Cache oauth credentials (#927)

packages/core/src/code_assist/oauth2.ts

@@ -10,6 +10,8 @@ import url from 'url';
 import crypto from 'crypto';
 import * as net from 'net';
 import open from 'open';
+import path from 'node:path';
+import { promises as fs } from 'node:fs';
 
 //  OAuth Client ID used to initiate OAuth2Client class.
 const OAUTH_CLIENT_ID =
@@ -36,7 +38,50 @@ const SIGN_IN_SUCCESS_URL =
 const SIGN_IN_FAILURE_URL =
   'https://developers.google.com/gemini-code-assist/auth_failure_gemini';
 
-export async function loginWithOauth(): Promise<OAuth2Client> {
+const GEMINI_DIR = '.gemini';
+const CREDENTIAL_FILENAME = 'oauth_creds.json';
+
+export async function getCachedCredentialClient(): Promise<OAuth2Client> {
+  try {
+    const creds = await fs.readFile(
+      path.join(process.cwd(), GEMINI_DIR, CREDENTIAL_FILENAME),
+      'utf-8',
+    );
+
+    const oAuth2Client = new OAuth2Client({
+      clientId: OAUTH_CLIENT_ID,
+      clientSecret: OAUTH_CLIENT_SECRET,
+    });
+    oAuth2Client.setCredentials(JSON.parse(creds));
+    // This will either return the existing token or refresh it.
+    await oAuth2Client.getAccessToken();
+    // If we are here, the token is valid.
+    return oAuth2Client;
+  } catch (_) {
+    // Could not load credentials.
+    throw new Error('Could not load credentials');
+  }
+}
+
+export async function clearCachedCredentials(): Promise<void> {
+  await fs.rm(path.join(process.cwd(), GEMINI_DIR, CREDENTIAL_FILENAME));
+}
+
+export async function getOauthClient(): Promise<OAuth2Client> {
+  try {
+    return await getCachedCredentialClient();
+  } catch (_) {
+    const loggedInClient = await webLoginClient();
+    await fs.mkdir(path.join(process.cwd(), GEMINI_DIR), { recursive: true });
+    await fs.writeFile(
+      path.join(process.cwd(), GEMINI_DIR, CREDENTIAL_FILENAME),
+      JSON.stringify(loggedInClient.credentials, null, 2),
+    );
+    return loggedInClient;
+  }
+}
+
+export async function webLoginClient(): Promise<OAuth2Client> {
   const port = await getAvailablePort();
   const oAuth2Client = new OAuth2Client({
     clientId: OAUTH_CLIENT_ID,
@@ -51,33 +96,37 @@ export async function loginWithOauth(): Promise<OAuth2Client> {
       scope: OAUTH_SCOPE,
       state,
     });
+    console.log(
+      `\n\nCode Assist login required.\n` +
+        `Attempting to open authentication page in your browser.\n` +
+        `Otherwise navigate to:\n\n${authURL}\n\n`,
+    );
     open(authURL);
+    console.log('Waiting for authentication...');
 
     const server = http.createServer(async (req, res) => {
       try {
         if (req.url!.indexOf('/oauth2callback') === -1) {
-          console.log('Unexpected request:', req.url);
           res.writeHead(HTTP_REDIRECT, { Location: SIGN_IN_FAILURE_URL });
           res.end();
           reject(new Error('Unexpected request: ' + req.url));
         }
         // acquire the code from the querystring, and close the web server.
         const qs = new url.URL(req.url!, 'http://localhost:3000').searchParams;
-        console.log('Processing request:', qs);
         if (qs.get('error')) {
           res.writeHead(HTTP_REDIRECT, { Location: SIGN_IN_FAILURE_URL });
           res.end();
+
           reject(new Error(`Error during authentication: ${qs.get('error')}`));
         } else if (qs.get('state') !== state) {
           res.end('State mismatch. Possible CSRF attack');
+
           reject(new Error('State mismatch. Possible CSRF attack'));
         } else if (qs.get('code')) {
           const code: string = qs.get('code')!;
-          console.log();
           const { tokens } = await oAuth2Client.getToken(code);
-          console.log('Logged in! Tokens:\n\n', tokens);
-
           oAuth2Client.setCredentials(tokens);
+
           res.writeHead(HTTP_REDIRECT, { Location: SIGN_IN_SUCCESS_URL });
           res.end();
           resolve(oAuth2Client);