/*
* 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 GARLIC_H__
#define GARLIC_H__

#include <inttypes.h>
#include <unordered_map>
#include <list>
#include <string>
#include <thread>
#include <mutex>
#include <memory>
#include "Crypto.h"
#include "I2NPProtocol.h"
#include "LeaseSet.h"
#include "Queue.h"
#include "Identity.h"

namespace i2p {
    namespace tunnel {
        class OutboundTunnel;
    }

    namespace garlic {

        enum GarlicDeliveryType {
            eGarlicDeliveryTypeLocal = 0,
            eGarlicDeliveryTypeDestination = 1,
            eGarlicDeliveryTypeRouter = 2,
            eGarlicDeliveryTypeTunnel = 3
        };

        struct ElGamalBlock {
            uint8_t sessionKey[32];
            uint8_t preIV[32];
            uint8_t padding[158];
        };

        const int INCOMING_TAGS_EXPIRATION_TIMEOUT = 960; // 16 minutes
        const int OUTGOING_TAGS_EXPIRATION_TIMEOUT = 720; // 12 minutes
        const int OUTGOING_TAGS_CONFIRMATION_TIMEOUT = 10; // 10 seconds
        const int LEASET_CONFIRMATION_TIMEOUT = 4000; // in milliseconds
        const int ROUTING_PATH_EXPIRATION_TIMEOUT = 30; // 30 seconds
        const int ROUTING_PATH_MAX_NUM_TIMES_USED = 100; // how many times might be used

        struct SessionTag : public i2p::data::Tag<32> {
            SessionTag(const uint8_t *buf, uint32_t ts = 0) : Tag<32>(buf), creationTime(ts) {};

            SessionTag() = default;

            SessionTag(const SessionTag &) = default;

            SessionTag &operator=(const SessionTag &) = default;

#ifndef _WIN32

            SessionTag(SessionTag &&) = default;

            SessionTag &operator=(SessionTag &&) = default;

#endif
            uint32_t creationTime; // seconds since epoch
        };

        // AESDecryption is associated with session tags and store key
        class AESDecryption : public i2p::crypto::CBCDecryption {
        public:

            AESDecryption(const uint8_t *key) : m_Key(key) {
                SetKey(key);
            }

            const i2p::crypto::AESKey &GetKey() const { return m_Key; };

        private:

            i2p::crypto::AESKey m_Key;
        };

        struct GarlicRoutingPath {
            std::shared_ptr<i2p::tunnel::OutboundTunnel> outboundTunnel;
            std::shared_ptr<const i2p::data::Lease> remoteLease;
            int rtt; // RTT
            uint32_t updateTime; // seconds since epoch
            int numTimesUsed;
        };

        class GarlicDestination;

        class GarlicRoutingSession {
        protected:

            enum LeaseSetUpdateStatus {
                eLeaseSetUpToDate = 0,
                eLeaseSetUpdated,
                eLeaseSetSubmitted,
                eLeaseSetDoNotSend
            };

        public:

            GarlicRoutingSession(GarlicDestination *owner, bool attachLeaseSet);

            GarlicRoutingSession();

            virtual ~GarlicRoutingSession();

            virtual std::shared_ptr<I2NPMessage> WrapSingleMessage(std::shared_ptr<const I2NPMessage> msg) = 0;

            virtual bool CleanupUnconfirmedTags() { return false; }; // for I2CP, override in ElGamalAESSession
            virtual bool MessageConfirmed(uint32_t msgID);

            virtual bool IsRatchets() const { return false; };

            virtual bool IsReadyToSend() const { return true; };

            virtual bool IsTerminated() const { return !GetOwner(); };

            virtual uint64_t GetLastActivityTimestamp() const { return 0; }; // non-zero for rathets only

            void SetLeaseSetUpdated() {
                if (m_LeaseSetUpdateStatus != eLeaseSetDoNotSend) m_LeaseSetUpdateStatus = eLeaseSetUpdated;
            };

            bool IsLeaseSetNonConfirmed() const { return m_LeaseSetUpdateStatus == eLeaseSetSubmitted; };

            bool IsLeaseSetUpdated() const { return m_LeaseSetUpdateStatus == eLeaseSetUpdated; };

            uint64_t GetLeaseSetSubmissionTime() const { return m_LeaseSetSubmissionTime; }

            void CleanupUnconfirmedLeaseSet(uint64_t ts);

            std::shared_ptr<GarlicRoutingPath> GetSharedRoutingPath();

            void SetSharedRoutingPath(std::shared_ptr<GarlicRoutingPath> path);

            GarlicDestination *GetOwner() const { return m_Owner; }

            void SetOwner(GarlicDestination *owner) { m_Owner = owner; }

        protected:

