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📅 Google Calendar → Slack Event Notifier

This Node.js app checks your Google Calendar (or an .ics link) every few minutes and sends you a Slack DM when an event is currently happening. It’s great for personal reminders, automatic daily check-ins, or alerting a team when meetings begin.

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🚀 Features

• ⏰ Checks upcoming or ongoing events automatically (default: every 5 minutes)
• 🧠 Prevents duplicate notifications per event
• 💬 Sends a formatted Slack message with event details
• 🔐 OAuth2 support for Google Calendar (or iCal alternative)
• ⚙️ Configurable via environment variables

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🧩 Tech Stack

• Node.js + Express — lightweight HTTP server
• Google APIs — for Calendar access (optional)
• Slack Web API — to send direct messages
• dotenv — environment configuration
• Custom getTodaysEvents() util — fetches calendar data from iCal or Google API

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⚙️ Installation

1. Clone the repository

   git clone https://github.com/yourusername/calendar-slack-notifier.git
   cd calendar-slack-notifier
   

2. Install dependencies

   npm install
   

3. Set up your environment file Create a .env file in the project root:

   SLACK_TOKEN=xoxb-your-slack-bot-token
   SLACK_USER_ID=U1234567890
   PORT=3000
   CALENDAR_URL=https://example.com/calendar.ics
   # (optional for Google OAuth)
   GOOGLE_CLIENT_ID=...
   GOOGLE_CLIENT_SECRET=...
   GOOGLE_REDIRECT_URI=http://localhost:3000/oauth/callback
   

4. Start the app

   node index.js
   

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🔑 OAuth Flow (Optional)

If you want to use Google Calendar API instead of .ics:

1. Visit

   http://localhost:3000/oauth/get-url
   

   to generate your OAuth login URL.

2. Authenticate with your Google account. The callback will be handled at:

   http://localhost:3000/oauth/callback
   

3. The resulting tokens will be stored (you can persist them using QuickDB or any small KV store).

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🕒 How It Works

• The app runs a scheduled interval every 5 minutes.

• Each run:

  1. Fetches today’s events from your calendar.
  2. Checks if an event is happening “now” (±5-minute grace period).
  3. Sends a Slack DM if it hasn’t already for that event.
  4. Cleans up old event entries after they end.

isNowBetween(start, end, graceMinutes = 5)

Determines if the current time falls within the event window (with a 5-minute grace).

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🔄 API Endpoints

Endpoint	Method	Description
/	GET	Returns a simple "meow:3" message to confirm the app is running
/force_refresh	POST	(WIP) Force refresh the event list (add password protection)
/oauth/get-url	GET	Generates Google OAuth URL
/oauth/callback	GET	Handles OAuth response and stores tokens

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💬 Example Slack Message

📅 *Daily Standup* is happening now! (09:00–09:30)

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🧠 Notes

• To adjust how often it checks for events, edit the interval at the bottom:

  5 * 1000 * 60 // 5 minutes
  

• Grace period can be modified in isNowBetween() (default: ±5 minutes).

• Ensure your Slack bot has the chat:write scope and permission to DM the target user.

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🐾 Example Logs

OwO the app is running, you can access it at http://localhost:3000
In 5 minutes you will get a slack dm if u have an event running now
✅ Sent alert for: Daily Standup

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📜 License

MIT License © 2025

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Would you like me to tailor this README to assume you’re only using iCal (and not Google OAuth), or should I keep both methods described?