refactor: use new components context

Signed-off-by: Camila Belo <camilaibs@gmail.com>

packages/frontend-app-api/src/extensions/Core.tsx

@@ -18,7 +18,9 @@ import {
   coreExtensionData,
   createExtension,
   createExtensionInput,
+  ComponentsProvider,
 } from '@backstage/frontend-plugin-api';
+import React from 'react';
 
 export const Core = createExtension({
   id: 'core',
@@ -44,8 +46,20 @@ export const Core = createExtension({
     root: coreExtensionData.reactElement,
   },
   factory({ inputs }) {
+    const components = inputs.components.reduce(
+      (rest, { component }) => ({
+        ...rest,
+        [component.ref.id]: component.impl,
+      }),
+      {},
+    );
+
     return {
-      root: inputs.root.element,
+      root: (
+        <ComponentsProvider value={components}>
+          {inputs.root.element}
+        </ComponentsProvider>
+      ),
     };
   },
 });

packages/frontend-app-api/src/extensions/CoreRoutes.tsx

@@ -19,10 +19,10 @@ import {
   createExtension,
   coreExtensionData,
   createExtensionInput,
+  coreNotFoundErrorPageComponentRef,
+  useComponent,
 } from '@backstage/frontend-plugin-api';
 import { useRoutes } from 'react-router-dom';
-// eslint-disable-next-line @backstage/no-relative-monorepo-imports
-import { useApp } from '../../../core-plugin-api/src/app/useApp';
 
 export const CoreRoutes = createExtension({
   id: 'core.routes',
@@ -39,8 +39,8 @@ export const CoreRoutes = createExtension({
   },
   factory({ inputs }) {
     const Routes = () => {
-      const app = useApp();
-      const { NotFoundErrorPage } = app.getComponents();
+      const NotFoundErrorPage = useComponent(coreNotFoundErrorPageComponentRef);
+
       const element = useRoutes([
         ...inputs.routes.map(route => ({
           path: `${route.path}/*`,

packages/frontend-plugin-api/src/components/ComponentsContext.tsx

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ComponentRef } from '@backstage/frontend-plugin-api';
+import {
+  createVersionedContext,
+  createVersionedValueMap,
+  useVersionedContext,
+} from '@backstage/version-bridge';
+import React from 'react';
+import { ComponentType, PropsWithChildren } from 'react';
+
+/** @public */
+export type ComponentsContextValue = Record<string, ComponentType<any>>;
+
+const ComponentsContext = createVersionedContext<{ 1: ComponentsContextValue }>(
+  'components-context',
+);
+
+/** @public */
+export function ComponentsProvider(
+  props: PropsWithChildren<{ value: ComponentsContextValue }>,
+) {
+  const { value, children } = props;
+  return (
+    <ComponentsContext.Provider value={createVersionedValueMap({ 1: value })}>
+      {children}
+    </ComponentsContext.Provider>
+  );
+}
+
+/** @public */
+export function useComponent<
+  P extends {},
+  T extends ComponentRef<ComponentType<P>>,
+>(ref: T): T['T'] {
+  const components = useVersionedContext<{ 1: ComponentsContextValue }>(
+    'components-context',
+  );
+  const component = components?.atVersion(1)?.[ref.id];
+  if (!component) {
+    throw new Error(`No implementation available for ${ref.id}`);
+  }
+  return component;
+}

packages/frontend-plugin-api/src/components/index.ts

@@ -14,6 +14,12 @@
  * limitations under the License.
  */
 
+export {
+  ComponentsProvider,
+  useComponent,
+  type ComponentsContextValue,
+} from './ComponentsContext';
+
 export {
   coreProgressComponentRef,
   coreBootErrorPageComponentRef,