			} else {
				masterLogger.Error(err, "unexpected error when worker update status in creating")
				return ctrl.Result{}, err
			}
		}
	}

	// 3. Ensure bootstrapped, we will block here util cluster is up and healthy
	workerLogger.Info("Ensuring cluster members")
	if requeue, err := r.ensureMembers(ctx, cluster); requeue {
		return ctrl.Result{RequeueAfter: 5 * time.Second}, err
	}

	// 4. Ensure cluster scaled
	workerLogger.Info("Ensuring cluster scaled")
	if requeue, err := r.ensureScaled(ctx, cluster); requeue {
		return ctrl.Result{Requeue: true, RequeueAfter: 5 * time.Second}, err
	}

	// .5 Ensure cluster upgraded
	workerLogger.Info("Ensuring cluster upgraded")
	if requeue, err := r.ensureUpgraded(ctx, cluster); requeue {
		return ctrl.Result{Requeue: true}, err
	}

	desired.Status.Phase = dsv1alpha1.DsPhaseFinished
	if err := r.Status().Patch(ctx, desired, client.MergeFrom(cluster)); err != nil {
		if apierrors.IsConflict(err) {
			return ctrl.Result{Requeue: true}, nil
		} else {
			masterLogger.Error(err, "unexpected error when worker update status in finished")
			return ctrl.Result{}, err
		}
	}

	workerLogger.Info("******************************************************")
	desired.Status.Phase = dsv1alpha1.DsPhaseNone
	return ctrl.Result{Requeue: false}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *DSWorkerReconciler) SetupWithManager(mgr ctrl.Manager) error {
	r.recorder = mgr.GetEventRecorderFor("worker-controller")
	return ctrl.NewControllerManagedBy(mgr).
		For(&dsv1alpha1.DSWorker{}).
		Owns(&corev1.Pod{}).
		Complete(r)
}

func (r *DSWorkerReconciler) ensureMembers(ctx context.Context, cluster *dsv1alpha1.DSWorker) (bool, error) {

	pms, err := r.podMemberSet(ctx, cluster)
	if err != nil {
		return true, err
	}
	if len(pms) > 0 {
		return !allMembersHealth(pms), nil
	} else {
		return false, nil
	}

}

func (r *DSWorkerReconciler) ensureScaled(ctx context.Context, cluster *dsv1alpha1.DSWorker) (bool, error) {
	// Get current members in this cluster
	ms, err := r.podMemberSet(ctx, cluster)
	if err != nil {
		return true, err
	}

	// Scale up
	if len(ms) < cluster.Spec.Replicas {
		err = r.createMember(ctx, cluster)
		if err != nil {
			r.recorder.Event(cluster, corev1.EventTypeWarning, "cannot create the new ds-dsworker pod", "the ds-dsworker pod had been created failed")
			return true, err
		}
		return true, err
	}

	// Scale down
	if len(ms) > cluster.Spec.Replicas {
		pod := &corev1.Pod{}
		member := ms.PickOne()
		pod.SetName(member.Name)
		pod.SetNamespace(member.Namespace)
		err = r.deleteMember(ctx, pod, cluster)
		if err != nil {
			return true, err
		}
		return true, err
	}

	return false, nil
}

func (r *DSWorkerReconciler) ensureUpgraded(ctx context.Context, cluster *dsv1alpha1.DSWorker) (bool, error) {

	ms, err := r.podMemberSet(ctx, cluster)
	if err != nil {
		return false, err
	}

	for _, memset := range ms {
		if memset.Version != cluster.Spec.Version {
			pod := &corev1.Pod{}
			pod.SetName(memset.Name)
			pod.SetNamespace(memset.Namespace)
			if err := r.deleteMember(ctx, pod, cluster); err != nil {
				return false, err
			}
			return true, nil
		}
	}
	return false, nil
}

func (r *DSWorkerReconciler) ensureDSWorkerDeleted(ctx context.Context, cluster *dsv1alpha1.DSWorker) error {
	if err := r.Client.Delete(ctx, cluster, client.PropagationPolicy(metav1.DeletePropagationOrphan)); err != nil {
		return err
	}
	return nil
}

func (r *DSWorkerReconciler) createMember(ctx context.Context, cluster *dsv1alpha1.DSWorker) error {
	workerLogger.Info("Starting add new member to cluster", "cluster", cluster.Name)
	defer workerLogger.Info("End add new member to cluster", "cluster", cluster.Name)

	// New Pod
	pod, err := r.newDSWorkerPod(ctx, cluster)
	if err != nil {
		return err
	}

	// Create pod
	if err = r.Client.Create(ctx, pod); err != nil && !apierrors.IsAlreadyExists(err) {
		return err
	}

	desired := cluster.DeepCopy()
	desired.Spec.Replicas += 1
	if err := r.Status().Patch(ctx, desired, client.MergeFrom(cluster)); err != nil {
		return err
	}
	return nil
}

func (r *DSWorkerReconciler) deleteMember(ctx context.Context, pod *corev1.Pod, cluster *dsv1alpha1.DSWorker) error {

	workerLogger.Info("begin delete pod", "pod name", pod.Name)
	if err := r.Client.Delete(ctx, pod); err != nil && !apierrors.IsNotFound(err) {
		return err
	}

	desired := cluster.DeepCopy()
	desired.Spec.Replicas -= 1
	if err := r.Status().Patch(ctx, desired, client.MergeFrom(cluster)); err != nil {
		return err
	}
	return nil
}