BusyBee - Universal Calendar Sync Engine

⚠️ Experimental - This project is under active development. Use with care in production.

Automated calendar synchronization that mirrors "busy" time slots across multiple calendars to prevent double-booking.

Features

• Full-mesh synchronization across Google Calendars and CalDAV
• Privacy-focused: synced events show only "Busy" status
• Automatic token refresh for long-running background operation
• Interactive configuration wizard
• Event lifecycle management (create, update, delete)
• Infinite loop prevention with sync markers
• Configurable sync interval

Limitations

• Timed events only: Only events with specific start/end times are synced. All-day and multi-day events are not currently supported.

Unfinished / Experimental Features

• Daemon mode (java -jar busybee.jar run) - Has not been tested
• Email alerts - Experimental, may be removed in a future release

Requirements

• JVM 21+

Quick Start

1. Build

./gradlew fatJar

2. Configure

java -jar busybee.jar configure

The wizard will guide you through:

1. Select "Google Calendar (OAuth)"
2. Enter OAuth Client ID/Secret (see below)
3. Browser opens for authorization
4. Copy authorization code
5. Done! Tokens saved automatically

3. Run

java -jar busybee.jar sync   # Run once
java -jar busybee.jar run    # Run as daemon (untested)

Getting OAuth Credentials (One-time)

1. Go to Google Cloud Console
2. Create OAuth 2.0 Client ID (Desktop app)
3. Note your Client ID and Client Secret
4. In OAuth consent screen → Test users → Add your email

That's it! The configure wizard handles the rest automatically.

Generic CalDAV

For Infomaniak, IceWarp, or other CalDAV providers:

java -jar busybee.jar configure

Select "Generic CalDAV" and provide URL, username, password.

Systemd Setup (Linux) - Untested

sudo cp src/scripts/busybee.service /etc/systemd/system/
sudo cp src/scripts/busybee.timer /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now busybee.timer

Configuration Options

Option	Description	Default
intervalMinutes	Sync interval	15
prefix	Sync event prefix	"BB"

How It Works

1. Fetches events from all configured calendars
2. Identifies "original" events (not synced)
3. Creates "[BB-]
   " placeholder events in all other calendars
4. On original event update: updates all synced blocks
5. On original event delete: removes all synced blocks

Security

• Tokens stored in local tokens/ directory (add to .gitignore)
• Synced events contain no sensitive details
• Run behind firewall/VPN for production use