feat(electron): add offline mode (#8086)

fix AF-1334

It seems `session.enableNetworkEmulation({ offline: true });` does not work - https://github.com/electron/electron/issues/21250

implemented using an in-house solution.

When turned on:

![image.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/T2klNLEk0wxLh4NRDzhk/6805735b-1006-4e51-be46-c047b0f1a82c.png)

packages/common/infra/src/modules/feature-flag/constant.ts

@@ -96,6 +96,13 @@ export const AFFINE_FLAGS = {
     configurable: isCanaryBuild,
     defaultState: isCanaryBuild,
   },
+  enable_offline_mode: {
+    category: 'affine',
+    displayName: 'Offline Mode',
+    description: 'Enables offline mode.',
+    configurable: isDesktopEnvironment,
+    defaultState: false,
+  },
 } satisfies { [key in string]: FlagInfo };
 
 export type AFFINE_FLAGS = typeof AFFINE_FLAGS;

packages/frontend/electron/src/main/protocol.ts

@@ -3,6 +3,7 @@ import { join } from 'node:path';
 import { net, protocol, session } from 'electron';
 
 import { CLOUD_BASE_URL } from './config';
+import { isOfflineModeEnabled } from './utils';
 import { getCookies } from './windows-manager';
 
 protocol.registerSchemesAsPrivileged([
@@ -105,9 +106,21 @@ export function registerProtocol() {
   session.defaultSession.webRequest.onBeforeSendHeaders((details, callback) => {
     const url = new URL(details.url);
     const pathname = url.pathname;
+    const protocol = url.protocol;
+    const origin = url.origin;
+
+    const sameOrigin = origin === CLOUD_BASE_URL || protocol === 'file:';
+
+    if (isOfflineModeEnabled() && (sameOrigin || 'devtools:' !== protocol)) {
+      callback({
+        cancel: true,
+      });
+      return;
+    }
+
     // session cookies are set to file:// on production
     // if sending request to the cloud, attach the session cookie (to affine cloud server)
-    if (isNetworkResource(pathname)) {
+    if (isNetworkResource(pathname) && sameOrigin) {
       const cookie = getCookies();
       if (cookie) {
         const cookieString = cookie.map(c => `${c.name}=${c.value}`).join('; ');

packages/frontend/electron/src/main/updater/electron-updater.ts

@@ -3,6 +3,7 @@ import { autoUpdater as defaultAutoUpdater } from 'electron-updater';
 
 import { buildType } from '../config';
 import { logger } from '../logger';
+import { isOfflineModeEnabled } from '../utils';
 import { AFFiNEUpdateProvider } from './affine-update-provider';
 import { updaterSubjects } from './event';
 import { WindowsUpdater } from './windows-updater';
@@ -54,7 +55,7 @@ export const setConfig = (newConfig: Partial<UpdaterConfig> = {}): void => {
 };
 
 export const checkForUpdates = async () => {
-  if (disabled || checkingUpdate) {
+  if (disabled || checkingUpdate || isOfflineModeEnabled()) {
     return;
   }
   checkingUpdate = true;

packages/frontend/electron/src/main/utils.ts

@@ -1,8 +1,8 @@
-import http from 'node:http';
-import https from 'node:https';
-
 import type { CookiesSetDetails } from 'electron';
 
+import { logger } from './logger';
+import { globalStateStorage } from './shared-storage/storage';
+
 export function parseCookie(
   cookieString: string,
   url: string
@@ -56,55 +56,15 @@ export function parseCookie(
   return details;
 }
 
-/**
- * Send a GET request to a specified URL.
- * This function uses native http/https modules instead of fetch to
- * bypassing set-cookies headers
- */
-export async function simpleGet(requestUrl: string): Promise<{
-  body: string;
-  headers: [string, string][];
-  statusCode: number;
-}> {
-  return new Promise((resolve, reject) => {
-    const parsedUrl = new URL(requestUrl);
-    const protocol = parsedUrl.protocol === 'https:' ? https : http;
-    const options = {
-      hostname: parsedUrl.hostname,
-      port: parsedUrl.port,
-      path: parsedUrl.pathname + parsedUrl.search,
-      method: 'GET',
-    };
-    const req = protocol.request(options, res => {
-      let data = '';
-      res.on('data', chunk => {
-        data += chunk;
-      });
-      res.on('end', () => {
-        resolve({
-          body: data,
-          headers: toStandardHeaders(res.headers),
-          statusCode: res.statusCode || 200,
-        });
-      });
-    });
-    req.on('error', error => {
-      reject(error);
-    });
-    req.end();
-  });
-
-  function toStandardHeaders(headers: http.IncomingHttpHeaders) {
-    const result: [string, string][] = [];
-    for (const [key, value] of Object.entries(headers)) {
-      if (Array.isArray(value)) {
-        value.forEach(v => {
-          result.push([key, v]);
-        });
-      } else {
-        result.push([key, value || '']);
-      }
-    }
-    return result;
+export const isOfflineModeEnabled = () => {
+  try {
+    return (
+      // todo(pengx17): better abstraction for syncing flags with electron
+      // packages/common/infra/src/modules/feature-flag/entities/flags.ts
+      globalStateStorage.get('affine-flag:enable_offline_mode') ?? false
+    );
+  } catch (error) {
+    logger.error('Failed to get offline mode flag', error);
+    return false;
   }
-}
+};