package tidbpodrescheduler

import (
	"context"
	"fmt"
	"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/tidbmanager"
	"github.com/tidbcloud/aws-shared-provider/pkg/types"
	corev1 "k8s.io/api/core/v1"
	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"
)

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

	Client       client.Client
	Namespace    string
	TidbManagers map[string]tidbmanager.TidbManager
}

// 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("tidbpodrescheduler")
	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 _, tManager := range r.TidbManagers {
		r.reschedule(ctx, tManager, nodeScoreMap.Status)
	}

	return ctrl.Result{}, nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *Reconciler) SetupWithManager(mgr manager.Manager) error {
	if err := mgr.GetFieldIndexer().IndexField(context.TODO(), &corev1.Pod{},
		"tidb.rescheduler.pending", func(obj client.Object) []string {
			pod := obj.(*corev1.Pod)
			if v := pod.Annotations[types.AnnoTidbReschedule]; v != "" && pod.Status.Phase == corev1.PodPending {
				return []string{v}
			}
			return nil
		},
	); err != nil {
		return fmt.Errorf("unable to add index for tidb.rescheduler.pending: %w", err)
	}

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

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