hijri_calendar

# HijriCalendar

`HijriCalendar` is an Elixir library for converting between Gregorian dates and
Islamic Hijri dates.

Current release focuses on:

- `Date` and `DateTime` conversion
- Hijri date representation and validation
- Month names
- Strategy-based calendar architecture

## Installation

Add `hijri_calendar` to your dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:hijri_calendar, "~> 0.1.0"}
  ]
end
```

## Quick start (`iex`)

From the project root:

```bash
iex -S mix
```

Then run:

```elixir
HijriCalendar.today()
HijriCalendar.now()

gregorian = ~D[2026-08-10]
hijri = HijriCalendar.from_gregorian(gregorian)
HijriCalendar.to_gregorian(hijri)

datetime = DateTime.new!(~D[2026-08-10], ~T[15:45:00], "Etc/UTC")
HijriCalendar.from_datetime(datetime)
HijriCalendar.to_datetime(hijri)

HijriCalendar.month_name(9)
```

## Public API

- `HijriCalendar.today/0`
- `HijriCalendar.now/0`
- `HijriCalendar.from_gregorian/1`
- `HijriCalendar.from_gregorian/2`
- `HijriCalendar.from_datetime/1`
- `HijriCalendar.from_datetime/2`
- `HijriCalendar.to_gregorian/1`
- `HijriCalendar.to_gregorian/2`
- `HijriCalendar.to_datetime/1`
- `HijriCalendar.to_datetime/2`
- `HijriCalendar.month_name/1`

## Calendar strategies

The API supports strategy selection:

- `:tabular`
- `:astronomical`
- `:umm_al_qura`

Example:

```elixir
gregorian = ~D[2026-08-10]

HijriCalendar.from_gregorian(gregorian, :tabular)
HijriCalendar.from_gregorian(gregorian, :astronomical)
HijriCalendar.from_gregorian(gregorian, :umm_al_qura)
```

`Astronomical` and `UmmAlQura` currently delegate to `Tabular` while keeping a
clean extension boundary for future implementations.

## Hijri date struct

```elixir
%HijriCalendar.Date{year: 1448, month: 2, day: 25}
```

Use validated construction with:

```elixir
HijriCalendar.Date.new(year, month, day)
```

## Development

```bash
mix format
mix test
mix credo
```