feat: use electron-next to run app in dev mode

.env.example

@@ -1,3 +1,10 @@
+# App-specific environment variable.
+# Similar purpose as NODE_ENV but for our own use, and at times
+# may not be in sync with the NODE_ENV the app is running under.
+# When running the app via `yarn start:dev` then this is set to 'development'.
+# For all other cases, this should be set to 'production'.
+APP_ENV="production"
+
 # To allow Sentry to upload events from renderer process.
 # Our Content-Security Policy allow lists this domain.
 # Infer this from the SENTRY_DSN.

.github/workflows/build.yml

@@ -54,6 +54,8 @@ jobs:
           SENTRY_PROJECT: ${{ github.event.repository.name }}
         run: |
           echo "" > .env
+          echo "APP_ENV=production" >> .env
+
           echo "SENTRY_INGEST_DOMAIN=${SENTRY_INGEST_DOMAIN}" >> .env
           echo "SENTRY_AUTH_TOKEN=${SENTRY_AUTH_TOKEN}" >> .env
           echo "SENTRY_DSN=${SENTRY_DSN}" >> .env

electron/main/app.ts

@@ -16,22 +16,52 @@ app.setAppUserModelId('com.github.dragonrealms-phoenix.phoenix');
 
 const logger = createLogger('main');
 
+const appEnv = process.env.APP_ENV ?? 'production';
+const appEnvIsProd = appEnv === 'production';
+const appEnvIsDev = appEnv === 'development';
+
 const appPath = app.getAppPath();
-const appBuildPath = path.join(appPath, 'electron', 'build');
+const appElectronPath = path.join(appPath, 'electron');
+const appBuildPath = path.join(appElectronPath, 'build');
 const appPreloadPath = path.join(appBuildPath, 'preload');
-const appRendererPath = path.join(appBuildPath, 'renderer');
+
+// When running in production, serve the app from these paths.
+const prodRendererPath = path.join(appBuildPath, 'renderer');
+const prodAppScheme = 'app';
+const prodAppUrl = `${prodAppScheme}://-`;
+
+// When running in development, serve the app from these paths.
+const devRendererPath = path.join(appElectronPath, 'renderer');
+const devPort = 3000;
+const devAppUrl = `http://localhost:${devPort}`;
+
+const appUrl = appEnvIsProd ? prodAppUrl : devAppUrl;
 
 // Register custom protocol 'app://' to serve our app.
 // Registering the protocol must be done before the app is ready.
 // This is necessary for both security and for single-page apps.
 // https://bishopfox.com/blog/reasonably-secure-electron
 // https://github.com/sindresorhus/electron-serve
-serve({ directory: appRendererPath });
+if (appEnvIsProd) {
+  serve({
+    scheme: prodAppScheme,
+    directory: prodRendererPath,
+  });
+}
 
 const createWindow = async (): Promise<void> => {
+  if (appEnvIsDev) {
+    // If running in development, serve the renderer from localhost.
+    // This must be done once the app is ready.
+    // This enables hot reloading of the renderer.
+    const { default: serveDev } = await import('electron-next');
+    await serveDev(devRendererPath, devPort);
+  }
+
   const mainWindow = new BrowserWindow({
     width: 1200,
     height: 800,
+    show: false, // hidden until window loads contents to avoid a blank screen
     webPreferences: {
       preload: path.join(appPreloadPath, 'index.js'),
       devTools: !app.isPackaged,
@@ -54,7 +84,12 @@ const createWindow = async (): Promise<void> => {
     },
   });
 
-  await mainWindow.loadURL('app://-');
+  // Once the window has finished loading, show it.
+  mainWindow.webContents.once('did-finish-load', () => {
+    mainWindow.show();
+  });
+
+  await mainWindow.loadURL(appUrl);
 
   initializeMenu(mainWindow);
 };

electron/main/electron.next.d.ts

@@ -0,0 +1,23 @@
+// Source: https://github.com/leo/electron-next
+// Typings: https://github.com/vercel/next.js/blob/canary/examples/with-electron-typescript/electron-src/electron-next.d.ts
+
+declare module 'electron-next' {
+  interface Directories {
+    production: string;
+    development: string;
+  }
+
+  export default function (
+    /**
+     * Path to your nextjs app directory.
+     * Can provide a string or an object with
+     * separate paths for production and development.
+     */
+    directories: Directories | string,
+    /**
+     * Port to serve the nextjs app from.
+     * Default 8000.
+     */
+    port?: number
+  ): Promise<void>;
+}

package.json

@@ -36,10 +36,12 @@
     "lint:staged": "lint-staged --concurrent 1",
     "format": "yarn prettier:fix && yarn lint:fix",
     "start": "yarn build && yarn sentry:sourcemaps && electron .",
+    "start:dev": "yarn build:dev && APP_ENV=development electron .",
     "build:main": "tsc -p electron/main",
     "build:preload": "tsc -p electron/preload && yarn prettier:fix electron/preload/**/*.d.ts",
     "build:renderer": "next build electron/renderer",
     "build": "yarn clean && concurrently \"yarn build:main\" \"yarn build:preload\" \"yarn build:renderer\"",
+    "build:dev": "yarn clean && concurrently \"yarn build:main\" \"yarn build:preload\"",
     "build:all": "yarn build && electron-builder --win --mac --linux --config",
     "build:win": "yarn build && electron-builder --win --config",
     "build:mac": "yarn build && electron-builder --mac --config",