/*
 * ZeroTier One - Global Peer to Peer Ethernet
 * Copyright (C) 2012-2013  ZeroTier Networks LLC
 *
 * This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * --
 *
 * ZeroTier may be used and distributed under the terms of the GPLv3, which
 * are available at: http://www.gnu.org/licenses/gpl-3.0.html
 *
 * If you would like to embed ZeroTier into a commercial application or
 * redistribute it in a modified binary form, please contact ZeroTier Networks
 * LLC. Start here: http://www.zerotier.com/
 */

#ifndef _ZT_NETWORK_HPP
#define _ZT_NETWORK_HPP

#include <stdint.h>

#include <string>
#include <set>
#include <map>
#include <vector>
#include <algorithm>
#include <stdexcept>

#include "Constants.hpp"
#include "NonCopyable.hpp"
#include "Utils.hpp"
#include "EthernetTap.hpp"
#include "Address.hpp"
#include "Mutex.hpp"
#include "SharedPtr.hpp"
#include "AtomicCounter.hpp"
#include "MulticastGroup.hpp"
#include "MAC.hpp"
#include "Dictionary.hpp"
#include "Identity.hpp"
#include "InetAddress.hpp"
#include "BandwidthAccount.hpp"
#include "NetworkConfig.hpp"
#include "CertificateOfMembership.hpp"

namespace ZeroTier {

class RuntimeEnvironment;
class NodeConfig;

/**
 * A virtual LAN
 *
 * Networks can be open or closed. Each network has an ID whose most
 * significant 40 bits are the ZeroTier address of the node that should
 * be contacted for network configuration. The least significant 24
 * bits are arbitrary, allowing up to 2^24 networks per managing
 * node.
 *
 * Open networks do not track membership. Anyone is allowed to communicate
 * over them. For closed networks, each peer must distribute a certificate
 * regularly that proves that they are allowed to communicate.
 */
class Network : NonCopyable
{
	friend class SharedPtr<Network>;
	friend class NodeConfig;

private:
	// Only NodeConfig can create, only SharedPtr can delete

	// Actual construction happens in newInstance()
	Network() throw() : _tap((EthernetTap *)0) {}

	~Network();

	/**
	 * Create a new Network instance and restore any saved state
	 *
	 * If there is no saved state, a dummy .conf is created on disk to remember
	 * this network across restarts.
	 *
	 * @param renv Runtime environment
	 * @param id Network ID
	 * @return Reference counted pointer to new network
	 * @throws std::runtime_error Unable to create tap device or other fatal error
	 */
	static SharedPtr<Network> newInstance(const RuntimeEnvironment *renv,uint64_t id);

	/**
	 * Causes all persistent disk presence to be erased on delete
	 */
	inline void destroyOnDelete() throw() { _destroyOnDelete = true; }

public:
	/**
	 * Possible network states
	 */
	enum Status
	{
		NETWORK_WAITING_FOR_FIRST_AUTOCONF,
		NETWORK_OK,
		NETWORK_ACCESS_DENIED,
		NETWORK_NOT_FOUND
	};

	/**
	 * @param s Status
	 * @return String description
	 */
	static const char *statusString(const Status s)
		throw();

	/**
	 * @return Network ID
	 */
	inline uint64_t id() const throw() { return _id; }

	/**
	 * @return Ethernet tap
	 */
	inline EthernetTap &tap() throw() { return *_tap; }

	/**
	 * @return Address of network's controlling node
	 */
	inline Address controller() throw() { return Address(_id >> 24); }

	/**
	 * @return Network ID in hexadecimal form
	 */
	inline std::string idString()
	{
		char buf[64];
		Utils::snprintf(buf,sizeof(buf),"%.16llx",(unsigned long long)_id);
		return std::string(buf);
	}

	/**
	 * Update multicast groups for this network's tap
	 *
	 * @return True if internal multicast group set has changed
	 */
	inline bool updateMulticastGroups()
	{
		Mutex::Lock _l(_lock);
		return _tap->updateMulticastGroups(_multicastGroups);
	}

	/**
	 * @return Latest set of multicast groups for this network's tap
	 */
	inline std::set<MulticastGroup> multicastGroups() const
	{
		Mutex::Lock _l(_lock);
		return _multicastGroups;
	}

	/**
	 * Set or update this network's configuration
	 *
	 * This is called by PacketDecoder when an update comes over the wire, or
	 * internally when an old config is reloaded from disk.
	 *
	 * @param conf Configuration in key/value dictionary form
	 * @param saveToDisk IF true (default), write config to disk
	 */
	void setConfiguration(const Dictionary &conf,bool saveToDisk = true);

	/**
	 * Causes this network to request an updated configuration from its master node now
	 */
	void requestConfiguration();

