/*
* Copyright (c) 2013-2022, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/

#ifndef NETDB_H__
#define NETDB_H__
// this file is called NetDb.hpp to resolve conflict with libc's netdb.h on case insensitive fs
#include <inttypes.h>
#include <set>
#include <unordered_map>
#include <list>
#include <string>
#include <thread>
#include <mutex>

#include "Base.h"
#include "Gzip.h"
#include "FS.h"
#include "Queue.h"
#include "I2NPProtocol.h"
#include "RouterInfo.h"
#include "LeaseSet.h"
#include "Tunnel.h"
#include "TunnelPool.h"
#include "Reseed.h"
#include "NetDbRequests.h"
#include "Family.h"
#include "version.h"
#include "util.h"

namespace i2p {
    namespace data {
        const int NETDB_MIN_ROUTERS = 90;
        const int NETDB_MIN_FLOODFILLS = 5;
        const int NETDB_FLOODFILL_EXPIRATION_TIMEOUT = 60 * 60; // 1 hour, in seconds
        const int NETDB_INTRODUCEE_EXPIRATION_TIMEOUT = 65 * 60;
        const int NETDB_MIN_EXPIRATION_TIMEOUT = 90 * 60; // 1.5 hours
        const int NETDB_MAX_EXPIRATION_TIMEOUT = 27 * 60 * 60; // 27 hours
        const int NETDB_MAX_OFFLINE_EXPIRATION_TIMEOUT = 180; // in days
        const int NETDB_PUBLISH_INTERVAL = 60 * 40;
        const int NETDB_PUBLISH_CONFIRMATION_TIMEOUT = 5; // in seconds
        const int NETDB_MAX_PUBLISH_EXCLUDED_FLOODFILLS = 15;
        const int NETDB_MIN_HIGHBANDWIDTH_VERSION = MAKE_VERSION_NUMBER(0, 9, 36); // 0.9.36
        const int NETDB_MIN_FLOODFILL_VERSION = MAKE_VERSION_NUMBER(0, 9, 38); // 0.9.38
        const int NETDB_MIN_SHORT_TUNNEL_BUILD_VERSION = MAKE_VERSION_NUMBER(0, 9, 51); // 0.9.51

        /** function for visiting a leaseset stored in a floodfill */
        typedef std::function<void(const IdentHash, std::shared_ptr<LeaseSet>)> LeaseSetVisitor;

        /** function for visiting a router info we have locally */
        typedef std::function<void(std::shared_ptr<const i2p::data::RouterInfo>)> RouterInfoVisitor;

        /** function for visiting a router info and determining if we want to use it */
        typedef std::function<bool(std::shared_ptr<const i2p::data::RouterInfo>)> RouterInfoFilter;

        class NetDb {
        public:

            NetDb();

            ~NetDb();

            void Start();

            void Stop();

            std::shared_ptr<const RouterInfo> AddRouterInfo(const uint8_t *buf, int len);

            bool AddRouterInfo(const IdentHash &ident, const uint8_t *buf, int len);

            bool AddLeaseSet(const IdentHash &ident, const uint8_t *buf, int len);

            bool AddLeaseSet2(const IdentHash &ident, const uint8_t *buf, int len, uint8_t storeType);

            std::shared_ptr<RouterInfo> FindRouter(const IdentHash &ident) const;

            std::shared_ptr<LeaseSet> FindLeaseSet(const IdentHash &destination) const;

            std::shared_ptr<RouterProfile> FindRouterProfile(const IdentHash &ident) const;

            void RequestDestination(const IdentHash &destination,
                                    RequestedDestination::RequestComplete requestComplete = nullptr,
                                    bool direct = true);

            void RequestDestinationFrom(const IdentHash &destination, const IdentHash &from, bool exploritory,
                                        RequestedDestination::RequestComplete requestComplete = nullptr);

            void HandleDatabaseStoreMsg(std::shared_ptr<const I2NPMessage> msg);

            void HandleDatabaseSearchReplyMsg(std::shared_ptr<const I2NPMessage> msg);

            void HandleDatabaseLookupMsg(std::shared_ptr<const I2NPMessage> msg);

            void HandleNTCP2RouterInfoMsg(std::shared_ptr<const I2NPMessage> m);

            void HandleDeliveryStatusMsg(std::shared_ptr<const I2NPMessage> msg);

            std::shared_ptr<const RouterInfo> GetRandomRouter() const;

            std::shared_ptr<const RouterInfo>
            GetRandomRouter(std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const;

            std::shared_ptr<const RouterInfo>
            GetHighBandwidthRandomRouter(std::shared_ptr<const RouterInfo> compatibleWith, bool reverse) const;

            std::shared_ptr<const RouterInfo>
            GetRandomPeerTestRouter(bool v4, const std::set<IdentHash> &excluded) const;

            std::shared_ptr<const RouterInfo>
            GetRandomSSU2PeerTestRouter(bool v4, const std::set<IdentHash> &excluded) const;

