Introduce DevicePlugin APIs

Summary:
This stack introduces Sandy device plugins, they are quite similar to normal plugins, but, a devicePlugin module is organized as

```
export function supportsDevice(device): boolean

export function devicePlugin(devicePluginClient)

export function Component
```

Device plugins get access to the device meta data and can subscribe to the `onLogEntry` callback and `onDestroy` lifecycle.

They will be able to store state just as normal plugins, but can't send or receive methods, so devicePluginClient is a bit limited.

This diff only sets up most of the new data structures, and makes sure everything still compiles and no existing tests fail.

To prevent this diff from becoming to big, actually loading, rendering and testing device plugins will be done in next diffs

Please take a critical look at the api proposed and the (especially) the public names used :)

Reviewed By: passy, nikoant

Differential Revision: D22691351

fbshipit-source-id: bdbbd7f86d14b646fc9a693ad19f33583a76f26d

desktop/flipper-plugin/src/plugin/DevicePlugin.tsx

@@ -0,0 +1,198 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {SandyPluginDefinition} from './SandyPluginDefinition';
+import {EventEmitter} from 'events';
+import {Atom} from '../state/atom';
+import {setCurrentPluginInstance} from './Plugin';
+
+export type DeviceLogListener = (entry: DeviceLogEntry) => void;
+
+export type DeviceLogEntry = {
+  readonly date: Date;
+  readonly pid: number;
+  readonly tid: number;
+  readonly app?: string;
+  readonly type: LogLevel;
+  readonly tag: string;
+  readonly message: string;
+};
+
+export type LogLevel =
+  | 'unknown'
+  | 'verbose'
+  | 'debug'
+  | 'info'
+  | 'warn'
+  | 'error'
+  | 'fatal';
+
+export interface Device {
+  isArchived: boolean;
+  onLogEntry(cb: DeviceLogListener): () => void;
+}
+
+export type DevicePluginPredicate = (device: Device) => boolean;
+
+export type DevicePluginFactory = (client: DevicePluginClient) => object;
+
+export interface DevicePluginClient {
+  readonly device: Device;
+
+  /**
+   * the onDestroy event is fired whenever a device is unloaded from Flipper, or a plugin is disabled.
+   */
+  onDestroy(cb: () => void): void;
+
+  /**
+   * the onActivate event is fired whenever the plugin is actived in the UI
+   */
+  onActivate(cb: () => void): void;
+
+  /**
+   * The counterpart of the `onActivate` handler.
+   */
+  onDeactivate(cb: () => void): void;
+}
+
+export interface RealFlipperDevice {
+  isArchived: boolean;
+  addLogListener(callback: DeviceLogListener): Symbol;
+  removeLogListener(id: Symbol): void;
+  addLogEntry(entry: DeviceLogEntry): void;
+}
+
+export class SandyDevicePluginInstance {
+  static is(thing: any): thing is SandyDevicePluginInstance {
+    return thing instanceof SandyDevicePluginInstance;
+  }
+
+  /** client that is bound to this instance */
+  client: DevicePluginClient;
+  /** the original plugin definition */
+  definition: SandyPluginDefinition;
+  /** the plugin instance api as used inside components and such  */
+  instanceApi: any;
+
+  activated = false;
+  destroyed = false;
+  events = new EventEmitter();
+
+  // temporarily field that is used during deserialization
+  initialStates?: Record<string, any>;
+  // all the atoms that should be serialized when making an export / import
+  rootStates: Record<string, Atom<any>> = {};
+
+  constructor(
+    realDevice: RealFlipperDevice,
+    definition: SandyPluginDefinition,
+    initialStates?: Record<string, any>,
+  ) {
+    this.definition = definition;
+    const device: Device = {
+      get isArchived() {
+        return realDevice.isArchived;
+      },
+      onLogEntry(cb) {
+        const handle = realDevice.addLogListener(cb);
+        return () => {
+          realDevice.removeLogListener(handle);
+        };
+      },
+    };
+    this.client = {
+      device,
+      onDestroy: (cb) => {
+        this.events.on('destroy', cb);
+      },
+      onActivate: (cb) => {
+        this.events.on('activate', cb);
+      },
+      onDeactivate: (cb) => {
+        this.events.on('deactivate', cb);
+      },
+    };
+    setCurrentPluginInstance(this);
+    this.initialStates = initialStates;
+    try {
+      this.instanceApi = definition
+        .asDevicePluginModule()
+        .devicePlugin(this.client);
+    } finally {
+      this.initialStates = undefined;
+      setCurrentPluginInstance(undefined);
+    }
+  }
+
+  // the plugin is selected in the UI
+  activate() {
+    this.assertNotDestroyed();
+    if (!this.activated) {
+      this.activated = true;
+      this.events.emit('activate');
+    }
+    // TODO:
+    // const pluginId = this.definition.id;
+    // if (!this.realClient.isBackgroundPlugin(pluginId)) {
+    //   this.realClient.initPlugin(pluginId); // will call connect() if needed
+    // }
+  }
+
+  // the plugin is deselected in the UI
+  deactivate() {
+    // TODO:
+    // if (this.destroyed) {
+    //   // this can happen if the plugin is disabled while active in the UI.
+    //   // In that case deinit & destroy is already triggered from the STAR_PLUGIN action
+    //   return;
+    // }
+    // const pluginId = this.definition.id;
+    // if (!this.realClient.isBackgroundPlugin(pluginId)) {
+    //   this.realClient.deinitPlugin(pluginId);
+    // }
+  }
+
+  disconnect() {
+    this.assertNotDestroyed();
+    if (this.activated) {
+      this.activated = false;
+      this.events.emit('deactivate');
+    }
+  }
+
+  destroy() {
+    this.assertNotDestroyed();
+    // TODO:
+    // if (this.activated) {
+    //   this.realClient.deinitPlugin(this.definition.id);
+    // }
+    this.events.emit('destroy');
+    this.destroyed = true;
+  }
+
+  toJSON() {
+    return '[SandyDevicePluginInstance]';
+  }
+
+  exportState() {
+    return Object.fromEntries(
+      Object.entries(this.rootStates).map(([key, atom]) => [key, atom.get()]),
+    );
+  }
+
+  isPersistable(): boolean {
+    return Object.keys(this.rootStates).length > 0;
+  }
+
+  private assertNotDestroyed() {
+    if (this.destroyed) {
+      throw new Error('Plugin has been destroyed already');
+    }
+  }
+}

