/*
* 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 ADDRESS_BOOK_H__
#define ADDRESS_BOOK_H__

#include <string.h>
#include <string>
#include <map>
#include <vector>
#include <iostream>
#include <mutex>
#include <memory>
#include <boost/asio.hpp>
#include "Base.h"
#include "Identity.h"
#include "Log.h"
#include "Destination.h"
#include "LeaseSet.h"

namespace i2p {
    namespace client {
        const int INITIAL_SUBSCRIPTION_UPDATE_TIMEOUT = 3; // in minutes
        const int INITIAL_SUBSCRIPTION_RETRY_TIMEOUT = 1; // in minutes
        const int CONTINIOUS_SUBSCRIPTION_UPDATE_TIMEOUT = 720; // in minutes (12 hours)
        const int CONTINIOUS_SUBSCRIPTION_RETRY_TIMEOUT = 5; // in minutes
        const int CONTINIOUS_SUBSCRIPTION_MAX_NUM_RETRIES = 10; // then update timeout
        const int SUBSCRIPTION_REQUEST_TIMEOUT = 120; //in second

        const uint16_t ADDRESS_RESOLVER_DATAGRAM_PORT = 53;
        const uint16_t ADDRESS_RESPONSE_DATAGRAM_PORT = 54;

        const size_t B33_ADDRESS_THRESHOLD = 52; // characters

        struct Address {
            enum {
                eAddressIndentHash, eAddressBlindedPublicKey, eAddressInvalid
            } addressType;
            i2p::data::IdentHash identHash;
            std::shared_ptr <i2p::data::BlindedPublicKey> blindedPublicKey;

            Address(const std::string &b32);

            Address(const i2p::data::IdentHash &hash);

            bool IsIdentHash() const { return addressType == eAddressIndentHash; };

            bool IsValid() const { return addressType != eAddressInvalid; };
        };

        inline std::string GetB32Address(const i2p::data::IdentHash &ident) {
            return ident.ToBase32().append(".b32.i2p");
        }

        class AddressBookStorage // interface for storage
        {
        public:

            virtual ~AddressBookStorage() {};

            virtual std::shared_ptr<const i2p::data::IdentityEx>
            GetAddress(const i2p::data::IdentHash &ident) const = 0;

            virtual void AddAddress(std::shared_ptr<const i2p::data::IdentityEx> address) = 0;

            virtual void RemoveAddress(const i2p::data::IdentHash &ident) = 0;

            virtual bool Init() = 0;

            virtual int Load(std::map <std::string, std::shared_ptr<Address>> &addresses) = 0;

            virtual int LoadLocal(std::map <std::string, std::shared_ptr<Address>> &addresses) = 0;

            virtual int Save(const std::map <std::string, std::shared_ptr<Address>> &addresses) = 0;

            virtual void SaveEtag(const i2p::data::IdentHash &subscription, const std::string &etag,
                                  const std::string &lastModified) = 0;

            virtual bool
            GetEtag(const i2p::data::IdentHash &subscription, std::string &etag, std::string &lastModified) = 0;

            virtual void ResetEtags() = 0;
        };

        class AddressBookSubscription;

        class AddressResolver;

        class AddressBook {
        public:

            AddressBook();

            ~AddressBook();

            void Start();

            void StartResolvers();

            void Stop();

            std::shared_ptr<const Address> GetAddress(const std::string &address);

            std::shared_ptr<const i2p::data::IdentityEx> GetFullAddress(const std::string &address);

            std::shared_ptr<const Address> FindAddress(const std::string &address);

            void LookupAddress(const std::string &address);

            void InsertAddress(const std::string &address, const std::string &jump); // for jump links
            void InsertFullAddress(std::shared_ptr<const i2p::data::IdentityEx> address);

            bool LoadHostsFromStream(std::istream &f, bool is_update);

            void DownloadComplete(bool success, const i2p::data::IdentHash &subscription, const std::string &etag,
                                  const std::string &lastModified);

            //This method returns the ".b32.i2p" address
            std::string ToAddress(const i2p::data::IdentHash &ident) { return GetB32Address(ident); }

            std::string ToAddress(std::shared_ptr<const i2p::data::IdentityEx> ident) {
                return ToAddress(ident->GetIdentHash());
            }

            bool GetEtag(const i2p::data::IdentHash &subscription, std::string &etag, std::string &lastModified);

        private:

            void StartSubscriptions();

            void StopSubscriptions();

            void LoadHosts();

            void LoadSubscriptions();

            void LoadLocal();

            void HandleSubscriptionsUpdateTimer(const boost::system::error_code &ecode);

            void StartLookups();

            void StopLookups();

            void HandleLookupResponse(const i2p::data::IdentityEx &from, uint16_t fromPort, uint16_t toPort,
                                      const uint8_t *buf, size_t len);

        private:

            std::mutex m_AddressBookMutex;
            std::map <std::string, std::shared_ptr<Address>> m_Addresses;
            std::map <i2p::data::IdentHash, std::shared_ptr<AddressResolver>> m_Resolvers; // local destination->resolver
            std::mutex m_LookupsMutex;
            std::map <uint32_t, std::string> m_Lookups; // nonce -> address
            AddressBookStorage *m_Storage;
            volatile bool m_IsLoaded, m_IsDownloading;
            int m_NumRetries;
            std::vector <std::shared_ptr<AddressBookSubscription>> m_Subscriptions;
            std::shared_ptr <AddressBookSubscription> m_DefaultSubscription; // in case if we don't know any addresses yet
            boost::asio::deadline_timer *m_SubscriptionsUpdateTimer;
            bool m_IsEnabled;
        };

        class AddressBookSubscription {
        public:

            AddressBookSubscription(AddressBook &book, const std::string &link);

            void CheckUpdates();

        private:

            bool MakeRequest();

        private:

            AddressBook &m_Book;
            std::string m_Link, m_Etag, m_LastModified;
            i2p::data::IdentHash m_Ident;
            // m_Etag must be surrounded by ""
        };

        class AddressResolver {
        public:

            AddressResolver(std::shared_ptr <ClientDestination> destination);

            ~AddressResolver();

            void AddAddress(const std::string &name, const i2p::data::IdentHash &ident);

        private:

            void
            HandleRequest(const i2p::data::IdentityEx &from, uint16_t fromPort, uint16_t toPort, const uint8_t *buf,
                          size_t len);

        private:

            std::shared_ptr <ClientDestination> m_LocalDestination;
            std::map <std::string, i2p::data::IdentHash> m_LocalAddresses;
        };
    }
}

#endif