# Modern CalDAV Web Client

A full-stack calendar application built with Rust, featuring a modern web interface for CalDAV calendar management.

## Motivation

While there are many excellent self-hosted CalDAV server implementations (Nextcloud, Radicale, Baikal, etc.), the web client ecosystem remains limited. Existing solutions like [AgenDAV](https://github.com/agendav/agendav) often suffer from outdated interfaces, bugs, and poor user experience. This project aims to provide a modern, fast, and reliable web interface for CalDAV servers.

## Features

### Calendar Management
- **Interactive Calendar Views**: Month and week views with intuitive navigation
- **Event Creation & Editing**: Comprehensive event forms with all standard iCalendar properties
- **Drag & Drop**: Move events between dates and times with automatic timezone conversion
- **CalDAV Integration**: Full bidirectional sync with any RFC-compliant CalDAV server

### Recurring Events
- **RFC 5545 Compliance**: Complete RRULE support with proper parsing and generation
- **Flexible Patterns**: Daily, weekly, monthly, and yearly recurrence with custom intervals
- **Advanced Options**: BYDAY rules, COUNT limits, UNTIL dates, and exception handling
- **Series Management**: Edit entire series or "this and future" events with proper UNTIL handling

### Modern Web Experience
- **Fast & Responsive**: Rust WebAssembly frontend for native-like performance  
- **Clean Interface**: Modern, intuitive design built with web standards
- **Real-time Updates**: Seamless synchronization with CalDAV servers
- **Timezone Aware**: Proper local time display with UTC storage

## Architecture

### Frontend (Yew WebAssembly)
- **Framework**: Yew for component-based UI development
- **Performance**: Rust WebAssembly for near-native browser performance
- **Models**: RFC 5545-compliant VEvent structures throughout
- **Services**: HTTP client for backend API communication
- **Views**: Responsive month/week calendar views with drag-and-drop

### Backend (Axum)  
- **Framework**: Axum async web framework with CORS support
- **Authentication**: JWT token management and validation
- **CalDAV Client**: Full CalDAV protocol implementation for server sync
- **API Design**: RESTful endpoints following calendar operation patterns
- **Data Flow**: Proxy between frontend and CalDAV servers with proper authentication

### Key Technical Features
- **RFC 5545 Compliance**: Complete iCalendar standard implementation
- **RRULE Processing**: Advanced recurrence rule parsing and generation
- **Timezone Handling**: Local time in UI, UTC for storage and CalDAV sync
- **Event Series**: Proper handling of recurring event modifications and exceptions
- **Build System**: Trunk for frontend bundling, Cargo workspaces for organization

## Getting Started

### Prerequisites

- Rust (latest stable version)
- Trunk (`cargo install trunk`)

### Development Setup

1. **Start the backend server** (serves API at http://localhost:3000):
   ```bash
   cargo run --manifest-path=backend/Cargo.toml
   ```

2. **Start the frontend development server** (serves at http://localhost:8080):
   ```bash
   trunk serve
   ```

3. **Access the application** at `http://localhost:8080`

### Building for Production

```bash
trunk build --release
```

### Development Commands

- `cargo check` - Check frontend compilation
- `cargo check --manifest-path=backend/Cargo.toml` - Check backend compilation  
- `trunk serve` - Start frontend development server with hot reload

## Project Structure

```
calendar/
├── frontend/                    # Yew WebAssembly frontend
│   ├── src/
│   │   ├── app.rs              # Main app component with routing
│   │   ├── components/         # UI components
│   │   │   ├── calendar.rs     # Main calendar container
│   │   │   ├── month_view.rs   # Month calendar view
│   │   │   ├── week_view.rs    # Week calendar view  
│   │   │   ├── create_event_modal.rs # Event creation form
│   │   │   └── ...
│   │   ├── models/
│   │   │   └── ical.rs         # RFC 5545 VEvent structures
│   │   └── services/
│   │       └── calendar_service.rs # HTTP client & RRULE logic
│   ├── index.html              # HTML template
│   └── Trunk.toml              # Frontend build config
├── backend/                     # Axum REST API server
│   └── src/
│       ├── main.rs             # Server entry point
│       ├── handlers/           # API endpoint handlers
│       │   ├── events.rs       # Event CRUD operations
│       │   └── series.rs       # Recurring event operations  
│       ├── auth.rs             # JWT authentication
│       └── calendar.rs         # CalDAV client implementation
└── CLAUDE.md                   # Development instructions
```

## CalDAV Compatibility

This client is designed to work with any RFC-compliant CalDAV server:

- **Baikal** - ✅ Fully tested with complete event and recurrence support
- **Nextcloud** - 🚧 Planned compatibility with calendar app
- **Radicale** - 🚧 Planned lightweight CalDAV server support  
- **Apple Calendar Server** - 🚧 Planned standards-compliant operation
- **Google Calendar** - 🚧 Planned CalDAV API compatibility

*Note: While the client follows RFC standards and should work with any compliant CalDAV server, we have currently only tested extensively with Baikal. Testing with other servers is planned.*