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

#include "BlockQueue.h"
#include <thread>
#include <libdevcore/Log.h>
#include <libethcore/EthashAux.h>
#include <libethcore/Exceptions.h>
#include <libethcore/BlockInfo.h>
#include "BlockChain.h"
using namespace std;
using namespace dev;
using namespace dev::eth;

#ifdef _WIN32
const char* BlockQueueChannel::name() { return EthOrange "[]>"; }
#else
const char* BlockQueueChannel::name() { return EthOrange "▣┅▶"; }
#endif


BlockQueue::BlockQueue()
{
	// Allow some room for other activity
	unsigned verifierThreads = std::max(thread::hardware_concurrency(), 3U) - 2U;
	for (unsigned i = 0; i < verifierThreads; ++i)
		m_verifiers.emplace_back([=](){
			setThreadName("verifier" + toString(i));
			this->verifierBody();
		});
}

BlockQueue::~BlockQueue()
{
	m_deleting = true;
	m_moreToVerify.notify_all();
	for (auto& i: m_verifiers)
		i.join();
}

void BlockQueue::verifierBody()
{
	while (!m_deleting)
	{
		std::pair<h256, bytes> work;

		{
			unique_lock<Mutex> l(m_verification);
			m_moreToVerify.wait(l, [&](){ return !m_unverified.empty() || m_deleting; });
			if (m_deleting)
				return;
			swap(work, m_unverified.front());
			m_unverified.pop_front();
			BlockInfo bi;
			bi.mixHash = work.first;
			m_verifying.push_back(make_pair(bi, bytes()));
		}

		std::pair<BlockInfo, bytes> res;
		swap(work.second, res.second);
		try {
			try {
				res.first.populate(res.second, CheckEverything, work.first);
				res.first.verifyInternals(&res.second);
			}
			catch (InvalidNonce&)
			{
				badBlock(res.second, "Invalid block nonce");
				cwarn << "  Nonce:" << res.first.nonce.hex();
				cwarn << "  PoWHash:" << res.first.headerHash(WithoutNonce).hex();
				cwarn << "  SeedHash:" << res.first.seedHash().hex();
				cwarn << "  Target:" << res.first.boundary().hex();
				cwarn << "  MixHash:" << res.first.mixHash.hex();
				Ethash::Result er = EthashAux::eval(res.first.seedHash(), res.first.headerHash(WithoutNonce), res.first.nonce);
				cwarn << "  Ethash v:" << er.value.hex();
				cwarn << "  Ethash mH:" << er.mixHash.hex();
				throw;
			}
			catch (Exception& _e)
			{
				badBlock(res.second, _e.what());
				throw;
			}

			RLP r(&res.second);
			for (auto const& uncle: r[2])
			{
				try
				{
					BlockInfo().populateFromHeader(RLP(uncle.data()), CheckEverything);
				}
				catch (InvalidNonce&)
				{
					badBlockHeader(uncle.data(), "Invalid uncle nonce");
					BlockInfo bi = BlockInfo::fromHeader(uncle.data(), CheckNothing);
					cwarn << "  Nonce:" << bi.nonce.hex();
					cwarn << "  PoWHash:" << bi.headerHash(WithoutNonce).hex();
					cwarn << "  SeedHash:" << bi.seedHash().hex();
					cwarn << "  Target:" << bi.boundary().hex();
					cwarn << "  MixHash:" << bi.mixHash.hex();
					Ethash::Result er = EthashAux::eval(bi.seedHash(), bi.headerHash(WithoutNonce), bi.nonce);
					cwarn << "  Ethash v:" << er.value.hex();
					cwarn << "  Ethash mH:" << er.mixHash.hex();
					throw;
				}
				catch (Exception& _e)
				{
					badBlockHeader(uncle.data(), _e.what());
					throw;
				}
			}
		}
		catch (...)
		{
			// bad block.
			{
				// has to be this order as that's how invariants() assumes.
				WriteGuard l2(m_lock);
				unique_lock<Mutex> l(m_verification);
				m_readySet.erase(work.first);
				m_knownBad.insert(work.first);
			}

