# imap-idle-caldav

A Python daemon that monitors an IMAP mailbox via IDLE for iMIP emails (event invitations, RSVP replies, cancellations) and ICS attachments, then updates a CalDAV calendar accordingly.

## Features

- **IMAP IDLE** — real-time monitoring with automatic reconnection and exponential backoff
- **iMIP support** — handles REQUEST (create/update), REPLY (attendee RSVP), and CANCEL methods
- **ICS attachments** — picks up `.ics` files and `application/ics` MIME parts
- **CalDAV sync** — creates, updates, and cancels events on any CalDAV server (Nextcloud, Radicale, etc.)
- **Graceful shutdown** — handles SIGTERM/SIGINT cleanly

## Installation

```bash
python3 -m venv .venv
source .venv/bin/activate
pip install -e .
```

## Configuration

Copy the example config and fill in your credentials:

```bash
cp config.example.yaml config.yaml
```

```yaml
imap:
  host: imap.example.com
  port: 993
  username: user@example.com
  password: secret
  folder: INBOX
  ssl: true

caldav:
  url: https://caldav.example.com/dav/calendars/user/calendar/
  username: user@example.com
  password: secret

logging:
  level: INFO   # DEBUG, INFO, WARNING, ERROR
```

## Usage

```bash
# Using the entry point
imap-idle-caldav -c config.yaml

# Or as a module
python -m imap_idle_caldav -c config.yaml
```

The daemon will connect to IMAP, enter IDLE mode, and process incoming calendar emails as they arrive. It re-idles every 5 minutes per RFC 2177 and automatically reconnects on disconnection.

## Systemd Service

Create a service user and install the app:

```bash
sudo useradd -r -s /usr/sbin/nologin imap-idle-caldav
sudo mkdir -p /opt/imap-idle-caldav
sudo python3 -m venv /opt/imap-idle-caldav/.venv
sudo /opt/imap-idle-caldav/.venv/bin/pip install .
```

Put your config in place:

```bash
sudo mkdir -p /etc/imap-idle-caldav
sudo cp config.yaml /etc/imap-idle-caldav/config.yaml
sudo chmod 600 /etc/imap-idle-caldav/config.yaml
sudo chown imap-idle-caldav: /etc/imap-idle-caldav/config.yaml
```

Install and start the service:

```bash
sudo cp imap-idle-caldav.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now imap-idle-caldav
```

Check status and logs:

```bash
sudo systemctl status imap-idle-caldav
sudo journalctl -u imap-idle-caldav -f
```

Edit the `ExecStart` path and `User` in the unit file if your install location or user differs.

## Project Structure

```
imap_idle_caldav/
├── __main__.py          # Entry point, signal handling
├── config.py            # YAML config loading & validation
├── imap_client.py       # IMAP connection & IDLE loop
├── email_processor.py   # ICS extraction from emails
└── caldav_client.py     # CalDAV create/update/cancel operations
```

## License

MIT