package addontemplate

import (
	"context"
	"time"

	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/client-go/dynamic/dynamicinformer"
	kubeinformers "k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/cache"
	"k8s.io/klog/v2"

	"open-cluster-management.io/addon-framework/pkg/addonfactory"
	"open-cluster-management.io/addon-framework/pkg/addonmanager"
	"open-cluster-management.io/addon-framework/pkg/utils"
	addonv1beta1 "open-cluster-management.io/api/addon/v1beta1"
	addonclient "open-cluster-management.io/api/client/addon/clientset/versioned"
	addoninformers "open-cluster-management.io/api/client/addon/informers/externalversions"
	addonlisterv1beta1 "open-cluster-management.io/api/client/addon/listers/addon/v1beta1"
	clusterv1informers "open-cluster-management.io/api/client/cluster/informers/externalversions"
	workv1client "open-cluster-management.io/api/client/work/clientset/versioned"
	workv1informers "open-cluster-management.io/api/client/work/informers/externalversions"
	clusterv1 "open-cluster-management.io/api/cluster/v1"
	"open-cluster-management.io/sdk-go/pkg/basecontroller/factory"

	addonindex "open-cluster-management.io/ocm/pkg/addon/index"
	"open-cluster-management.io/ocm/pkg/addon/templateagent"
	"open-cluster-management.io/ocm/pkg/common/queue"
)

// addonTemplateController monitors ManagedClusterAddOns on hub to get all the in-used addon templates,
// and starts an addon manager for every addon template to handle agent requests deployed by this template
type addonTemplateController struct {
	// addonManagers holds all addon managers that will be deployed with template type addons.
	// The key is the name of the template type addon.
	addonManagers map[string]context.CancelFunc

	kubeConfig                 *rest.Config
	addonClient                addonclient.Interface
	workClient                 workv1client.Interface
	kubeClient                 kubernetes.Interface
	cmaLister                  addonlisterv1beta1.ClusterManagementAddOnLister
	managedClusterAddonIndexer cache.Indexer
	addonInformers             addoninformers.SharedInformerFactory
	clusterInformers           clusterv1informers.SharedInformerFactory
	dynamicInformers           dynamicinformer.DynamicSharedInformerFactory
	workInformers              workv1informers.SharedInformerFactory
	runControllerFunc          runController
}

type runController func(ctx context.Context, addonName string) error

// NewAddonTemplateController returns an instance of addonTemplateController
func NewAddonTemplateController(
	hubKubeconfig *rest.Config,
	hubKubeClient kubernetes.Interface,
	addonClient addonclient.Interface,
	workClient workv1client.Interface,
	addonInformers addoninformers.SharedInformerFactory,
	clusterInformers clusterv1informers.SharedInformerFactory,
	dynamicInformers dynamicinformer.DynamicSharedInformerFactory,
	workInformers workv1informers.SharedInformerFactory,
	runController ...runController,
) factory.Controller {
	c := &addonTemplateController{
		kubeConfig:                 hubKubeconfig,
		kubeClient:                 hubKubeClient,
		addonClient:                addonClient,
		workClient:                 workClient,
		cmaLister:                  addonInformers.Addon().V1beta1().ClusterManagementAddOns().Lister(),
		managedClusterAddonIndexer: addonInformers.Addon().V1beta1().ManagedClusterAddOns().Informer().GetIndexer(),
		addonManagers:              make(map[string]context.CancelFunc),
		addonInformers:             addonInformers,
		clusterInformers:           clusterInformers,
		dynamicInformers:           dynamicInformers,
		workInformers:              workInformers,
	}

	if len(runController) > 0 {
		c.runControllerFunc = runController[0]
	} else {
		// easy to mock in unit tests
		c.runControllerFunc = c.runController
	}
	return factory.New().
		WithInformersQueueKeysFunc(
			queue.QueueKeyByMetaNamespaceName,
			addonInformers.Addon().V1beta1().ClusterManagementAddOns().Informer()).
		WithFilteredEventsInformersQueueKeysFunc(
			queue.QueueKeyByMetaName,
			func(obj interface{}) bool {
				mca, ok := obj.(*addonv1beta1.ManagedClusterAddOn)
				if !ok {
					return false
				}

				// Only process ManagedClusterAddOns that reference AddOnTemplates
				for _, configRef := range mca.Status.ConfigReferences {
					if configRef.ConfigGroupResource.Group == "addon.open-cluster-management.io" &&
						configRef.ConfigGroupResource.Resource == "addontemplates" {
						return true
					}
				}
				return false
			},
			addonInformers.Addon().V1beta1().ManagedClusterAddOns().Informer()).
		WithBareInformers(
			// do not need to queue, just make sure the controller reconciles after the addonTemplate cache is synced
			// otherwise, there will be "xx-addon-template" not found" errors in the log as the controller uses the
			// addonTemplate lister to get the template object
			addonInformers.Addon().V1alpha1().AddOnTemplates().Informer()).
		WithSync(c.sync).
		ToController("addon-template-controller")
}

func (c *addonTemplateController) stopUnusedManagers(
	ctx context.Context, syncCtx factory.SyncContext, addOnName string) error {
	logger := klog.FromContext(ctx)

	// Check if all managed cluster addon instances are deleted before stopping the manager
	// This ensures the manager continues running while ManagedClusterAddOns exist
	addons, err := c.managedClusterAddonIndexer.ByIndex(addonindex.ManagedClusterAddonByName, addOnName)
	if err != nil {
		return err
	}

