#include "socket/iocp.h"

#include "utils/thread_pool.h"

namespace Network {

IOCP::IOCP() {
  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::registerTCPSocket(Socket& sock, std::uint32_t bufsize) {
#ifdef _WIN32
  HANDLE returnData = ::CreateIoCompletionPort((HANDLE)sock.sock,
                                               completionPort_, sock.sock, 0);
  if (returnData == 0) completionPort_ = returnData;

  IOCPPASSINDATA* recv_data = new IOCPPASSINDATA(bufsize);
  recv_data->event = IOCPEVENT::READ;
  recv_data->socket = std::make_shared<Socket>(sock);
  recv_data->IOCPInstance = this;
  DWORD recvbytes = 0, flags = 0;

  int result = SOCKET_ERROR;

  result = ::WSARecv(recv_data->socket->sock, &recv_data->wsabuf, 1, &recvbytes,
                     &flags, &recv_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);
    }
  }

#endif
}

void IOCP::registerUDPSocket(IOCPPASSINDATA* data, Address recv_addr) {
#ifdef _WIN32
  HANDLE returnData = ::CreateIoCompletionPort(
      (HANDLE)data->socket->sock, completionPort_, data->socket->sock, 0);
  if (returnData == 0) completionPort_ = returnData;

  IOCPPASSINDATA* recv_data = new IOCPPASSINDATA(data->bufsize);
  recv_data->event = IOCPEVENT::READ;
  recv_data->socket = data->socket;
  DWORD recvbytes = 0, flags = 0;

  int result = SOCKET_ERROR;

  ::WSARecvFrom(recv_data->socket->sock, &recv_data->wsabuf, 1, &recvbytes,
                &flags, &recv_addr.addr, &recv_addr.length,
                &recv_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);
    }
  }

#endif
}

int IOCP::recv(Socket& sock, std::vector<char>& data) {
  std::lock_guard lock(*GetRecvQueueMutex_(sock.sock));
  auto queue = GetRecvQueue_(sock.sock);

  std::uint32_t left_data = data.size();
  std::uint32_t copied = 0;

  while (!queue->empty() && left_data != 0) {
    auto front = queue->front();
    queue->pop_front();

    std::uint32_t offset = front.second;
    std::uint32_t available = front.first.size() - offset;
    std::uint32_t to_copy = (left_data < available) ? left_data : available;

    ::memcpy(data.data() + copied, front.first.data() + offset, to_copy);
    copied += to_copy;
    left_data -= to_copy;
    offset += to_copy;

    if (offset < front.first.size()) {
      front.second = offset;
      queue->push_front(front);
      break;
    }
  }

  return copied;
}

int IOCP::send(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(data.size());
  packet->event = IOCPEVENT::WRITE;
  packet->socket = std::make_shared<Network::Socket>(sock);
  packet->IOCPInstance = this;
  ::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));
    delete data;
    IOCPThread->enqueueJob(
        [this](utils::ThreadPool* th, std::uint8_t __) { iocpWatcher_(th); },
        0);
    return;
  } else {
    data->transferredbytes = cbTransfrred;
  }

  std::vector<char> buf(16384);  // SSL_read최대 반환 크기
  int red_data = 0;
  std::lock_guard lock(*GetRecvQueueMutex_(sock));
  auto queue_list = GetRecvQueue_(sock);
  if (data->event == IOCPEVENT::READ) {
    ::memcpy(buf.data(), data->wsabuf.buf, data->transferredbytes);
    queue_list->emplace_back(std::make_pair(
        std::vector<char>(buf.begin(), buf.begin() + data->transferredbytes),
        0));
    DWORD recvbytes = 0, flags = 0;

    IOCPPASSINDATA* recv_data = new IOCPPASSINDATA(data->bufsize);
    recv_data->event = IOCPEVENT::READ;
    recv_data->socket = data->socket;

    delete data;
    ::WSARecv(recv_data->socket->sock, &recv_data->wsabuf, 1, &recvbytes,
              &flags, &recv_data->overlapped, NULL);
  } else {  // WRITE 시, 무시한다.
    spdlog::debug("writed {} bytes to {}", cbTransfrred,
                  (std::string)(data->socket->remoteAddr));
    delete data;
  }
  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