# API Reference

## Functions

### `toHijri(date, options?)`

Converts a Gregorian `Date` to a Hijri date object.

```typescript
function toHijri(date: Date, options?: ConversionOptions): HijriDate | null;
```

**Parameters**

| Name      | Type                | Description                                                          |
| --------- | ------------------- | -------------------------------------------------------------------- |
| `date`    | `Date`              | Any valid JavaScript `Date`.                                         |
| `options` | `ConversionOptions` | Optional. `{ calendar: 'uaq' }` (default) or `{ calendar: 'fcna' }`. |

For the default `'uaq'` calendar, the local year/month/day components of the Date are used. For `'fcna'`, UTC components are used (since FCNA month boundaries are defined in UTC).

**Returns** `HijriDate | null`

For UAQ: returns `null` if the date falls outside the table range (before 1 Muharram 1318 H / 1900-04-30, or at/after 1 Muharram 1501 H / 2077-11-17).
For FCNA: returns `null` only for dates before 1 Muharram 1 AH (pre-Islamic epoch).

**Throws** `Error("Invalid Gregorian date")` if the argument is not a valid `Date` instance.

**Example**

```javascript
toHijri(new Date(2023, 2, 23, 12)); // { hy: 1444, hm: 9, hd: 1 }  (UAQ)
toHijri(new Date(2025, 2, 1, 12)); // { hy: 1446, hm: 9, hd: 1 }  (UAQ)
toHijri(new Date(2025, 2, 1, 12), { calendar: 'fcna' }); // { hy: 1446, hm: 9, hd: 1 }  (FCNA)
toHijri(new Date(1800, 0, 1), { calendar: 'uaq' }); // null (before table range)
```

---

### `toGregorian(hy, hm, hd, options?)`

Converts a Hijri date to a Gregorian `Date`.

```typescript
function toGregorian(hy: number, hm: number, hd: number, options?: ConversionOptions): Date;
```

**Parameters**

| Name      | Type                | Description                                                          |
| --------- | ------------------- | -------------------------------------------------------------------- |
| `hy`      | `number`            | Hijri year (1318–1500 for UAQ; any year ≥ 1 for FCNA)                |
| `hm`      | `number`            | Hijri month (1–12)                                                   |
| `hd`      | `number`            | Hijri day (1–29 or 1–30 depending on the month)                      |
| `options` | `ConversionOptions` | Optional. `{ calendar: 'uaq' }` (default) or `{ calendar: 'fcna' }`. |

**Returns** `Date`

Returns a UTC Date at midnight.

**Throws** `Error("Invalid Hijri date")` if the date fails validation.

**Example**

```javascript
toGregorian(1444, 9, 1); // 2023-03-23T00:00:00.000Z
toGregorian(1446, 9, 1, { calendar: 'fcna' }); // 2025-03-01T00:00:00.000Z
toGregorian(1446, 10, 1, { calendar: 'fcna' }); // 2025-03-30T00:00:00.000Z
toGregorian(1444, 0, 1); // throws: month 0 is invalid
```

---

### `formatHijriDate(date, format)`

Formats a Hijri date using a format string with Hijri-specific tokens.

```typescript
function formatHijriDate(date: HijriDate, format: string): string;
```

**Parameters**

| Name     | Type        | Description                                          |
| -------- | ----------- | ---------------------------------------------------- |
| `date`   | `HijriDate` | A Hijri date object with `hy`, `hm`, `hd` properties |
| `format` | `string`    | Format string with tokens listed below               |

**Returns** `string`

Tokens in the format string are replaced with the corresponding Hijri values. Unrecognized substrings pass through unchanged.

**Format tokens**

| Token            | Description                  | Example          |
| ---------------- | ---------------------------- | ---------------- |
| `iYYYY`          | Year, 4 digits               | `1444`           |
| `iYY`            | Year, last 2 digits          | `44`             |
| `iMMMM`          | Month, full name             | `Ramadan`        |
| `iMMM`           | Month, medium name           | `Ramadan`        |
| `iMM`            | Month, 2 digits, zero-padded | `09`             |
| `iM`             | Month, no padding            | `9`              |
| `iDD`            | Day, 2 digits, zero-padded   | `01`             |
| `iD`             | Day, no padding              | `1`              |
| `iEEEE`          | Weekday, full name           | `Yawm al-Khamis` |
| `iEEE`           | Weekday, abbreviated         | `Kham`           |
| `iE`             | Weekday, numeric (Sunday=1)  | `5`              |
| `ioooo`          | Era, full                    | `AH`             |
| `iooo`           | Era, abbreviated             | `AH`             |
| `HH`             | Hour, 24h, zero-padded       | `14`             |
| `H`              | Hour, 24h                    | `14`             |
| `hh`             | Hour, 12h, zero-padded       | `02`             |
| `h`              | Hour, 12h                    | `2`              |
| `mm`             | Minute, zero-padded          | `05`             |
| `m`              | Minute                       | `5`              |
| `ss`             | Second, zero-padded          | `30`             |
| `s`              | Second                       | `30`             |
| `a`              | AM/PM                        | `AM`             |
| `z`, `zz`, `zzz` | Timezone name                | `UTC`            |
| `Z`, `ZZ`        | Timezone offset              | `+00:00`         |

Time, timezone, and weekday tokens are computed from a Gregorian DateTime derived from the Hijri date using the UAQ calendar. For FCNA-derived dates in months where UAQ and FCNA start on different days, weekday and time tokens will reflect the UAQ Gregorian equivalent, not the FCNA one. Pure Hijri tokens (`iYYYY`, `iMM`, `iDD`, `iMMMM`, etc.) are always accurate regardless of which calendar system produced the date.

