/*
 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 Miner.h
 * @author Gav Wood <i@gavwood.com>
 * @date 2015
 */

#pragma once

#include <thread>
#include <list>
#include <atomic>
#include <libdevcore/Common.h>
#include <libdevcore/Worker.h>
#include <libethcore/Common.h>

namespace dev
{

namespace eth
{

/**
 * @brief Describes the progress of a mining operation.
 */
struct MiningProgress
{
//	MiningProgress& operator+=(MiningProgress const& _mp) { hashes += _mp.hashes; ms = std::max(ms, _mp.ms); return *this; }
	uint64_t hashes = 0;		///< Total number of hashes computed.
	uint64_t ms = 0;			///< Total number of milliseconds of mining thus far.
	uint64_t rate() const { return hashes * 1000 / ms; }
};

struct MineInfo: public MiningProgress {};

inline std::ostream& operator<<(std::ostream& _out, MiningProgress _p)
{
	_out << _p.rate() << " H/s = " <<  _p.hashes << " hashes / " << (double(_p.ms) / 1000) << " s";
	return _out;
}

template <class PoW> class GenericMiner;

/**
 * @brief Class for hosting one or more Miners.
 * @warning Must be implemented in a threadsafe manner since it will be called from multiple
 * miner threads.
 */
template <class PoW> class GenericFarmFace
{
public:
	using WorkPackage = typename PoW::WorkPackage;
	using Solution = typename PoW::Solution;
	using Miner = GenericMiner<PoW>;

	/**
	 * @brief Called from a Miner to note a WorkPackage has a solution.
	 * @param _p The solution.
	 * @param _wp The WorkPackage that the Solution is for; this will be reset if the work is accepted.
	 * @param _finder The miner that found it.
	 * @return true iff the solution was good (implying that mining should be .
	 */
	virtual bool submitProof(Solution const& _p, Miner* _finder) = 0;
};

/**
 * @brief A miner - a member and adoptee of the Farm.
 * @warning Not threadsafe. It is assumed Farm will synchronise calls to/from this class.
 */
template <class PoW> class GenericMiner
{
public:
	using WorkPackage = typename PoW::WorkPackage;
	using Solution = typename PoW::Solution;
	using FarmFace = GenericFarmFace<PoW>;
	using ConstructionInfo = std::pair<FarmFace*, unsigned>;

	GenericMiner(ConstructionInfo const& _ci):
		m_farm(_ci.first),
		m_index(_ci.second)
	{}

	// API FOR THE FARM TO CALL IN WITH

	void setWork(WorkPackage const& _work = WorkPackage())
	{
		auto old = m_work;
		{
			Guard l(x_work);
			m_work = _work;
		}
		if (!!_work)
		{
			pause();
			kickOff();
		}
		else if (!_work && !!old)
			pause();
		m_hashCount = 0;
	}

	uint64_t hashCount() const { return m_hashCount; }

	void resetHashCount() { m_hashCount = 0; }

	unsigned index() const { return m_index; }

protected:

	// REQUIRED TO BE REIMPLEMENTED BY A SUBCLASS:

	/**
	 * @brief Begin working on a given work package, discarding any previous work.
	 * @param _work The package for which to find a solution.
	 */
	virtual void kickOff() = 0;

	/**
	 * @brief No work left to be done. Pause until told to kickOff().
	 */
	virtual void pause() = 0;

	// AVAILABLE FOR A SUBCLASS TO CALL:

	/**
	 * @brief Notes that the Miner found a solution.
	 * @param _s The solution.
	 * @return true if the solution was correct and that the miner should pause.
	 */
	bool submitProof(Solution const& _s)
	{
		if (!m_farm)
			return true;
		if (m_farm->submitProof(_s, this))
		{
			Guard l(x_work);
			m_work.reset();
			return true;
		}
		return false;
	}

	WorkPackage const& work() const { Guard l(x_work); return m_work; }

	void accumulateHashes(unsigned _n) { m_hashCount += _n; }

private:
	FarmFace* m_farm = nullptr;
	unsigned m_index;

	uint64_t m_hashCount = 0;

	WorkPackage m_work;
	mutable Mutex x_work;
};

}
}