/*
	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 Session.h
 * @author Gav Wood <i@gavwood.com>
 * @author Alex Leverington <nessence@gmail.com>
 * @date 2014
 */

#pragma once

#include <mutex>
#include <array>
#include <deque>
#include <set>
#include <memory>
#include <utility>

#include <libdevcore/Common.h>
#include <libdevcore/RLP.h>
#include <libdevcore/Guards.h>
#include "RLPXFrameCoder.h"
#include "RLPXSocket.h"
#include "Common.h"

namespace dev
{

namespace p2p
{

class Peer;
class ReputationManager;

/**
 * @brief The Session class
 * @todo Document fully.
 */
class Session: public std::enable_shared_from_this<Session>
{
	friend class Host;
	friend class HostCapabilityFace;

public:
	Session(Host* _server, RLPXFrameCoder* _io, std::shared_ptr<RLPXSocket> const& _s, std::shared_ptr<Peer> const& _n, PeerSessionInfo _info);
	virtual ~Session();

	void start();
	void disconnect(DisconnectReason _reason);

	void ping();

	bool isConnected() const { return m_socket->ref().is_open(); }

	NodeId id() const;
	unsigned socketId() const { Guard l(x_info); return m_info.socketId; }

	template <class PeerCap>
	std::shared_ptr<PeerCap> cap() const { try { return std::static_pointer_cast<PeerCap>(m_capabilities.at(std::make_pair(PeerCap::name(), PeerCap::version()))); } catch (...) { return nullptr; } }
	template <class PeerCap>
	std::shared_ptr<PeerCap> cap(u256 const& _version) const { try { return std::static_pointer_cast<PeerCap>(m_capabilities.at(std::make_pair(PeerCap::name(), _version))); } catch (...) { return nullptr; } }

	static RLPStream& prep(RLPStream& _s, PacketType _t, unsigned _args = 0);
	void sealAndSend(RLPStream& _s);

	ReputationManager& repMan() const;
	int rating() const;
	void addRating(int _r);

	void addNote(std::string const& _k, std::string const& _v) { Guard l(x_info); m_info.notes[_k] = _v; }

	PeerSessionInfo info() const { Guard l(x_info); return m_info; }

	void ensureNodesRequested();
	void serviceNodesRequest();

private:
	void send(bytes&& _msg);

	/// Drop the connection for the reason @a _r.
	void drop(DisconnectReason _r);

	/// Perform a read on the socket.
	void doRead();
	
	/// Check error code after reading and drop peer if error code.
	bool checkRead(std::size_t _expected, boost::system::error_code _ec, std::size_t _length);

	/// Perform a single round of the write operation. This could end up calling itself asynchronously.
	void write();

	/// Deliver RLPX packet to Session or Capability for interpretation.
	bool readPacket(uint16_t _capId, PacketType _t, RLP const& _r);

	/// Interpret an incoming Session packet.
	bool interpret(PacketType _t, RLP const& _r);
	
	/// @returns true iff the _msg forms a valid message for sending or receiving on the network.
	static bool checkPacket(bytesConstRef _msg);

	Host* m_server;							///< The host that owns us. Never null.

	RLPXFrameCoder* m_io;						///< Transport over which packets are sent.
	std::shared_ptr<RLPXSocket> m_socket;		///< Socket of peer's connection.
	Mutex x_writeQueue;						///< Mutex for the write queue.
	std::deque<bytes> m_writeQueue;			///< The write queue.
	std::array<byte, 16777216> m_data;			///< Buffer for ingress packet data.
	bytes m_incoming;						///< Read buffer for ingress bytes.

	unsigned m_protocolVersion = 0;			///< The protocol version of the peer.
	std::shared_ptr<Peer> m_peer;			///< The Peer object.
	bool m_dropped = false;					///< If true, we've already divested ourselves of this peer. We're just waiting for the reads & writes to fail before the shared_ptr goes OOS and the destructor kicks in.

	mutable Mutex x_info;
	PeerSessionInfo m_info;						///< Dynamic information about this peer.

	bool m_theyRequestedNodes = false;		///< Has the peer requested nodes from us without receiveing an answer from us?
	bool m_weRequestedNodes = false;		///< Have we requested nodes from the peer and not received an answer yet?

	std::chrono::steady_clock::time_point m_connect;		///< Time point of connection.
	std::chrono::steady_clock::time_point m_ping;			///< Time point of last ping.
	std::chrono::steady_clock::time_point m_lastReceived;	///< Time point of last message.

	std::map<CapDesc, std::shared_ptr<Capability>> m_capabilities;	///< The peer's capability set.
};

}
}