#include "../include/sibs/BootstrapConnection.hpp"
#include "../include/Log.hpp"
#include <sibs/SafeDeserializer.hpp>
#include <chrono>
#include <unordered_set>

namespace chrono = std::chrono;

namespace sibs
{
    BootstrapConnection::BootstrapConnection(const Ipv4 &bootstrapAddress) : 
        alive(true),
        putThreadCount(0)
    {
        connections.onRemoveDisconnectedPeer([this](std::shared_ptr<DirectConnectionPeer> peer)
        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            for(auto &it : subscribeData)
            {
                for(auto subscribedPeersIt = it.second.peers.begin(), end = it.second.peers.end();
                    subscribedPeersIt != end;
                    ++subscribedPeersIt)
                {
                    if(peer->address == (*subscribedPeersIt)->address)
                    {
                        it.second.peers.erase(subscribedPeersIt);
                        break;
                    }
                }
            }
        });

        PubSubResult connectResult = PubSubResult::OK;
        std::string connectResultStr;
        bool connected = false;
        connections.connectServer(bootstrapAddress, [this, &connectResult, &connectResultStr, &connected](std::shared_ptr<DirectConnectionPeer> peer, PubSubResult result, const std::string &resultStr)
        {
            serverPeer = peer;
            connectResult = result;
            connectResultStr = resultStr;
            connected = true;
        }, std::bind(&BootstrapConnection::receiveDataFromServer, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4));
        
        while(!connected)
        {
            std::this_thread::sleep_for(std::chrono::milliseconds(10));
        }
        
        if(connectResult != PubSubResult::OK)
        {
            std::string errMsg = "Failed to connect to bootstrap node, error: ";
            errMsg += connectResultStr;
            throw BootstrapConnectionException(errMsg);
        }
    }

    BootstrapConnection::~BootstrapConnection()
    {
        alive = false;
        while(putThreadCount > 0)
        {
            std::this_thread::sleep_for(std::chrono::milliseconds(100));
        }
    }
    
    // TODO: This is vulnerable against MitM attack, replace with asymmetric cryptography, get data signed with server private key and verify against known server public key
    void BootstrapConnection::receiveDataFromServer(std::shared_ptr<DirectConnectionPeer> peer, MessageType messageType, const void *data, const usize size)
    {
        if(messageType != MessageType::SUBSCRIBE)
        {
            Log::warn("BootstrapConnection::receiveDataFromServer: received message from server that was not subscribe");
            return;
        }

        Log::debug("BootstrapConnection::receiveDataFromServer: Received subscriber(s) from bootstrap node");
        sibs::SafeDeserializer deserializer((const u8*)data, size);
        PubsubKey pubsubKey;
        deserializer.extract(pubsubKey.data.data(), PUBSUB_KEY_LENGTH);
        
        // we want lock to live this whole scope so we dont connect to peer when cancelListen is called
        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            auto subscribeDataIt = subscribeData.find(pubsubKey);
            if(subscribeDataIt == subscribeData.end())
            {
                Log::debug("BootstrapConnection::receiveDataFromServer: No listener found for key '%s', ignoring...", pubsubKey.toString().c_str());
                return;
            }
        }
        
        while(!deserializer.empty())
        {
            sa_family_t addressFamily = deserializer.extract<u16>();
            if(addressFamily == AF_INET)
            {
                in_addr_t ipv4Address = deserializer.extract<u32>();
                u16 port = deserializer.extract<u16>();
                Ipv4 newPeerAddress;
                newPeerAddress.address.sin_family = addressFamily;
                newPeerAddress.address.sin_addr.s_addr = ipv4Address;
                newPeerAddress.address.sin_port = port;
                memset(newPeerAddress.address.sin_zero, 0, sizeof(newPeerAddress.address.sin_zero));
                Log::debug("BootstrapConnection::receiveDataFromServer: received subscriber (ip: %s, port: %d) from bootstrap node", newPeerAddress.getAddress().c_str(), newPeerAddress.getPort());
                connections.connect(newPeerAddress, [this, pubsubKey](std::shared_ptr<DirectConnectionPeer> peer, PubSubResult result, const std::string &resultStr)
                {
                    if(result == PubSubResult::OK)
                    {
                        std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
                        auto subscribeDataIt = subscribeData.find(pubsubKey);
                        if(subscribeDataIt == subscribeData.end())
                        {
                            Log::warn("BootstrapConnection::receiveDataFromServer: No listener found for key '%s', ignoring...", pubsubKey.toString().c_str());
                            return;
                        }
                        subscribeDataIt->second.peers.push_back(peer);
                        ++peer->sharedKeys;
                        Log::debug("BootstrapConnection::receiveDataFromServer: Connected to peer (ip: %s, port: %d) given by bootstrap node", peer->address.getAddress().c_str(), peer->address.getPort());
                    }
                    else
                        Log::error("BootstrapConnection::receiveDataFromServer: Failed to connect to peer given by bootstrap node, error: %s", resultStr.c_str());
                }, std::bind(&BootstrapConnection::receiveDataFromPeer, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4));
            }
            else
            {
                Log::error("BootstrapConnection::receiveDataFromServer: Unknown address family: %d", addressFamily);
                return;
            }
        }
    }
    
