#include "../include/Database.hpp"
#include "../include/Group.hpp"
#include "../include/User.hpp"
#include <opendht.h>
#include <fmt/format.h>
#include <sodium/crypto_box_curve25519xchacha20poly1305.h>
#include <thread>
#include <chrono>
#include <sibs/SafeSerializer.hpp>
#include <sibs/SafeDeserializer.hpp>
#include <cassert>

using namespace dht;
using namespace std;
using namespace chrono_literals;

static int databaseCount = 0;
// TODO: Verify time_t is always signed
static time_t timeOffset = 0; // Updated by comparing local time with ntp server
static thread *ntpThread = nullptr;
static bool timestampSynced = false;
static InfoHash CREATE_DATA_HASH = InfoHash::get("__odhtdb__.create_data");
static InfoHash ADD_DATA_HASH = InfoHash::get("__odhtdb__.add_data");

#define OPENDHT_INFOHASH_LEN 20

namespace odhtdb
{
    Database::Database(const char *bootstrapNodeAddr, u16 port)
    {
        node.run(port, dht::crypto::generateIdentity(), true);
        fmt::MemoryWriter portStr;
        portStr << port;
        node.bootstrap(bootstrapNodeAddr, portStr.c_str());

        // TODO: Make this work for multiple threads initializing database at same time
        ++databaseCount;
        if(databaseCount == 1)
        {
            if(ntpThread)
                delete ntpThread;

            ntpThread = new thread([]()
            {
                ntp::NtpClient ntpClient("pool.ntp.org");
                while(databaseCount > 0)
                {
                    ntp::NtpTimestamp ntpTimestamp = ntpClient.getTimestamp();
                    timeOffset = time(nullptr) - ntpTimestamp.seconds;
                    timestampSynced = true;
                    // TODO: Also use timestamp fraction (milliseconds)
                    this_thread::sleep_for(60s);
                }
                timestampSynced = false;
            });

            // TODO: Catch std::system_error instead of this if-statement
            if(ntpThread->joinable())
                ntpThread->detach();
        }

        while(!timestampSynced)
        {
            this_thread::sleep_for(10ms);
        }
    }

    Database::~Database()
    {
        // TODO: Make this work for multiple threads removing database object at same time
        --databaseCount;
        node.join();
    }

    void Database::seed()
    {
        // TODO: Use cached files and seed those. If none exists, request new files to seed.
        // If nobody requests my cached files in a long time, request new files to seed and remove cached files
        // (only if there are plenty of other seeders for the cached files. This could also cause race issue 
        // where all nodes with a cached file delete it at same time)

        using std::placeholders::_1;
        node.listen(CREATE_DATA_HASH, bind(&Database::listenCreateData, this, _1));
        node.listen(ADD_DATA_HASH, bind(&Database::listenAddData, this, _1));
    }

    void Database::create(const Key &key, Group *primaryAdminGroup)
    {
        // TODO: Append fractions to get real microseconds time
        u64 timeMicroseconds = ((u64)getSyncedTimestampUtc().seconds) * 1000000ull;
        stagedCreateObjects.emplace_back(StagedCreateObject(key, primaryAdminGroup, timeMicroseconds));
    }

    void Database::add(const Key &key, DataView data)
    {
        // TODO: Append fractions to get real microseconds time
        u64 timeMicroseconds = ((u64)getSyncedTimestampUtc().seconds) * 1000000ull;
        stagedAddObjects.emplace_back(StagedAddObject(key, data, timeMicroseconds));
    }

    void Database::commit()
    {
        // TODO: Combine staged objects into one object for efficiency.
        // TODO: Add rollback

        for(StagedCreateObject &stagedObject : stagedCreateObjects)
        {
            commitStagedCreateObject(stagedObject);
        }
        stagedCreateObjects.clear();

        for(StagedAddObject &stagedObject : stagedAddObjects)
        {
            commitStagedAddObject(stagedObject);
        }
        stagedAddObjects.clear();
    }

    void Database::commitStagedCreateObject(const StagedCreateObject &stagedObject)
    {
        // TODO: Use (ed25519 or poly1305) and curve25519
        // TODO: Implement gas and price (refill when serving content (seeding) or by waiting. This is done to prevent spamming and bandwidth leeching)
        sibs::SafeSerializer serializer;
        assert(stagedObject.key.hashedKey.size() == OPENDHT_INFOHASH_LEN);
        serializer.add(stagedObject.key.hashedKey.data(), stagedObject.key.hashedKey.size());
        serializer.add(stagedObject.timestamp);
        serializer.add((u8)stagedObject.primaryAdminGroup->getName().size());
        serializer.add((u8*)stagedObject.primaryAdminGroup->getName().data(), stagedObject.primaryAdminGroup->getName().size());
        serializer.add((u32)stagedObject.primaryAdminGroup->getUsers().size());
        for(User *user : stagedObject.primaryAdminGroup->getUsers())
        {
            serializer.add((u8)user->getName().size());
            serializer.add((u8*)user->getName().data(), user->getName().size());
        }
        
