frontend/core: restructure api a bit

frontend/packages/app/src/entities/index.ts

@@ -1,6 +1,6 @@
 import {
   createEntityKind,
-  createOverviewPage,
+  createWidgetView,
   createEntityView,
 } from '@backstage/core';
 import ComputerIcon from '@material-ui/icons/Computer';
@@ -8,7 +8,7 @@ import MockEntityPage from './MockEntityPage';
 import MockEntityCard from './MockEntityCard';
 
 /* SERVICE */
-const serviceOverviewPage = createOverviewPage()
+const serviceOverviewPage = createWidgetView()
   .addComponent(MockEntityCard)
   .addComponent(MockEntityCard);
 

frontend/packages/core/src/api/api.ts

@@ -0,0 +1,25 @@
+import AppBuilder from './app/AppBuilder';
+import EntityKind, { EntityConfig } from './entity/EntityKind';
+import WidgetViewBuilder from './widgetView/WidgetViewBuilder';
+import EntityViewBuilder from './entityView/EntityViewPageBuilder';
+import BackstagePlugin, { PluginConfig } from './plugin/Plugin';
+
+export function createApp() {
+  return new AppBuilder();
+}
+
+export function createEntityKind(config: EntityConfig) {
+  return new EntityKind(config);
+}
+
+export function createWidgetView() {
+  return new WidgetViewBuilder();
+}
+
+export function createEntityView() {
+  return new EntityViewBuilder();
+}
+
+export function createPlugin(config: PluginConfig): BackstagePlugin {
+  return new BackstagePlugin(config);
+}

frontend/packages/core/src/api/app/AppBuilder.tsx

@@ -1,10 +1,10 @@
 import React, { ComponentType, FC } from 'react';
+import { Route, Switch, useParams } from 'react-router-dom';
 import { AppContextProvider } from './AppContext';
-import { App, EntityConfig, AppComponentBuilder } from './types';
-import { Route, Switch, useParams, Redirect } from 'react-router-dom';
-import EntityKind from './EntityKind';
-import { EntityContextProvider } from './EntityContext';
-import { BackstagePlugin } from './types';
+import { App, AppComponentBuilder } from './types';
+import EntityKind, { EntityConfig } from '../entity/EntityKind';
+import { EntityContextProvider } from '../entityView/EntityContext';
+import BackstagePlugin, { registerSymbol } from '../plugin/Plugin';
 
 class AppImpl implements App {
   constructor(private readonly entities: Map<string, EntityKind>) {}
@@ -30,7 +30,7 @@ function builtComponent(
 
 export default class AppBuilder {
   private readonly entities = new Map<string, EntityKind>();
-  private readonly plugins = new Map<string, BackstagePlugin>();
+  private readonly plugins = new Set<BackstagePlugin>();
 
   registerEntityKind(...entity: EntityKind[]) {
     for (const e of entity) {
@@ -44,11 +44,10 @@ export default class AppBuilder {
 
   registerPlugin(...plugin: BackstagePlugin[]) {
     for (const p of plugin) {
-      const { id } = p;
-      if (this.plugins.has(id)) {
-        throw new Error(`Plugin '${id}' is already registered`);
+      if (this.plugins.has(p)) {
+        throw new Error(`Plugin '${p}' is already registered`);
       }
-      this.plugins.set(id, p);
+      this.plugins.add(p);
     }
   }
 
@@ -98,30 +97,8 @@ export default class AppBuilder {
     const pluginRoutes = new Array<JSX.Element>();
 
     for (const plugin of this.plugins.values()) {
-      plugin.register({
-        router: {
-          registerRoute(path, component, options = {}) {
-            if (path.startsWith('/entity/')) {
-              throw new Error(
-                `Plugin ${plugin.id} tried to register forbidden route ${path}`,
-              );
-            }
-            pluginRoutes.push(
-              <Route path={path} component={component} {...options} />,
-            );
-          },
-          registerRedirect(path, target, options = {}) {
-            if (path.startsWith('/entity/')) {
-              throw new Error(
-                `Plugin ${plugin.id} tried to register forbidden redirect ${path}`,
-              );
-            }
-            pluginRoutes.push(
-              <Redirect path={path} to={target} {...options} />,
-            );
-          },
-        },
-      });
+      const { routes = [] } = plugin[registerSymbol]();
+      pluginRoutes.push(...routes);
     }
 
