/*
 * 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_WORLD_HPP
#define ZT_WORLD_HPP

#include "Buffer.hpp"
#include "Constants.hpp"
#include "ECC.hpp"
#include "Identity.hpp"
#include "InetAddress.hpp"

#include <string>
#include <vector>

/**
 * Maximum number of roots (sanity limit, okay to increase)
 *
 * A given root can (through multi-homing) be distributed across any number of
 * physical endpoints, but having more than one is good to permit total failure
 * of one root or its withdrawal due to compromise without taking the whole net
 * down.
 */
#define ZT_WORLD_MAX_ROOTS 4

/**
 * Maximum number of stable endpoints per root (sanity limit, okay to increase)
 */
#define ZT_WORLD_MAX_STABLE_ENDPOINTS_PER_ROOT 32

/**
 * The (more than) maximum length of a serialized World
 */
#define ZT_WORLD_MAX_SERIALIZED_LENGTH (((1024 + (32 * ZT_WORLD_MAX_STABLE_ENDPOINTS_PER_ROOT)) * ZT_WORLD_MAX_ROOTS) + ZT_ECC_PUBLIC_KEY_SET_LEN + ZT_ECC_SIGNATURE_LEN + 128)

/**
 * World ID for Earth
 *
 * This is the ID for the ZeroTier World used on planet Earth. It is unrelated
 * to the public network 8056c2e21c000001 of the same name. It was chosen
 * from Earth's approximate distance from the sun in kilometers.
 */
#define ZT_WORLD_ID_EARTH 149604618

/**
 * World ID for Mars -- for future use by SpaceX or others
 */
#define ZT_WORLD_ID_MARS 227883110

namespace ZeroTier {

/**
 * A world definition (formerly known as a root topology)
 *
 * Think of a World as a single data center. Within this data center a set
 * of distributed fault tolerant root servers provide stable anchor points
 * for a peer to peer network that provides VLAN service. Updates to a world
 * definition can be published by signing them with the previous revision's
 * signing key, and should be very infrequent.
 *
 * The maximum data center size is approximately 2.5 cubic light seconds,
 * since many protocols have issues with >5s RTT latencies.
 *
 * ZeroTier operates a World for Earth capable of encompassing the planet, its
 * orbits, the Moon (about 1.3 light seconds), and nearby Lagrange points. A
 * world ID for Mars and nearby space is defined but not yet used, and a test
 * world ID is provided for testing purposes.
 */
class World {
  public:
    /**
     * World type -- do not change IDs
     */
    enum Type {
        TYPE_NULL = 0,
        TYPE_PLANET = 1,   // Planets, of which there is currently one (Earth)
        TYPE_MOON = 127    // Moons, which are user-created and many
    };

    /**
     * Upstream server definition in world/moon
     */
    struct Root {
        Identity identity;
        std::vector<InetAddress> stableEndpoints;

        inline bool operator==(const Root& r) const
        {
            return ((identity == r.identity) && (stableEndpoints == r.stableEndpoints));
        }
        inline bool operator!=(const Root& r) const
        {
            return (! (*this == r));
        }
        inline bool operator<(const Root& r) const
        {
            return (identity < r.identity);
        }   // for sorting
    };

    /**
     * Construct an empty / null World
     */
    World() : _id(0), _ts(0), _type(TYPE_NULL)
    {
    }

    /**
     * @return Root servers for this world and their stable endpoints
     */
    inline const std::vector<World::Root>& roots() const
    {
        return _roots;
    }

    /**
     * @return World type: planet or moon
     */
    inline Type type() const
    {
        return _type;
    }

    /**
     * @return World unique identifier
     */
    inline uint64_t id() const
    {
        return _id;
    }

    /**
     * @return World definition timestamp
     */
    inline uint64_t timestamp() const
    {
        return _ts;
    }

    /**
     * @return C25519 signature
     */
    inline const ECC::Signature& signature() const
    {
        return _signature;
    }

    /**
     * @return Public key that must sign next update
     */
    inline const ECC::Public& updatesMustBeSignedBy() const
    {
        return _updatesMustBeSignedBy;
    }

    /**
     * Check whether a world update should replace this one
     *
     * @param update Candidate update
     * @return True if update is newer than current, matches its ID and type, and is properly signed (or if current is NULL)
     */
    inline bool shouldBeReplacedBy(const World& update)
    {
        if ((_id == 0) || (_type == TYPE_NULL)) {
            return true;
        }
        if ((_id == update._id) && (_ts < update._ts) && (_type == update._type)) {
            Buffer<ZT_WORLD_MAX_SERIALIZED_LENGTH> tmp;
            update.serialize(tmp, true);
            return ECC::verify(_updatesMustBeSignedBy, tmp.data(), tmp.size(), update._signature);
        }
        return false;
    }

