/*
	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 PeerNetwork.cpp
 * @authors:
 *   Gav Wood <i@gavwood.com>
 *   Eric Lombrozo <elombrozo@gmail.com>
 * @date 2014
 */

#include "PeerServer.h"

#include <sys/types.h>
#ifdef _WIN32
// winsock is already included
// #include <winsock.h>
#else
#include <ifaddrs.h>
#endif

#include <set>
#include <chrono>
#include <thread>
#include <libethsupport/Common.h>
#include <libethsupport/UPnP.h>
#include <libethcore/Exceptions.h>
#include "BlockChain.h"
#include "TransactionQueue.h"
#include "PeerSession.h"
using namespace std;
using namespace eth;

// Addresses we will skip during network interface discovery
// Use a vector as the list is small
// Why this and not names?
// Under MacOSX loopback (127.0.0.1) can be named lo0 and br0 are bridges (0.0.0.0)
static const set<bi::address> c_rejectAddresses = {
	{bi::address_v4::from_string("127.0.0.1")},
	{bi::address_v6::from_string("::1")},
	{bi::address_v4::from_string("0.0.0.0")},
	{bi::address_v6::from_string("::")}
};

PeerServer::PeerServer(std::string const& _clientVersion, BlockChain const& _ch, unsigned int _networkId, unsigned short _port, NodeMode _m, string const& _publicAddress, bool _upnp):
	m_clientVersion(_clientVersion),
	m_mode(_m),
	m_listenPort(_port),
	m_chain(&_ch),
	m_acceptor(m_ioService, bi::tcp::endpoint(bi::tcp::v4(), _port)),
	m_socket(m_ioService),
	m_key(KeyPair::create()),
	m_networkId(_networkId)
{
	populateAddresses();
	determinePublic(_publicAddress, _upnp);
	ensureAccepting();
	clog(NetNote) << "Id:" << toHex(m_key.address().ref().cropped(0, 4)) << "Mode: " << (_m == NodeMode::PeerServer ? "PeerServer" : "Full");
}

PeerServer::PeerServer(std::string const& _clientVersion, BlockChain const& _ch, unsigned int _networkId, NodeMode _m, string const& _publicAddress, bool _upnp):
	m_clientVersion(_clientVersion),
	m_mode(_m),
	m_listenPort(0),
	m_chain(&_ch),
	m_acceptor(m_ioService, bi::tcp::endpoint(bi::tcp::v4(), 0)),
	m_socket(m_ioService),
	m_key(KeyPair::create()),
	m_networkId(_networkId)
{
	m_listenPort = m_acceptor.local_endpoint().port();

	// populate addresses.
	populateAddresses();
	determinePublic(_publicAddress, _upnp);
	ensureAccepting();
	clog(NetNote) << "Id:" << toHex(m_key.address().ref().cropped(0, 4)) << "Mode: " << (m_mode == NodeMode::PeerServer ? "PeerServer" : "Full");
}

PeerServer::PeerServer(std::string const& _clientVersion, BlockChain const& _ch, unsigned int _networkId, NodeMode _m):
	m_clientVersion(_clientVersion),
	m_mode(_m),
	m_listenPort(0),
	m_chain(&_ch),
	m_acceptor(m_ioService, bi::tcp::endpoint(bi::tcp::v4(), 0)),
	m_socket(m_ioService),
	m_key(KeyPair::create()),
	m_networkId(_networkId)
{
	// populate addresses.
	populateAddresses();
	clog(NetNote) << "Id:" << toHex(m_key.address().ref().cropped(0, 4)) << "Mode: " << (m_mode == NodeMode::PeerServer ? "PeerServer" : "Full");
}

PeerServer::~PeerServer()
{
	for (auto const& i: m_peers)
		if (auto p = i.second.lock())
			p->disconnect(ClientQuit);
	delete m_upnp;
}

unsigned PeerServer::protocolVersion()
{
	return c_protocolVersion;
}

void PeerServer::determinePublic(string const& _publicAddress, bool _upnp)
{
	if (_upnp)
		try
		{
			m_upnp = new UPnP;
		}
		catch (NoUPnPDevice) {}	// let m_upnp continue as null - we handle it properly.

