# Gmail Reader

Monorepo with a React + Vite + DaisyUI client, a Fastify API, and a Gmail push watcher. The API owns Google OAuth, stores tokens in SQLite, and calls the Gmail API with `gmail.readonly`. The browser only receives an HTTP-only session cookie. The watcher reuses those tokens, calls `users.watch`, and runs each new INBOX message through a handler pipeline.

## Prerequisites

- Node.js 20+
- A Google Cloud OAuth **Web application** client with:
  - Scope: `https://www.googleapis.com/auth/gmail.readonly`
  - Authorized JavaScript origin: `https://oauth.0dev.web.id` (and `http://localhost:5173` for local)
  - Authorized redirect URIs:
    - `https://oauth.0dev.web.id/callback`
    - `http://localhost:5173/callback` (local; Vite proxies this to Fastify)

## Local development

```bash
cp .env.example .env
```

Fill in `GOOGLE_CLIENT_ID`, `GOOGLE_CLIENT_SECRET`, and a long `SESSION_SECRET`. Keep:

```
GOOGLE_REDIRECT_URI=http://localhost:5173/callback
```

Then:

```bash
npm install
npm run dev
```

- UI: http://localhost:5173
- API: http://localhost:3000
- Watcher (optional): `npm run dev:watcher` → http://localhost:3001

Vite proxies `/auth`, `/callback`, and `/api` to Fastify so the Google redirect stays on the same origin as the SPA.

Sign in via the UI at least once so SQLite has a refresh token before starting the watcher.

## Production (one process)

Build the frontend, then start Fastify. Fastify serves `apps/web/dist` and handles `/callback` itself.

```bash
npm install
npm run build
NODE_ENV=production GOOGLE_REDIRECT_URI=https://oauth.0dev.web.id/callback npm start
```

Point your reverse proxy at the Fastify port (`PORT`, default 3000). Send the whole host to that one process — SPA, `/api`, `/auth`, and `/callback` must share `https://oauth.0dev.web.id`.

Example Caddy:

```
oauth.0dev.web.id {
  reverse_proxy 127.0.0.1:3000
}
```

SQLite is stored at `apps/api/data/app.db`. Keep that directory writable and backed up.

## Gmail push watcher

Gmail does not POST to you directly. It publishes to **Cloud Pub/Sub**, which push-delivers to `POST /pubsub/gmail`.

### GCP setup

1. Enable **Gmail API** and **Cloud Pub/Sub** in the same Google Cloud project as the OAuth client.
2. Create a topic, e.g. `projects/YOUR_PROJECT/topics/gmail-push`.
3. Grant **Pub/Sub Publisher** on that topic to `serviceAccount:gmail-api-push@system.gserviceaccount.com`.
4. Create a **push subscription** whose endpoint is publicly reachable HTTPS, e.g. `https://oauth.0dev.web.id/pubsub/gmail?token=YOUR_TOKEN`.
5. Put the topic name and token in `.env` (`GOOGLE_PUBSUB_TOPIC`, `PUBSUB_VERIFICATION_TOKEN`).

Start after a user has signed in through the web app:

```bash
npm run start:watcher
```

Example Caddy (API on 3000, watcher on 3001):

```
oauth.0dev.web.id {
  handle /pubsub/gmail* {
    reverse_proxy 127.0.0.1:3001
  }
  handle {
    reverse_proxy 127.0.0.1:3000
  }
}
```

The watcher renews `users.watch` on startup and every 12 hours. Handlers run in sequence per new message: log the event, then fetch and log the message body. A handler may pass fields to the next one or `break` the chain.

## What it does

- Sign in with Google (server-side authorization code flow)
- List latest mail
- Search with Gmail query syntax (`from:`, `subject:`, `newer_than:`, …)
- Open a message and read decoded plain-text content
- Watch INBOX via Gmail push (Pub/Sub) and run a sequential handler pipeline (log event, then fetch and log the message)
- Watch INBOX via Gmail push (Pub/Sub) and run a sequential handler pipeline (log event, then fetch and log the message)