// ResourceSingularizer implements RESTMapper
// It converts a resource name from plural to singular (e.g., from pods to pod)
func (m *DefaultRESTMapper) ResourceSingularizer(resourceType string) (string, error) {
	partialResource := unversioned.GroupVersionResource{Resource: resourceType}
	resources, err := m.ResourcesFor(partialResource)
	if err != nil {
		return resourceType, err
	}

	singular := unversioned.GroupVersionResource{}
	for _, curr := range resources {
		currSingular, ok := m.pluralToSingular[curr]
		if !ok {
			continue
		}
		if singular.IsEmpty() {
			singular = currSingular
			continue
		}

		if currSingular.Resource != singular.Resource {
			return resourceType, fmt.Errorf("multiple possibile singular resources (%v) found for %v", resources, resourceType)
		}
	}

	if singular.IsEmpty() {
		return resourceType, fmt.Errorf("no singular of resource %v has been defined", resourceType)
	}

	return singular.Resource, nil
}

// coerceResourceForMatching makes the resource lower case and converts internal versions to unspecified (legacy behavior)
func coerceResourceForMatching(resource unversioned.GroupVersionResource) unversioned.GroupVersionResource {
	resource.Resource = strings.ToLower(resource.Resource)
	if resource.Version == runtime.APIVersionInternal {
		resource.Version = ""
	}

	return resource
}

// deleteAllContentForGroupVersionResource will use the dynamic client to delete each resource identified in gvr.
// It returns an estimate of the time remaining before the remaining resources are deleted.
// If estimate > 0, not all resources are guaranteed to be gone.
func deleteAllContentForGroupVersionResource(
	kubeClient clientset.Interface,
	clientPool dynamic.ClientPool,
	opCache operationNotSupportedCache,
	gvr unversioned.GroupVersionResource,
	namespace string,
	namespaceDeletedAt unversioned.Time,
) (int64, error) {
	glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - namespace: %s, gvr: %v", namespace, gvr)

	// estimate how long it will take for the resource to be deleted (needed for objects that support graceful delete)
	estimate, err := estimateGracefulTermination(kubeClient, gvr, namespace, namespaceDeletedAt)
	if err != nil {
		glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - unable to estimate - namespace: %s, gvr: %v, err: %v", namespace, gvr, err)
		return estimate, err
	}
	glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - estimate - namespace: %s, gvr: %v, estimate: %v", namespace, gvr, estimate)

	// get a client for this group version...
	dynamicClient, err := clientPool.ClientForGroupVersion(gvr.GroupVersion())
	if err != nil {
		glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - unable to get client - namespace: %s, gvr: %v, err: %v", namespace, gvr, err)
		return estimate, err
	}

	// first try to delete the entire collection
	deleteCollectionSupported, err := deleteCollection(dynamicClient, opCache, gvr, namespace)
	if err != nil {
		return estimate, err
	}

	// delete collection was not supported, so we list and delete each item...
	if !deleteCollectionSupported {
		err = deleteEachItem(dynamicClient, opCache, gvr, namespace)
		if err != nil {
			return estimate, err
		}
	}

	// verify there are no more remaining items
	// it is not an error condition for there to be remaining items if local estimate is non-zero
	glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - checking for no more items in namespace: %s, gvr: %v", namespace, gvr)
	unstructuredList, listSupported, err := listCollection(dynamicClient, opCache, gvr, namespace)
	if err != nil {
		glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - error verifying no items in namespace: %s, gvr: %v, err: %v", namespace, gvr, err)
		return estimate, err
	}
	if !listSupported {
		return estimate, nil
	}
	glog.V(5).Infof("namespace controller - deleteAllContentForGroupVersionResource - items remaining - namespace: %s, gvr: %v, items: %v", namespace, gvr, len(unstructuredList.Items))
	if len(unstructuredList.Items) != 0 && estimate == int64(0) {
		return estimate, fmt.Errorf("unexpected items still remain in namespace: %s for gvr: %v", namespace, gvr)
	}
	return estimate, nil
}

func (o *ResourceConfig) ResourceEnabled(resource unversioned.GroupVersionResource) bool {
	versionOverride, versionExists := o.GroupVersionResourceConfigs[resource.GroupVersion()]
	if !versionExists {
		return false
	}
	if !versionOverride.Enable {
		return false
	}

	if versionOverride.DisabledResources.Has(resource.Resource) {
		return false
	}

	if len(versionOverride.EnabledResources) > 0 {
		return versionOverride.EnabledResources.Has(resource.Resource)
	}

	return true
}

// estimateGrracefulTermination will estimate the graceful termination required for the specific entity in the namespace
func estimateGracefulTermination(kubeClient clientset.Interface, groupVersionResource unversioned.GroupVersionResource, ns string, namespaceDeletedAt unversioned.Time) (int64, error) {
	groupResource := groupVersionResource.GroupResource()
	glog.V(5).Infof("namespace controller - estimateGracefulTermination - group %s, resource: %s", groupResource.Group, groupResource.Resource)
	estimate := int64(0)
	var err error
	switch groupResource {
	case unversioned.GroupResource{Group: "", Resource: "pods"}:
		estimate, err = estimateGracefulTerminationForPods(kubeClient, ns)
	}
	if err != nil {
		return estimate, err
	}
	// determine if the estimate is greater than the deletion timestamp
	duration := time.Since(namespaceDeletedAt.Time)
	allowedEstimate := time.Duration(estimate) * time.Second
	if duration >= allowedEstimate {
		estimate = int64(0)
	}
	return estimate, nil
}

