/*
	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 EthereumHost.h
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#pragma once

#include <mutex>
#include <unordered_map>
#include <vector>
#include <unordered_set>
#include <memory>
#include <utility>
#include <thread>

#include <libdevcore/Guards.h>
#include <libdevcore/Worker.h>
#include <libethcore/Common.h>
#include <libp2p/Common.h>
#include "CommonNet.h"
#include "EthereumPeer.h"
#include "DownloadMan.h"

namespace dev
{

class RLPStream;

namespace eth
{

class TransactionQueue;
class BlockQueue;
class BlockChainSync;

struct EthereumHostTrace: public LogChannel { static const char* name(); static const int verbosity = 6; };

/**
 * @brief The EthereumHost class
 * @warning None of this is thread-safe. You have been warned.
 * @doWork Syncs to peers and sends new blocks and transactions.
 */
class EthereumHost: public p2p::HostCapability<EthereumPeer>, Worker
{
public:
	/// Start server, but don't listen.
	EthereumHost(BlockChain const& _ch, TransactionQueue& _tq, BlockQueue& _bq, u256 _networkId);

	/// Will block on network process events.
	virtual ~EthereumHost();

	unsigned protocolVersion() const { return c_protocolVersion; }
	u256 networkId() const { return m_networkId; }
	void setNetworkId(u256 _n) { m_networkId = _n; }

	void reset();

	DownloadMan const& downloadMan() const { return m_man; }
	DownloadMan& downloadMan() { return m_man; }
	bool isSyncing() const;
	bool isBanned(p2p::NodeId const& _id) const { return !!m_banned.count(_id); }

	void noteNewTransactions() { m_newTransactions = true; }
	void noteNewBlocks() { m_newBlocks = true; }

	BlockChain const& chain() const { return m_chain; }
	BlockQueue& bq() { return m_bq; }
	BlockQueue const& bq() const { return m_bq; }
	SyncStatus status() const;
	h256 latestBlockSent() { return m_latestBlockSent; }
	static char const* stateName(SyncState _s) { return s_stateNames[static_cast<int>(_s)]; }

	static unsigned const c_oldProtocolVersion;
	void foreachPeer(std::function<bool(std::shared_ptr<EthereumPeer>)> const& _f) const;

	void onPeerStatus(std::shared_ptr<EthereumPeer> _peer);
	void onPeerHashes(std::shared_ptr<EthereumPeer> _peer, h256s const& _hashes);
	void onPeerBlocks(std::shared_ptr<EthereumPeer> _peer, RLP const& _r);
	void onPeerNewHashes(std::shared_ptr<EthereumPeer> _peer, h256s const& _hashes);
	void onPeerNewBlock(std::shared_ptr<EthereumPeer> _peer, RLP const& _r);
	void onPeerTransactions(std::shared_ptr<EthereumPeer> _peer, RLP const& _r);
	void onPeerAborting();

private:
	static char const* const s_stateNames[static_cast<int>(SyncState::Size)];

	std::tuple<std::vector<std::shared_ptr<EthereumPeer>>, std::vector<std::shared_ptr<EthereumPeer>>, std::vector<std::shared_ptr<p2p::Session>>> randomSelection(unsigned _percent = 25, std::function<bool(EthereumPeer*)> const& _allow = [](EthereumPeer const*){ return true; });

	/// Sync with the BlockChain. It might contain one of our mined blocks, we might have new candidates from the network.
	virtual void doWork() override;

	void maintainTransactions();
	void maintainBlocks(h256 const& _currentBlock);
	void onTransactionImported(ImportResult _ir, h256 const& _h, h512 const& _nodeId);

	///	Check to see if the network peer-state initialisation has happened.
	bool isInitialised() const { return (bool)m_latestBlockSent; }

	/// Initialises the network peer-state, doing the stuff that needs to be once-only. @returns true if it really was first.
	bool ensureInitialised();

	virtual void onStarting() override { startWorking(); }
	virtual void onStopping() override { stopWorking(); }

	BlockChainSync* sync();

	BlockChain const& m_chain;
	TransactionQueue& m_tq;					///< Maintains a list of incoming transactions not yet in a block on the blockchain.
	BlockQueue& m_bq;						///< Maintains a list of incoming blocks not yet on the blockchain (to be imported).

	u256 m_networkId;

	h256 m_latestBlockSent;
	h256Hash m_transactionsSent;

	std::unordered_set<p2p::NodeId> m_banned;

	bool m_newTransactions = false;
	bool m_newBlocks = false;

	mutable Mutex x_sync;
	mutable Mutex x_transactions;
	DownloadMan m_man;
	std::unique_ptr<BlockChainSync> m_sync;
	std::atomic<time_t> m_syncStart = { 0 };
};

}
}