/*
 * 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: 2026-01-01
 *
 * 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 "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