desktop/flipper-plugin/src/plugin/Plugin.tsx

@@ -10,6 +10,7 @@
 import {SandyPluginDefinition} from './SandyPluginDefinition';
 import {EventEmitter} from 'events';
 import {Atom} from '../state/atom';
+import {SandyDevicePluginInstance} from './DevicePlugin';
 
 type EventsContract = Record<string, any>;
 type MethodsContract = Record<string, (params: any) => Promise<any>>;
@@ -87,14 +88,27 @@ export interface RealFlipperClient {
   ): Promise<Object>;
 }
 
-export type FlipperPluginFactory<
+export type PluginFactory<
   Events extends EventsContract,
   Methods extends MethodsContract
 > = (client: FlipperClient<Events, Methods>) => object;
 
 export type FlipperPluginComponent = React.FC<{}>;
 
-export let currentPluginInstance: SandyPluginInstance | undefined = undefined;
+let currentPluginInstance:
+  | SandyPluginInstance
+  | SandyDevicePluginInstance
+  | undefined = undefined;
+
+export function setCurrentPluginInstance(
+  instance: typeof currentPluginInstance,
+) {
+  currentPluginInstance = instance;
+}
+
+export function getCurrentPluginInstance(): typeof currentPluginInstance {
+  return currentPluginInstance;
+}
 
 export class SandyPluginInstance {
   static is(thing: any): thing is SandyPluginInstance {
@@ -154,13 +168,13 @@ export class SandyPluginInstance {
         this.events.on('deeplink', callback);
       },
     };
-    currentPluginInstance = this;
+    setCurrentPluginInstance(this);
     this.initialStates = initialStates;
     try {
-      this.instanceApi = definition.module.plugin(this.client);
+      this.instanceApi = definition.asPluginModule().plugin(this.client);
     } finally {
       this.initialStates = undefined;
-      currentPluginInstance = undefined;
+      setCurrentPluginInstance(undefined);
     }
   }
 

desktop/flipper-plugin/src/plugin/PluginContext.tsx

@@ -8,15 +8,16 @@
  */
 
 import {createContext, useContext} from 'react';
-import {SandyPluginInstance, FlipperPluginFactory} from './Plugin';
+import {SandyPluginInstance, PluginFactory} from './Plugin';
+import {SandyDevicePluginInstance, DevicePluginFactory} from './DevicePlugin';
 
 export const SandyPluginContext = createContext<
-  SandyPluginInstance | undefined
+  SandyPluginInstance | SandyDevicePluginInstance | undefined
 >(undefined);
 
-export function usePlugin<PluginFactory extends FlipperPluginFactory<any, any>>(
-  plugin: PluginFactory,
-): ReturnType<PluginFactory> {
+export function usePlugin<
+  Factory extends PluginFactory<any, any> | DevicePluginFactory
+>(plugin: Factory): ReturnType<Factory> {
   const pluginInstance = useContext(SandyPluginContext);
   if (!pluginInstance) {
     throw new Error('Plugin context not available');
@@ -25,9 +26,12 @@ export function usePlugin<PluginFactory extends FlipperPluginFactory<any, any>>(
   // return of this function is strongly typed, without the user needing to create it's own
   // context.
   // But since we pass it, let's make sure the user did request the proper context
-  if (pluginInstance.definition.module.plugin !== plugin) {
+  const pluginFromDefinition = pluginInstance.definition.isDevicePlugin
+    ? pluginInstance.definition.asDevicePluginModule().devicePlugin
+    : pluginInstance.definition.asPluginModule().plugin;
+  if (pluginFromDefinition !== plugin) {
     throw new Error(
-      `Plugin context (${pluginInstance.definition.module.plugin}) didn't match the type of the requested plugin (${plugin})`,
+      `Plugin in context (${pluginFromDefinition}) didn't match the type of the requested plugin (${plugin})`,
     );
   }
   return pluginInstance.instanceApi;