            LeaseSetUpdateStatus GetLeaseSetUpdateStatus() const { return m_LeaseSetUpdateStatus; }

            void SetLeaseSetUpdateStatus(LeaseSetUpdateStatus status) { m_LeaseSetUpdateStatus = status; }

            uint32_t GetLeaseSetUpdateMsgID() const { return m_LeaseSetUpdateMsgID; }

            void SetLeaseSetUpdateMsgID(uint32_t msgID) { m_LeaseSetUpdateMsgID = msgID; }

            void SetLeaseSetSubmissionTime(uint64_t ts) { m_LeaseSetSubmissionTime = ts; }

            std::shared_ptr<I2NPMessage> CreateEncryptedDeliveryStatusMsg(uint32_t msgID);

        private:

            GarlicDestination *m_Owner;

            LeaseSetUpdateStatus m_LeaseSetUpdateStatus;
            uint32_t m_LeaseSetUpdateMsgID;
            uint64_t m_LeaseSetSubmissionTime; // in milliseconds

            std::shared_ptr<GarlicRoutingPath> m_SharedRoutingPath;

        public:

            // for HTTP only
            virtual size_t GetNumOutgoingTags() const { return 0; };
        };

        //using GarlicRoutingSessionPtr = std::shared_ptr<GarlicRoutingSession>;
        typedef std::shared_ptr<GarlicRoutingSession> GarlicRoutingSessionPtr; // TODO: replace to using after switch to 4.8

        class ElGamalAESSession : public GarlicRoutingSession, public std::enable_shared_from_this<ElGamalAESSession> {
            struct UnconfirmedTags {
                UnconfirmedTags(int n) : numTags(n), tagsCreationTime(0) { sessionTags = new SessionTag[numTags]; };

                ~UnconfirmedTags() { delete[] sessionTags; };
                uint32_t msgID;
                int numTags;
                SessionTag *sessionTags;
                uint32_t tagsCreationTime;
            };

        public:

            ElGamalAESSession(GarlicDestination *owner,
                              std::shared_ptr<const i2p::data::RoutingDestination> destination,
                              int numTags, bool attachLeaseSet);

            ElGamalAESSession(const uint8_t *sessionKey, const SessionTag &sessionTag); // one time encryption
            ~ElGamalAESSession() {};

            std::shared_ptr<I2NPMessage> WrapSingleMessage(std::shared_ptr<const I2NPMessage> msg);

            bool MessageConfirmed(uint32_t msgID);

            bool CleanupExpiredTags(); // returns true if something left
            bool CleanupUnconfirmedTags(); // returns true if something has been deleted

        private:

            size_t CreateAESBlock(uint8_t *buf, std::shared_ptr<const I2NPMessage> msg);

            size_t
            CreateGarlicPayload(uint8_t *payload, std::shared_ptr<const I2NPMessage> msg, UnconfirmedTags *newTags);

            size_t CreateGarlicClove(uint8_t *buf, std::shared_ptr<const I2NPMessage> msg, bool isDestination);

            size_t CreateDeliveryStatusClove(uint8_t *buf, uint32_t msgID);

            void TagsConfirmed(uint32_t msgID);

            UnconfirmedTags *GenerateSessionTags();

        private:

            std::shared_ptr<const i2p::data::RoutingDestination> m_Destination;

            i2p::crypto::AESKey m_SessionKey;
            std::list<SessionTag> m_SessionTags;
            int m_NumTags;
            std::map<uint32_t, std::unique_ptr<UnconfirmedTags> > m_UnconfirmedTagsMsgs; // msgID->tags

            i2p::crypto::CBCEncryption m_Encryption;

        public:

            // for HTTP only
            size_t GetNumOutgoingTags() const { return m_SessionTags.size(); };
        };

        typedef std::shared_ptr<ElGamalAESSession> ElGamalAESSessionPtr;

        class ECIESX25519AEADRatchetSession;

        typedef std::shared_ptr<ECIESX25519AEADRatchetSession> ECIESX25519AEADRatchetSessionPtr;

        class ReceiveRatchetTagSet;

        typedef std::shared_ptr<ReceiveRatchetTagSet> ReceiveRatchetTagSetPtr;
        struct ECIESX25519AEADRatchetIndexTagset {
            int index;
            ReceiveRatchetTagSetPtr tagset;
        };

        class GarlicDestination : public i2p::data::LocalDestination {
        public:

            GarlicDestination();

