/*
* 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