/*
	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 EthashAux.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#pragma once

#include <condition_variable>
#include <libethash/ethash.h>
#include <libdevcore/Log.h>
#include <libdevcore/Worker.h>
#include "BlockInfo.h"

namespace dev
{
namespace eth
{

/// Proof of work definition for Ethash.
struct EthashProofOfWork
{
	struct Solution
	{
		Nonce nonce;
		h256 mixHash;
	};

	struct Result
	{
		h256 value;
		h256 mixHash;
	};

	struct WorkPackage
	{
		WorkPackage() = default;
		WorkPackage(BlockHeader const& _bh) :
			boundary(_bh.boundary()),
			headerHash(_bh.hashWithout()),
			seedHash(_bh.seedHash())
		{ }
		void reset() { headerHash = h256(); }
		operator bool() const { return headerHash != h256(); }

		h256 boundary;
		h256 headerHash;	///< When h256() means "pause until notified a new work package is available".
		h256 seedHash;

		uint64_t startNonce = 0;
		int exSizeBits = -1;
	};
};

class EthashAux
{
public:
	static EthashAux* get();

	struct LightAllocation
	{
		LightAllocation(h256 const& _seedHash);
		~LightAllocation();
		bytesConstRef data() const;
		EthashProofOfWork::Result compute(h256 const& _headerHash, Nonce const& _nonce) const;
		ethash_light_t light;
		uint64_t size;
	};

	using LightType = std::shared_ptr<LightAllocation>;

	static h256 seedHash(unsigned _number);
	static uint64_t number(h256 const& _seedHash);

	static LightType light(h256 const& _seedHash);

	static EthashProofOfWork::Result eval(h256 const& _seedHash, h256 const& _headerHash, Nonce const& _nonce) noexcept;

private:
	EthashAux() = default;

	Mutex x_lights;
	std::unordered_map<h256, LightType> m_lights;

	Mutex x_epochs;
	std::unordered_map<h256, unsigned> m_epochs;
	h256s m_seedHashes;
};

}
}