            ~GarlicDestination();

            void CleanUp();

            void SetNumTags(int numTags) { m_NumTags = numTags; };

            int GetNumTags() const { return m_NumTags; };

            void SetNumRatchetInboundTags(int numTags) { m_NumRatchetInboundTags = numTags; };

            int GetNumRatchetInboundTags() const { return m_NumRatchetInboundTags; };

            std::shared_ptr<GarlicRoutingSession>
            GetRoutingSession(std::shared_ptr<const i2p::data::RoutingDestination> destination, bool attachLeaseSet);

            void CleanupExpiredTags();

            void RemoveDeliveryStatusSession(uint32_t msgID);

            std::shared_ptr<I2NPMessage> WrapMessageForRouter(std::shared_ptr<const i2p::data::RouterInfo> router,
                                                              std::shared_ptr<I2NPMessage> msg);

            void AddSessionKey(const uint8_t *key, const uint8_t *tag); // one tag
            void AddECIESx25519Key(const uint8_t *key, uint64_t tag); // one tag
            virtual bool SubmitSessionKey(const uint8_t *key, const uint8_t *tag); // from different thread
            virtual void SubmitECIESx25519Key(const uint8_t *key, uint64_t tag); // from different thread
            void DeliveryStatusSent(GarlicRoutingSessionPtr session, uint32_t msgID);

            uint64_t AddECIESx25519SessionNextTag(ReceiveRatchetTagSetPtr tagset);

            void AddECIESx25519Session(const uint8_t *staticKey, ECIESX25519AEADRatchetSessionPtr session);

            void RemoveECIESx25519Session(const uint8_t *staticKey);

            void HandleECIESx25519GarlicClove(const uint8_t *buf, size_t len);

            uint8_t *GetPayloadBuffer();

            virtual void ProcessGarlicMessage(std::shared_ptr<I2NPMessage> msg);

            virtual void ProcessDeliveryStatusMessage(std::shared_ptr<I2NPMessage> msg);

            virtual void SetLeaseSetUpdated();

            virtual std::shared_ptr<const i2p::data::LocalLeaseSet> GetLeaseSet() = 0; // TODO
            virtual std::shared_ptr<i2p::tunnel::TunnelPool> GetTunnelPool() const = 0;

        protected:

            void AddECIESx25519Key(const uint8_t *key, const uint8_t *tag); // one tag
            bool HandleECIESx25519TagMessage(uint8_t *buf, size_t len); // return true if found
            virtual void HandleI2NPMessage(const uint8_t *buf, size_t len) = 0; // called from clove only
            virtual bool
            HandleCloveI2NPMessage(I2NPMessageType typeID, const uint8_t *payload, size_t len, uint32_t msgID) = 0;

            void HandleGarlicMessage(std::shared_ptr<I2NPMessage> msg);

            void HandleDeliveryStatusMessage(uint32_t msgID);

            void SaveTags();

            void LoadTags();

        private:

            void HandleAESBlock(uint8_t *buf, size_t len, std::shared_ptr<AESDecryption> decryption,
                                std::shared_ptr<i2p::tunnel::InboundTunnel> from);

            void HandleGarlicPayload(uint8_t *buf, size_t len, std::shared_ptr<i2p::tunnel::InboundTunnel> from);

        private:

            // outgoing sessions
            int m_NumTags;
            std::mutex m_SessionsMutex;
            std::unordered_map<i2p::data::IdentHash, ElGamalAESSessionPtr> m_Sessions;
            std::unordered_map<i2p::data::Tag<32>, ECIESX25519AEADRatchetSessionPtr> m_ECIESx25519Sessions; // static key -> session
            uint8_t *m_PayloadBuffer; // for ECIESX25519AEADRatchet
            // incoming
            int m_NumRatchetInboundTags;
            std::unordered_map<SessionTag, std::shared_ptr<AESDecryption>, std::hash<i2p::data::Tag<32> > > m_Tags;
            std::unordered_map<uint64_t, ECIESX25519AEADRatchetIndexTagset> m_ECIESx25519Tags; // session tag -> session
            ReceiveRatchetTagSetPtr m_LastTagset; // tagset last message came for
            // DeliveryStatus
            std::mutex m_DeliveryStatusSessionsMutex;
            std::unordered_map<uint32_t, GarlicRoutingSessionPtr> m_DeliveryStatusSessions; // msgID -> session

        public:

            // for HTTP only
            size_t GetNumIncomingTags() const { return m_Tags.size(); }

            size_t GetNumIncomingECIESx25519Tags() const { return m_ECIESx25519Tags.size(); }

            const decltype(m_Sessions)
            &

            GetSessions() const { return m_Sessions; };
            const decltype(m_ECIESx25519Sessions)
            &

            GetECIESx25519Sessions() const { return m_ECIESx25519Sessions; }
        };

        void CleanUpTagsFiles();

    }
}

#endif