	bi::tcp::resolver r(m_ioService);
	if (m_upnp && m_upnp->isValid() && m_peerAddresses.size())
	{
		clog(NetNote) << "External addr: " << m_upnp->externalIP();
		int p = m_upnp->addRedirect(m_peerAddresses[0].to_string().c_str(), m_listenPort);
		if (p)
			clog(NetNote) << "Punched through NAT and mapped local port" << m_listenPort << "onto external port" << p << ".";
		else
		{
			// couldn't map
			clog(NetWarn) << "Couldn't punch through NAT (or no NAT in place). Assuming " << m_listenPort << " is local & external port.";
			p = m_listenPort;
		}

		auto eip = m_upnp->externalIP();
		if (eip == string("0.0.0.0") && _publicAddress.empty())
			m_public = bi::tcp::endpoint(bi::address(), (unsigned short)p);
		else
		{
			m_public = bi::tcp::endpoint(bi::address::from_string(_publicAddress.empty() ? eip : _publicAddress), (unsigned short)p);
			m_addresses.push_back(m_public.address().to_v4());
		}
	}
	else
	{
		// No UPnP - fallback on given public address or, if empty, the assumed peer address.
		m_public = bi::tcp::endpoint(_publicAddress.size() ? bi::address::from_string(_publicAddress)
									: m_peerAddresses.size() ? m_peerAddresses[0]
									: bi::address(), m_listenPort);
		m_addresses.push_back(m_public.address().to_v4());
	}
}

void PeerServer::populateAddresses()
{
#ifdef _WIN32
	WSAData wsaData;
	if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0)
		throw NoNetworking();

	char ac[80];
	if (gethostname(ac, sizeof(ac)) == SOCKET_ERROR)
	{
		clog(NetWarn) << "Error " << WSAGetLastError() << " when getting local host name.";
		WSACleanup();
		throw NoNetworking();
	}

	struct hostent* phe = gethostbyname(ac);
	if (phe == 0)
	{
		clog(NetWarn) << "Bad host lookup.";
		WSACleanup();
		throw NoNetworking();
	}

	for (int i = 0; phe->h_addr_list[i] != 0; ++i)
	{
		struct in_addr addr;
		memcpy(&addr, phe->h_addr_list[i], sizeof(struct in_addr));
		char *addrStr = inet_ntoa(addr);
		bi::address ad(bi::address::from_string(addrStr));
		m_addresses.push_back(ad.to_v4());
		bool isLocal = std::find(c_rejectAddresses.begin(), c_rejectAddresses.end(), ad) != c_rejectAddresses.end();
		if (!isLocal)
			m_peerAddresses.push_back(ad.to_v4());
		clog(NetNote) << "Address: " << ac << " = " << m_addresses.back() << (isLocal ? " [LOCAL]" : " [PEER]");
	}

	WSACleanup();
#else
	ifaddrs* ifaddr;
	if (getifaddrs(&ifaddr) == -1)
		throw NoNetworking();

	bi::tcp::resolver r(m_ioService);

	for (ifaddrs* ifa = ifaddr; ifa; ifa = ifa->ifa_next)
	{
		if (!ifa->ifa_addr)
			continue;
		if (ifa->ifa_addr->sa_family == AF_INET)
		{
			char host[NI_MAXHOST];
			if (getnameinfo(ifa->ifa_addr, sizeof(struct sockaddr_in), host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST))
				continue;
			// TODO: Make exception safe when no internet.
			auto it = r.resolve({host, "30303"});
			bi::tcp::endpoint ep = it->endpoint();
			bi::address ad = ep.address();
			m_addresses.push_back(ad.to_v4());
			bool isLocal = std::find(c_rejectAddresses.begin(), c_rejectAddresses.end(), ad) != c_rejectAddresses.end();
			if (!isLocal)
				m_peerAddresses.push_back(ad.to_v4());
			clog(NetNote) << "Address: " << host << " = " << m_addresses.back() << (isLocal ? " [LOCAL]" : " [PEER]");
		}
	}

	freeifaddrs(ifaddr);
#endif
}

std::map<Public, bi::tcp::endpoint> PeerServer::potentialPeers()
{
	std::map<Public, bi::tcp::endpoint> ret;
	if (!m_public.address().is_unspecified())
		ret.insert(make_pair(m_key.pub(), m_public));
	for (auto i: m_peers)
		if (auto j = i.second.lock())
		{
			auto ep = j->endpoint();
			// Skip peers with a listen port of zero or are on a private network
			bool peerOnNet = (j->m_listenPort != 0 && !isPrivateAddress(ep.address()));
			if (peerOnNet && ep.port() && j->m_id)
				ret.insert(make_pair(i.first, ep));
		}
	return ret;
}

void PeerServer::ensureAccepting()
{
	if (m_accepting == false)
	{
		clog(NetNote) << "Listening on local port " << m_listenPort << " (public: " << m_public << ")";
		m_accepting = true;
		m_acceptor.async_accept(m_socket, [=](boost::system::error_code ec)
		{
			if (!ec)
				try
				{
					try {
						clog(NetNote) << "Accepted connection from " << m_socket.remote_endpoint();
					} catch (...){}
					bi::address remoteAddress = m_socket.remote_endpoint().address();
					// Port defaults to 0 - we let the hello tell us which port the peer listens to
					auto p = std::make_shared<PeerSession>(this, std::move(m_socket), m_networkId, remoteAddress);
					p->start();
				}
				catch (std::exception const& _e)
				{
					clog(NetWarn) << "ERROR: " << _e.what();
				}
			m_accepting = false;
			if (ec.value() != 1 && (m_mode == NodeMode::PeerServer || m_peers.size() < m_idealPeerCount * 2))
				ensureAccepting();
		});
	}
}