     const routes = [...pluginRoutes, ...entityRoutes];

frontend/packages/core/src/api/app/types.ts

@@ -0,0 +1,12 @@
+import { ComponentType } from 'react';
+import { EntityConfig } from '../entity/EntityKind';
+
+export type App = {
+  getEntityConfig(kind: string): EntityConfig;
+};
+
+export class AppComponentBuilder<T = any> {
+  build(_app: App): ComponentType<T> {
+    throw new Error('Must override build() in AppComponentBuilder');
+  }
+}

frontend/packages/core/src/api/entity/EntityKind.ts

@@ -0,0 +1,20 @@
+import { ComponentType } from 'react';
+import { AppComponentBuilder } from '../app/types';
+
+export type EntityConfig = {
+  kind: string;
+  title: string;
+  icon: React.ComponentType<{ fontSize: number }>;
+  color: {
+    primary: string;
+    secondary: string;
+  };
+  pages: {
+    list?: ComponentType<{}> | AppComponentBuilder;
+    view?: ComponentType<{}> | AppComponentBuilder;
+  };
+};
+
+export default class EntityKind {
+  constructor(readonly config: EntityConfig) {}
+}

frontend/packages/core/src/api/entityView/EntityContext.tsx

@@ -1,5 +1,5 @@
 import React, { createContext, useContext, FC } from 'react';
-import { EntityConfig } from './types';
+import { EntityConfig } from '../entity/EntityKind';
 
 type Value = {
   config: EntityConfig;

frontend/packages/core/src/api/entityView/EntityViewPageBuilder.tsx

@@ -1,10 +1,10 @@
 import React, { ComponentType, FC } from 'react';
-import { AppComponentBuilder, App } from './types';
-import { useEntity, useEntityUri, useEntityConfig } from './EntityContext';
 import { Route, Redirect, Switch } from 'react-router-dom';
 import List from '@material-ui/core/List';
 import ListItem from '@material-ui/core/ListItem';
-import EntityLink from './EntityLink';
+import { AppComponentBuilder, App } from '../app/types';
+import { useEntity, useEntityUri, useEntityConfig } from './EntityContext';
+import EntityLink from '../../components/EntityLink/EntityLink';
 
 const EntityLayout: FC<{}> = ({ children }) => {
   const config = useEntityConfig();

frontend/packages/core/src/api/index.ts

@@ -0,0 +1,8 @@
+export * from './types';
+export * from './api';
+export { useApp } from './app/AppContext';
+export {
+  useEntity,
+  useEntityConfig,
+  useEntityUri,
+} from './entityView/EntityContext';

frontend/packages/core/src/api/plugin/Plugin.tsx

@@ -0,0 +1,98 @@
+import React from 'react';
+import { Route, Redirect } from 'react-router-dom';
+
+export type PluginConfig = {
+  id: string;
+  register?(hooks: PluginHooks): void;
+};
+
+export type PluginHooks = {
+  router: Router;
+};
+
+export type RouteOptions = {
+  // Whether the route path must match exactly, defaults to true.
+  exact?: boolean;
+};
+
+export type RedirectOptions = {
+  // Whether the route path must match exactly, defaults to true.
+  exact?: boolean;
+};
+
+export type Router = {
+  registerRoute(
+    path: string,
+    Component: React.ComponentType<any>,
+    options?: RouteOptions,
+  ): void;
+  registerRedirect(
+    path: string,
+    target: string,
+    options?: RedirectOptions,
+  ): void;
+};
+
+export type PluginRegistrationResult = {
+  routes?: JSX.Element[];
+};
+
+export const registerSymbol = Symbol('plugin-register');
+
+export default class Plugin {
+  private result?: PluginRegistrationResult;
+
+  constructor(private readonly config: PluginConfig) {}
+
+  [registerSymbol](): PluginRegistrationResult {
+    if (this.result) {
+      return this.result;
+    }
+    if (!this.config.register) {
+      return {};
+    }
+
+    const { id } = this.config;
+
+    const routes = new Array<JSX.Element>();
+
+    this.config.register({
+      router: {
+        registerRoute(path, component, options = {}) {
+          if (path.startsWith('/entity/')) {
+            throw new Error(
+              `Plugin ${id} tried to register forbidden route ${path}`,
+            );
+          }
+          const { exact = true } = options;
+          routes.push(
+            <Route
+              key={path}
+              path={path}
+              component={component}
+              exact={exact}
+            />,
+          );
+        },
+        registerRedirect(path, target, options = {}) {
+          if (path.startsWith('/entity/')) {
+            throw new Error(
+              `Plugin ${id} tried to register forbidden redirect ${path}`,
+            );
+          }
+          const { exact = true } = options;
+          routes.push(
+            <Redirect key={path} path={path} to={target} exact={exact} />,
+          );
+        },
+      },
+    });
+
+    this.result = { routes };
+    return this.result;
+  }
+
+  toString() {
+    return `plugin{${this.config.id}}`;
+  }
+}

