package objectwatcher

import (
	"context"
	"fmt"
	"sync"

	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/klog/v2"
	"sigs.k8s.io/controller-runtime/pkg/client"

	configv1alpha1 "github.com/karmada-io/karmada/pkg/apis/config/v1alpha1"
	workv1alpha1 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha1"
	workv1alpha2 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha2"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter"
	"github.com/karmada-io/karmada/pkg/util"
	"github.com/karmada-io/karmada/pkg/util/fedinformer/genericmanager"
	"github.com/karmada-io/karmada/pkg/util/fedinformer/keys"
	"github.com/karmada-io/karmada/pkg/util/helper"
	"github.com/karmada-io/karmada/pkg/util/lifted"
	"github.com/karmada-io/karmada/pkg/util/restmapper"
)

// ObjectWatcher manages operations for object dispatched to member clusters.
type ObjectWatcher interface {
	Create(clusterName string, desireObj *unstructured.Unstructured) error
	Update(clusterName string, desireObj, clusterObj *unstructured.Unstructured) error
	Delete(clusterName string, desireObj *unstructured.Unstructured) error
	NeedsUpdate(clusterName string, desiredObj, clusterObj *unstructured.Unstructured) (bool, error)
}

// ClientSetFunc is used to generate client set of member cluster
type ClientSetFunc func(c string, client client.Client) (*util.DynamicClusterClient, error)

type objectWatcherImpl struct {
	Lock                 sync.RWMutex
	RESTMapper           meta.RESTMapper
	KubeClientSet        client.Client
	VersionRecord        map[string]map[string]string
	ClusterClientSetFunc ClientSetFunc
	resourceInterpreter  resourceinterpreter.ResourceInterpreter
	InformerManager      genericmanager.MultiClusterInformerManager
}

// NewObjectWatcher returns an instance of ObjectWatcher
func NewObjectWatcher(kubeClientSet client.Client, restMapper meta.RESTMapper, clusterClientSetFunc ClientSetFunc, interpreter resourceinterpreter.ResourceInterpreter) ObjectWatcher {
	return &objectWatcherImpl{
		KubeClientSet:        kubeClientSet,
		VersionRecord:        make(map[string]map[string]string),
		RESTMapper:           restMapper,
		ClusterClientSetFunc: clusterClientSetFunc,
		resourceInterpreter:  interpreter,
		InformerManager:      genericmanager.GetInstance(),
	}
}

func (o *objectWatcherImpl) Create(clusterName string, desireObj *unstructured.Unstructured) error {
	dynamicClusterClient, err := o.ClusterClientSetFunc(clusterName, o.KubeClientSet)
	if err != nil {
		klog.Errorf("Failed to build dynamic cluster client for cluster %s.", clusterName)
		return err
	}

	gvr, err := restmapper.GetGroupVersionResource(o.RESTMapper, desireObj.GroupVersionKind())
	if err != nil {
		klog.Errorf("Failed to create resource(kind=%s, %s/%s) in cluster %s as mapping GVK to GVR failed: %v", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, err)
		return err
	}

	fedKey, err := keys.FederatedKeyFunc(clusterName, desireObj)
	if err != nil {
		klog.Errorf("Failed to get FederatedKey %s, error: %v", desireObj.GetName(), err)
		return err
	}
	_, err = helper.GetObjectFromCache(o.RESTMapper, o.InformerManager, fedKey)
	if err != nil {
		if !apierrors.IsNotFound(err) {
			klog.Errorf("Failed to get resource %v from member cluster, err is %v ", desireObj.GetName(), err)
			return err
		}

		clusterObj, err := dynamicClusterClient.DynamicClientSet.Resource(gvr).Namespace(desireObj.GetNamespace()).Create(context.TODO(), desireObj, metav1.CreateOptions{})
		if err != nil {
			klog.Errorf("Failed to create resource(kind=%s, %s/%s) in cluster %s, err is %v ", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, err)
			return err
		}

		klog.Infof("Created resource(kind=%s, %s/%s) on cluster: %s", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName)
		// record version
		o.recordVersion(clusterObj, dynamicClusterClient.ClusterName)
	}

	return nil
}

func (o *objectWatcherImpl) retainClusterFields(desired, observed *unstructured.Unstructured) (*unstructured.Unstructured, error) {
	// Pass the same ResourceVersion as in the cluster object for update operation, otherwise operation will fail.
	desired.SetResourceVersion(observed.GetResourceVersion())