// test the list and watch functions correctly converts the ListOptions
func TestGCListWatcher(t *testing.T) {
	testHandler := &fakeActionHandler{}
	srv, clientConfig := testServerAndClientConfig(testHandler.ServeHTTP)
	defer srv.Close()
	clientPool := dynamic.NewClientPool(clientConfig, dynamic.LegacyAPIPathResolverFunc)
	podResource := unversioned.GroupVersionResource{Version: "v1", Resource: "pods"}
	client, err := clientPool.ClientForGroupVersion(podResource.GroupVersion())
	if err != nil {
		t.Fatal(err)
	}
	lw := gcListWatcher(client, podResource)
	lw.Watch(api.ListOptions{ResourceVersion: "1"})
	lw.List(api.ListOptions{ResourceVersion: "1"})
	if e, a := 2, len(testHandler.actions); e != a {
		t.Errorf("expect %d requests, got %d", e, a)
	}
	if e, a := "resourceVersion=1", testHandler.actions[0].query; e != a {
		t.Errorf("expect %s, got %s", e, a)
	}
	if e, a := "resourceVersion=1", testHandler.actions[1].query; e != a {
		t.Errorf("expect %s, got %s", e, a)
	}
}

// TODO turn this into reusable method checking available resources
func contains(resourcesList map[string]*unversioned.APIResourceList, resource unversioned.GroupVersionResource) bool {
	if resourcesList == nil {
		return false
	}
	resourcesGroup, ok := resourcesList[resource.GroupVersion().String()]
	if !ok {
		return false
	}
	for _, item := range resourcesGroup.APIResources {
		if resource.Resource == item.Name {
			return true
		}
	}
	return false
}

// patchResource divides PatchResource for easier unit testing
func patchResource(
	ctx api.Context,
	admit updateAdmissionFunc,
	timeout time.Duration,
	versionedObj runtime.Object,
	patcher rest.Patcher,
	name string,
	patchType api.PatchType,
	patchJS []byte,
	namer ScopeNamer,
	copier runtime.ObjectCopier,
	resource unversioned.GroupVersionResource,
	codec runtime.Codec,
) (runtime.Object, error) {

	namespace := api.NamespaceValue(ctx)

	var (
		originalObjJS        []byte
		originalPatchedObjJS []byte
		lastConflictErr      error
	)

	// applyPatch is called every time GuaranteedUpdate asks for the updated object,
	// and is given the currently persisted object as input.
	applyPatch := func(_ api.Context, _, currentObject runtime.Object) (runtime.Object, error) {
		// Make sure we actually have a persisted currentObject
		if hasUID, err := hasUID(currentObject); err != nil {
			return nil, err
		} else if !hasUID {
			return nil, errors.NewNotFound(resource.GroupResource(), name)
		}

		switch {
		case len(originalObjJS) == 0 || len(originalPatchedObjJS) == 0:
			// first time through,
			// 1. apply the patch
			// 2. save the originalJS and patchedJS to detect whether there were conflicting changes on retries
			if js, err := runtime.Encode(codec, currentObject); err != nil {
				return nil, err
			} else {
				originalObjJS = js
			}

			if js, err := getPatchedJS(patchType, originalObjJS, patchJS, versionedObj); err != nil {
				return nil, err
			} else {
				originalPatchedObjJS = js
			}

			objToUpdate := patcher.New()
			if err := runtime.DecodeInto(codec, originalPatchedObjJS, objToUpdate); err != nil {
				return nil, err
			}
			if err := checkName(objToUpdate, name, namespace, namer); err != nil {
				return nil, err
			}
			return objToUpdate, nil

		default:
			// on a conflict,
			// 1. build a strategic merge patch from originalJS and the patchedJS.  Different patch types can
			//    be specified, but a strategic merge patch should be expressive enough handle them.  Build the
			//    patch with this type to handle those cases.
			// 2. build a strategic merge patch from originalJS and the currentJS
			// 3. ensure no conflicts between the two patches
			// 4. apply the #1 patch to the currentJS object
			currentObjectJS, err := runtime.Encode(codec, currentObject)
			if err != nil {
				return nil, err
			}
			currentPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, currentObjectJS, versionedObj)
			if err != nil {
				return nil, err
			}
			originalPatch, err := strategicpatch.CreateStrategicMergePatch(originalObjJS, originalPatchedObjJS, versionedObj)
			if err != nil {
				return nil, err
			}

			diff1 := make(map[string]interface{})
			if err := json.Unmarshal(originalPatch, &diff1); err != nil {
				return nil, err
			}
			diff2 := make(map[string]interface{})
			if err := json.Unmarshal(currentPatch, &diff2); err != nil {
				return nil, err
			}
			hasConflicts, err := strategicpatch.HasConflicts(diff1, diff2)
			if err != nil {
				return nil, err
			}
			if hasConflicts {
				glog.V(4).Infof("patchResource failed for resource %s, because there is a meaningful conflict.\n diff1=%v\n, diff2=%v\n", name, diff1, diff2)
				// Return the last conflict error we got if we have one
				if lastConflictErr != nil {
					return nil, lastConflictErr
				}
				// Otherwise manufacture one of our own
//.........这里部分代码省略.........