# Reforger PAK Unpacker (Node.js)

Node.js library to extract files from Arma Reforger `.pak` archive files.

## Features

- Extract all files from PAK archives
- Extract specific files by name
- List all files in an archive
- Support for Zlib compressed files
- Async and sync APIs
- Easy integration into Express.js or other Node.js applications

## Installation

```bash
npm install
```

## Usage

### Basic Example - Extract All Files

```javascript
const { PakUnpacker } = require('./PakUnpacker');

async function extractPak() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    console.log(`Found ${unpacker.entries.length} files`);

    await unpacker.extract('./output');
    console.log('Extraction complete!');
}

extractPak();
```

### List Files in Archive

```javascript
const { PakUnpacker } = require('./PakUnpacker');

async function listFiles() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    const files = unpacker.listFiles();
    files.forEach(file => {
        console.log(`${file.name} - ${file.size} bytes (${file.compressed ? 'Compressed' : 'Uncompressed'})`);
    });
}

listFiles();
```

### Extract a Specific File

```javascript
const { PakUnpacker } = require('./PakUnpacker');

async function extractFile() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    await unpacker.load();

    const fileData = await unpacker.getFile('config.json');

    if (fileData) {
        console.log('File content:', fileData.toString('utf8'));
    } else {
        console.log('File not found');
    }
}

extractFile();
```

### Synchronous API

```javascript
const { PakUnpacker } = require('./PakUnpacker');

function extractPakSync() {
    const unpacker = new PakUnpacker('path/to/file.pak');
    unpacker.loadSync();

    console.log(`Found ${unpacker.entries.length} files`);

    unpacker.extractSync('./output');
    console.log('Extraction complete!');
}

extractPakSync();
```

## API Integration Example

### Express.js REST API

```javascript
const express = require('express');
const { PakUnpacker } = require('./PakUnpacker');
const app = express();

// List all files in a PAK archive
app.get('/api/pak/:pakName/files', async (req, res) => {
    try {
        const unpacker = new PakUnpacker(`./paks/${req.params.pakName}.pak`);
        await unpacker.load();

        const files = unpacker.listFiles();
        res.json({ success: true, files });
    } catch (error) {
        res.status(500).json({ success: false, error: error.message });
    }
});

// Extract a specific file
app.get('/api/pak/:pakName/extract/:fileName(*)', async (req, res) => {
    try {
        const unpacker = new PakUnpacker(`./paks/${req.params.pakName}.pak`);
        await unpacker.load();

        const fileData = await unpacker.getFile(req.params.fileName);

        if (fileData) {
            res.setHeader('Content-Type', 'application/octet-stream');
            res.send(fileData);
        } else {
            res.status(404).json({ success: false, error: 'File not found' });
        }
    } catch (error) {
        res.status(500).json({ success: false, error: error.message });
    }
});

app.listen(3000, () => {
    console.log('Server running on port 3000');
});
```

## PAK File Format

Reforger PAK files have the following structure:

1. **FORM Block**: Header with size (Big Endian Int32)
2. **HEAD Block**: 32 bytes header data
3. **DATA Block**: Size + data block
4. **Entries Block**: Directory and file entries

### Entry Types
- **Type 0**: Directory (with child count)
- **Type 1**: File (with offset, size, original size, compression info)

### Compression
- **None** (0x00): No compression
- **Zlib** (0x106): Deflate compression with 2-byte Zlib header

## API Reference

### Class: PakUnpacker

#### Constructor
```javascript
new PakUnpacker(filePath)
```
- `filePath` (string): Path to the .pak file

#### Methods

##### async load()
Load and parse the PAK file asynchronously.

##### loadSync()
Load and parse the PAK file synchronously (blocking).

##### async extract(dstDir)
Extract all files to the destination directory.
- `dstDir` (string): Destination directory path

##### extractSync(dstDir)
Extract all files synchronously.
- `dstDir` (string): Destination directory path

##### async getFile(fileName)
Get a specific file's data by name.
- `fileName` (string): Name or partial name of the file
- Returns: `Promise<Buffer|null>`

##### getFileSync(fileName)
Get a specific file's data synchronously.
- `fileName` (string): Name or partial name of the file
- Returns: `Buffer|null`

##### listFiles()
List all files in the PAK archive.
- Returns: Array of objects with `{name, size, originalSize, compressed}` properties

#### Properties

- `entries` (Array): Array of PakEntryFile objects
- `formSize` (number): Size of the FORM block
- `dataSize` (number): Size of the DATA block
- `entriesSize` (number): Size of the entries block

## Requirements

- Node.js >= 14.0.0
- No external dependencies (uses built-in modules only)

## License

MIT

## Credits

Converted from the original C# implementation.