    void BootstrapConnection::receiveDataFromPeer(std::shared_ptr<DirectConnectionPeer> peer, MessageType messageType, const void *data, const usize size)
    {
        if(size < PUBSUB_KEY_LENGTH)
            return;

        PubsubKey pubsubKey;
        memcpy(pubsubKey.data.data(), data, PUBSUB_KEY_LENGTH);
        if(messageType == MessageType::DATA)
        {
            subscribeDataMutex.lock();
            auto listenerFuncIt = subscribeData.find(pubsubKey);
            if(listenerFuncIt == subscribeData.end())
            {
                subscribeDataMutex.unlock();
                Log::debug("BootstrapConnection::receiveDataFromPeer: No listener found for key '%s', ignoring...", pubsubKey.toString().c_str());
                return;
            }
            auto listenCallbackFunc = listenerFuncIt->second.listenCallbackFunc;
            subscribeDataMutex.unlock();

            if(listenCallbackFunc)
            {
                bool continueListening = listenCallbackFunc(peer.get(), (const u8*)data + PUBSUB_KEY_LENGTH, size - PUBSUB_KEY_LENGTH);
                if(!continueListening)
                    cancelListen({ pubsubKey });
            }
        }
        else if(messageType == MessageType::UNSUBSCRIBE)
        {
            Log::debug("BootstrapConnection::receiveDataFromPeer: peer (ip: %s, port: %d) unsubscribed from key '%s'", peer->address.getAddress().c_str(), peer->address.getPort(), pubsubKey.toString().c_str());
            std::lock_guard<std::recursive_mutex> subscribersMutex(subscribeDataMutex);
            auto peersListIt = subscribeData.find(pubsubKey);
            if(peersListIt == subscribeData.end())
                return;

            for(auto it = peersListIt->second.peers.begin(); it != peersListIt->second.peers.end(); ++it)
            {
                auto existingPeer = *it;
                if(*existingPeer == *peer)
                {
                    peersListIt->second.peers.erase(it);
                    --peer->sharedKeys;
                    if(peer->sharedKeys <= 0)
                        connections.removePeer(peer->socket->udtSocket);
                    break;
                }
            }
        }
        else
        {
            Log::warn("BootstrapConnection::receiveDataFromPeer: received message from peer that was not data or unsubscribe");
        }
    }

    ListenHandle BootstrapConnection::listen(const PubsubKey &pubsubKey, BoostrapConnectionListenCallbackFunc callbackFunc, bool registerCallbackFunc)
    {
        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            auto it = subscribeData.find(pubsubKey);
            if(it != subscribeData.end())
            {
                Log::warn("BootstrapConnection::listen called on existing listener, overwriting callback function");
                if(registerCallbackFunc)
                    it->second.listenCallbackFunc = callbackFunc;
                return { pubsubKey };
            }
            auto &data = subscribeData[pubsubKey];
            if(registerCallbackFunc)
                data.listenCallbackFunc = callbackFunc;
            data.listenStartTimeMs = chrono::duration_cast<chrono::milliseconds>(chrono::system_clock::now().time_since_epoch()).count();
        }

        auto message = std::make_shared<Message>(MessageType::SUBSCRIBE);
        message->append(pubsubKey.data.data(), pubsubKey.data.size());
        Log::debug("BootstrapConnection::listen: starting to listen to %s", pubsubKey.toString().c_str());
        connections.send(serverPeer, message, [](PubSubResult result, const std::string &resultStr)
        {
            Log::debug("BootstrapConnection::listen: PubSubResult: %d, result string: %s", result, resultStr.c_str());
        });

        return { pubsubKey };
    }
    
    ListenHandle BootstrapConnection::listen(const PubsubKey &pubsubKey, BoostrapConnectionListenCallbackFunc callbackFunc)
    {
        return listen(pubsubKey, callbackFunc, true);
    }
    
    bool BootstrapConnection::put(const PubsubKey &pubsubKey, const void *data, const usize size)
    {
        if(size > 819200) // 800kb
            return false;

