# Date Calculator

An Obsidian plugin that adds dynamic date calculations to your notes using `date-calc` fenced code blocks and inline code.

## Features

### Fenced Code Blocks
Add `date-calc` code blocks to your notes for rich date calculations:

```date-calc
type: birthday
birthday: 1992-08-16
```

### Inline Code
Use inline code for quick calculations: `date-calc: birthday=1992-08-16`

**Note about Live Preview**: Inline code works in both Reading view and Live Preview mode. In Live Preview, the result appears after the inline code (e.g., `date-calc: birthday=1992-08-16` → Age: 32 years old...). However, inline code does **not** work for live-preview in Source mode - you'll see the literal code until you switch to Reading view or Live Preview mode.

## Supported Calculation Types

### Birthday (`birthday`)
Calculates age and time until next birthday with enhanced personalization features.

**Fields:**
- `birthday` (or `birthdate`, `date`): Birth date in YYYY-MM-DD format
- `name` (optional): Person's name for personalized output
- `gender` (optional): `male`/`m`, `female`/`f`, or `neutral` for appropriate pronouns
- `label` (optional): Custom label (defaults to "Age:")

**Frontmatter Support:** If not provided in the code block, the plugin will look for `birthday`/`birthdate`, `name`, and `gender` properties in the note's frontmatter.

**Examples:**
```date-calc
type: birthday
name: Alice
birthday: 1992-08-16
gender: female
```

```date-calc
type: birthday
birthday: 2000-05-21
label: "John's age:"
```

### Countdown (`countdown` or `until`)
Shows time remaining until a target date.

**Fields:**
- `to` (or `date`, `until`): Target date/time
- `from` (optional): Starting date/time (defaults to now)
- `label` (optional): Prefix label for the output

**Examples:**
```date-calc
type: countdown
label: New Year
to: 2025-12-31 23:59
```

```date-calc
type: countdown
label: Sprint ends
to: 2025-10-15 17:00
from: 2025-10-01 09:00
```

### Since (`since`)
Shows time elapsed since an event (or time until if the event is in the future).

**Fields:**
- `since` (or `from`, `date`): Event date/time

**Example:**
```date-calc
type: since
since: 2024-12-20
```

### Difference (`diff`)
Calculates the time difference between two specific dates.

**Fields:**
- `from` (or `start`): Start date/time
- `to` (or `end`): End date/time

**Examples:**
```date-calc
type: diff
from: 2024-02-29
to: 2025-03-01
```

```date-calc
type: diff
from: 2025-09-19 08:00
to: 2025-09-19 16:30
```

## Inline Usage

You can use inline code for quick calculations:

- `date-calc: birthday=1992-08-16` → Birthday summary
- `date-calc: to=2025-12-31 label="New Year"` → Countdown
- `date-calc: since=2024-12-20` → Time since event
- `date-calc: from=2025-09-19 to=2025-09-20` → Date difference

**YAML Format:** Inline code also accepts YAML/inline-map format:
`date-calc: {type: birthday, birthday: 1992-08-16, name: Alice}`

**Frontmatter Integration:** For inline birthday calculations, if no date is provided, the plugin will use the note's frontmatter `birthday`/`birthdate` property.

## Date Formats

- **Dates:** YYYY-MM-DD (e.g., `2025-12-31`)
- **Date + Time:** YYYY-MM-DD HH:mm (e.g., `2025-12-31 23:59`)
- **Timezone:** All calculations use your local timezone
- **Birthday Calculations:** Normalized to local midnight to avoid timezone inconsistencies

## Error Handling

The plugin provides helpful error messages for common issues:

- **Invalid YAML:** Shows parsing error details
- **Missing Required Fields:** Indicates which fields are needed
- **Invalid Dates:** Warns about unrecognizable date formats

Example of invalid YAML:
```date-calc
this: is: not: valid
```

Example of missing field:
```date-calc
type: diff
from: 2025-01-01
# Error: missing required "to" field
```

## Live Preview and Rendering

- **Fenced Code Blocks:** Work in all view modes (Source, Live Preview, Reading)
- **Inline Code:** Works in Reading view and Live Preview mode
  - In Live Preview: Shows result after the inline code with an arrow (→)
  - In Source mode: Shows literal code until you switch views
- **Code Inside Fenced Blocks:** Intentionally ignored to allow documentation examples

## Troubleshooting Inline Code

If inline code isn't rendering:

1. **Check View Mode:** Switch to Reading view or Live Preview mode
2. **Syntax:** Use single backticks (not triple): `date-calc: birthday=1992-08-16`
3. **Refresh:** Try toggling the note view or reloading the app
4. **Plugin Status:** Disable and re-enable the plugin if needed

The plugin's inline processor runs late in the processing chain to avoid conflicts with other processors.

## Styling

You can customize the appearance of date calculations using the CSS class `date-calc` in your snippets or theme.

For inline calculations, use the class `date-calc-inline`.

## Tips

- Use ISO date format (YYYY-MM-DD) for best compatibility
- Birthday calculations handle leap years and timezone edge cases
- For personalized birthday messages, add `name` and `gender` to your note's frontmatter
- The plugin integrates with Obsidian's metadata cache for frontmatter access