/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package com.l2jserver.communityserver.network.netcon.crypt;

import java.io.IOException;
import java.util.logging.Logger;

public class NewCrypt
{
	protected static Logger _log = Logger.getLogger(NewCrypt.class.getName());
	BlowfishEngine _crypt;
	BlowfishEngine _decrypt;

	public NewCrypt(final byte[] blowfishKey)
	{
		_crypt = new BlowfishEngine();
		_crypt.init(true, blowfishKey);
		_decrypt = new BlowfishEngine();
		_decrypt.init(false, blowfishKey);
	}

	public NewCrypt(final String key)
	{
		this(key.getBytes());
	}

	public static final boolean verifyChecksum(byte[] raw)
	{
		return NewCrypt.verifyChecksum(raw, 0, raw.length);
	}

	public static final boolean verifyChecksum(byte[] raw, final int offset, final int size)
	{
		// check if size is multiple of 4 and if there is more then only the checksum
		if ((size & 3) != 0 || size <= 4)
		{
			return false;
		}

		long chksum = 0;
		int count = size-4;
		long check = -1;
		int i;

		for (i = offset; i<count; i+=4)
		{
			check = raw[i] &0xff;
			check |= raw[i+1] << 8 &0xff00;
			check |= raw[i+2] << 0x10 &0xff0000;
			check |= raw[i+3] << 0x18 &0xff000000;

			chksum ^= check;
		}

		check = raw[i] &0xff;
		check |= raw[i+1] << 8 &0xff00;
		check |= raw[i+2] << 0x10 &0xff0000;
		check |= raw[i+3] << 0x18 &0xff000000;

		return check == chksum;
	}

	public static final void appendChecksum(byte[] raw)
	{
		NewCrypt.appendChecksum(raw, 0, raw.length);
	}

	public static final void appendChecksum(byte[] raw, final int offset, final int size)
	{
		long chksum = 0;
		int count = size-4;
		long ecx;
		int i;

		for (i = offset; i<count; i+=4)
		{
			ecx = raw[i] &0xff;
			ecx |= raw[i+1] << 8 &0xff00;
			ecx |= raw[i+2] << 0x10 &0xff0000;
			ecx |= raw[i+3] << 0x18 &0xff000000;

			chksum ^= ecx;
		}

		ecx = raw[i] &0xff;
		ecx |= raw[i+1] << 8 &0xff00;
		ecx |= raw[i+2] << 0x10 &0xff0000;
		ecx |= raw[i+3] << 0x18 &0xff000000;

		raw[i] = (byte) (chksum &0xff);
		raw[i+1] = (byte) (chksum >>0x08 &0xff);
		raw[i+2] = (byte) (chksum >>0x10 &0xff);
		raw[i+3] = (byte) (chksum >>0x18 &0xff);
	}

	/**
	 * Packet is first XOR encoded with <code>key</code>
	 * Then, the last 4 bytes are overwritten with the the XOR "key".
	 * Thus this assume that there is enough room for the key to fit without overwriting data.
	 * @param raw The raw bytes to be encrypted
	 * @param key The 4 bytes (int) XOR key
	 */
	public static final void encXORPass(byte[] raw, int key)
	{
		NewCrypt.encXORPass(raw, 0, raw.length, key);
	}

	/**
	 * Packet is first XOR encoded with <code>key</code>
	 * Then, the last 4 bytes are overwritten with the the XOR "key".
	 * Thus this assume that there is enough room for the key to fit without overwriting data.
	 * @param raw The raw bytes to be encrypted
	 * @param offset The begining of the data to be encrypted
	 * @param size Length of the data to be encrypted
	 * @param key The 4 bytes (int) XOR key
	 */
	public static final void encXORPass(byte[] raw, final int offset, final int size, int key)
	{
		int stop = size-8;
		int pos = 4 + offset;
		int edx;
		int ecx = key; // Initial xor key

		while (pos < stop)
		{
			edx = (raw[pos] & 0xFF);
			edx |= (raw[pos+1] & 0xFF) << 8;
			edx |= (raw[pos+2] & 0xFF) << 16;
			edx |=  (raw[pos+3] & 0xFF) << 24;

			ecx += edx;

			edx ^= ecx;

			raw[pos++] = (byte) (edx & 0xFF);
			raw[pos++] = (byte) (edx >> 8 & 0xFF);
			raw[pos++] = (byte) (edx >> 16 & 0xFF);
			raw[pos++] = (byte) (edx >> 24 & 0xFF);
		}

		raw[pos++] = (byte) (ecx & 0xFF);
		raw[pos++] = (byte) (ecx >> 8 & 0xFF);
		raw[pos++] = (byte) (ecx >> 16 & 0xFF);
		raw[pos++] = (byte) (ecx >> 24 & 0xFF);
	}


	public final byte[] decrypt(byte[] raw) throws IOException
	{
		byte[] result = new byte[raw.length];
		int count = raw.length /8;

		for (int i=0; i<count;i++)
		{
			_decrypt.processBlock(raw,i*8,result,i*8);
		}

		return result;
	}

	public final void decrypt(byte[] raw, final int offset, final int size) throws IOException
	{
		byte[] result = new byte[size];
		int count = size /8;

		for (int i=0; i<count;i++)
		{
			_decrypt.processBlock(raw,offset + i*8,result,i*8);
		}
		
		System.arraycopy(result, 0, raw, offset, size);
	}

	public final byte[] crypt(byte[] raw) throws IOException
	{
		int count = raw.length /8;
		byte[] result = new byte[raw.length];

		for (int i=0; i<count;i++)
		{
			_crypt.processBlock(raw,i*8,result,i*8);
		}

		return result;
	}

	public final void crypt(byte[] raw, final int offset, final int size) throws IOException
	{
		int count = size/8;
		byte[] result = new byte[size];

		for (int i=0; i<count;i++)
		{
			_crypt.processBlock(raw,offset + i*8,result,i*8);
		}
		
		System.arraycopy(result, 0, raw, offset, size);
	}
}