        // TODO: Verify if serializer buffer needs to survive longer than this scope
        Value value(serializer.getBuffer().data(), serializer.getBuffer().size());
        node.put(CREATE_DATA_HASH, move(value), [](bool ok)
        {
            // TODO: Handle failure to put data
            if(!ok)
                fprintf(stderr, "Failed to put: %s, what to do?\n", "commitStagedCreateObject");
        }, time_point(), false);
    }

    void Database::commitStagedAddObject(const StagedAddObject &stagedObject)
    {
        // TODO: Use (ed25519 or poly1305) and curve25519
        // TODO: Implement gas and price (refill when serving content (seeding) or by waiting. This is done to prevent spamming and bandwidth leeching)
        sibs::SafeSerializer serializer;
        assert(stagedObject.key.hashedKey.size() == OPENDHT_INFOHASH_LEN);
        serializer.add(stagedObject.key.hashedKey.data(), stagedObject.key.hashedKey.size());
        serializer.add(stagedObject.timestamp);
        serializer.add((u8*)stagedObject.data.data, stagedObject.data.size);

        // TODO: Verify if serializer buffer needs to survive longer than this scope
        Value value(serializer.getBuffer().data(), serializer.getBuffer().size());
        node.put(ADD_DATA_HASH, move(value), [](bool ok)
        {
            // TODO: Handle failure to put data
            if(!ok)
                fprintf(stderr, "Failed to put: %s, what to do?\n", "commitStagedAddObject");
        }, time_point(), false);
    }

    ntp::NtpTimestamp Database::getSyncedTimestampUtc() const
    {
        assert(timestampSynced);
        ntp::NtpTimestamp timestamp;
        timestamp.seconds = time(nullptr) - timeOffset;
        timestamp.fractions = 0; // TODO: Set this
        return timestamp;
    }

    StagedCreateObject Database::deserializeCreateRequest(const std::shared_ptr<dht::Value> &value)
    {
        StagedCreateObject result;

        sibs::SafeDeserializer deserializer(value->data.data(), value->data.size());
        u8 entryKeyRaw[OPENDHT_INFOHASH_LEN];
        deserializer.extract(entryKeyRaw, OPENDHT_INFOHASH_LEN);
        result.key.hashedKey = InfoHash(entryKeyRaw, OPENDHT_INFOHASH_LEN);
        result.timestamp = deserializer.extract<u64>();

        return result;
    }

    StagedAddObject Database::deserializeAddRequest(const std::shared_ptr<dht::Value> &value)
    {
        StagedAddObject result;

        sibs::SafeDeserializer deserializer(value->data.data(), value->data.size());
        u8 entryKeyRaw[OPENDHT_INFOHASH_LEN];
        deserializer.extract(entryKeyRaw, OPENDHT_INFOHASH_LEN);
        result.key.hashedKey = InfoHash(entryKeyRaw, OPENDHT_INFOHASH_LEN);
        result.timestamp = deserializer.extract<u64>();

        return result;
    }

    bool Database::listenCreateData(const std::vector<std::shared_ptr<dht::Value>> &values)
    {
        for(const shared_ptr<Value> &value : values)
        {
            try
            {
                StagedCreateObject createObject = deserializeCreateRequest(value);
            }
            catch (sibs::DeserializeException &e)
            {
                fprintf(stderr, "Warning: Failed to deserialize 'create' request: %s\n", e.what());
            }
        }
        return true;
    }

    bool Database::listenAddData(const std::vector<std::shared_ptr<dht::Value>> &values)
    {
        for(const shared_ptr<Value> &value : values)
        {
            try
            {
                StagedAddObject addObject = deserializeAddRequest(value);
            }
            catch (sibs::DeserializeException &e)
            {
                fprintf(stderr, "Warning: Failed to deserialize 'add' request: %s\n", e.what());
            }
        }
        return true;
    }
}