/*
 * Created on 29-Apr-2005
 * Created by Paul Gardner
 * Copyright (C) 2005, 2006 Aelitis, All Rights Reserved.
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 * AELITIS, SAS au capital de 46,603.30 euros
 * 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
 *
 */

package com.aelitis.azureus.core.util.bloom.impl;

import java.math.BigInteger;
import java.util.Random;

import com.aelitis.azureus.core.util.bloom.BloomFilter;

public abstract class 
BloomFilterImpl
	implements BloomFilter
{
	/*
	private static final boolean	USE_BIG_INTS	= false;
	private static final char[]	HEX_CHARS = "0123456789ABCDEF".toCharArray();
	private static final BigInteger	bi_zero		= new BigInteger("0");
	private static final BigInteger	bi_a2		= new BigInteger(""+a2);
	private static final BigInteger	bi_a3		= new BigInteger(""+a3);
	private static final BigInteger	bi_a4		= new BigInteger(""+a4);
	
	private static final BigInteger	bi_b2		= new BigInteger(""+b2);
	private static final BigInteger	bi_b3		= new BigInteger(""+b3);
	private static final BigInteger	bi_b4		= new BigInteger(""+b4);
	*/
	
		// change the hash num and you gotta change the hash function below!!!!
	
	private static final int	HASH_NUM	= 5;
	
	private static final int	a2		= 2;
	private static final int	a3		= 3;
	private static final int	a4		= 5;
	
	private static final int	b2		= 51;
	private static final int	b3		= 145;
	private static final int	b4		= 216;
	

	

	private int			max_entries;
	private BigInteger	bi_max_entries;
	
	private int			entry_count;
	
	public 
	BloomFilterImpl(
		int		_max_entries )
	{
		bi_max_entries	= new BigInteger( ""+(((_max_entries/2)*2)+1));
				
		max_entries	= bi_max_entries.intValue();
	}
	
	protected int
	getMaxEntries()
	{
		return( max_entries );
	}
	
	public int
	add(
		byte[]		value )
	{
		return( add( bytesToInteger( value )));
	}
	
	public int
	remove(
		byte[]		value )
	{
		return( remove( bytesToInteger( value )));
	}
	
	public int
	count(
		byte[]		value )
	{
		return( count( bytesToInteger( value )));
	}
	
	public boolean
	contains(
		byte[]		value )
	{
		return( contains( bytesToInteger( value )));
	}


	
	protected int
	add(
		int		value )
	{
		int	count = 0xffff;

		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
					
				// v = value BEFORE inc
			
			int	v = incValue( index );
			
			if ( v < count ){
				
				count = v;
			}
		}
		
		if ( count == 0 ){
			
			entry_count++;
		}
		
			// count is the smallest val found *before* incrementing
				
		return( trimValue( count + 1 ));
	}
	
	protected int
	remove(
		int		value )
	{
		int	count = 0xffff;
		
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
				
				// v = value BEFORE dec
			
			int	v = decValue( index );
			
			if ( v < count ){
				
				count = v;
			}
		}		
		
		if ( count == 1 && entry_count > 0 ){
			
			entry_count--;
		}
		
			// count is the value BEFORE dec, decrease one further
		
		return( trimValue( count - 1 ));
	}
	
	protected int
	count(
		int		value )
	{
		int	count = 0xffff;
		
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
			
			int	v = getValue( index );
				
			if ( v < count ){
				
				count	= v;
			}
		}
		
		return( count );	
	}
	
	protected boolean
	contains(
		int		value )
	{
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
			
			int	v = getValue( index );
				
			if ( v == 0 ){
				
				return( false );
			}
		}
		
		return( true );		
	}
	
	
	protected abstract int
	getValue(
		int		index );

	
	protected abstract int
	incValue(
		int		index );
	
	protected abstract int
	decValue(
		int		index );
	
	protected abstract int
	trimValue(
		int		value );

	protected int
	getHash(
		int			function,
		int			value )
	{
		long	res;
		
		switch( function ){
			case 0:
			{
					// x mod p
				
				res = value;
				
				break;
			}
			case 1:
			{
				 	// x^2 mod p
				
				res	= value * value;
				
				break;
			}
			case 2:
			{
					// bx + a mod p
				
				res = value *  a2 + b2;
				
				break;
			}
			case 3:
			{
					// cx + d mod p
				
				res = value * a3 + b3;
				
				break;

			}
			case 4:
			{
					// ex + f mod p
				
				res = value * a4 + b4;
				
				break;
			}
			default:
			{
				System.out.println( "**** BloomFilter hash function doesn't exist ****" );
				
				res = 0;
			}
		}
		
		// System.out.println( "hash[" + function + "] " + value + "->" + r );
		
		return( Math.abs( (int)res % max_entries ));
	}
	
	protected int
	bytesToInteger(
		byte[]		data )
	{
		int	res = 0x51f7ac81;
		
		for (int i=0;i<data.length;i++){
			
			//res ^= (data[i]&0xff)<<((i%4)*8);
			
			res = res * 191 + (data[i]&0xff);
		}
		
		return( res );
	}
	
	
	/*
	protected int
	add(
		BigInteger		value )
	{
		entry_count++;
		
