//
// Created by loki on 2/2/20.
//

extern "C" {
#include <moonlight-common-c/src/Rtsp.h>
}

#include "config.h"
#include "input.h"
#include "main.h"
#include "network.h"
#include "rtsp.h"
#include "stream.h"
#include "sync.h"

namespace asio = boost::asio;

using asio::ip::tcp;
using asio::ip::udp;

using namespace std::literals;

namespace stream {

//FIXME: Quick and dirty workaround for bug in MinGW 9.3 causing a linker error when using std::to_string
template<class T>
std::string to_string(T &&t) {
  std::stringstream ss;
  ss << std::forward<T>(t);
  return ss.str();
}

constexpr auto RTSP_SETUP_PORT = 48010;

void free_msg(PRTSP_MESSAGE msg) {
  freeMessage(msg);

  delete msg;
}

class rtsp_server_t;

using msg_t      = util::safe_ptr<RTSP_MESSAGE, free_msg>;
using cmd_func_t = std::function<void(rtsp_server_t *, net::peer_t, msg_t &&)>;

void print_msg(PRTSP_MESSAGE msg);
void cmd_not_found(net::host_t::pointer host, net::peer_t peer, msg_t &&req);

class rtsp_server_t {
public:
  ~rtsp_server_t() {
    if(_host) {
      clear();
    }
  }

  int bind(std::uint16_t port) {
    {
      auto lg = _session_slots.lock();

      _session_slots->resize(config::stream.channels);
      _slot_count = config::stream.channels;
    }

    _host = net::host_create(_addr, 1, port);

    return !(bool)_host;
  }

  void session_raise(launch_session_t launch_session) {
    //FIXME: If client abandons us at this stage, _slot_count won't be raised again.
    --_slot_count;
    launch_event.raise(launch_session);
  }

  int session_count() const {
    return config::stream.channels - _slot_count;
  }

  template<class T, class X>
  void iterate(std::chrono::duration<T, X> timeout) {
    ENetEvent event;
    auto res = enet_host_service(_host.get(), &event, std::chrono::floor<std::chrono::milliseconds>(timeout).count());

    if(res > 0) {
      switch(event.type) {
      case ENET_EVENT_TYPE_RECEIVE: {
        net::packet_t packet { event.packet };
        net::peer_t peer { event.peer };

        msg_t req { new msg_t::element_type };

        //TODO: compare addresses of the peers
        if(_queue_packet.second == nullptr) {
          parseRtspMessage(req.get(), (char *)packet->data, packet->dataLength);
          for(auto option = req->options; option != nullptr; option = option->next) {
            if("Content-length"sv == option->option) {
              _queue_packet = std::make_pair(peer, std::move(packet));
              return;
            }
          }
        }
        else {
          std::vector<char> full_payload;

          auto old_msg     = std::move(_queue_packet);
          auto &old_packet = old_msg.second;

          std::string_view new_payload { (char *)packet->data, packet->dataLength };
          std::string_view old_payload { (char *)old_packet->data, old_packet->dataLength };
          full_payload.resize(new_payload.size() + old_payload.size());

          std::copy(std::begin(old_payload), std::end(old_payload), std::begin(full_payload));
          std::copy(std::begin(new_payload), std::end(new_payload), std::begin(full_payload) + old_payload.size());

          parseRtspMessage(req.get(), full_payload.data(), full_payload.size());
        }

        print_msg(req.get());

        msg_t resp;
        auto func = _map_cmd_cb.find(req->message.request.command);
        if(func != std::end(_map_cmd_cb)) {
          func->second(this, peer, std::move(req));
        }
        else {
          cmd_not_found(host(), peer, std::move(req));
        }

        return;
      }
      case ENET_EVENT_TYPE_CONNECT:
        BOOST_LOG(info) << "CLIENT CONNECTED TO RTSP"sv;
        break;
      case ENET_EVENT_TYPE_DISCONNECT:
        BOOST_LOG(info) << "CLIENT DISCONNECTED FROM RTSP"sv;
        break;
      case ENET_EVENT_TYPE_NONE:
        break;
      }
    }
  }

  void map(const std::string_view &type, cmd_func_t cb) {
    _map_cmd_cb.emplace(type, std::move(cb));
  }

  void clear(bool all = true) {
    auto lg = _session_slots.lock();

    for(auto &slot : *_session_slots) {
      if(slot && (all || session::state(*slot) == session::state_e::STOPPING)) {
        session::stop(*slot);
        session::join(*slot);

        slot.reset();

        ++_slot_count;
      }
    }

    if(all) {
      std::for_each(_host->peers, _host->peers + _host->peerCount, [](auto &peer) {
        enet_peer_disconnect_now(&peer, 0);
      });
    }
  }

  void clear(std::shared_ptr<session_t> *session_p) {
    auto lg = _session_slots.lock();

    session_p->reset();

