package manager

import (
	"context"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go/service/autoscaling"
	"github.com/aws/aws-sdk-go/service/autoscaling/autoscalingiface"
	"github.com/crossplane-contrib/provider-aws/apis/autoscaling/v1beta1"
	"github.com/crossplane-contrib/provider-aws/apis/eks/manualv1alpha1"
	"github.com/go-logr/logr"
	"github.com/pingcap/errors"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/utils/pointer"
	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/reconcile"

	"github.com/tidbcloud/eks-provider/controllers"
	cloudv1 "github.com/tidbcloud/infra-api/api/v1"
	"github.com/tidbcloud/infra-provider/pkg/config"
	"github.com/tidbcloud/infra-provider/pkg/consts"
	"github.com/tidbcloud/infra-provider/pkg/controllers/common"
	"github.com/tidbcloud/infra-provider/pkg/k8s"
	metricsctrl "github.com/tidbcloud/infra-provider/pkg/metrics/controller"
	"github.com/tidbcloud/infra-provider/pkg/namer"
	"github.com/tidbcloud/infra-provider/pkg/procedure"
)

const (
	protectionKey      = "tidbcloud.com/scale-in-protection"
	protectionEnabled  = "enabled"
	protectionDisabled = "disabled"
	protectionUnknow   = "unknown"

	tidbclusterName = "tidb-cluster"
)

type ClusterNodeProtectorRegister struct {
	InfraClient client.Client
	AWSSVC      procedure.AWSService
	Config      config.RootConfig
}

// NewClusterNodeProtectorRegister create a new ClusterNodeProtectorRegister.
func NewClusterNodeProtectorRegister(infraClient client.Client, awsSVC procedure.AWSService, Config config.RootConfig) *ClusterNodeProtectorRegister {
	return &ClusterNodeProtectorRegister{
		InfraClient: infraClient,
		AWSSVC:      awsSVC,
		Config:      Config,
	}
}

var _ k8s.DataplaneReconcilerRegister = &ClusterNodeProtectorRegister{}

// Register implements NetworkReconcilerRegister interface.
func (c *ClusterNodeProtectorRegister) Register(nctx *k8s.DataplaneContext) error {
	assumeRole, err := nctx.KubeCluster.GetAssumeRole()
	if err != nil {
		return err
	}
	role := &procedure.AssumedRole{
		RoleARN:    assumeRole.RoleARN,
		ExternalID: assumeRole.ExternalID,
	}

	as := c.AWSSVC.AutoScalingAPI(role)
	logger := ctrl.Log.WithName("controllers").WithName("NodeProtector").
		WithValues("network", nctx.KubeCluster.GetName())

	protecter := &ClusterNodeProtector{
		InfraClient: c.InfraClient,
		AWSSVC:      c.AWSSVC,
		Log:         logger,
		shootClient: nctx.Manager.GetClient(),
		autoscaling: as,
	}

	logger.Info("registering node protector")

	// pod should be indexed by .spec.nodeName
	if err := nctx.Manager.GetFieldIndexer().IndexField(context.TODO(), &corev1.Pod{}, "spec.nodeName", func(obj client.Object) []string {
		pod := obj.(*corev1.Pod)
		return []string{pod.Spec.NodeName}
	}); err != nil {
		return err
	}

	err = ctrl.NewControllerManagedBy(nctx.Manager).
		Named(nctx.KubeCluster.GetName() + "_nodes").
		For(&corev1.Node{}).
		WithOptions(controller.Options{RateLimiter: common.DefaultRateLimiter(), MaxConcurrentReconciles: controllers.GetMaxConcurrentReconciles(c.Config, "clusterNodeProtector")}).
		Complete(protecter)
	if err != nil {
		return err
	}

	return nil
}

// ClusterNodeProtector protects the node inuse
type ClusterNodeProtector struct {
	InfraClient client.Client
	AWSSVC      procedure.AWSService

	autoscaling autoscalingiface.AutoScalingAPI
	Log         logr.Logger
	shootClient client.Client
}

var _ reconcile.Reconciler = &ClusterNodeProtector{}

func (c *ClusterNodeProtector) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	start := time.Now()
	logger := log.FromContext(ctx)
	defer func() {
		metricsctrl.ReconcileDuration.
			WithLabelValues("node_protector").
			Observe(time.Since(start).Seconds())
	}()

	node := &corev1.Node{}
	err := c.shootClient.Get(ctx, req.NamespacedName, node)
	if err != nil {
		logger.Error(err, "failed to get Node", "name", req.NamespacedName)
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	// nodegroup not manage by cluster, shortcut to skip
	com := node.Labels[namer.ComponentSelectorKey]
	logger.Info("node component label", "name", req.NamespacedName, "component", com)
	switch cloudv1.ComponentType(com) {
	case cloudv1.ComponentTiProxy, cloudv1.ComponentTiDB, cloudv1.ComponentPD, cloudv1.ComponentTiKV, cloudv1.ComponentTiFlash:
	default:
		logger.Info("skip non-data node", "name", req.NamespacedName)
		return ctrl.Result{}, nil
	}

	podList := &corev1.PodList{}
	err = c.shootClient.List(ctx, podList, client.MatchingFields(map[string]string{
		"spec.nodeName": node.Name,
	}))
	if err != nil {
		logger.Error(err, "failed to list pods on the node", "node", node.Name)
		return ctrl.Result{}, errors.AddStack(err)
	}
	logger.Info("listed pods on node", "node", node.Name, "podCount", len(podList.Items))

	expectProtection := protectionDisabled
	for _, pod := range podList.Items {
		if comp, ok := getPodComponentType(&pod); ok {
			logger.Info("found data pod on node", "node", node.Name, "pod", pod.Name, "component", *comp)
			expectProtection = protectionEnabled
		}
	}

