add main to renderer command API

src/main/ipcCommands.ts

@@ -0,0 +1,56 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2023 Vendicated and Vencord contributors
+ */
+
+import { randomUUID } from "crypto";
+import { ipcMain } from "electron";
+import { IpcEvents } from "shared/IpcEvents";
+
+import { mainWin } from "./mainWindow";
+
+const resolvers = new Map<string, Record<"resolve" | "reject", (data: any) => void>>();
+
+export interface IpcMessage {
+    nonce: string;
+    message: string;
+    data?: any;
+}
+
+export interface IpcResponse {
+    nonce: string;
+    ok: boolean;
+    data?: any;
+}
+
+/**
+ * Sends a message to the renderer process and waits for a response.
+ * `data` must be serializable as it will be sent over IPC.
+ *
+ * You must add a handler for the message in the renderer process.
+ */
+export function sendRendererCommand<T = any>(message: string, data?: any) {
+    const nonce = randomUUID();
+
+    const promise = new Promise<T>((resolve, reject) => {
+        resolvers.set(nonce, { resolve, reject });
+    });
+
+    mainWin.webContents.send(IpcEvents.IPC_COMMAND, { nonce, message, data });
+
+    return promise;
+}
+
+ipcMain.on(IpcEvents.IPC_COMMAND, (_event, { nonce, ok, data }: IpcResponse) => {
+    const resolver = resolvers.get(nonce);
+    if (!resolver) throw new Error(`Unknown message: ${nonce}`);
+
+    if (ok) {
+        resolver.resolve(data);
+    } else {
+        resolver.reject(data);
+    }
+
+    resolvers.delete(nonce);
+});