frontend/packages/core/src/api/types.ts

@@ -0,0 +1,10 @@
+export type User = {
+  id: string;
+  email: string;
+};
+
+export type UserApi = {
+  isLoggedIn(): Promise<boolean>;
+
+  getUser(): Promise<User>;
+};

frontend/packages/core/src/api/widgetView/WidgetViewBuilder.tsx

@@ -1,12 +1,12 @@
 import React, { ComponentType, FC } from 'react';
-import { App, AppComponentBuilder } from './types';
+import { App, AppComponentBuilder } from '../app/types';
 
 type Props = {
   app: App;
   cards: ComponentType<any>[];
 };
 
-const OverviewPageComponent: FC<Props> = ({ cards }) => {
+const WidgetViewComponent: FC<Props> = ({ cards }) => {
   return (
     <div>
       {cards.map(CardComponent => (
@@ -16,16 +16,16 @@ const OverviewPageComponent: FC<Props> = ({ cards }) => {
   );
 };
 
-type OverviewPageRegistration = {
+type WidgetViewRegistration = {
   type: 'component';
   component: ComponentType<any>;
 };
 
-export default class OverviewPageBuilder extends AppComponentBuilder {
-  private readonly registrations = new Array<OverviewPageRegistration>();
+export default class WidgetViewBuilder extends AppComponentBuilder {
+  private readonly registrations = new Array<WidgetViewRegistration>();
   private output?: ComponentType<any>;
 
-  addComponent(component: ComponentType<any>): OverviewPageBuilder {
+  addComponent(component: ComponentType<any>): WidgetViewBuilder {
     this.registrations.push({ type: 'component', component });
     return this;
   }
@@ -40,11 +40,11 @@ export default class OverviewPageBuilder extends AppComponentBuilder {
         case 'component':
           return reg.component;
         default:
-          throw new Error(`Unknown OverviewPageBuilder registration`);
+          throw new Error(`Unknown WidgetViewBuilder registration`);
       }
     });
 
-    this.output = () => <OverviewPageComponent app={app} cards={cards} />;
+    this.output = () => <WidgetViewComponent app={app} cards={cards} />;
     return this.output;
   }
 }

frontend/packages/core/src/appApi/EntityKind.ts

@@ -1,5 +0,0 @@
-import { EntityConfig } from './types';
-
-export default class EntityKind {
-  constructor(readonly config: EntityConfig) {}
-}

frontend/packages/core/src/appApi/api.ts

@@ -1,25 +0,0 @@
-import AppBuilder from './AppBuilder';
-import { EntityConfig, PluginConfig, BackstagePlugin } from './types';
-import EntityKind from './EntityKind';
-import OverviewPageBuilder from './OverviewPageBuilder';
-import EntityViewBuilder from './EntityViewPageBuilder';
-
-export function createApp() {
-  return new AppBuilder();
-}
-
-export function createEntityKind(config: EntityConfig) {
-  return new EntityKind(config);
-}
-
-export function createOverviewPage() {
-  return new OverviewPageBuilder();
-}
-
-export function createEntityView() {
-  return new EntityViewBuilder();
-}
-
-export function createPlugin(config: PluginConfig): BackstagePlugin {
-  return { register() {}, ...config };
-}

frontend/packages/core/src/appApi/createPlugin.test.ts

@@ -1,8 +0,0 @@
-import createPlugin from './createPlugin';
-
-describe('createPlugin', () => {
-  it('should create a plugin', () => {
-    const plugin = createPlugin({ id: 'my-plugin' });
-    expect(plugin.id).toBe('my-plugin');
-  });
-});

