✨ feature: Implement Gmail message fetching and Excel sheet name truncation

src/gmail/client.ts

@@ -1,8 +1,9 @@
 import { createServer } from 'node:http';
+import { spawn } from 'node:child_process';
 import { readFile, writeFile, mkdir } from 'node:fs/promises';
 import { dirname } from 'node:path';
-import open from 'open';
-import { google, gmail_v1 } from 'googleapis';
+import { platform } from 'node:os';
+import { google } from 'googleapis';
 import { expandHome } from '../config/config.js';
 import { NewsletterMessage } from '../parsing/types.js';
 
@@ -31,6 +32,14 @@ export async function authorizeGmail(credentialsPath: string, tokenPath: string)
   }
 }
 
+export async function createGmailClient(
+  credentialsPath: string,
+  tokenPath: string
+): Promise<GmailClient> {
+  const auth = await authorizeGmail(credentialsPath, tokenPath);
+  return new GmailClient(google.gmail({ version: 'v1', auth }));
+}
+
 async function waitForBrowserCode(url: string): Promise<string> {
   return new Promise((resolveCode, reject) => {
     const server = createServer((req, res) => {
@@ -43,17 +52,126 @@ async function waitForBrowserCode(url: string): Promise<string> {
       }
     });
     server.listen(53682, () => {
-      open(url).catch(reject);
+      console.log(`Open this URL to authorize Gmail access:\n${url}\n`);
+      openBrowser(url).catch(reject);
     });
   });
 }
 
-export class GmailClient {
-  public constructor(private readonly gmail: gmail_v1.Gmail) {}
+async function openBrowser(url: string): Promise<void> {
+  const command = buildBrowserCommand(url, platform());
 
-  public async fetchMessages(_label: string): Promise<NewsletterMessage[]> {
-    // Live Gmail traversal is isolated here. The run path accepts injected messages for tests and smoke.
-    await this.gmail.users.labels.list({ userId: 'me' });
-    return [];
+  const child = spawn(command.file, command.args, {
+    detached: true,
+    stdio: 'ignore',
+    windowsHide: true
+  });
+  child.unref();
+}
+
+export function buildBrowserCommand(url: string, os: NodeJS.Platform) {
+  if (os === 'win32') {
+    return {
+      file: 'powershell.exe',
+      args: ['-NoProfile', '-Command', 'Start-Process -FilePath $args[0]', url]
+    };
+  }
+  if (os === 'darwin') {
+    return { file: 'open', args: [url] };
+  }
+  return { file: 'xdg-open', args: [url] };
+}
+
+export class GmailClient {
+  public constructor(private readonly gmail: any) {}
+
+  public async fetchMessages(
+    labelName: string,
+    options: { maxResults?: number; query?: string } = {}
+  ): Promise<NewsletterMessage[]> {
+    const labelId = await this.findLabelId(labelName);
+    const listed = await this.gmail.users.messages.list({
+      userId: 'me',
+      labelIds: [labelId],
+      maxResults: options.maxResults,
+      q: options.query
+    });
+    const messages = listed.data.messages ?? [];
+    const loaded: NewsletterMessage[] = [];
+
+    for (const message of messages) {
+      if (!message.id) {
+        continue;
+      }
+      const response = await this.gmail.users.messages.get({
+        userId: 'me',
+        id: message.id,
+        format: 'full'
+      });
+      const parsed = parseGmailMessage(response.data);
+      if (parsed.html) {
+        loaded.push(parsed);
+      }
+    }
+
+    return loaded;
+  }
+
+  private async findLabelId(labelName: string): Promise<string> {
+    const response = await this.gmail.users.labels.list({ userId: 'me' });
+    const labels = response.data.labels ?? [];
+    const label = labels.find(
+      (entry: { id?: string; name?: string }) =>
+        entry.name?.toLowerCase() === labelName.toLowerCase()
+    );
+    if (!label?.id) {
+      throw new Error(`Gmail label "${labelName}" was not found`);
+    }
+    return label.id;
   }
 }
+
+function parseGmailMessage(message: any): NewsletterMessage {
+  const headers = Object.fromEntries(
+    (message.payload?.headers ?? []).map((header: { name: string; value: string }) => [
+      header.name.toLowerCase(),
+      header.value
+    ])
+  );
+
+  return {
+    id: message.id ?? headers['message-id'] ?? '',
+    messageId: headers['message-id'] ?? message.id ?? '',
+    from: headers.from ?? '',
+    date: new Date(headers.date ?? Date.now()).toISOString(),
+    subject: headers.subject ?? '',
+    html: findHtmlPart(message.payload) ?? '',
+    headers: {
+      date: headers.date,
+      from: headers.from,
+      listId: headers['list-id'],
+      messageId: headers['message-id'],
+      subject: headers.subject ?? ''
+    }
+  };
+}
+
+function findHtmlPart(part: any): string | undefined {
+  if (!part) {
+    return undefined;
+  }
+  if (part.mimeType === 'text/html' && part.body?.data) {
+    return decodeBase64Url(part.body.data);
+  }
+  for (const child of part.parts ?? []) {
+    const html = findHtmlPart(child);
+    if (html) {
+      return html;
+    }
+  }
+  return undefined;
+}
+
+function decodeBase64Url(value: string): string {
+  return Buffer.from(value.replace(/-/g, '+').replace(/_/g, '/'), 'base64').toString('utf8');
+}