strongly typed rpc

app/rpc.ts

@@ -1,15 +1,18 @@
 import {EventEmitter} from 'events';
 import {ipcMain, BrowserWindow} from 'electron';
 import {v4 as uuidv4} from 'uuid';
+import {TypedEmitter, MainEvents, RendererEvents, FilterNever} from '../common';
 
-export class Server extends EventEmitter {
+export class Server {
+  emitter: TypedEmitter<MainEvents>;
   destroyed = false;
   win: BrowserWindow;
   id!: string;
+
   constructor(win: BrowserWindow) {
-    super();
+    this.emitter = new EventEmitter();
     this.win = win;
-    this.ipcListener = this.ipcListener.bind(this);
+    this.emit = this.emit.bind(this);
 
     if (this.destroyed) {
       return;
@@ -18,7 +21,6 @@ export class Server extends EventEmitter {
     const uid = uuidv4();
     this.id = uid;
 
-    // eslint-disable-next-line @typescript-eslint/unbound-method
     ipcMain.on(uid, this.ipcListener);
 
     // we intentionally subscribe to `on` instead of `once`
@@ -33,23 +35,34 @@ export class Server extends EventEmitter {
     return this.win.webContents;
   }
 
-  ipcListener(event: any, {ev, data}: {ev: string; data: any}) {
+  ipcListener = (event: any, {ev, data}: {ev: keyof MainEvents; data: any}) => this.emitter.emit(ev, data);
-    super.emit(ev, data);
-  }
 
-  emit(ch: string, data: any = {}): any {
+  on = <U extends keyof MainEvents>(ev: U, fn: (arg0: MainEvents[U]) => void) => {
+    this.emitter.on(ev, fn);
+    return this;
+  };
+
+  once = <U extends keyof MainEvents>(ev: U, fn: (arg0: MainEvents[U]) => void) => {
+    this.emitter.once(ev, fn);
+    return this;
+  };
+
+  emit<U extends Exclude<keyof RendererEvents, FilterNever<RendererEvents>>>(ch: U): boolean;
+  emit<U extends FilterNever<RendererEvents>>(ch: U, data: RendererEvents[U]): boolean;
+  emit<U extends keyof RendererEvents>(ch: U, data?: RendererEvents[U]) {
     // This check is needed because data-batching can cause extra data to be
     // emitted after the window has already closed
     if (!this.win.isDestroyed()) {
       this.wc.send(this.id, {ch, data});
+      return true;
     }
+    return false;
   }
 
   destroy() {
-    this.removeAllListeners();
+    this.emitter.removeAllListeners();
     this.wc.removeAllListeners();
     if (this.id) {
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       ipcMain.removeListener(this.id, this.ipcListener);
     } else {
       // mark for `genUid` in constructor

app/ui/window.ts

@@ -206,8 +206,8 @@ export function newWindow(
       session.resize({cols, rows});
     }
   });
-  rpc.on('data', ({uid, data, escaped}: {uid: string; data: string; escaped: boolean}) => {
+  rpc.on('data', ({uid, data, escaped}) => {
-    const session = sessions.get(uid);
+    const session = uid && sessions.get(uid);
     if (session) {
       if (escaped) {
         const escapedData = session.shell?.endsWith('cmd.exe')
@@ -255,10 +255,10 @@ export function newWindow(
   });
   // pass on the full screen events from the window to react
   rpc.win.on('enter-full-screen', () => {
-    rpc.emit('enter full screen', {});
+    rpc.emit('enter full screen');
   });
   rpc.win.on('leave-full-screen', () => {
-    rpc.emit('leave full screen', {});
+    rpc.emit('leave full screen');
   });
   const deleteSessions = () => {
     sessions.forEach((session, key) => {
@@ -280,9 +280,9 @@ export function newWindow(
     const protocol = typeof url === 'string' && new URL(url).protocol;
     if (protocol === 'file:') {
       const path = fileURLToPath(url);
-      return {data: path, escaped: true};
+      return {uid: null, data: path, escaped: true};
     } else if (protocol === 'http:' || protocol === 'https:') {
-      return {data: url};
+      return {uid: null, data: url};
     }
   };
 