frontend/packages/core/src/appApi/createPlugin.ts

@@ -1,10 +0,0 @@
-import { BackstagePlugin, PluginConfig } from './types';
-
-function createPlugin(config: PluginConfig): BackstagePlugin {
-  return {
-    register() {},
-    ...config,
-  };
-}
-
-export default createPlugin;

frontend/packages/core/src/appApi/index.ts

@@ -1,5 +0,0 @@
-export * from './types';
-export * from './api';
-export { useApp } from './AppContext';
-export { useEntity, useEntityConfig, useEntityUri } from './EntityContext';
-export { default as EntityLink } from './EntityLink';

frontend/packages/core/src/appApi/types.ts

@@ -1,73 +0,0 @@
-import { ComponentType } from 'react';
-
-export type EntityConfig = {
-  kind: string;
-  title: string;
-  icon: React.ComponentType<{ fontSize: number }>;
-  color: {
-    primary: string;
-    secondary: string;
-  };
-  pages: {
-    list?: ComponentType<{}> | AppComponentBuilder;
-    view?: ComponentType<{}> | AppComponentBuilder;
-  };
-};
-
-export type App = {
-  getEntityConfig(kind: string): EntityConfig;
-};
-
-export class AppComponentBuilder<T = any> {
-  build(_app: App): ComponentType<T> {
-    throw new Error('Must override build() in AppComponentBuilder');
-  }
-}
-
-export type User = {
-  id: string;
-  email: string;
-};
-
-export type UserApi = {
-  isLoggedIn(): Promise<boolean>;
-
-  getUser(): Promise<User>;
-};
-
-export type PluginConfig = {
-  id: string;
-  register?(hooks: PluginHooks): void;
-};
-
-export interface BackstagePlugin {
-  id: string;
-  register(hooks: PluginHooks): void;
-}
-
-export type PluginHooks = {
-  router: Router;
-};
-
-export type RouteOptions = {
-  // Whether the route path must match exactly, defaults to true.
-  exact?: boolean;
-};
-
-export type RedirectOptions = {
-  // Whether the route path must match exactly, defaults to true.
-  exact?: boolean;
-};
-
-export type Router = {
-  registerRoute(
-    path: string,
-    Component: React.ComponentType<any>,
-    options?: RouteOptions,
-  ): void;
-  registerRedirect(
-    path: string,
-    target: string,
-    options?: RedirectOptions,
-  ): void;
-};

frontend/packages/core/src/components/EntityLink/index.ts

@@ -0,0 +1 @@
+export { default } from './EntityLink';

frontend/packages/core/src/index.ts

@@ -1,9 +1,9 @@
-export * from './appApi';
+export * from './api';
+export { default as EntityLink } from './components/EntityLink';
 export { default as Page } from '../src/layout/Page';
 export { gradients, theme } from '../src/layout/Page';
 export { default as Header } from '../src/layout/Header/Header';
 export { default as HeaderLabel } from '../src/layout/HeaderLabel';
 export { default as InfoCard } from '../src/layout/InfoCard';
 export { default as ErrorBoundary } from '../src/layout/ErrorBoundary';
-
 export { default as BackstageTheme } from '../src/theme/BackstageTheme';

frontend/packages/plugins/_template/{{ cookiecutter.plugin_name }}/src/plugin.test.ts

@@ -2,6 +2,6 @@ import plugin from './plugin';
 
 describe('{{ cookiecutter.plugin_name }}', () => {
   it('should export plugin', () => {
-    expect(plugin.id).toBe('{{ cookiecutter.plugin_name }}');
+    expect(plugin).toBeDefined();
   });
 });

frontend/packages/plugins/hello-world/src/plugin.test.ts

@@ -2,6 +2,6 @@ import plugin from './plugin';
 
 describe('plugin', () => {
   it('should export plugin', () => {
-    expect(plugin.id).toBe('hello-world');
+    expect(plugin).toBeDefined();
   });
 });

frontend/packages/plugins/home-page/src/plugin.test.ts

@@ -2,6 +2,6 @@ import plugin from './plugin';
 
 describe('home-page', () => {
   it('should export plugin', () => {
-    expect(plugin.id).toBe('home-page');
+    expect(plugin).toBeDefined();
   });
 });

frontend/packages/plugins/login/src/plugin.test.ts

@@ -2,6 +2,6 @@ import plugin from './plugin';
 
 describe('login', () => {
   it('should export plugin', () => {
-    expect(plugin.id).toBe('login');
+    expect(plugin).toBeDefined();
   });
 });