	// Retain finalizers since they will typically be set by
	// controllers in a member cluster.  It is still possible to set the fields
	// via overrides.
	desired.SetFinalizers(observed.GetFinalizers())

	// Retain ownerReferences since they will typically be set by controllers in a member cluster.
	desired.SetOwnerReferences(observed.GetOwnerReferences())

	// Retain annotations since they will typically be set by controllers in a member cluster
	// and be set by user in karmada-controller-plane.
	util.RetainAnnotations(desired, observed)

	// Retain labels since they will typically be set by controllers in a member cluster
	// and be set by user in karmada-controller-plane.
	util.RetainLabels(desired, observed)

	if o.resourceInterpreter.HookEnabled(desired.GroupVersionKind(), configv1alpha1.InterpreterOperationRetain) {
		return o.resourceInterpreter.Retain(desired, observed)
	}

	return desired, nil
}

func (o *objectWatcherImpl) Update(clusterName string, desireObj, clusterObj *unstructured.Unstructured) error {
	updateAllowed := o.allowUpdate(clusterName, desireObj, clusterObj)
	if !updateAllowed {
		// The existing resource is not managed by Karmada, and no conflict resolution found, avoid updating the existing resource by default.
		return fmt.Errorf("resource(kind=%s, %s/%s) already exist in cluster %v and the %s strategy value is empty, karmada will not manage this resource",
			desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, workv1alpha2.ResourceConflictResolutionAnnotation,
		)
	}

	dynamicClusterClient, err := o.ClusterClientSetFunc(clusterName, o.KubeClientSet)
	if err != nil {
		klog.Errorf("Failed to build dynamic cluster client for cluster %s.", clusterName)
		return err
	}

	gvr, err := restmapper.GetGroupVersionResource(o.RESTMapper, desireObj.GroupVersionKind())
	if err != nil {
		klog.Errorf("Failed to update resource(kind=%s, %s/%s) in cluster %s as mapping GVK to GVR failed: %v", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, err)
		return err
	}

	desireObj, err = o.retainClusterFields(desireObj, clusterObj)
	if err != nil {
		klog.Errorf("Failed to retain fields for resource(kind=%s, %s/%s) in cluster %s: %v", clusterObj.GetKind(), clusterObj.GetNamespace(), clusterObj.GetName(), clusterName, err)
		return err
	}

	resource, err := dynamicClusterClient.DynamicClientSet.Resource(gvr).Namespace(desireObj.GetNamespace()).Update(context.TODO(), desireObj, metav1.UpdateOptions{})
	if err != nil {
		klog.Errorf("Failed to update resource(kind=%s, %s/%s) in cluster %s, err is %v ", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, err)
		return err
	}

	klog.Infof("Updated resource(kind=%s, %s/%s) on cluster: %s", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName)

	// record version
	o.recordVersion(resource, clusterName)
	return nil
}

func (o *objectWatcherImpl) Delete(clusterName string, desireObj *unstructured.Unstructured) error {
	dynamicClusterClient, err := o.ClusterClientSetFunc(clusterName, o.KubeClientSet)
	if err != nil {
		klog.Errorf("Failed to build dynamic cluster client for cluster %s.", clusterName)
		return err
	}

	gvr, err := restmapper.GetGroupVersionResource(o.RESTMapper, desireObj.GroupVersionKind())
	if err != nil {
		klog.Errorf("Failed to delete resource(kind=%s, %s/%s) in cluster %s as mapping GVK to GVR failed: %v", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName, err)
		return err
	}

	// Set deletion strategy to background explicitly even though it's the default strategy for most of the resources.
	// The reason for this is to fix the exception case that Kubernetes does on Job(batch/v1).
	// In kubernetes, the Job's default deletion strategy is "Orphan", that will cause the "Pods" created by "Job"
	// still exist after "Job" has been deleted.
	// Refer to https://github.com/karmada-io/karmada/issues/969 for more details.
	deleteBackground := metav1.DeletePropagationBackground
	deleteOption := metav1.DeleteOptions{
		PropagationPolicy: &deleteBackground,
	}

	err = dynamicClusterClient.DynamicClientSet.Resource(gvr).Namespace(desireObj.GetNamespace()).Delete(context.TODO(), desireObj.GetName(), deleteOption)
	if err != nil && !apierrors.IsNotFound(err) {
		klog.Errorf("Failed to delete resource %v in cluster %s, err is %v ", desireObj.GetName(), clusterName, err)
		return err
	}
	klog.Infof("Deleted resource(kind=%s, %s/%s) on cluster: %s", desireObj.GetKind(), desireObj.GetNamespace(), desireObj.GetName(), clusterName)

	objectKey := o.genObjectKey(desireObj)
	o.deleteVersionRecord(dynamicClusterClient.ClusterName, objectKey)

	return nil
}

func (o *objectWatcherImpl) genObjectKey(obj *unstructured.Unstructured) string {
	return obj.GroupVersionKind().String() + "/" + obj.GetNamespace() + "/" + obj.GetName()
}