        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            auto listenCallbackFuncIt = subscribeData.find(pubsubKey);
            if(listenCallbackFuncIt != subscribeData.end() && listenCallbackFuncIt->second.listenCallbackFunc)
                listenCallbackFuncIt->second.listenCallbackFunc(nullptr, data, size);

            if(listenCallbackFuncIt == subscribeData.end())
            {
                Log::warn("BootstrapConnection::put on key '%s' which we are not listening to, automatically listening now", pubsubKey.toString().c_str());
                listen(pubsubKey, nullptr, false);
            }
        }
        
        auto message = std::make_shared<Message>(MessageType::DATA);
        message->append(pubsubKey.data.data(), pubsubKey.data.size());
        message->append(data, size);
        std::thread([this, pubsubKey, message]()
        {
            ++putThreadCount;
            std::unordered_set<int> peersMessaged;
            std::vector<std::shared_ptr<DirectConnectionPeer>> peersToMessage;
            i64 listenStartTimeMs = 0;
            while(alive)
            {
                {
                    std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
                    auto subscribeIt = subscribeData.find(pubsubKey);
                    if(subscribeIt == subscribeData.end())
                    {
                        Log::warn("BootstrapConnection::put with no subscribers on same key '%s'", pubsubKey.toString().c_str());
                        std::this_thread::sleep_for(std::chrono::milliseconds(200));
                        goto checkPutAttemptDuration;
                    }

                    listenStartTimeMs = subscribeIt->second.listenStartTimeMs;
                    
                    for(auto &peer : subscribeIt->second.peers)
                    {
                        if(peersMessaged.find(peer->socket->udtSocket) == peersMessaged.end())
                        {
                            peersToMessage.push_back(peer);
                            peersMessaged.insert(peer->socket->udtSocket);
                        }
                    }
                }

                if(!peersToMessage.empty())
                {
                    for(auto &peer : peersToMessage)
                    {
                        connections.send(peer, message);
                    }
                    peersToMessage.clear();
                }
                
                checkPutAttemptDuration:
                const i64 half_min_ms = 1000 * 30;
                i64 now = chrono::duration_cast<chrono::milliseconds>(chrono::system_clock::now().time_since_epoch()).count();
                if(now - listenStartTimeMs > half_min_ms)
                    break;
                
                std::this_thread::sleep_for(std::chrono::milliseconds(200));
            }
            --putThreadCount;
        }).detach();
        return true;
    }

    bool BootstrapConnection::cancelListen(const ListenHandle &listener)
    {
        std::vector<std::shared_ptr<DirectConnectionPeer>> peersToMessage;
        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            auto it = subscribeData.find(listener.key);
            if(it == subscribeData.end())
                return false;

            peersToMessage = it->second.peers;
        }

        auto message = std::make_shared<Message>(MessageType::UNSUBSCRIBE);
        message->append(listener.key.data.data(), listener.key.data.size());
        connections.send(serverPeer, message);

        for(auto &peer : peersToMessage)
        {
            --peer->sharedKeys;
            if(peer->sharedKeys <= 0)
            {
                // disconnect from peer
                connections.removePeer(peer->socket->udtSocket);
            }
            else
            {
                // unsubscribe from peers request, even if they dont accept it we wont listen to messages from the key anymore
                connections.send(peer, message);
            }
        }

        {
            std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
            auto it = subscribeData.find(listener.key);
            if(it != subscribeData.end())
                subscribeData.erase(it);
        }
        return true;
    }

    bool BootstrapConnection::areWeListeningOnKey(const PubsubKey &pubsubKey)
    {
        std::lock_guard<std::recursive_mutex> lock(subscribeDataMutex);
        return subscribeData.find(pubsubKey) != subscribeData.end();
    }

    std::vector<std::shared_ptr<DirectConnectionPeer>> BootstrapConnection::getPeers()
    {
        return connections.getPeers();
    }
}