void PeerServer::connect(std::string const& _addr, unsigned short _port) noexcept
{
	try
	{
		connect(bi::tcp::endpoint(bi::address::from_string(_addr), _port));
	}
	catch (exception const& e)
	{
		// Couldn't connect
		clog(NetNote) << "Bad host " << _addr << " (" << e.what() << ")";
	}
}

void PeerServer::connect(bi::tcp::endpoint const& _ep)
{
	clog(NetNote) << "Attempting connection to " << _ep;
	bi::tcp::socket* s = new bi::tcp::socket(m_ioService);
	s->async_connect(_ep, [=](boost::system::error_code const& ec)
	{
		if (ec)
		{
			clog(NetNote) << "Connection refused to " << _ep << " (" << ec.message() << ")";
			for (auto i = m_incomingPeers.begin(); i != m_incomingPeers.end(); ++i)
				if (i->second.first == _ep && i->second.second < 3)
				{
					m_freePeers.push_back(i->first);
					goto OK;
				}
			// for-else
			clog(NetNote) << "Giving up.";
			OK:;
		}
		else
		{
			auto p = make_shared<PeerSession>(this, std::move(*s), m_networkId, _ep.address(), _ep.port());
			clog(NetNote) << "Connected to " << _ep;
			p->start();
		}
		delete s;
	});
}

bool PeerServer::sync()
{
	bool ret = false;
	if (isInitialised())
		for (auto i = m_peers.begin(); i != m_peers.end();)
		{
			auto p = i->second.lock();
			if (p && p->m_socket.is_open() &&
					(p->m_disconnect == chrono::steady_clock::time_point::max() || chrono::steady_clock::now() - p->m_disconnect < chrono::seconds(1)))	// kill old peers that should be disconnected.
				++i;
			else
			{
				i = m_peers.erase(i);
				ret = true;
			}
		}
	return ret;
}

bool PeerServer::ensureInitialised(BlockChain& _bc, TransactionQueue& _tq)
{
	if (m_latestBlockSent == h256())
	{
		// First time - just initialise.
		m_latestBlockSent = _bc.currentHash();
		clog(NetNote) << "Initialising: latest=" << m_latestBlockSent;

		for (auto const& i: _tq.transactions())
			m_transactionsSent.insert(i.first);
		m_lastPeersRequest = chrono::steady_clock::time_point::min();
		return true;
	}
	return false;
}

bool PeerServer::sync(BlockChain& _bc, TransactionQueue& _tq, OverlayDB& _o)
{
	bool ret = ensureInitialised(_bc, _tq);

	if (sync())
		ret = true;

	if (m_mode == NodeMode::Full)
	{
		for (auto it = m_incomingTransactions.begin(); it != m_incomingTransactions.end(); ++it)
			if (_tq.import(&*it))
			{}//ret = true;		// just putting a transaction in the queue isn't enough to change the state - it might have an invalid nonce...
			else
				m_transactionsSent.insert(sha3(*it));	// if we already had the transaction, then don't bother sending it on.
		m_incomingTransactions.clear();

		auto h = _bc.currentHash();
		bool resendAll = (h != m_latestBlockSent);

		// Send any new transactions.
		for (auto j: m_peers)
			if (auto p = j.second.lock())
			{
				bytes b;
				uint n = 0;
				for (auto const& i: _tq.transactions())
					if ((!m_transactionsSent.count(i.first) && !p->m_knownTransactions.count(i.first)) || p->m_requireTransactions || resendAll)
					{
						b += i.second;
						++n;
						m_transactionsSent.insert(i.first);
					}
				if (n)
				{
					RLPStream ts;
					PeerSession::prep(ts);
					ts.appendList(n + 1) << TransactionsPacket;
					ts.appendRaw(b, n).swapOut(b);
					seal(b);
					p->send(&b);
				}
				p->m_knownTransactions.clear();
				p->m_requireTransactions = false;
			}

