C4Group reader in Java, still needs Packing/Unpacking but has the main magic done

C4Group.java

package de.beheh.lorry;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.BitSet;
import java.util.Date;
import java.util.zip.Inflater;

/**
 *
 * @author benedict
 */
public class C4Group {

	/* C4Group Constants */
	private static final int C4GROUP_HEADER_LENGTH = 204;
	private static final int C4GROUP_VERSION1 = 0x01;
	private static final int C4GROUP_VERSION2 = 0x02;
	private static final int INFLATE_BUFFER_SIZE = 1024;
	/* C4Group Pointer*/
	File group;
	DataInputStream groupStream;
	/* C4GroupHeader Values */
	String groupAuthor = null;
	int groupChildCount = 0;
	int groupCreation = 0;
	Date groupModified = null;
	boolean groupIsOriginal = false;

	/**
	 *
	 * @param path
	 * @throws FileNotFoundException
	 */
	public C4Group(String path) throws FileNotFoundException {
		this(new File(path));
	}

	/**
	 *
	 * @param group
	 * @throws FileNotFoundException
	 */
	public C4Group(File group) throws FileNotFoundException {
		this.group = group;
		groupStream = new DataInputStream(new BufferedInputStream(new FileInputStream(group)));
		try {
			if(groupStream.read() != 0x1e || groupStream.read() != 0x8c) {
				throw new Exception("file is not a c4group");
			}

			/* Gzip header */
			groupStream.read(); //compression method
			BitSet flags = ByteConverter.byteToBitSet((byte) groupStream.read()); //flags
			groupStream.readInt();
			readBytes(groupStream, 1); //xfl
			groupStream.readByte(); //os, should be 11 = ntfs for c4groups

			/* deflated Body */
			Inflater inflater = new Inflater(true);
			ByteArrayOutputStream inflatedData = new ByteArrayOutputStream();
			while(!inflater.finished()) {
				while(inflater.needsInput()) {
					byte[] buffer = new byte[INFLATE_BUFFER_SIZE];
					groupStream.mark(1024);
					groupStream.read(buffer);
					inflater.setInput(buffer);
				}
				byte[] inflatedBuffer = new byte[INFLATE_BUFFER_SIZE];
				int length = inflater.inflate(inflatedBuffer);
				inflatedData.write(inflatedBuffer, 0, length);
			}
			int remaining = inflater.getRemaining();
			inflater.end();
			//FileOutputStream f = new FileOutputStream("/home/benedict/c4group.hex");
			//f.write(scramble(inflatedData.toByteArray()));
			LittleEndianDataInputStream groupData = new LittleEndianDataInputStream(new ByteArrayInputStream(scramble(inflatedData.toByteArray())));
			inflatedData.close();

			/* Gzip footer */
			groupStream.reset();
			groupStream.skip(INFLATE_BUFFER_SIZE - remaining);
			//@TODO footer
			groupStream.close();

			/* C4GroupHeader */
			if(!new String(readBytes(groupData, 25)).equals("RedWolf Design GrpFolder ")) {
				throw new Exception("invalid c4group version");
			}

			groupData.skip(3); //reserved

			int groupVersion1 = groupData.readLittleEndianInt();
			int groupVersion2 = groupData.readLittleEndianInt();
			if(groupVersion1 != C4GROUP_VERSION1 || groupVersion2 != C4GROUP_VERSION2) {
				throw new Exception("incorrect c4group version (found " + groupVersion1 + "." + groupVersion2 + ", expected " + C4GROUP_VERSION1 + "." + C4GROUP_VERSION2 + ")");
			}

			groupChildCount = groupData.readLittleEndianInt();
			groupAuthor = new String(readBytes(groupData, 32));

			groupData.skip(32); //reserved
			groupModified = new Date((long) groupData.readLittleEndianInt() * 1000);
			groupIsOriginal = (groupData.readLittleEndianInt() == 1234567) ? true : false;

			groupData.skip(92); //reserved

			/*for(int i = 0; i < groupChildCount; i++) {
				System.out.println(new String(readBytes(groupData, 257)));
				readBytes(groupData, 59);
			}*/

			groupData.close();
		} catch(Exception ex) {
			ex.printStackTrace(System.err);
		}
	}

	/**
	 * Scrambles the according to the Clonk source code.
	 *
	 * @param input the input to scramble
	 * @return the scrambled bytes
	 */
	private byte[] scramble(byte[] input) {
		int i;
		byte tmp;
		for(i = 0; i < C4GROUP_HEADER_LENGTH; i++) {
			input[i] ^= 237;
		}
		for(i = 0; (i + 2) < C4GROUP_HEADER_LENGTH; i += 3) {
			tmp = input[i];
			input[i] = input[i + 2];
			input[i + 2] = tmp;
		}
		return input;
	}

	public String getAuthor() {
		return groupAuthor;
	}

	public boolean isOriginal() {
		return groupIsOriginal;
	}

	private byte[] readBytes(InputStream read, int length) throws IOException {
		byte[] bytes = new byte[length];
		for(int i = 0; i < length; i++) {
			bytes[i] = (byte) read.read();
		}
		return bytes;
	}
}