            std::shared_ptr<const RouterInfo> GetRandomSSUV6Router() const; // TODO: change to v6 peer test later
            std::shared_ptr<const RouterInfo> GetRandomIntroducer(bool v4, const std::set<IdentHash> &excluded) const;

            std::shared_ptr<const RouterInfo>
            GetRandomSSU2Introducer(bool v4, const std::set<IdentHash> &excluded) const;

            std::shared_ptr<const RouterInfo>
            GetClosestFloodfill(const IdentHash &destination, const std::set<IdentHash> &excluded,
                                bool closeThanUsOnly = false) const;

            std::vector<IdentHash> GetClosestFloodfills(const IdentHash &destination, size_t num,
                                                        std::set<IdentHash> &excluded,
                                                        bool closeThanUsOnly = false) const;

            std::shared_ptr<const RouterInfo>
            GetClosestNonFloodfill(const IdentHash &destination, const std::set<IdentHash> &excluded) const;

            std::shared_ptr<const RouterInfo> GetRandomRouterInFamily(FamilyID fam) const;

            void SetUnreachable(const IdentHash &ident, bool unreachable);

            void PostI2NPMsg(std::shared_ptr<const I2NPMessage> msg);

            /** set hidden mode, aka don't publish our RI to netdb and don't explore */
            void SetHidden(bool hide);

            void Reseed();

            Families &GetFamilies() { return m_Families; };

            // for web interface
            int GetNumRouters() const { return m_RouterInfos.size(); };

            int GetNumFloodfills() const { return m_Floodfills.size(); };

            int GetNumLeaseSets() const { return m_LeaseSets.size(); };

            /** visit all lease sets we currently store */
            void VisitLeaseSets(LeaseSetVisitor v);

            /** visit all router infos we have currently on disk, usually insanely expensive, does not access in memory RI */
            void VisitStoredRouterInfos(RouterInfoVisitor v);

            /** visit all router infos we have loaded in memory, cheaper than VisitLocalRouterInfos but locks access while visiting */
            void VisitRouterInfos(RouterInfoVisitor v);

            /** visit N random router that match using filter, then visit them with a visitor, return number of RouterInfos that were visited */
            size_t VisitRandomRouterInfos(RouterInfoFilter f, RouterInfoVisitor v, size_t n);

            void ClearRouterInfos() { m_RouterInfos.clear(); };

            std::shared_ptr<RouterInfo::Buffer>
            NewRouterInfoBuffer() { return m_RouterInfoBuffersPool.AcquireSharedMt(); };

            void PopulateRouterInfoBuffer(std::shared_ptr<RouterInfo> r);

            std::shared_ptr<Lease> NewLease(const Lease &lease) { return m_LeasesPool.AcquireSharedMt(lease); };

            uint32_t GetPublishReplyToken() const { return m_PublishReplyToken; };

        private:

            void Load();

            bool LoadRouterInfo(const std::string &path, uint64_t ts);

            void SaveUpdated();

            void Run(); // exploratory thread
            void Explore(int numDestinations);

            void Publish();

            void Flood(const IdentHash &ident, std::shared_ptr<I2NPMessage> floodMsg);

            void ManageLeaseSets();

            void ManageRequests();

            void ReseedFromFloodfill(const RouterInfo &ri, int numRouters = 40, int numFloodfills = 20);

            std::shared_ptr<const RouterInfo> AddRouterInfo(const uint8_t *buf, int len, bool &updated);

            std::shared_ptr<const RouterInfo>
            AddRouterInfo(const IdentHash &ident, const uint8_t *buf, int len, bool &updated);

            template<typename Filter>
            std::shared_ptr<const RouterInfo> GetRandomRouter(Filter filter) const;

        private:

            mutable std::mutex m_LeaseSetsMutex;
            std::unordered_map<IdentHash, std::shared_ptr<LeaseSet> > m_LeaseSets;
            mutable std::mutex m_RouterInfosMutex;
            std::unordered_map<IdentHash, std::shared_ptr<RouterInfo> > m_RouterInfos;
            mutable std::mutex m_FloodfillsMutex;
            std::list<std::shared_ptr<RouterInfo> > m_Floodfills;

            bool m_IsRunning;
            std::thread *m_Thread;
            i2p::util::Queue<std::shared_ptr<const I2NPMessage> > m_Queue; // of I2NPDatabaseStoreMsg

            GzipInflator m_Inflator;
            Reseeder *m_Reseeder;
            Families m_Families;
            i2p::fs::HashedStorage m_Storage;

            friend class NetDbRequests;

            NetDbRequests m_Requests;

            bool m_PersistProfiles;

            /** router info we are bootstrapping from or nullptr if we are not currently doing that*/
            std::shared_ptr<RouterInfo> m_FloodfillBootstrap;

            /** true if in hidden mode */
            bool m_HiddenMode;

            std::set<IdentHash> m_PublishExcluded;
            uint32_t m_PublishReplyToken = 0;

            i2p::util::MemoryPoolMt<RouterInfo::Buffer> m_RouterInfoBuffersPool;
            i2p::util::MemoryPoolMt<Lease> m_LeasesPool;
        };

        extern NetDb netdb;
    }
}

#endif