			unique_lock<Mutex> l(m_verification);
			for (auto it = m_verifying.begin(); it != m_verifying.end(); ++it)
				if (it->first.mixHash == work.first)
				{
					m_verifying.erase(it);
					goto OK1;
				}
			cwarn << "GAA BlockQueue corrupt: job cancelled but cannot be found in m_verifying queue.";
			OK1:;
			continue;
		}

		bool ready = false;
		{
			unique_lock<Mutex> l(m_verification);
			if (m_verifying.front().first.mixHash == work.first)
			{
				// we're next!
				m_verifying.pop_front();
				m_verified.push_back(move(res));
				while (m_verifying.size() && !m_verifying.front().second.empty())
				{
					m_verified.push_back(move(m_verifying.front()));
					m_verifying.pop_front();
				}
				ready = true;
			}
			else
			{
				for (auto& i: m_verifying)
					if (i.first.mixHash == work.first)
					{
						i = move(res);
						goto OK;
					}
				cwarn << "GAA BlockQueue corrupt: job finished but cannot be found in m_verifying queue.";
				OK:;
			}
		}
		if (ready)
			m_onReady();
	}
}

ImportResult BlockQueue::import(bytesConstRef _block, BlockChain const& _bc, bool _isOurs)
{
	// Check if we already know this block.
	h256 h = BlockInfo::headerHash(_block);

	cblockq << "Queuing block" << h << "for import...";

	UpgradableGuard l(m_lock);

	if (m_readySet.count(h) || m_drainingSet.count(h) || m_unknownSet.count(h) || m_knownBad.count(h))
	{
		// Already know about this one.
		cblockq << "Already known.";
		return ImportResult::AlreadyKnown;
	}

	// VERIFY: populates from the block and checks the block is internally coherent.
	BlockInfo bi;

	try
	{
		// TODO: quick verify
		bi.populate(_block);
		bi.verifyInternals(_block);
	}
	catch (Exception const& _e)
	{
		cwarn << "Ignoring malformed block: " << diagnostic_information(_e);
		return ImportResult::Malformed;
	}

	// Check block doesn't already exist first!
	if (_bc.details(h))
	{
		cblockq << "Already known in chain.";
		return ImportResult::AlreadyInChain;
	}

	UpgradeGuard ul(l);
	DEV_INVARIANT_CHECK;

	// Check it's not in the future
	(void)_isOurs;
	if (bi.timestamp > (u256)time(0)/* && !_isOurs*/)
	{
		m_future.insert(make_pair((unsigned)bi.timestamp, make_pair(h, _block.toBytes())));
		char buf[24];
		time_t bit = (unsigned)bi.timestamp;
		if (strftime(buf, 24, "%X", localtime(&bit)) == 0)
			buf[0] = '\0'; // empty if case strftime fails
		cblockq << "OK - queued for future [" << bi.timestamp << "vs" << time(0) << "] - will wait until" << buf;
		return ImportResult::FutureTime;
	}
	else
	{
		// We now know it.
		if (m_knownBad.count(bi.parentHash))
		{
			m_knownBad.insert(bi.hash());
			// bad parent; this is bad too, note it as such
			return ImportResult::BadChain;
		}
		else if (!m_readySet.count(bi.parentHash) && !m_drainingSet.count(bi.parentHash) && !_bc.isKnown(bi.parentHash))
		{
			// We don't know the parent (yet) - queue it up for later. It'll get resent to us if we find out about its ancestry later on.
			cblockq << "OK - queued as unknown parent:" << bi.parentHash;
			m_unknown.insert(make_pair(bi.parentHash, make_pair(h, _block.toBytes())));
			m_unknownSet.insert(h);

			return ImportResult::UnknownParent;
		}
		else
		{
			// If valid, append to blocks.
			cblockq << "OK - ready for chain insertion.";
			DEV_GUARDED(m_verification)
				m_unverified.push_back(make_pair(h, _block.toBytes()));
			m_moreToVerify.notify_one();
			m_readySet.insert(h);

			noteReady_WITH_LOCK(h);

