/*
 * Copyright (c)2019 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2023-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#ifndef ZT_MULTICASTER_HPP
#define ZT_MULTICASTER_HPP

#include <stdint.h>
#include <string.h>

#include <map>
#include <vector>
#include <list>

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

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 up and resort 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;
		uint64_t timestamp; // time of last notification
	};

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

		uint64_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