// recordVersion will add or update resource version records
func (o *objectWatcherImpl) recordVersion(clusterObj *unstructured.Unstructured, clusterName string) {
	objVersion := lifted.ObjectVersion(clusterObj)
	objectKey := o.genObjectKey(clusterObj)
	if o.isClusterVersionRecordExist(clusterName) {
		o.updateVersionRecord(clusterName, objectKey, objVersion)
	} else {
		o.addVersionRecord(clusterName, objectKey, objVersion)
	}
}

// isClusterVersionRecordExist checks if the version record map of given member cluster exist
func (o *objectWatcherImpl) isClusterVersionRecordExist(clusterName string) bool {
	o.Lock.RLock()
	defer o.Lock.RUnlock()

	_, exist := o.VersionRecord[clusterName]

	return exist
}

// getVersionRecord will return the recorded version of given resource(if exist)
func (o *objectWatcherImpl) getVersionRecord(clusterName, resourceName string) (string, bool) {
	o.Lock.RLock()
	defer o.Lock.RUnlock()

	version, exist := o.VersionRecord[clusterName][resourceName]
	return version, exist
}

// addVersionRecord will add new version record of given resource
func (o *objectWatcherImpl) addVersionRecord(clusterName, resourceName, version string) {
	o.Lock.Lock()
	defer o.Lock.Unlock()
	o.VersionRecord[clusterName] = map[string]string{resourceName: version}
}

// updateVersionRecord will update the recorded version of given resource
func (o *objectWatcherImpl) updateVersionRecord(clusterName, resourceName, version string) {
	o.Lock.Lock()
	defer o.Lock.Unlock()
	o.VersionRecord[clusterName][resourceName] = version
}

// deleteVersionRecord will delete the recorded version of given resource
func (o *objectWatcherImpl) deleteVersionRecord(clusterName, resourceName string) {
	o.Lock.Lock()
	defer o.Lock.Unlock()
	delete(o.VersionRecord[clusterName], resourceName)
}

func (o *objectWatcherImpl) NeedsUpdate(clusterName string, desiredObj, clusterObj *unstructured.Unstructured) (bool, error) {
	// get resource version
	version, exist := o.getVersionRecord(clusterName, desiredObj.GroupVersionKind().String()+"/"+desiredObj.GetNamespace()+"/"+desiredObj.GetName())
	if !exist {
		klog.Errorf("Failed to update resource(kind=%s, %s/%s) in cluster %s for the version record does not exist", desiredObj.GetKind(), desiredObj.GetNamespace(), desiredObj.GetName(), clusterName)
		return false, fmt.Errorf("failed to update resource(kind=%s, %s/%s) in cluster %s for the version record does not exist", desiredObj.GetKind(), desiredObj.GetNamespace(), desiredObj.GetName(), clusterName)
	}

	return lifted.ObjectNeedsUpdate(desiredObj, clusterObj, version), nil
}

func (o *objectWatcherImpl) allowUpdate(clusterName string, desiredObj, clusterObj *unstructured.Unstructured) bool {
	// If the existing resource is managed by Karmada, then the updating is allowed.
	if util.GetLabelValue(desiredObj.GetLabels(), workv1alpha1.WorkNameLabel) == util.GetLabelValue(clusterObj.GetLabels(), workv1alpha1.WorkNameLabel) {
		return true
	}

	// This happens when promoting workload to the Karmada control plane
	conflictResolution := util.GetAnnotationValue(desiredObj.GetAnnotations(), workv1alpha2.ResourceConflictResolutionAnnotation)
	if conflictResolution == workv1alpha2.ResourceConflictResolutionOverwrite {
		return true
	}

	// The existing resource is not managed by Karmada, and no conflict resolution found, avoid updating the existing resource by default.
	klog.Warningf("resource(kind=%s, %s/%s) already exist in cluster %v and the %s strategy value is empty, karmada will not manage this resource",
		desiredObj.GetKind(), desiredObj.GetNamespace(), desiredObj.GetName(), clusterName, workv1alpha2.ResourceConflictResolutionAnnotation,
	)
	return false
}