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
			
			byte	v = getValue( index );
			
			if ( v < 15 ){
				
				setValue( index, (byte)(v+1));
			}
		}
	}
	
	public void
	remove(
		BigInteger		value )
	{
		entry_count--;
		
		if ( entry_count < 0 ){
			
			entry_count	= 0;
		}
		
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
			
			byte	v = getValue( index );
			
			if ( v > 0 ){
				
				setValue( index, (byte)(v-1));
			}
		}		
	}
	
	public boolean
	contains(
		BigInteger		value )
	{
		for (int i=0;i<HASH_NUM;i++){
			
			int	index = getHash( i, value );
			
			int	v = getValue( index );
				
			if ( v == 0 ){
				
				return( false );
			}
		}
		
		return( true );		
	}
	
		protected int
	getHash(
		int			function,
		BigInteger	value )
	{
		BigInteger	res;
		
		switch( function ){
			case 0:
			{
					// x mod p
				
				res = value;
				
				break;
			}
			case 1:
			{
				 	// x^2 mod p
				
				res	= value.pow(2);
				
				break;
			}
			case 2:
			{
					// bx + a mod p
				
				res = value.multiply( bi_a2 ).add( bi_b2 );
				
				break;
			}
			case 3:
			{
					// cx + d mod p
				
				res = value.multiply( bi_a3 ).add( bi_b3 );
				
				break;

			}
			case 4:
			{
					// ex + f mod p
				
				res = value.multiply( bi_a4 ).add( bi_b4 );
				
				break;
			}
			default:
			{
				System.out.println( "**** BloomFilter hash function doesn't exist ****" );
				
				res = new BigInteger("0");
			}
		}
		
		int	r = 0;
		
		while(true){
			
			BigInteger	x = res.divide( bi_max_entries );
			
			if ( x.compareTo( bi_zero) == 0 ){
				
				r += res.mod( bi_max_entries ).intValue();
				
				break;
			}
			
			r += x.mod( bi_max_entries ).intValue();

			res = x;
		}
		
		
		// System.out.println( "hash[" + function + "] " + value + "->" + r );
		
		return( r % max_entries );
	}
	
	protected BigInteger
	bytesToBigInteger(
		byte[]		data )
	{
		StringBuffer	buffer = new StringBuffer(data.length*2);
		
		for (int i=0;i<data.length;i++){
			
			buffer.append( HEX_CHARS[(data[i]>>4)&0x0f] );
			
			buffer.append( HEX_CHARS[data[i]&0x0f] );
		}
				
		BigInteger	res		= new BigInteger( new String(buffer), 16 );	
		
		return( res );
	}
	*/
	
	
	public int
	getEntryCount()
	{
		return( entry_count );
	}
	
	public int
	getSize()
	{
		return( max_entries );
	}
	
	 protected static byte[] 
	 getSerialization(
	 	byte[]	address,
	 	int		port )
	 {
		    //combine address and port bytes into one
		    byte[] full_address = new byte[ address.length +2 ];
		    System.arraycopy( address, 0, full_address, 0, address.length );
		    full_address[ address.length ] = (byte)(port >> 8);
		    full_address[ address.length +1 ] = (byte)(port & 0xff);
		    return full_address;
	}
	 
	public static void
	main(
		String[]	args )
	{
		Random	rand = new Random();

		/*
		BloomFilter b1 = new BloomFilterAddRemove8Bit(10000);

		for (int i=0;i<260;i++){
			
			System.out.println( b1.add( "parp".getBytes()) + ", count = " + b1.count( "parp".getBytes()) + ", ent = " + b1.getEntryCount());
			
		}
		
		for (int i=0;i<260;i++){
			
			System.out.println( b1.remove( "parp".getBytes())+ ", count = " + b1.count( "parp".getBytes()) + ", ent = " + b1.getEntryCount());
		}
		*/
		
		/*

		BloomFilter b1 = new BloomFilterAddOnly(90*10/3);

		byte[]	key1 = new byte[4];

		for (int i=0;i<200;i++){
			
			
			if ( i%2==0){
				rand.nextBytes( key1 );
			}
			
			b1.add( key1 );
			
			System.out.println( "entries = " + b1.getEntryCount() + ", act = " + i );
		}
		
		System.exit(0);
		*/
		
		
		int	fp_count = 0;
		
		for (int j=0;j<1000;j++){
			
			long	start = System.currentTimeMillis();
			
			BloomFilter b = new BloomFilterAddRemove8Bit(10000);
			//BloomFilter b = new BloomFilterAddOnly(10000);
			
			int	fp = 0;
			
			for (int i=0;i<1000;i++){
				
				//String	key = "" + rand.nextInt();
				
				byte[]	key = new byte[6];
				
				rand.nextBytes( key );
				
				//key  = getSerialization( key, 6881 );
				
				if ( i%2 == 0 ){
					
					b.add( key  );
				
					if ( !b.contains( key )){
						
						System.out.println( "false negative on add!!!!" );
					}
				}else{
					
					if ( b.contains( key )){
						
						fp++;
					}
				}
				
				/*
				if ( i%2 == 0 ){
					
					b.remove( key  );
				
					if ( b.contains( key )){
					
						System.out.println( "false positive" );
					}
				}
				*/
			}	
			
			System.out.println( "" + (System.currentTimeMillis() - start + ", fp = " + fp ));
			
			if ( fp > 0 ){
				
				fp_count++;
			}
		}
		
		System.out.println( fp_count );
	}
}
