/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * (c) ZeroTier, Inc.
 * https://www.zerotier.com/
 */

#ifndef ZT_MULTICASTER_HPP
#define ZT_MULTICASTER_HPP

#include "Address.hpp"
#include "Constants.hpp"
#include "Hashtable.hpp"
#include "MAC.hpp"
#include "MulticastGroup.hpp"
#include "Mutex.hpp"
#include "OutboundMulticast.hpp"
#include "SharedPtr.hpp"
#include "Utils.hpp"

#include <list>
#include <map>
#include <stdint.h>
#include <string.h>
#include <vector>

namespace ZeroTier {

class RuntimeEnvironment;
class CertificateOfMembership;
class Packet;
class Network;

/**
 * Database of known multicast peers within a network
 */
class Multicaster {
  public:
	Multicaster(const RuntimeEnvironment* renv);
	~Multicaster();

	/**
	 * Add or update a member in a multicast group
	 *
	 * @param now Current time
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param member New member address
	 */
	inline void add(void* tPtr, int64_t now, uint64_t nwid, const MulticastGroup& mg, const Address& member)
	{
		Mutex::Lock _l(_groups_m);
		_add(tPtr, now, nwid, mg, _groups[Multicaster::Key(nwid, mg)], member);
	}

	/**
	 * Add multiple addresses from a binary array of 5-byte address fields
	 *
	 * It's up to the caller to check bounds on the array before calling this.
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param now Current time
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param addresses Raw binary addresses in big-endian format, as a series of 5-byte fields
	 * @param count Number of addresses
	 * @param totalKnown Total number of known addresses as reported by peer
	 */
	void addMultiple(void* tPtr, int64_t now, uint64_t nwid, const MulticastGroup& mg, const void* addresses, unsigned int count, unsigned int totalKnown);

	/**
	 * Remove a multicast group member (if present)
	 *
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param member Member to unsubscribe
	 */
	void remove(uint64_t nwid, const MulticastGroup& mg, const Address& member);

	/**
	 * Append gather results to a packet by choosing registered multicast recipients at random
	 *
	 * This appends the following fields to the packet:
	 *   <[4] 32-bit total number of known members in this multicast group>
	 *   <[2] 16-bit number of members enumerated in this packet>
	 *   <[...] series of 5-byte ZeroTier addresses of enumerated members>
	 *
	 * If zero is returned, the first two fields will still have been appended.
	 *
	 * @param queryingPeer Peer asking for gather (to skip in results)
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param appendTo Packet to append to
	 * @param limit Maximum number of 5-byte addresses to append
	 * @return Number of addresses appended
	 * @throws std::out_of_range Buffer overflow writing to packet
	 */
	unsigned int gather(const Address& queryingPeer, uint64_t nwid, const MulticastGroup& mg, Buffer<ZT_PROTO_MAX_PACKET_LENGTH>& appendTo, unsigned int limit) const;

	/**
	 * Get subscribers to a multicast group
	 *
	 * @param nwid Network ID
	 * @param mg Multicast group
	 */
	std::vector<Address> getMembers(uint64_t nwid, const MulticastGroup& mg, unsigned int limit) const;

	/**
	 * Send a multicast
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param now Current time
	 * @param network Network
	 * @param origin Origin of multicast (to not return to sender) or NULL if none
	 * @param mg Multicast group
	 * @param src Source Ethernet MAC address or NULL to skip in packet and compute from ZT address (non-bridged mode)
	 * @param etherType Ethernet frame type
	 * @param data Packet data
	 * @param len Length of packet data
	 */
	void send(void* tPtr, int64_t now, const SharedPtr<Network>& network, const Address& origin, const MulticastGroup& mg, const MAC& src, unsigned int etherType, const void* data, unsigned int len);

	/**
	 * Clean database
	 *
	 * @param RR Runtime environment
	 * @param now Current time
	 */
	void clean(int64_t now);

  private:
	struct Key {
		Key() : nwid(0), mg()
		{
		}
		Key(uint64_t n, const MulticastGroup& g) : nwid(n), mg(g)
		{
		}

		uint64_t nwid;
		MulticastGroup mg;

		inline bool operator==(const Key& k) const
		{
			return ((nwid == k.nwid) && (mg == k.mg));
		}
		inline bool operator!=(const Key& k) const
		{
			return ((nwid != k.nwid) || (mg != k.mg));
		}
		inline unsigned long hashCode() const
		{
			return (mg.hashCode() ^ (unsigned long)(nwid ^ (nwid >> 32)));
		}
	};

	struct MulticastGroupMember {
		MulticastGroupMember()
		{
		}
		MulticastGroupMember(const Address& a, uint64_t ts) : address(a), timestamp(ts)
		{
		}

		inline bool operator<(const MulticastGroupMember& a) const
		{
			return (address < a.address);
		}
		inline bool operator==(const MulticastGroupMember& a) const
		{
			return (address == a.address);
		}
		inline bool operator!=(const MulticastGroupMember& a) const
		{
			return (address != a.address);
		}
		inline bool operator<(const Address& a) const
		{
			return (address < a);
		}
		inline bool operator==(const Address& a) const
		{
			return (address == a);
		}
		inline bool operator!=(const Address& a) const
		{
			return (address != a);
		}

		Address address;
		int64_t timestamp;	 // time of last notification
	};

	struct MulticastGroupStatus {
		MulticastGroupStatus() : lastExplicitGather(0)
		{
		}

		int64_t lastExplicitGather;
		std::list<OutboundMulticast> txQueue;		 // pending outbound multicasts
		std::vector<MulticastGroupMember> members;	 // members of this group
	};

	void _add(void* tPtr, int64_t now, uint64_t nwid, const MulticastGroup& mg, MulticastGroupStatus& gs, const Address& member);

	const RuntimeEnvironment* const RR;

	Hashtable<Multicaster::Key, MulticastGroupStatus> _groups;
	Mutex _groups_m;
};

}	// namespace ZeroTier

#endif