**Weekday numbering**

The weekday arrays follow the Islamic convention where Sunday is the first day:

| Index | Day       | `iE` value |
| ----- | --------- | ---------- |
| 0     | Sunday    | 1          |
| 1     | Monday    | 2          |
| 2     | Tuesday   | 3          |
| 3     | Wednesday | 4          |
| 4     | Thursday  | 5          |
| 5     | Friday    | 6          |
| 6     | Saturday  | 7          |

**Example**

```javascript
const d = { hy: 1444, hm: 9, hd: 1 };

formatHijriDate(d, 'iYYYY-iMM-iDD'); // "1444-09-01"
formatHijriDate(d, 'iMMMM iD, iYYYY'); // "Ramadan 1, 1444"
formatHijriDate(d, 'iEEEE, iD iMMMM iYYYY ioooo'); // "Yawm al-Khamis, 1 Ramadan 1444 AH"
```

---

### `isValidHijriDate(hy, hm, hd, options?)`

Checks whether a Hijri date is valid for the given calendar system.

```typescript
function isValidHijriDate(hy: number, hm: number, hd: number, options?: ConversionOptions): boolean;
```

**Returns** `boolean`

For UAQ (default): returns `false` if `hy` is outside 1318–1500, `hm` is outside 1–12, or `hd` exceeds the actual days in that month.

For FCNA: `hy` must be ≥ 1, `hm` must be 1–12, and `hd` must not exceed the computed FCNA month length.

**Example**

```javascript
isValidHijriDate(1444, 9, 1); // true
isValidHijriDate(1444, 9, 30); // false - Ramadan 1444 has 29 days (UAQ)
isValidHijriDate(1317, 1, 1); // false - before table range
isValidHijriDate(1501, 1, 1); // false - sentinel boundary
isValidHijriDate(1, 1, 1, { calendar: 'fcna' }); // true  - FCNA supports all years
isValidHijriDate(1600, 1, 1, { calendar: 'fcna' }); // true  - beyond UAQ table, FCNA computed
```

---

## Types

```typescript
interface HijriDate {
  hy: number; // Hijri year
  hm: number; // Hijri month (1–12)
  hd: number; // Hijri day (1–30)
}

// Calendar system selector.
// 'uaq': Umm al-Qura (default): table-based, covers 1318–1500 H.
// 'fcna': FCNA/ISNA: astronomical calculation, works for all Hijri years >= 1 AH.
type CalendarSystem = 'uaq' | 'fcna';

interface ConversionOptions {
  calendar?: CalendarSystem;
}

interface HijriYearRecord {
  hy: number; // Hijri year
  dpm: number; // days-per-month bitmask
  gy: number; // Gregorian year of 1 Muharram
  gm: number; // Gregorian month of 1 Muharram
  gd: number; // Gregorian day of 1 Muharram
}
```

---

## Type exports

```typescript
import type {
  HijriDate, // { hy, hm, hd }
  HijriYearRecord, // UAQ table row
  CalendarSystem, // 'uaq' | 'fcna'
  ConversionOptions, // { calendar?: CalendarSystem }
} from 'luxon-hijri';
```

## Data exports

```javascript
import {
  hDatesTable, // HijriYearRecord[] - 184 entries (183 real years + 1 sentinel)
  hmLong, // string[12] - full month names
  hmMedium, // string[12] - medium month names
  hmShort, // string[12] - abbreviated month names
  hwLong, // string[7] - full weekday names (Sunday-first order)
  hwShort, // string[7] - abbreviated weekday names
  hwNumeric, // number[7] - weekday numbers (1-7, Sunday=1)
  formatPatterns, // Record<string, string> - token reference map
} from 'luxon-hijri';
```

**Month name arrays** (index 0 = Muharram, index 11 = Dhul Hijjah)

| Index | `hmLong`      | `hmMedium`  | `hmShort` |
| ----- | ------------- | ----------- | --------- |
| 0     | Muharram      | Muharram    | Muh       |
| 1     | Safar         | Safar       | Saf       |
| 2     | Rabi'l Awwal  | Rabi1       | Ra1       |
| 3     | Rabi'l Thani  | Rabi2       | Ra2       |
| 4     | Jumadal Awwal | Jumada1     | Ju1       |
| 5     | Jumadal Thani | Jumada2     | Ju2       |
| 6     | Rajab         | Rajab       | Raj       |
| 7     | Sha'ban       | Shaban      | Shb       |
| 8     | Ramadan       | Ramadan     | Ram       |
| 9     | Shawwal       | Shawwal     | Shw       |
| 10    | Dhul Qi'dah   | Dhul-Qidah  | DhQ       |
| 11    | Dhul Hijjah   | Dhul-Hijjah | DhH       |

**Weekday arrays** (index 0 = Sunday, index 6 = Saturday)

| Index | `hwLong`           | `hwShort` | `hwNumeric` |
| ----- | ------------------ | --------- | ----------- |
| 0     | Yawm al-Ahad       | Ahad      | 1           |
| 1     | Yawm al-Ithnayn    | Ithn      | 2           |
| 2     | Yawm ath-Thulatha' | Thul      | 3           |
| 3     | Yawm al-Arba`a'    | Arba      | 4           |
| 4     | Yawm al-Khamis     | Kham      | 5           |
| 5     | Yawm al-Jum`a      | Jum`a     | 6           |
| 6     | Yawm as-Sabt       | Sabt      | 7           |

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