common.d.ts

@@ -0,0 +1,96 @@
+import type parseUrl from 'parse-url';
+
+export type Session = {
+  uid: string;
+  rows: number | null;
+  cols: number | null;
+  splitDirection?: 'HORIZONTAL' | 'VERTICAL';
+  shell: string | null;
+  pid: number | null;
+  activeUid?: string;
+};
+
+export type sessionExtraOptions = {
+  cwd: string | undefined;
+  splitDirection?: 'HORIZONTAL' | 'VERTICAL';
+  activeUid?: string | null;
+  isNewGroup?: boolean;
+};
+
+export type MainEvents = {
+  close: never;
+  command: string;
+  data: {uid: string | null; data: string; escaped?: boolean | null};
+  exit: {uid: string};
+  'info renderer': {uid: string; type: string};
+  init: null;
+  maximize: never;
+  minimize: never;
+  new: sessionExtraOptions;
+  'open context menu': string;
+  'open external': {url: string};
+  'open hamburger menu': {x: number; y: number};
+  'quit and install': never;
+  resize: {uid: string; cols: number; rows: number};
+  unmaximize: never;
+};
+
+export type RendererEvents = {
+  ready: never;
+  'add notification': {text: string; url: string; dismissable: boolean};
+  'update available': {releaseNotes: string; releaseName: string; releaseUrl: string; canInstall: boolean};
+  'open ssh': ReturnType<typeof parseUrl>;
+  'open file': {path: string};
+  'move jump req': number | 'last';
+  'reset fontSize req': never;
+  'move left req': never;
+  'move right req': never;
+  'prev pane req': never;
+  'decrease fontSize req': never;
+  'increase fontSize req': never;
+  'next pane req': never;
+  'session break req': never;
+  'session quit req': never;
+  'session search close': never;
+  'session search': never;
+  'session stop req': never;
+  'session tmux req': never;
+  'session del line beginning req': never;
+  'session del line end req': never;
+  'session del word left req': never;
+  'session del word right req': never;
+  'session move line beginning req': never;
+  'session move line end req': never;
+  'session move word left req': never;
+  'session move word right req': never;
+  'term selectAll': never;
+  reload: never;
+  'session clear req': never;
+  'split request horizontal': {activeUid?: string};
+  'split request vertical': {activeUid?: string};
+  'termgroup add req': {activeUid?: string};
+  'termgroup close req': never;
+  'session add': Session;
+  'session data': string;
+  'session exit': {uid: string};
+  'windowGeometry change': {isMaximized: boolean};
+  move: {bounds: {x: number; y: number}};
+  'enter full screen': never;
+  'leave full screen': never;
+  'session data send': {uid: string | null; data: string; escaped?: boolean};
+};
+
+/**
+ * Get keys of T where the value is not never
+ */
+export type FilterNever<T> = {[K in keyof T]: T[K] extends never ? never : K}[keyof T];
+
+export interface TypedEmitter<Events> {
+  on<E extends keyof Events>(event: E, listener: (args: Events[E]) => void): this;
+  once<E extends keyof Events>(event: E, listener: (args: Events[E]) => void): this;
+  emit<E extends Exclude<keyof Events, FilterNever<Events>>>(event: E): boolean;
+  emit<E extends FilterNever<Events>>(event: E, data: Events[E]): boolean;
+  emit<E extends keyof Events>(event: E, data?: Events[E]): boolean;
+  removeListener<E extends keyof Events>(event: E, listener: (args: Events[E]) => void): this;
+  removeAllListeners<E extends keyof Events>(event?: E): this;
+}

lib/actions/header.ts

@@ -39,7 +39,7 @@ export function maximize() {
     dispatch({
       type: UI_WINDOW_MAXIMIZE,
       effect() {
-        rpc.emit('maximize', null);
+        rpc.emit('maximize');
       }
     });
   };
@@ -50,7 +50,7 @@ export function unmaximize() {
     dispatch({
       type: UI_WINDOW_UNMAXIMIZE,
       effect() {
-        rpc.emit('unmaximize', null);
+        rpc.emit('unmaximize');
       }
     });
   };
@@ -72,7 +72,7 @@ export function minimize() {
     dispatch({
       type: UI_WINDOW_MINIMIZE,
       effect() {
-        rpc.emit('minimize', null);
+        rpc.emit('minimize');
       }
     });
   };
@@ -83,7 +83,7 @@ export function close() {
     dispatch({
       type: UI_WINDOW_CLOSE,
       effect() {
-        rpc.emit('close', null);
+        rpc.emit('close');
       }
     });
   };

lib/actions/sessions.ts

@@ -17,7 +17,15 @@ import {
 } from '../constants/sessions';
 import {HyperState, session, HyperDispatch, HyperActions} from '../hyper';
 
