Support exporting public API from a plugin

Reviewed By: passy

Differential Revision: D36098167

fbshipit-source-id: 90182248d0541a1d8eff92a391a56422537c0595

desktop/flipper-plugin/src/__tests__/api.node.tsx

@@ -110,6 +110,7 @@ test('Correct top level API exposed', () => {
       "FileDescriptor",
       "FileEncoding",
       "FlipperLib",
+      "FlipperPluginInstance",
       "FlipperServerForServerAddOn",
       "HighlightManager",
       "Idler",

desktop/flipper-plugin/src/index.tsx

@@ -25,7 +25,10 @@ export {
   CrashLogListener,
   SandyDevicePluginInstance as _SandyDevicePluginInstance,
 } from './plugin/DevicePlugin';
-export {SandyPluginDefinition as _SandyPluginDefinition} from './plugin/SandyPluginDefinition';
+export {
+  SandyPluginDefinition as _SandyPluginDefinition,
+  FlipperPluginInstance,
+} from './plugin/SandyPluginDefinition';
 export {SandyPluginRenderer as _SandyPluginRenderer} from './plugin/PluginRenderer';
 export {
   SandyPluginContext as _SandyPluginContext,

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

@@ -223,6 +223,8 @@ export abstract class BasePluginInstance {
   definition: SandyPluginDefinition;
   /** the plugin instance api as used inside components and such  */
   instanceApi: any;
+  /** the plugin public api exposed over the wire via flipper-server-companion  */
+  companionApi?: any;
   /** the device owning this plugin */
   readonly device: Device;
 
@@ -276,6 +278,11 @@ export abstract class BasePluginInstance {
     setCurrentPluginInstance(this);
     try {
       this.instanceApi = batched(factory)();
+
+      const apiFactory = this.definition.module.API;
+      if (apiFactory) {
+        this.companionApi = apiFactory(this.instanceApi);
+      }
     } finally {
       // check if we have both an import handler and rootStates; probably dev error
       if (this.importHandler && Object.keys(this.rootStates).length > 0) {

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

@@ -11,12 +11,21 @@ import {ActivatablePluginDetails} from 'flipper-common';
 import {PluginFactory, FlipperPluginComponent} from './Plugin';
 import {DevicePluginPredicate, DevicePluginFactory} from './DevicePlugin';
 
+export type FlipperPluginAPI<T extends (...args: any[]) => object> = (
+  pluginInstance: ReturnType<T>,
+) => object;
+
+export type FlipperPluginInstance<T extends (...args: any[]) => object> =
+  Parameters<FlipperPluginAPI<T>>[0];
+
 /**
  * FlipperPluginModule describe the exports that are provided by a typical Flipper Desktop plugin
  */
 export type FlipperDevicePluginModule = {
   /** predicate that determines if this plugin applies to the currently selcted device */
   supportsDevice?: DevicePluginPredicate; // TODO T84453692: remove this function after some transition period in favor of BaseDevice.supportsPlugin.
+  /** the factory function that exposes plugin API over the wire */
+  API?: FlipperPluginAPI<DevicePluginFactory>;
   /** the factory function that initializes a plugin instance */
   devicePlugin: DevicePluginFactory;
   /** the component type that can render this plugin */
@@ -29,6 +38,8 @@ export type FlipperDevicePluginModule = {
 export type FlipperPluginModule<
   Factory extends PluginFactory<any, any, any, any>,
 > = {
+  /** the factory function that exposes plugin API over the wire */
+  API?: FlipperPluginAPI<Factory>;
   /** the factory function that initializes a plugin instance */
   plugin: Factory;
   /** the component type that can render this plugin */