    /**
     * @return True if this World is non-empty
     */
    inline operator bool() const
    {
        return (_type != TYPE_NULL);
    }

    template <unsigned int C> inline void serialize(Buffer<C>& b, bool forSign = false) const
    {
        if (forSign) {
            b.append((uint64_t)0x7f7f7f7f7f7f7f7fULL);
        }

        b.append((uint8_t)_type);
        b.append((uint64_t)_id);
        b.append((uint64_t)_ts);
        b.append(_updatesMustBeSignedBy.data, ZT_ECC_PUBLIC_KEY_SET_LEN);
        if (! forSign) {
            b.append(_signature.data, ZT_ECC_SIGNATURE_LEN);
        }
        b.append((uint8_t)_roots.size());
        for (std::vector<Root>::const_iterator r(_roots.begin()); r != _roots.end(); ++r) {
            r->identity.serialize(b);
            b.append((uint8_t)r->stableEndpoints.size());
            for (std::vector<InetAddress>::const_iterator ep(r->stableEndpoints.begin()); ep != r->stableEndpoints.end(); ++ep) {
                ep->serialize(b);
            }
        }
        if (_type == TYPE_MOON) {
            b.append((uint16_t)0);   // no attached dictionary (for future use)
        }

        if (forSign) {
            b.append((uint64_t)0xf7f7f7f7f7f7f7f7ULL);
        }
    }

    template <unsigned int C> inline unsigned int deserialize(const Buffer<C>& b, unsigned int startAt = 0)
    {
        unsigned int p = startAt;

        _roots.clear();

        switch ((Type)b[p++]) {
            case TYPE_NULL:   // shouldn't ever really happen in serialized data but it's not invalid
                _type = TYPE_NULL;
                break;
            case TYPE_PLANET:
                _type = TYPE_PLANET;
                break;
            case TYPE_MOON:
                _type = TYPE_MOON;
                break;
            default:
                throw ZT_EXCEPTION_INVALID_SERIALIZED_DATA_INVALID_TYPE;
        }

        _id = b.template at<uint64_t>(p);
        p += 8;
        _ts = b.template at<uint64_t>(p);
        p += 8;
        memcpy(_updatesMustBeSignedBy.data, b.field(p, ZT_ECC_PUBLIC_KEY_SET_LEN), ZT_ECC_PUBLIC_KEY_SET_LEN);
        p += ZT_ECC_PUBLIC_KEY_SET_LEN;
        memcpy(_signature.data, b.field(p, ZT_ECC_SIGNATURE_LEN), ZT_ECC_SIGNATURE_LEN);
        p += ZT_ECC_SIGNATURE_LEN;
        const unsigned int numRoots = (unsigned int)b[p++];
        if (numRoots > ZT_WORLD_MAX_ROOTS) {
            throw ZT_EXCEPTION_INVALID_SERIALIZED_DATA_OVERFLOW;
        }
        for (unsigned int k = 0; k < numRoots; ++k) {
            _roots.push_back(Root());
            Root& r = _roots.back();
            p += r.identity.deserialize(b, p);
            unsigned int numStableEndpoints = b[p++];
            if (numStableEndpoints > ZT_WORLD_MAX_STABLE_ENDPOINTS_PER_ROOT) {
                throw ZT_EXCEPTION_INVALID_SERIALIZED_DATA_OVERFLOW;
            }
            for (unsigned int kk = 0; kk < numStableEndpoints; ++kk) {
                r.stableEndpoints.push_back(InetAddress());
                p += r.stableEndpoints.back().deserialize(b, p);
            }
        }
        if (_type == TYPE_MOON) {
            p += b.template at<uint16_t>(p) + 2;
        }

        return (p - startAt);
    }

    inline bool operator==(const World& w) const
    {
        return (
            (_id == w._id) && (_ts == w._ts) && (memcmp(_updatesMustBeSignedBy.data, w._updatesMustBeSignedBy.data, ZT_ECC_PUBLIC_KEY_SET_LEN) == 0) && (memcmp(_signature.data, w._signature.data, ZT_ECC_SIGNATURE_LEN) == 0)
            && (_roots == w._roots) && (_type == w._type));
    }
    inline bool operator!=(const World& w) const
    {
        return (! (*this == w));
    }

    /**
     * Create a World object signed with a key pair
     *
     * @param t World type
     * @param id World ID
     * @param ts World timestamp / revision
     * @param sk Key that must be used to sign the next future update to this world
     * @param roots Roots and their stable endpoints
     * @param signWith Key to sign this World with (can have the same public as the next-update signing key, but doesn't have to)
     * @return Signed World object
     */
    static inline World make(World::Type t, uint64_t id, uint64_t ts, const ECC::Public& sk, const std::vector<World::Root>& roots, const ECC::Pair& signWith)
    {
        World w;
        w._id = id;
        w._ts = ts;
        w._type = t;
        w._updatesMustBeSignedBy = sk;
        w._roots = roots;

        Buffer<ZT_WORLD_MAX_SERIALIZED_LENGTH> tmp;
        w.serialize(tmp, true);
        w._signature = ECC::sign(signWith, tmp.data(), tmp.size());

        return w;
    }

  protected:
    uint64_t _id;
    uint64_t _ts;
    Type _type;
    ECC::Public _updatesMustBeSignedBy;
    ECC::Signature _signature;
    std::vector<Root> _roots;
};

}   // namespace ZeroTier

#endif