-export function addSession({uid, shell, pid, cols, rows, splitDirection, activeUid}: session) {
+export function addSession({
+  uid,
+  shell,
+  pid,
+  cols,
+  rows,
+  splitDirection,
+  activeUid
+}: Pick<session, 'uid' | 'shell' | 'pid' | 'cols' | 'rows' | 'splitDirection' | 'activeUid'>) {
   return (dispatch: HyperDispatch, getState: () => HyperState) => {
     const {sessions} = getState();
     const now = Date.now();

lib/actions/term-groups.ts

@@ -13,7 +13,7 @@ import {setActiveSession, ptyExitSession, userExitSession} from './sessions';
 import {ITermState, ITermGroup, HyperState, HyperDispatch, HyperActions} from '../hyper';
 
 function requestSplit(direction: 'VERTICAL' | 'HORIZONTAL') {
-  return (activeUid: string) =>
+  return (activeUid: string | undefined) =>
     (dispatch: HyperDispatch, getState: () => HyperState): void => {
       dispatch({
         type: SESSION_REQUEST,
@@ -40,7 +40,7 @@ export function resizeTermGroup(uid: string, sizes: number[]): HyperActions {
   };
 }
 
-export function requestTermGroup(activeUid: string) {
+export function requestTermGroup(activeUid: string | undefined) {
   return (dispatch: HyperDispatch, getState: () => HyperState) => {
     dispatch({
       type: TERM_GROUP_REQUEST,

lib/actions/updater.ts

@@ -6,7 +6,7 @@ export function installUpdate(): HyperActions {
   return {
     type: UPDATE_INSTALL,
     effect: () => {
-      rpc.emit('quit and install', null);
+      rpc.emit('quit and install');
     }
   };
 }

lib/utils/rpc.ts

@@ -1,13 +1,17 @@
 import {EventEmitter} from 'events';
 import {IpcRenderer, IpcRendererEvent} from 'electron';
 import electron from 'electron';
+import {FilterNever, MainEvents, RendererEvents, TypedEmitter} from '../../common';
+
 export default class Client {
-  emitter: EventEmitter;
+  emitter: TypedEmitter<RendererEvents>;
   ipc: IpcRenderer;
   id!: string;
+
   constructor() {
     this.emitter = new EventEmitter();
     this.ipc = electron.ipcRenderer;
+    this.emit = this.emit.bind(this);
     if (window.__rpcId) {
       setTimeout(() => {
         this.id = window.__rpcId;
@@ -27,35 +31,43 @@ export default class Client {
     }
   }
 
-  ipcListener = (event: any, {ch, data}: {ch: string; data: any}) => {
+  ipcListener = <U extends keyof RendererEvents>(
-    this.emitter.emit(ch, data);
+    event: IpcRendererEvent,
+    {ch, data}: {ch: U; data: RendererEvents[U]}
+  ) => this.emitter.emit(ch, data);
+
+  on = <U extends keyof RendererEvents>(ev: U, fn: (arg0: RendererEvents[U]) => void) => {
+    this.emitter.on(ev, fn);
+    return this;
   };
 
-  on(ev: string, fn: (...args: any[]) => void) {
+  once = <U extends keyof RendererEvents>(ev: U, fn: (arg0: RendererEvents[U]) => void) => {
-    this.emitter.on(ev, fn);
-  }
-
-  once(ev: string, fn: (...args: any[]) => void) {
     this.emitter.once(ev, fn);
-  }
+    return this;
+  };
 
-  emit(ev: string, data: any) {
+  emit<U extends Exclude<keyof MainEvents, FilterNever<MainEvents>>>(ch: U): boolean;
+  emit<U extends FilterNever<MainEvents>>(ch: U, data: MainEvents[U]): boolean;
+  emit<U extends keyof MainEvents>(ev: U, data?: MainEvents[U]) {
     if (!this.id) {
       throw new Error('Not ready');
     }
     this.ipc.send(this.id, {ev, data});
+    return true;
   }
 
-  removeListener(ev: string, fn: (...args: any[]) => void) {
+  removeListener = <U extends keyof RendererEvents>(ev: U, fn: (arg0: RendererEvents[U]) => void) => {
     this.emitter.removeListener(ev, fn);
-  }
+    return this;
+  };
 
-  removeAllListeners() {
+  removeAllListeners = () => {
     this.emitter.removeAllListeners();
-  }
+    return this;
+  };
 
-  destroy() {
+  destroy = () => {
     this.removeAllListeners();
     this.ipc.removeAllListeners(this.id);
-  }
+  };
 }