// 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
				return nil, errors.NewConflict(resource.GroupResource(), name, nil)
			}

			newlyPatchedObjJS, err := getPatchedJS(api.StrategicMergePatchType, currentObjectJS, originalPatch, versionedObj)
			if err != nil {
				return nil, err
			}
			objToUpdate := patcher.New()
			if err := runtime.DecodeInto(codec, newlyPatchedObjJS, objToUpdate); err != nil {
				return nil, err
			}
			return objToUpdate, nil
		}
	}

	// applyAdmission is called every time GuaranteedUpdate asks for the updated object,
	// and is given the currently persisted object and the patched object as input.
	applyAdmission := func(ctx api.Context, patchedObject runtime.Object, currentObject runtime.Object) (runtime.Object, error) {
		return patchedObject, admit(patchedObject, currentObject)
	}

	updatedObjectInfo := rest.DefaultUpdatedObjectInfo(nil, copier, applyPatch, applyAdmission)

	return finishRequest(timeout, func() (runtime.Object, error) {
		updateObject, _, updateErr := patcher.Update(ctx, name, updatedObjectInfo)
		for i := 0; i < MaxPatchConflicts && (errors.IsConflict(updateErr)); i++ {
			lastConflictErr = updateErr
			updateObject, _, updateErr = patcher.Update(ctx, name, updatedObjectInfo)
		}
		return updateObject, updateErr
	})
}
func (tc *patchTestCase) Run(t *testing.T) {
	t.Logf("Starting test %s", tc.name)

	namespace := tc.startingPod.Namespace
	name := tc.startingPod.Name

	codec := testapi.Default.Codec()
	admit := tc.admit
	if admit == nil {
		admit = func(updatedObject runtime.Object, currentObject runtime.Object) error {
			return nil
		}
	}

	testPatcher := &testPatcher{}
	testPatcher.t = t
	testPatcher.startingPod = tc.startingPod
	testPatcher.updatePod = tc.updatePod

	ctx := api.NewDefaultContext()
	ctx = api.WithNamespace(ctx, namespace)

	namer := &testNamer{namespace, name}
	copier := runtime.ObjectCopier(api.Scheme)
	resource := unversioned.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"}

	versionedObj, err := api.Scheme.ConvertToVersion(&api.Pod{}, unversioned.GroupVersion{Version: "v1"})
	if err != nil {
		t.Errorf("%s: unexpected error: %v", tc.name, err)
		return
	}

	for _, patchType := range []api.PatchType{api.JSONPatchType, api.MergePatchType, api.StrategicMergePatchType} {
		// TODO SUPPORT THIS!
		if patchType == api.JSONPatchType {
			continue
		}
		t.Logf("Working with patchType %v", patchType)

		originalObjJS, err := runtime.Encode(codec, tc.startingPod)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			return
		}
		changedJS, err := runtime.Encode(codec, tc.changedPod)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			return
		}

		patch := []byte{}
		switch patchType {
		case api.JSONPatchType:
			continue

		case api.StrategicMergePatchType:
			patch, err = strategicpatch.CreateStrategicMergePatch(originalObjJS, changedJS, versionedObj)
			if err != nil {
				t.Errorf("%s: unexpected error: %v", tc.name, err)
				return
			}

		case api.MergePatchType:
			patch, err = jsonpatch.CreateMergePatch(originalObjJS, changedJS)
			if err != nil {
				t.Errorf("%s: unexpected error: %v", tc.name, err)
				return
			}

		}

		resultObj, err := patchResource(ctx, admit, 1*time.Second, versionedObj, testPatcher, name, patchType, patch, namer, copier, resource, codec)
		if len(tc.expectedError) != 0 {
			if err == nil || err.Error() != tc.expectedError {
				t.Errorf("%s: expected error %v, but got %v", tc.name, tc.expectedError, err)
				return
			}
		} else {
			if err != nil {
				t.Errorf("%s: unexpected error: %v", tc.name, err)
				return
			}
		}

		if tc.expectedPod == nil {
			if resultObj != nil {
				t.Errorf("%s: unexpected result: %v", tc.name, resultObj)
			}
			return
		}

		resultPod := resultObj.(*api.Pod)

		// roundtrip to get defaulting
		expectedJS, err := runtime.Encode(codec, tc.expectedPod)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			return
		}
		expectedObj, err := runtime.Decode(codec, expectedJS)
		if err != nil {
			t.Errorf("%s: unexpected error: %v", tc.name, err)
			return
		}
		reallyExpectedPod := expectedObj.(*api.Pod)

		if !reflect.DeepEqual(*reallyExpectedPod, *resultPod) {
			t.Errorf("%s mismatch: %v\n", tc.name, diff.ObjectGoPrintDiff(reallyExpectedPod, resultPod))
			return
		}
	}

}