# Org2Ics - Bidirectional Org/iCalendar Converter

A C# console application that provides bidirectional conversion between .org diary files and .ics (iCalendar) format.

## Description

This tool converts between .org files containing diary entries and iCalendar (.ics) files. It supports:
- **Org to ICS**: Convert diary entries to all-day calendar events named "Chronolog"
- **ICS to Org**: Convert calendar events back to org diary format with proper date headers

## Features

- **Bidirectional conversion** between .org and .ics formats
- **Auto-detection** of input file format based on file extension
- **Org to ICS conversion**:
  - Parses .org files with level 3 headings (***) containing dates in YYYY-MM-DD format
  - Extracts diary content for each date entry
  - Creates all-day events with the title "Chronolog"
  - Includes diary content as event descriptions
- **ICS to Org conversion**:
  - Parses standard .ics calendar files
  - Extracts event dates and descriptions
  - Organizes entries by year and month
  - Creates proper org-mode structure with level 3 date headers
- **Proper character escaping** for both formats
- **Round-trip compatibility** for seamless conversion between formats

## Usage

```bash
dotnet run <input.org|input.ics> [output.ics|output.org]
```

### Parameters

- `input.org|input.ics`: Path to the input file (required)
  - `.org` files will be converted to `.ics` format
  - `.ics` files will be converted to `.org` format
- `output.ics|output.org`: Path to the output file (optional, auto-determined if not specified)

### Examples

```bash
# Convert diary.org to diary.ics
dotnet run diary.org

# Convert calendar.ics to calendar.org
dotnet run calendar.ics

# Specify custom output filename
dotnet run diary.org my-calendar.ics
dotnet run calendar.ics my-diary.org

# Round-trip conversion
dotnet run diary.org calendar.ics
dotnet run calendar.ics diary-restored.org
```

## File Format Support

### Org File Format (.org → .ics)

The converter expects .org files with the following structure:

```org
* My Diary

** Month Section

*** 2025-01-15

This is the diary content for January 15th, 2025.
It can span multiple lines and paragraphs.

*** 2025-01-16

Another diary entry for the next day.

** Another Section

*** 2025-02-01

February entry content here.
```

**Requirements:**
- Level 3 headings (starting with `***`) must contain dates in `YYYY-MM-DD` format
- Everything after a date heading until the next heading becomes the diary content for that date
- Non-date headings are ignored

### ICS File Format (.ics → .org)

The converter can parse standard iCalendar files and extracts:
- Event dates (both all-day and timed events)
- Event descriptions or summaries as diary content
- Events are organized chronologically and grouped by month

**Supported:**
- `DTSTART;VALUE=DATE:` (all-day events)
- `DTSTART:` (timed events - date portion used)
- `DESCRIPTION:` field content
- `SUMMARY:` field content (when no description available)
- Proper unescaping of iCalendar text formatting

## Output Formats

### Generated .ics Files (from .org)
- Standard iCalendar format (RFC 5545 compliant)
- All-day events spanning from the diary date to the next day
- Event title: "Chronolog"
- Event description: The diary content for that date
- Unique identifiers for each event

### Generated .org Files (from .ics)
- Proper org-mode structure with hierarchical headings
- Level 1: "Diary" (root heading)
- Level 2: Month and year groupings (e.g., "January 2025")
- Level 3: Individual date entries (e.g., "*** 2025-01-15")
- Content: Event descriptions properly formatted for org-mode

## Building

```bash
dotnet build
```

## Requirements

- .NET 8.0 or higher
- No additional dependencies required

## License

This project is provided as-is for educational and personal use.