#include "socket/iocp.h"

#include "utils/thread_pool.h"

namespace Network {

IOCP::IOCP() : IOCPThread_(nullptr), proto_(SessionProtocol::TCP) {
  gen_ = std::mt19937(rd_());
  jitterDist_ = std::uniform_int_distribution<int>(-10, 10);
}

IOCP::~IOCP() { destruct(); }

void IOCP::init(utils::ThreadPool* __IOCPThread, SessionProtocol proto) {
  IOCPThread_ = __IOCPThread;
  proto_ = proto;

#ifdef _WIN32
  completionPort_ = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);
  if (completionPort_ == NULL) {
    spdlog::critical("CreateIoCompletionPort()");
    std::exit(EXIT_FAILURE);
  }
  int tCount = __IOCPThread->threadCount;

  spdlog::info("Resizing threadpool size to: {}", tCount * 2);

  __IOCPThread->respawnWorker(tCount * 2);

  for (int i = 0; i < tCount; i++)
    IOCPThread_->enqueueJob(
        [this](utils::ThreadPool* th, std::uint8_t __) { iocpWatcher_(th); },
        0);
#endif
}

void IOCP::destruct() {
#ifdef __linux__

#endif
}

void IOCP::registerSocket(std::shared_ptr<Socket> sock) {
#ifdef _WIN32
  HANDLE returnData = ::CreateIoCompletionPort((HANDLE)sock->sock,
                                               completionPort_, sock->sock, 0);
  if (returnData == 0) completionPort_ = returnData;
#endif
}

std::future<std::vector<char>> IOCP::recvFull(std::shared_ptr<Socket> sock,
                                              std::uint32_t bufsize) {
  auto promise = std::make_shared<std::promise<std::vector<char>>>();
  auto future = promise->get_future();

  auto buffer = std::make_shared<std::vector<char>>();
  buffer->reserve(bufsize);

  std::function<void(std::uint32_t)> recvChunk;
  recvChunk = [=](std::uint32_t remaining) mutable {
    this->recv(sock, remaining,
               [=](utils::ThreadPool* th, IOCPPASSINDATA* data) {
                 buffer->insert(buffer->end(), data->wsabuf.buf,
                                data->wsabuf.buf + data->transferredbytes);

                 std::uint32_t still_left =
                     bufsize - static_cast<std::uint32_t>(buffer->size());
                 if (still_left > 0) {
                   recvChunk(still_left);
                 } else {
                   promise->set_value(std::move(*buffer));
                 }

                 return std::list<char>();
               });
  };

  recvChunk(bufsize);

  return future;
}

std::list<char> DEFAULT_RECVALL_CALLBACK(utils::ThreadPool* th,
                                         IOCPPASSINDATA* data) {
  std::list<char> return_value;
  return_value.insert(return_value.end(), data->wsabuf.buf,
                      data->wsabuf.buf + data->transferredbytes);

  if (data->transferredbytes < data->wsabuf.len) {
    auto future = data->IOCPInstance->recv(
        data->socket, data->wsabuf.len - data->transferredbytes,
        DEFAULT_RECVALL_CALLBACK);
    auto result = future.get();
    return_value.insert(return_value.end(), result.begin(), result.end());
  }

  return return_value;
}

std::future<std::list<char>> IOCP::recv(
    std::shared_ptr<Socket> sock, std::uint32_t bufsize,
    std::function<std::list<char>(utils::ThreadPool*, IOCPPASSINDATA*)>
        callback) {
  std::lock_guard lock(*GetRecvQueueMutex(sock->sock));
  auto queue = GetRecvQueue(sock->sock);

  Network::IOCPPASSINDATA* data;
  std::packaged_task<std::list<char>(utils::ThreadPool*, IOCPPASSINDATA*)> task;
  std::future<std::list<char>> future;
  if (callback != nullptr) {
    task = std::packaged_task<std::list<char>(utils::ThreadPool*,
                                              IOCPPASSINDATA*)>(callback);
    future = task.get_future();
    data = new Network::IOCPPASSINDATA(sock, bufsize, this, std::move(task));
  } else {
    data = new Network::IOCPPASSINDATA(sock, bufsize, this);
  }

  int result = SOCKET_ERROR;
  DWORD recvbytes = 0, flags = 0;
  result = ::WSARecv(sock->sock, &data->wsabuf, 1, &recvbytes, &flags,
                     &data->overlapped, NULL);
  if (result == SOCKET_ERROR) {
    int err = ::WSAGetLastError();
    if (err != WSA_IO_PENDING) {
      auto err_msg = std::format("WSARecv failed: {}", err);
      throw std::runtime_error(err_msg);
    }
  }

  return future;
}

int IOCP::send(std::shared_ptr<Socket> sock, std::vector<char>& data) {
  auto lk = GetSendQueueMutex(sock->sock);
  auto queue = GetSendQueue(sock->sock);
  std::lock_guard lock(*lk);