	/**
	 * Add or update a membership certificate
	 *
	 * This cert must have been signature checked first. Certs older than the
	 * cert on file are ignored and the newer cert remains in the database.
	 *
	 * @param cert Certificate of membership
	 */
	void addMembershipCertificate(const CertificateOfMembership &cert);

	/**
	 * Push our membership certificate to a peer
	 *
	 * @param peer Destination peer address
	 * @param force If true, push even if we've already done so within required time frame
	 * @param now Current time
	 */
	inline void pushMembershipCertificate(const Address &peer,bool force,uint64_t now)
	{
		Mutex::Lock _l(_lock);
		if ((_config)&&(!_config->isOpen())&&(_config->com()))
			_pushMembershipCertificate(peer,force,now);
	}

	/**
	 * @param peer Peer address to check
	 * @return True if peer is allowed to communicate on this network
	 */
	bool isAllowed(const Address &peer) const;

	/**
	 * Perform cleanup and possibly save state
	 */
	void clean();

	/**
	 * @return Time of last updated configuration or 0 if none
	 */
	inline uint64_t lastConfigUpdate() const throw() { return _lastConfigUpdate; }

	/** 
	 * Force this network's status to a particular state based on config reply
	 */
	inline void forceStatusTo(const Status s)
		throw()
	{
		Mutex::Lock _l(_lock);
		_status = s;
	}

	/**
	 * @return Status of this network
	 */
	inline Status status() const
		throw()
	{
		Mutex::Lock _l(_lock);
		return _status;
	}

	/**
	 * @return True if this network is in "OK" status and can accept traffic from us
	 */
	inline bool isUp() const
		throw()
	{
		Mutex::Lock _l(_lock);
		return ((_config)&&(_status == NETWORK_OK)&&(_ready));
	}

	/**
	 * Update multicast balance for an address and multicast group, return whether packet is allowed
	 *
	 * @param a Address that wants to send/relay packet
	 * @param mg Multicast group
	 * @param bytes Size of packet
	 * @return True if packet is within budget
	 */
	inline bool updateAndCheckMulticastBalance(const Address &a,const MulticastGroup &mg,unsigned int bytes)
	{
		Mutex::Lock _l(_lock);
		if (!_config)
			return false;
		std::pair<Address,MulticastGroup> k(a,mg);
		std::map< std::pair<Address,MulticastGroup>,BandwidthAccount >::iterator bal(_multicastRateAccounts.find(k));
		if (bal == _multicastRateAccounts.end()) {
			NetworkConfig::MulticastRate r(_config->multicastRate(mg));
			bal = _multicastRateAccounts.insert(std::pair< std::pair<Address,MulticastGroup>,BandwidthAccount >(k,BandwidthAccount(r.preload,r.maxBalance,r.accrual))).first;
		}
		return bal->second.deduct(bytes);
	}

	/**
	 * Get current network config or throw exception
	 *
	 * This version never returns null. Instead it throws a runtime error if
	 * there is no current configuration. Callers should check isUp() first or
	 * use config2() to get with the potential for null.
	 *
	 * Since it never returns null, it's safe to config()->whatever().
	 *
	 * @return Network configuration (never null)
	 * @throws std::runtime_error Network configuration unavailable
	 */
	inline SharedPtr<NetworkConfig> config() const
	{
		Mutex::Lock _l(_lock);
		if (_config)
			return _config;
		throw std::runtime_error("no configuration");
	}

	/**
	 * Get current network config or return NULL
	 *
	 * @return Network configuration -- may be NULL
	 */
	inline SharedPtr<NetworkConfig> config2() const
		throw()
	{
		Mutex::Lock _l(_lock);
		return _config;
	}

private:
	static void _CBhandleTapData(void *arg,const MAC &from,const MAC &to,unsigned int etherType,const Buffer<4096> &data);

	void _pushMembershipCertificate(const Address &peer,bool force,uint64_t now);
	void _restoreState();
	void _dumpMulticastCerts();

	uint64_t _id;

	const RuntimeEnvironment *_r;

	EthernetTap *_tap;
	std::set<MulticastGroup> _multicastGroups;

	std::map< std::pair<Address,MulticastGroup>,BandwidthAccount > _multicastRateAccounts;
	std::map<Address,CertificateOfMembership> _membershipCertificates;
	std::map<Address,uint64_t> _lastPushedMembershipCertificate;
	SharedPtr<NetworkConfig> _config;

	volatile uint64_t _lastConfigUpdate;
	volatile Status _status;
	volatile bool _destroyOnDelete;
	volatile bool _ready;

	Mutex _lock;

	AtomicCounter __refCount;
};

} // naemspace ZeroTier

#endif