	logger.Info("calculated expected protection", "node", node.Name, "expectProtection", expectProtection, "currentProtection", node.Annotations[protectionKey])

	protection := node.Annotations[protectionKey]
	if protection == expectProtection {
		logger.Info("protection already in expected state, skip", "node", node.Name, "protection", protection)
		return ctrl.Result{}, nil
	}

	var asgName string
	var instanceIds []*string

	// start get asg name
	logger.Info("start to get asg name", "node", node.Name)
	if managedNGName, ok := node.Labels["eks.amazonaws.com/nodegroup"]; ok {
		// the node belongs to a managed nodegroup
		ngCR := &manualv1alpha1.NodeGroup{}
		if err = c.InfraClient.Get(ctx, types.NamespacedName{Name: managedNGName}, ngCR); err != nil {
			logger.Error(err, "failed to get managed nodegroup CR", "nodegroup", managedNGName)
			return ctrl.Result{}, err
		}
		asgs := ngCR.Status.AtProvider.Resources.AutoScalingGroups
		if len(asgs) == 0 {
			// The asg status may not be set by crossplane when node already added to k8s.
			// To avoid annoying error message, we only return error when the nodegroup is created after some time.
			if time.Since(ngCR.CreationTimestamp.Time) > 5*time.Minute {
				logger.Error(nil, "no AutoScalingGroup found for managed nodegroup after timeout", "nodegroup", managedNGName)
				return ctrl.Result{}, errors.New("no AutoScalingGroup found")
			}

			logger.Info("no AutoScalingGroup found for managed nodegroup, requeue", "nodegroup", managedNGName)
			return ctrl.Result{RequeueAfter: time.Second * 5}, nil
		}
		asgName = asgs[0].Name
		logger.Info("got asg name from managed nodegroup", "nodegroup", managedNGName, "asgName", asgName)
	} else {
		// the node belongs to a self-managed nodegroup
		asgCR := &v1beta1.AutoScalingGroup{}
		if err = c.InfraClient.Get(ctx, types.NamespacedName{
			Name: node.Labels["Name"],
		}, asgCR); err != nil {
			logger.Error(err, "failed to get self-managed asg CR", "asgNameLabel", node.Labels["Name"])
			return ctrl.Result{}, err
		}
		if asgCR.Status.AtProvider.AutoScalingGroupName == nil {
			// The asg status may not be set by crossplane when node already added to k8s.
			// To avoid annoying error message, we only return error when the nodegroup is created after some time.
			if time.Since(asgCR.CreationTimestamp.Time) > 5*time.Minute {
				logger.Error(nil, "no AutoScalingGroup found for self-managed asg after timeout", "asgNameLabel", node.Labels["Name"])
				return ctrl.Result{}, errors.New("no AutoScalingGroup found")
			}

			logger.Info("no AutoScalingGroup found for self-managed asg, requeue", "asgNameLabel", node.Labels["Name"])
			return ctrl.Result{RequeueAfter: time.Second * 5}, nil
		}
		asgName = *asgCR.Status.AtProvider.AutoScalingGroupName
		logger.Info("got asg name from self-managed asg", "asgName", asgName)
	}

	// start get instanceIds
	providerID := node.Spec.ProviderID
	if providerID == "" {
		return ctrl.Result{}, errors.New("empty node.Spec.ProviderID")
	}
	instanceID := providerID[strings.LastIndex(providerID, "/")+1:]
	instanceIds = []*string{pointer.String(instanceID)}

	logger.Info("updating scale-in protection to expected", "node", node.Name, "asgName", asgName, "instanceID", instanceID, "enable", expectProtection == protectionEnabled)
	err = setScaleInProtection(ctx, c.autoscaling, asgName, instanceIds, expectProtection == protectionEnabled)
	if err != nil {
		logger.Error(err, "failed to update scale-in protection to expected", "node", node.Name, "asgName", asgName, "instanceID", instanceID)
		return ctrl.Result{}, err
	}

	logger.Info("patching node annotation for protection", "node", node.Name, "key", protectionKey, "value", expectProtection)
	err = patchAnnKey(ctx, c.shootClient, node, protectionKey, expectProtection)
	if err != nil {
		logger.Error(err, "failed to patch node annotation for protection", "node", node.Name, "key", protectionKey, "value", expectProtection)
		return ctrl.Result{}, err
	}

	logger.Info("finished reconcile node protection", "node", node.Name, "finalProtection", expectProtection)
	return ctrl.Result{}, nil
}

func patchAnnKey(ctx context.Context, cli client.Client, node *corev1.Node, key string, value string) error {
	patch := client.MergeFrom(node.DeepCopy())

	if node.Annotations == nil {
		node.Annotations = make(map[string]string)
	}
	node.Annotations[key] = value

	return cli.Patch(ctx, node, patch)
}

func setScaleInProtection(ctx context.Context, cli autoscalingiface.AutoScalingAPI, asgName string, instanceIds []*string, enable bool) error {
	input := &autoscaling.SetInstanceProtectionInput{
		AutoScalingGroupName: &asgName,
		InstanceIds:          instanceIds,
		ProtectedFromScaleIn: &enable,
	}
	_, err := cli.SetInstanceProtection(input)
	if err != nil {
		return err
	}

	return nil
}

func getPodComponentType(pod *corev1.Pod) (*cloudv1.ComponentType, bool) {
	var component cloudv1.ComponentType

	name := pod.Labels[consts.NameLabelKey]
	if name != tidbclusterName {
		return nil, false
	}

	componentName, ok := pod.Labels[consts.ComponentLabelKey]
	if !ok {
		return nil, false
	}

	component = cloudv1.ComponentType(componentName)
	return &component, true
}