  Network::IOCPPASSINDATA* packet = new Network::IOCPPASSINDATA(sock, data.size(), this);
  packet->event = IOCPEVENT::WRITE;
  ::memcpy(packet->wsabuf.buf, data.data(), data.size());
  packet->wsabuf.len = data.size();
  queue->push_back(packet);

  IOCPThread_->enqueueJob(
      [this, sock = sock->sock](utils::ThreadPool* th, std::uint8_t __) {
        packet_sender_(sock);
      },
      0);
  return 0;
}

int IOCP::GetRecvedBytes(SOCKET sock) {
  auto queue = GetRecvQueue(sock);
  std::lock_guard lock(socket_mod_mutex_);

  int bytes = 0;
  for (auto it : *queue) {
    bytes += it.first.size() - it.second;
  }

  return bytes;
}

void IOCP::iocpWatcher_(utils::ThreadPool* IOCPThread) {
  IOCPPASSINDATA* data;
  SOCKET sock;
  DWORD cbTransfrred;
  int jitter = jitterDist_(gen_);
  int retVal = GetQueuedCompletionStatus(completionPort_, &cbTransfrred,
                                         (PULONG_PTR)&sock,
                                         (LPOVERLAPPED*)&data, 1000 + jitter);

  if (retVal == 0 || cbTransfrred == 0) {
    DWORD lasterror = GetLastError();
    if (lasterror == WAIT_TIMEOUT) {
      IOCPThread->enqueueJob(
          [this](utils::ThreadPool* th, std::uint8_t __) { iocpWatcher_(th); },
          0);
      return;
    }
    data->event = IOCPEVENT::QUIT;
    spdlog::debug("Disconnected. [{}]",
                  (std::string)(data->socket->remoteAddr));
    auto task = [this, IOCPThread, data = std::move(data)](
                    utils::ThreadPool* th, std::uint8_t __) {
      if (data->callback.valid()) {
        data->callback(th, data);
      }
      data->socket->destruct();
      delete data;
    };
    IOCPThread->enqueueJob(task, 0);
    IOCPThread->enqueueJob(
        [this](utils::ThreadPool* th, std::uint8_t __) { iocpWatcher_(th); },
        0);
    return;
  } else {
    data->transferredbytes = cbTransfrred;
  }

  auto task = [this, IOCPThread, data = std::move(data)](utils::ThreadPool* th,
                                                         std::uint8_t __) {
    if (data->callback.valid()) data->callback(th, data);
    delete data;
  };
  IOCPThread->enqueueJob(task, 0);
  IOCPThread->enqueueJob(
      [this](utils::ThreadPool* th, std::uint8_t __) { iocpWatcher_(th); }, 0);
}

std::shared_ptr<std::list<IOCPPASSINDATA*>> IOCP::GetSendQueue(SOCKET sock) {
  std::lock_guard lock(socket_mod_mutex_);
  if (send_queue_.find(sock) == send_queue_.end()) {
    send_queue_[sock] = std::make_shared<std::list<IOCPPASSINDATA*>>(
        std::list<IOCPPASSINDATA*>());
  }
  return send_queue_[sock];
}

std::shared_ptr<std::list<std::pair<std::vector<char>, std::uint32_t>>>
IOCP::GetRecvQueue(SOCKET sock) {
  std::lock_guard lock(socket_mod_mutex_);
  if (recv_queue_.find(sock) == recv_queue_.end()) {
    recv_queue_[sock] = std::make_shared<
        std::list<std::pair<std::vector<char>, std::uint32_t>>>(
        std::list<std::pair<std::vector<char>, std::uint32_t>>());
  }
  return recv_queue_[sock];
}

std::shared_ptr<std::mutex> IOCP::GetSendQueueMutex(SOCKET sock) {
  std::lock_guard lock(socket_mod_mutex_);
  if (send_queue_mutex_.find(sock) == send_queue_mutex_.end()) {
    send_queue_mutex_[sock] = std::make_shared<std::mutex>();
  }
  return send_queue_mutex_[sock];
}

std::shared_ptr<std::mutex> IOCP::GetRecvQueueMutex(SOCKET sock) {
  std::lock_guard lock(socket_mod_mutex_);
  if (recv_queue_mutex_.find(sock) == recv_queue_mutex_.end()) {
    recv_queue_mutex_[sock] = std::make_shared<std::mutex>();
  }
  return recv_queue_mutex_[sock];
}

void IOCP::packet_sender_(SOCKET sock) {
  auto queue = GetSendQueue(sock);
  std::unique_lock lock(*GetSendQueueMutex(sock));

  std::vector<char> buf(16384);
  WSABUF wsabuf;
  DWORD sendbytes = 0;

  while (!queue->empty()) {
    auto front = queue->front();
    queue->pop_front();
    front->event = IOCPEVENT::WRITE;

    int data_len = 0;

    data_len = front->wsabuf.len;
    wsabuf.buf = front->wsabuf.buf;
    wsabuf.len = data_len;
    ::WSASend(sock, &wsabuf, 1, &sendbytes, 0, nullptr, nullptr);
  }
}

}  // namespace Network