desktop/flipper-plugin/src/plugin/PluginRenderer.tsx

@@ -10,9 +10,10 @@
 import React, {memo, useEffect, createElement} from 'react';
 import {SandyPluginContext} from './PluginContext';
 import {SandyPluginInstance} from './Plugin';
+import {SandyDevicePluginInstance} from './DevicePlugin';
 
 type Props = {
-  plugin: SandyPluginInstance;
+  plugin: SandyPluginInstance | SandyDevicePluginInstance;
 };
 
 /**

desktop/flipper-plugin/src/plugin/SandyPluginDefinition.tsx

@@ -8,20 +8,29 @@
  */
 
 import {PluginDetails} from 'flipper-plugin-lib';
-import {FlipperPluginFactory, FlipperPluginComponent} from './Plugin';
+import {PluginFactory, FlipperPluginComponent} from './Plugin';
+import {DevicePluginPredicate, DevicePluginFactory} from './DevicePlugin';
 
 /**
  * FlipperPluginModule describe the exports that are provided by a typical Flipper Desktop plugin
  */
-export type FlipperPluginModule<
-  Factory extends FlipperPluginFactory<any, any>
-> = {
+export type FlipperDevicePluginModule = {
+  /** predicate that determines if this plugin applies to the currently selcted device */
+  supportsDevice: DevicePluginPredicate;
+  /** the factory function that initializes a plugin instance */
+  devicePlugin: DevicePluginFactory;
+  /** the component type that can render this plugin */
+  Component: FlipperPluginComponent;
+};
+
+/**
+ * FlipperPluginModule describe the exports that are provided by a typical Flipper Desktop plugin
+ */
+export type FlipperPluginModule<Factory extends PluginFactory<any, any>> = {
   /** the factory function that initializes a plugin instance */
   plugin: Factory;
   /** the component type that can render this plugin */
   Component: FlipperPluginComponent;
-  // TODO: support device plugins T68738317
-  // devicePlugin: FlipperPluginFactory
 };
 
 /**
@@ -32,8 +41,9 @@ export type FlipperPluginModule<
  */
 export class SandyPluginDefinition {
   id: string;
-  module: FlipperPluginModule<any>;
+  module: FlipperPluginModule<any> | FlipperDevicePluginModule;
   details: PluginDetails;
+  isDevicePlugin: boolean;
 
   // TODO: Implement T68683476
   exportPersistedState:
@@ -47,13 +57,28 @@ export class SandyPluginDefinition {
       ) => Promise<any /* TODO: StaticPersistedState | undefined */>)
     | undefined = undefined;
 
-  constructor(details: PluginDetails, module: FlipperPluginModule<any>) {
+  constructor(
+    details: PluginDetails,
+    module: FlipperPluginModule<any> | FlipperDevicePluginModule,
+  );
+  constructor(details: PluginDetails, module: any) {
     this.id = details.id;
     this.details = details;
-    if (!module.plugin || typeof module.plugin !== 'function') {
-      throw new Error(
-        `Flipper plugin '${this.id}' should export named function called 'plugin'`,
-      );
+    if (module.supportsDevice) {
+      // device plugin
+      this.isDevicePlugin = true;
+      if (!module.devicePlugin || typeof module.devicePlugin !== 'function') {
+        throw new Error(
+          `Flipper device plugin '${this.id}' should export named function called 'devicePlugin'`,
+        );
+      }
+    } else {
+      this.isDevicePlugin = false;
+      if (!module.plugin || typeof module.plugin !== 'function') {
+        throw new Error(
+          `Flipper plugin '${this.id}' should export named function called 'plugin'`,
+        );
+      }
     }
     if (!module.Component || typeof module.Component !== 'function') {
       throw new Error(
@@ -64,6 +89,16 @@ export class SandyPluginDefinition {
     this.module.Component.displayName = `FlipperPlugin(${this.id})`;
   }
 
+  asDevicePluginModule(): FlipperDevicePluginModule {
+    if (!this.isDevicePlugin) throw new Error('Not a device plugin');
+    return this.module as FlipperDevicePluginModule;
+  }
+
+  asPluginModule(): FlipperPluginModule<any> {
+    if (this.isDevicePlugin) throw new Error('Not an application plugin');
+    return this.module as FlipperPluginModule<any>;
+  }
+
   get packageName() {
     return this.details.name;
   }