			return ImportResult::Success;
		}
	}
}

bool BlockQueue::doneDrain(h256s const& _bad)
{
	WriteGuard l(m_lock);
	DEV_INVARIANT_CHECK;
	m_drainingSet.clear();
	if (_bad.size())
	{
		vector<pair<BlockInfo, bytes>> old;
		DEV_GUARDED(m_verification)
			swap(m_verified, old);
		for (auto& b: old)
		{
			if (m_knownBad.count(b.first.parentHash))
			{
				m_knownBad.insert(b.first.hash());
				m_readySet.erase(b.first.hash());
			}
			else
				DEV_GUARDED(m_verification)
					m_verified.push_back(std::move(b));
		}
	}
	m_knownBad += _bad;
	return !m_readySet.empty();
}

void BlockQueue::tick(BlockChain const& _bc)
{
	vector<pair<h256, bytes>> todo;
	{
		UpgradableGuard l(m_lock);
		if (m_future.empty())
			return;

		cblockq << "Checking past-future blocks...";

		unsigned t = time(0);
		if (t <= m_future.begin()->first)
			return;

		cblockq << "Past-future blocks ready.";

		{
			UpgradeGuard l2(l);
			DEV_INVARIANT_CHECK;
			auto end = m_future.lower_bound(t);
			for (auto i = m_future.begin(); i != end; ++i)
				todo.push_back(move(i->second));
			m_future.erase(m_future.begin(), end);
		}
	}
	cblockq << "Importing" << todo.size() << "past-future blocks.";

	for (auto const& b: todo)
		import(&b.second, _bc);
}

template <class T> T advanced(T _t, unsigned _n)
{
	std::advance(_t, _n);
	return _t;
}

QueueStatus BlockQueue::blockStatus(h256 const& _h) const
{
	ReadGuard l(m_lock);
	return
		m_readySet.count(_h) ?
			QueueStatus::Ready :
		m_drainingSet.count(_h) ?
			QueueStatus::Importing :
		m_unknownSet.count(_h) ?
			QueueStatus::UnknownParent :
		m_knownBad.count(_h) ?
			QueueStatus::Bad :
			QueueStatus::Unknown;
}

void BlockQueue::drain(std::vector<std::pair<BlockInfo, bytes>>& o_out, unsigned _max)
{
	WriteGuard l(m_lock);
	DEV_INVARIANT_CHECK;
	if (m_drainingSet.empty())
	{
		DEV_GUARDED(m_verification)
		{
			o_out.resize(min<unsigned>(_max, m_verified.size()));
			for (unsigned i = 0; i < o_out.size(); ++i)
				swap(o_out[i], m_verified[i]);
			m_verified.erase(m_verified.begin(), advanced(m_verified.begin(), o_out.size()));
		}
		for (auto const& bs: o_out)
		{
			// TODO: @optimise use map<h256, bytes> rather than vector<bytes> & set<h256>.
			auto h = bs.first.hash();
			m_drainingSet.insert(h);
			m_readySet.erase(h);
		}
	}
}

bool BlockQueue::invariants() const
{
	Guard l(m_verification);
	return m_readySet.size() == m_verified.size() + m_unverified.size() + m_verifying.size();
}

void BlockQueue::noteReady_WITH_LOCK(h256 const& _good)
{
	DEV_INVARIANT_CHECK;
	list<h256> goodQueue(1, _good);
	bool notify = false;
	while (!goodQueue.empty())
	{
		auto r = m_unknown.equal_range(goodQueue.front());
		goodQueue.pop_front();
		for (auto it = r.first; it != r.second; ++it)
		{
			DEV_GUARDED(m_verification)
				m_unverified.push_back(it->second);
			auto newReady = it->second.first;
			m_unknownSet.erase(newReady);
			m_readySet.insert(newReady);
			goodQueue.push_back(newReady);
			notify = true;
		}
		m_unknown.erase(r.first, r.second);
	}
	if (notify)
		m_moreToVerify.notify_all();
}

void BlockQueue::retryAllUnknown()
{
	WriteGuard l(m_lock);
	DEV_INVARIANT_CHECK;
	for (auto it = m_unknown.begin(); it != m_unknown.end(); ++it)
	{
		DEV_GUARDED(m_verification)
			m_unverified.push_back(it->second);
		auto newReady = it->second.first;
		m_unknownSet.erase(newReady);
		m_readySet.insert(newReady);
		m_moreToVerify.notify_one();
	}
	m_unknown.clear();
	m_moreToVerify.notify_all();
}