#include <vector>
#ifdef _WIN32
#define NOMINMAX
#include <WinSock2.h>
#ifndef SHUT_RD
#define SHUT_RD SD_RECEIVE
#endif

#ifndef SHUT_WR
#define SHUT_WR SD_SEND
#endif

#ifndef SHUT_RDWR
#define SHUT_RDWR SD_BOTH
#endif
#else
#include <netdb.h>
#endif
#include "io_buf.h"
#include "cache.h"
#include "network.h"
#include "reductions.h"

using namespace VW::config;

struct sender
{
  io_buf* buf;
  int sd;
  vw* all;  // loss ring_size others
  example** delay_ring;
  size_t sent_index;
  size_t received_index;

  ~sender()
  {
    buf->files.delete_v();
    buf->space.delete_v();
    free(delay_ring);
    delete buf;
  }
};

void open_sockets(sender& s, std::string host)
{
  s.sd = open_socket(host.c_str());
  s.buf = new io_buf();
  s.buf->files.push_back(s.sd);
}

void send_features(io_buf* b, example& ec, uint32_t mask)
{
  // note: subtracting 1 b/c not sending constant
  output_byte(*b, (unsigned char)(ec.indices.size() - 1));

  for (namespace_index ns : ec.indices)
  {
    if (ns == constant_namespace)
      continue;
    output_features(*b, ns, ec.feature_space[ns], mask);
  }
  b->flush();
}

void receive_result(sender& s)
{
  float res, weight;

  get_prediction(s.sd, res, weight);
  example& ec = *s.delay_ring[s.received_index++ % s.all->p->ring_size];
  ec.pred.scalar = res;

  label_data& ld = ec.l.simple;
  ec.loss = s.all->loss->getLoss(s.all->sd, ec.pred.scalar, ld.label) * ec.weight;

  return_simple_example(*(s.all), nullptr, ec);
}

void learn(sender& s, LEARNER::single_learner&, example& ec)
{
  if (s.received_index + s.all->p->ring_size / 2 - 1 == s.sent_index)
    receive_result(s);

  s.all->set_minmax(s.all->sd, ec.l.simple.label);
  s.all->p->lp.cache_label(&ec.l, *s.buf);  // send label information.
  cache_tag(*s.buf, ec.tag);
  send_features(s.buf, ec, (uint32_t)s.all->parse_mask);
  s.delay_ring[s.sent_index++ % s.all->p->ring_size] = &ec;
}

void finish_example(vw&, sender&, example&) {}

void end_examples(sender& s)
{
  // close our outputs to signal finishing.
  while (s.received_index != s.sent_index) receive_result(s);
  shutdown(s.buf->files[0], SHUT_WR);
}

LEARNER::base_learner* sender_setup(options_i& options, vw& all)
{
  std::string host;

  option_group_definition sender_options("Network sending");
  sender_options.add(make_option("sendto", host).keep().help("send examples to <host>"));
  options.add_and_parse(sender_options);

  if (!options.was_supplied("sendto"))
  {
    return nullptr;
  }

  auto s = scoped_calloc_or_throw<sender>();
  s->sd = -1;
  open_sockets(*s.get(), host);

  s->all = &all;
  s->delay_ring = calloc_or_throw<example*>(all.p->ring_size);

  LEARNER::learner<sender, example>& l = init_learner(s, learn, learn, 1);
  l.set_finish_example(finish_example);
  l.set_end_examples(end_examples);
  return make_base(l);
}