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README.md

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+# 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.