/*
This file is part of cpp-ethereum.

cpp-ethereum 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.

cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file BloomFilter.cpp
* @author Vladislav Gluhovsky <vlad@ethdev.com>
* @date June 2015
*/

#include "BloomFilter.h"

using namespace std;
using namespace dev;
using namespace dev::shh;

bool BloomFilter::matches(AbridgedTopic const& _t) const
{
	static unsigned const c_match = ~unsigned(0);
	unsigned topic = AbridgedTopic::Arith(_t).convert_to<unsigned>();
	unsigned matchingBits = m_filter & topic;
	matchingBits |= ~topic;
	return (c_match == matchingBits);
}

void SharedBloomFilter::add(AbridgedTopic const& _t)
{
	unsigned const topic = AbridgedTopic::Arith(_t).convert_to<unsigned>();
	m_filter |= topic;

	unsigned nextBit = 1;
	for (unsigned i = 0; i < ArrSize; ++i, nextBit <<= 1)
		if (topic & nextBit)
			if (m_refCounter[i] != numeric_limits<unsigned short>::max())
				m_refCounter[i]++;
			//else: overflow

	// in order to encounter overflow, you have to set at least 65536 filters simultaneously.
	// even then, the problem will only arise after at least 65536 filters will be be removed.
	// we assume, it will never happen.
}

void SharedBloomFilter::remove(AbridgedTopic const& _t)
{
	unsigned const topic = AbridgedTopic::Arith(_t).convert_to<unsigned>();

	unsigned nextBit = 1;
	for (unsigned i = 0; i < ArrSize; ++i, nextBit <<= 1)
		if (topic & nextBit)
		{
			if (m_refCounter[i])
				m_refCounter[i]--;

			if (!m_refCounter[i])
				m_filter &= ~nextBit;
		}
}