package tidbnodescaler

import (
	"context"
	"time"

	serverlessv1alpha1 "github.com/tidbcloud/aws-shared-provider/apis/serverless/v1alpha1"
	"github.com/tidbcloud/aws-shared-provider/pkg/manager"
	"github.com/tidbcloud/aws-shared-provider/pkg/types"
	corev1 "k8s.io/api/core/v1"
	"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"
	"sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
)

const (
	maxScaleDownDisabledScore = 50
)

// Reconciler reconciles a node-score-map NodeScore object.
type Reconciler struct {
	controller.Controller

	ProviderType string
	Client       client.Client
	Recorder     record.EventRecorder
	Namespace    string
}

// Reconcile is part of the main kubernetes reconciliation loop which aims to
// move the current state of the cluster closer to the desired state.
func (r *Reconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	logger := log.FromContext(ctx).WithName("tidbnodescaler")
	ctx = log.IntoContext(ctx, logger)

	logger.V(2).Info("start reconcile")
	start := time.Now()
	defer func() {
		logger.V(2).Info("finish reconcile", "time", time.Since(start))
	}()

	nodeScoreMap := &serverlessv1alpha1.NodeScore{}
	if err := r.Client.Get(ctx, req.NamespacedName, nodeScoreMap); err != nil {
		logger.Error(err, "failed to get node score map")
		return ctrl.Result{}, err
	}

	for nodeName, score := range nodeScoreMap.Status.ResourceNodeScore {
		node := &corev1.Node{}
		if err := r.Client.Get(ctx, client.ObjectKey{Name: nodeName}, node); err != nil {
			logger.Error(err, "failed to get node", "nodeName", nodeName)
			return ctrl.Result{}, err
		}
		if node.DeletionTimestamp != nil {
			logger.V(1).Info("node is terminating, skip", "nodeName", nodeName)
			continue
		}

		if score < maxScaleDownDisabledScore {
			r.trySetScaleDownDisabledNode(ctx, node, score)
		} else {
			r.tryRemoveScaleDownDisabledNode(ctx, node, score)
		}
	}

	return ctrl.Result{}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *Reconciler) SetupWithManager(mgr manager.Manager) error {
	r.Recorder = mgr.GetEventRecorderFor("TidbNodeScaler")

	byFilterFuncs := predicate.NewPredicateFuncs(func(object client.Object) bool {
		nodeScore := object.(*serverlessv1alpha1.NodeScore)
		return nodeScore.Name == types.NodeScoreMap && nodeScore.Namespace == r.Namespace &&
			len(nodeScore.Status.ResourceNodeScore) > 0
	})

	return ctrl.NewControllerManagedBy(mgr).Named("TidbNodeScaler").For(&serverlessv1alpha1.NodeScore{}).
		WithEventFilter(byFilterFuncs).
		Complete(r)
}