	// Check if there are still ManagedClusterAddOns for this addon
	if len(addons) > 0 {
		logger.Info("ManagedClusterAddOn still exists, waiting for deletion",
			"addonName", addOnName, "count", len(addons))
		// No need to requeue since we now watch ManagedClusterAddon events
		return nil
	}

	stopFunc, ok := c.addonManagers[addOnName]
	if ok {
		logger.Info("Start to stop the manager for addon", "addonName", addOnName)
		stopFunc()
		delete(c.addonManagers, addOnName)
		logger.Info("The manager for addon stopped", "addonName", addOnName)
	}
	return nil
}

func (c *addonTemplateController) sync(ctx context.Context, syncCtx factory.SyncContext, addonName string) error {
	logger := klog.FromContext(ctx).WithValues("addonName", addonName)
	ctx = klog.NewContext(ctx, logger)

	cma, err := c.cmaLister.Get(addonName)
	if err != nil {
		if errors.IsNotFound(err) {
			return c.stopUnusedManagers(ctx, syncCtx, addonName)
		}
		return err
	}

	if !templateagent.SupportAddOnTemplate(cma) {
		return c.stopUnusedManagers(ctx, syncCtx, cma.Name)
	}

	_, exist := c.addonManagers[addonName]
	if exist {
		logger.V(4).Info("There already is a manager started for addon, skipping")
		return nil
	}

	logger.Info("Starting an addon manager for addon")

	stopFunc := c.startManager(ctx, addonName)
	c.addonManagers[addonName] = stopFunc
	return nil
}

func (c *addonTemplateController) startManager(
	pctx context.Context,
	addonName string) context.CancelFunc {
	ctx, stopFunc := context.WithCancel(pctx)
	logger := klog.FromContext(ctx)
	go func() {
		err := c.runControllerFunc(ctx, addonName)
		if err != nil {
			logger.Error(err, "Error running controller for addon")
			utilruntime.HandleError(err)
		}

		// use the parent context to start all shared informers, otherwise once the context is cancelled,
		// the informers will stop and all other shared go routines will be impacted.
		c.workInformers.Start(pctx.Done())
		c.addonInformers.Start(pctx.Done())
		c.clusterInformers.Start(pctx.Done())
		c.dynamicInformers.Start(pctx.Done())

		<-ctx.Done()
		logger.Info("Addon Manager stopped")
	}()
	return stopFunc
}

func (c *addonTemplateController) runController(ctx context.Context, addonName string) error {
	logger := klog.FromContext(ctx)
	mgr, err := addonmanager.NewWithOptionFuncs(c.kubeConfig, addonmanager.WithTemplateMode(true))
	if err != nil {
		return err
	}

	kubeInformers := kubeinformers.NewSharedInformerFactoryWithOptions(c.kubeClient, 10*time.Minute,
		kubeinformers.WithTweakListOptions(func(listOptions *metav1.ListOptions) {
			selector := &metav1.LabelSelector{
				MatchExpressions: []metav1.LabelSelectorRequirement{
					{
						Key:      addonv1beta1.AddonLabelKey,
						Operator: metav1.LabelSelectorOpIn,
						Values:   []string{addonName},
					},
				},
			}
			listOptions.LabelSelector = metav1.FormatLabelSelector(selector)
		}),
	)
	getValuesClosure := func(cluster *clusterv1.ManagedCluster, addon *addonv1beta1.ManagedClusterAddOn) (addonfactory.Values, error) {
		return templateagent.GetAddOnRegistriesPrivateValuesFromClusterAnnotation(klog.FromContext(ctx), cluster, addon)
	}
	agentAddon := templateagent.NewCRDTemplateAgentAddon(
		ctx,
		addonName,
		c.kubeClient,
		c.addonClient,
		c.addonInformers, // use the shared informers, whose cache is synced already
		kubeInformers.Rbac().V1().RoleBindings().Lister(),
		// image overrides from cluster annotation has lower priority than from the addonDeploymentConfig
		getValuesClosure,
		addonfactory.GetAddOnDeploymentConfigValues(
			utils.NewAddOnDeploymentConfigGetter(c.addonClient),
			addonfactory.ToAddOnCustomizedVariableValues,
			templateagent.ToAddOnNodePlacementPrivateValues,
			templateagent.ToAddOnRegistriesPrivateValues,
			templateagent.ToAddOnInstallNamespacePrivateValues,
			templateagent.ToAddOnProxyPrivateValues,
			templateagent.ToAddOnResourceRequirementsPrivateValues,
		),
	)
	err = mgr.AddAgent(agentAddon)
	if err != nil {
		return err
	}

	err = mgr.StartWithInformers(ctx, c.workClient, c.workInformers.Work().V1().ManifestWorks(),
		kubeInformers, c.addonInformers, c.clusterInformers, c.dynamicInformers)
	if err != nil {
		return err
	}
	kubeInformers.Start(ctx.Done())

	// trigger the manager to reconcile for the existing managed cluster addons
	mcas, err := c.managedClusterAddonIndexer.ByIndex(addonindex.ManagedClusterAddonByName, addonName)
	if err != nil {
		logger.Info("Failed to list ManagedClusterAddOns by index", "error", err)
	} else {
		for _, mca := range mcas {
			addon, ok := mca.(*addonv1beta1.ManagedClusterAddOn)
			if ok {
				mgr.Trigger(addon.Namespace, addonName)
			}
		}
	}

	return nil
}