package manager

import (
	"context"
	"fmt"
	"sync/atomic"
	"time"

	"github.com/juju/errors"
	cloudv1 "github.com/tidbcloud/infra-api/api/v1"
	"github.com/tidbcloud/serverless-service/internal/config"
	"github.com/tidbcloud/serverless-service/internal/domain/constant"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/utils/pointer"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/cache"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
)

var (
	globalMgr manager.Manager
	// initialized prevents the manager being initialized multiple times.
	initialized atomic.Bool

	NoSyncPeriod                 = pointer.Duration(0)
	InfraAPIClientDefaultTimeout = 60 * time.Second
	DefaultUnsafeDisableDeepCopy = true
)

func NewInfraManager() manager.Manager {
	if initialized.Swap(true) {
		return globalMgr
	}

	mgr, err := newManager(config.Global().InfraAPIConfig)
	if err != nil {
		panic(fmt.Sprintf("initialize the infra manager failed: %s", err.Error()))
	}

	globalMgr = mgr
	return mgr
}

func newManager(cfg config.InfraAPIConfig) (manager.Manager, error) {
	scheme := runtime.NewScheme()
	utilruntime.Must(cloudv1.AddToScheme(scheme))
	utilruntime.Must(corev1.AddToScheme(scheme))

	if cfg.KubeConfigPath == "" {
		return nil, errors.New("infra API server kubeconfig path is empty")
	}
	restCfg, err := clientcmd.BuildConfigFromFlags("", cfg.KubeConfigPath)
	if err != nil {
		return nil, errors.Annotate(err, "retrieve infra API server kubeconfig failed")
	}

	// set timeout for infra api client, ref to https://github.com/kubernetes/client-go/blob/master/rest/config.go
	restCfg.Timeout = InfraAPIClientDefaultTimeout
	labelSelector, err := metav1.LabelSelectorAsSelector(&metav1.LabelSelector{ // we only care about serverless tier
		MatchExpressions: []metav1.LabelSelectorRequirement{
			{
				Key:      constant.LabelKeyProviderType,
				Operator: metav1.LabelSelectorOpIn,
				Values:   constant.AllFreeTierProviderTypes(),
			},
		},
	})
	if err != nil {
		return nil, errors.Annotate(err, "create label selector failed")
	}

	mgr, err := ctrl.NewManager(restCfg,
		ctrl.Options{
			Scheme:         scheme,
			Metrics:        metricsserver.Options{BindAddress: "0"}, // disable metrics
			LeaderElection: false,
			Cache: cache.Options{
				SyncPeriod: NoSyncPeriod,
				Scheme:     scheme,
				ByObject: map[client.Object]cache.ByObject{
					&cloudv1.Branch{}: {
						Label:                 labelSelector,
						UnsafeDisableDeepCopy: &DefaultUnsafeDisableDeepCopy,
					},
					&cloudv1.Export{}: {
						Label:                 labelSelector,
						UnsafeDisableDeepCopy: &DefaultUnsafeDisableDeepCopy,
					},
					&cloudv1.Import{}: {
						Label:                 labelSelector,
						UnsafeDisableDeepCopy: &DefaultUnsafeDisableDeepCopy,
					},
				},
			},
		},
	)
	if err != nil {
		return nil, errors.Annotate(err, "create controller-runtime manager failed")
	}

	if err := mgr.GetFieldIndexer().IndexField(context.Background(), &cloudv1.Branch{}, "status.phase", func(obj client.Object) []string {
		branch := obj.(*cloudv1.Branch)
		return []string{string(branch.Status.Phase)}
	}); err != nil {
		return nil, errors.Annotate(err, "index field status.phase for branch failed")
	}
	globalMgr = mgr
	return mgr, nil
}