Split Billing WhatsApp Bot

A WhatsApp bot built with Go and whatsmeow that helps friends split bills easily.

Features

• Create and manage bills in WhatsApp groups
• Add participants and items
• Send a photo of your bill to extract items and amounts automatically (using OpenAI API)
• Calculate how much each person owes
• Send private WhatsApp messages to each participant when a bill is closed, showing their share and payment instructions
• Multi-language support: English and Indonesian (see /lang command)
• Translation system for easy localization

Installation

1. Ensure you have Go 1.16+ installed

2. Clone the repository

3. Install dependencies:

   go mod tidy

4. Build the application:

   go build -o build/split-billing-bot cmd/main.go

Web QR Code UI

• When you start the bot, it also runs a web server at http://localhost:8080/.
• Open this page in your browser to view and scan the WhatsApp QR code for login.

Usage

1. Run the application:

   ./build/split-billing-bot

2. Open your browser and go to http://localhost:8080/ to view the QR code.

3. Scan the QR code with WhatsApp to log in.

4. The bot will now process commands in your chats.

Command List

• /new [name] - Create a new bill
• /add [item] [amount] - Add an item to the current bill (optional)
• Send a photo of your bill to add all items at once (optional, requires OpenAI API key)
• /join [bill_name] - Join the current bill as a participant (optional)
• /calculate - Calculate and show how much each person owes in the current bill
• /close - Close the current bill and send private messages to all participants
• /help - Show available commands
• /lang [indonesia|english] - Change bot language preference for this chat

Example

1. /new Sarapan
2. Each person types /join to participate
3. Send a photo of your bill to add all items at once (optional)
4. /calculate
5. /close when done (each participant receives a private message with their share)

TODO

• Add image processing for bill images using LLM
• Send message to the participants WhatsApp number when bill is closed
• When user types /join, send message to the user that they have joined the bill
• Add bill name to the /join command
• Add bill name to the /calculate command
• Add bill name to the /close command
• Add bill name to the /help command
• Change the database server to use PostgreSQL
• Use Docker to containerize the application
• Use GitHub Actions to deploy the application to a VPS
• Add unit tests
• Add integration tests

Translations

• The bot supports English and Indonesian. Use /lang indonesia or /lang english to switch.
• To add a new language, edit or add files in internal/translations/ following the existing structure.
• It's not perfect, but it works.

Contributing

Pull requests are welcome! For major changes, please open an issue first to discuss what you would like to change.

If you find a bug or have a feature request, please open an issue on GitHub.

License

MIT