# Vet Label Printer Client

This is a Docker-based MQTT client that listens for print requests, generates vet drug prescription labels, and prints them using a Brother QL printer.

## Setup

1. Configure the environment variables in `.env`:
   - `MQTT_HOST`: MQTT broker hostname
   - `MQTT_PORT`: MQTT broker port
   - `MQTT_TOPIC_SUB`: Topic to subscribe for print requests
   - `MQTT_TOPIC_PUB_ERRORS`: Topic to publish errors
   - `PRINTER_DEVICE`: Printer device path (e.g., /dev/usb/lp0)
   - `PRINTER_MODEL`: Printer model (e.g., QL-800)
   - `LABEL_SIZE_DEFAULT`: Default label size (e.g., 29x90)

2. Build and run with Docker Compose:
   ```bash
   docker-compose up --build
   ```

## MQTT Message Format

The client subscribes to the configured topic and expects JSON messages like:

```json
{
  "template_id": "vet_label",
  "label_size": "29x90",
  "variables": {
    "practice_name": "Many Tears Animal Rescue",
    "animal_name": "Rosie 468837",
    "drug_name": "Amoxicillin 50mg",
    "dosage": "1 tablet twice daily with food",
    "quantity": "14 tablets",
    "vet_initials": "Frank Molina"
  },
  "test": false
}
```

- `template_id`: Identifier for the label template (currently only "vet_label" supported)
- `label_size`: Size of the label (passed to brother-ql)
- `variables`: Key-value pairs for label content
- `test`: If true, saves PNG to `/app/output/` instead of printing

## Error Handling

Any errors during processing are published to the error topic as JSON:

```json
{
  "error": "Error message",
  "original_payload": "{original message}"
}
```

## Adding New Templates

To add new label templates, edit `templates.py` and add to the `TEMPLATES` dict.