		// Send any new blocks.
		if (h != m_latestBlockSent)
		{
			// TODO: find where they diverge and send complete new branch.
			RLPStream ts;
			PeerSession::prep(ts);
			ts.appendList(2) << BlocksPacket;
			bytes b;
			ts.appendRaw(_bc.block(_bc.currentHash())).swapOut(b);
			seal(b);
			for (auto j: m_peers)
				if (auto p = j.second.lock())
				{
					if (!p->m_knownBlocks.count(_bc.currentHash()))
						p->send(&b);
					p->m_knownBlocks.clear();
				}
		}
		m_latestBlockSent = h;

		for (int accepted = 1, n = 0; accepted; ++n)
		{
			accepted = 0;

			if (m_incomingBlocks.size())
				for (auto it = prev(m_incomingBlocks.end());; --it)
				{
					try
					{
						_bc.import(*it, _o);
						it = m_incomingBlocks.erase(it);
						++accepted;
						ret = true;
					}
					catch (UnknownParent)
					{
						// Don't (yet) know its parent. Leave it for later.
						m_unknownParentBlocks.push_back(*it);
						it = m_incomingBlocks.erase(it);
					}
					catch (...)
					{
						// Some other error - erase it.
						it = m_incomingBlocks.erase(it);
					}

					if (it == m_incomingBlocks.begin())
						break;
				}
			if (!n && accepted)
			{
				for (auto i: m_unknownParentBlocks)
					m_incomingBlocks.push_back(i);
				m_unknownParentBlocks.clear();
			}
		}

		// Connect to additional peers
		while (m_peers.size() < m_idealPeerCount)
		{
			if (m_freePeers.empty())
			{
				if (chrono::steady_clock::now() > m_lastPeersRequest + chrono::seconds(10))
				{
					RLPStream s;
					bytes b;
					(PeerSession::prep(s).appendList(1) << GetPeersPacket).swapOut(b);
					seal(b);
					for (auto const& i: m_peers)
						if (auto p = i.second.lock())
							if (p->isOpen())
								p->send(&b);
					m_lastPeersRequest = chrono::steady_clock::now();
				}


				if (!m_accepting)
					ensureAccepting();

				break;
			}

			auto x = time(0) % m_freePeers.size();
			m_incomingPeers[m_freePeers[x]].second++;
			connect(m_incomingPeers[m_freePeers[x]].first);
			m_freePeers.erase(m_freePeers.begin() + x);
		}
	}

	// platform for consensus of social contract.
	// restricts your freedom but does so fairly. and that's the value proposition.
	// guarantees that everyone else respect the rules of the system. (i.e. obeys laws).

	// We'll keep at most twice as many as is ideal, halfing what counts as "too young to kill" until we get there.
	for (uint old = 15000; m_peers.size() > m_idealPeerCount * 2 && old > 100; old /= 2)
		while (m_peers.size() > m_idealPeerCount)
		{
			// look for worst peer to kick off
			// first work out how many are old enough to kick off.
			shared_ptr<PeerSession> worst;
			unsigned agedPeers = 0;
			for (auto i: m_peers)
				if (auto p = i.second.lock())
					if ((m_mode != NodeMode::PeerServer || p->m_caps != 0x01) && chrono::steady_clock::now() > p->m_connect + chrono::milliseconds(old))	// don't throw off new peers; peer-servers should never kick off other peer-servers.
					{
						++agedPeers;
						if ((!worst || p->m_rating < worst->m_rating || (p->m_rating == worst->m_rating && p->m_connect > worst->m_connect)))	// kill older ones
							worst = p;
					}
			if (!worst || agedPeers <= m_idealPeerCount)
				break;
			worst->disconnect(TooManyPeers);
		}

	return ret;
}

std::vector<PeerInfo> PeerServer::peers(bool _updatePing) const
{
    if (_updatePing)
        const_cast<PeerServer*>(this)->pingAll();
	this_thread::sleep_for(chrono::milliseconds(200));
	std::vector<PeerInfo> ret;
	for (auto& i: m_peers)
		if (auto j = i.second.lock())
			if (j->m_socket.is_open())
				ret.push_back(j->m_info);
	return ret;
}

void PeerServer::pingAll()
{
	for (auto& i: m_peers)
		if (auto j = i.second.lock())
			j->ping();
}

bytes PeerServer::savePeers() const
{
	RLPStream ret;
	int n = 0;
	for (auto& i: m_peers)
		if (auto p = i.second.lock())
			if (p->m_socket.is_open() && p->endpoint().port())
			{
				ret.appendList(3) << p->endpoint().address().to_v4().to_bytes() << p->endpoint().port() << p->m_id;
				n++;
			}
	return RLPStream(n).appendRaw(ret.out(), n).out();
}

void PeerServer::restorePeers(bytesConstRef _b)
{
	for (auto i: RLP(_b))
	{
		auto k = (Public)i[2];
		if (!m_incomingPeers.count(k))
		{
			m_incomingPeers.insert(make_pair(k, make_pair(bi::tcp::endpoint(bi::address_v4(i[0].toArray<byte, 4>()), i[1].toInt<short>()), 0)));
			m_freePeers.push_back(k);
		}
	}
}