    ++_slot_count;
  }

  std::shared_ptr<session_t> *accept(std::shared_ptr<session_t> &session) {
    auto lg = _session_slots.lock();

    for(auto &slot : *_session_slots) {
      if(!slot) {
        slot = session;
        return &slot;
      }
    }

    return nullptr;
  }

  net::host_t::pointer host() const {
    return _host.get();
  }

  safe::event_t<launch_session_t> launch_event;

private:
  // named _queue_packet because I want to make it an actual queue
  // It's like this for convenience sake
  std::pair<net::peer_t, net::packet_t> _queue_packet;

  std::unordered_map<std::string_view, cmd_func_t> _map_cmd_cb;

  util::sync_t<std::vector<std::shared_ptr<session_t>>> _session_slots;

  int _slot_count;
  ENetAddress _addr;
  net::host_t _host;
};

rtsp_server_t server;

void launch_session_raise(launch_session_t launch_session) {
  server.session_raise(launch_session);
}

int session_count() {
  // Ensure session_count is up to date
  server.clear(false);

  return server.session_count();
}

void respond(net::host_t::pointer host, net::peer_t peer, msg_t &resp) {
  auto payload = std::make_pair(resp->payload, resp->payloadLength);

  auto lg = util::fail_guard([&]() {
    resp->payload       = payload.first;
    resp->payloadLength = payload.second;
  });

  resp->payload       = nullptr;
  resp->payloadLength = 0;

  int serialized_len;
  util::c_ptr<char> raw_resp { serializeRtspMessage(resp.get(), &serialized_len) };
  BOOST_LOG(debug)
    << "---Begin Response---"sv << std::endl
    << std::string_view { raw_resp.get(), (std::size_t)serialized_len } << std::endl
    << std::string_view { payload.first, (std::size_t)payload.second } << std::endl
    << "---End Response---"sv << std::endl;

  std::string_view tmp_resp { raw_resp.get(), (size_t)serialized_len };
  {
    auto packet = enet_packet_create(tmp_resp.data(), tmp_resp.size(), ENET_PACKET_FLAG_RELIABLE);
    if(enet_peer_send(peer, 0, packet)) {
      enet_packet_destroy(packet);
      return;
    }

    enet_host_flush(host);
  }

  if(payload.second > 0) {
    auto packet = enet_packet_create(payload.first, payload.second, ENET_PACKET_FLAG_RELIABLE);
    if(enet_peer_send(peer, 0, packet)) {
      enet_packet_destroy(packet);
      return;
    }

    enet_host_flush(host);
  }
}

void respond(net::host_t::pointer host, net::peer_t peer, POPTION_ITEM options, int statuscode, const char *status_msg, int seqn, const std::string_view &payload) {
  msg_t resp { new msg_t::element_type };
  createRtspResponse(resp.get(), nullptr, 0, const_cast<char *>("RTSP/1.0"), statuscode, const_cast<char *>(status_msg), seqn, options, const_cast<char *>(payload.data()), (int)payload.size());

  respond(host, peer, resp);
}

void cmd_not_found(net::host_t::pointer host, net::peer_t peer, msg_t &&req) {
  respond(host, peer, nullptr, 404, "NOT FOUND", req->sequenceNumber, {});
}

void cmd_option(rtsp_server_t *server, net::peer_t peer, msg_t &&req) {
  OPTION_ITEM option {};

  // I know these string literals will not be modified
  option.option = const_cast<char *>("CSeq");

  auto seqn_str  = to_string(req->sequenceNumber);
  option.content = const_cast<char *>(seqn_str.c_str());

  respond(server->host(), peer, &option, 200, "OK", req->sequenceNumber, {});
}

void cmd_describe(rtsp_server_t *server, net::peer_t peer, msg_t &&req) {
  OPTION_ITEM option {};

  // I know these string literals will not be modified
  option.option = const_cast<char *>("CSeq");

  auto seqn_str  = to_string(req->sequenceNumber);
  option.content = const_cast<char *>(seqn_str.c_str());

  std::stringstream ss;
  if(config::video.hevc_mode != 1) {
    ss << "sprop-parameter-sets=AAAAAU"sv << std::endl;
  }

  for(int x = 0; x < audio::MAX_STREAM_CONFIG; ++x) {
    auto &stream_config = audio::stream_configs[x];
    std::uint8_t mapping[platf::speaker::MAX_SPEAKERS];

    auto mapping_p = stream_config.mapping;

    /**
     * GFE advertises incorrect mapping for normal quality configurations,
     * as a result, Moonlight rotates all channels from index '3' to the right
     * To work around this, rotate channels to the left from index '3'
     */
    if(x == audio::SURROUND51 || x == audio::SURROUND71) {
      std::copy_n(mapping_p, stream_config.channelCount, mapping);
      std::rotate(mapping + 3, mapping + 4, mapping + audio::MAX_STREAM_CONFIG);

      mapping_p = mapping;
    }

    ss << "a=fmtp:97 surround-params="sv << stream_config.channelCount << stream_config.streams << stream_config.coupledStreams;

    std::for_each_n(mapping_p, stream_config.channelCount, [&ss](std::uint8_t digit) {
      ss << (char)(digit + '0');
    });

    ss << std::endl;
  }

  respond(server->host(), peer, &option, 200, "OK", req->sequenceNumber, ss.str());
}

void cmd_setup(rtsp_server_t *server, net::peer_t peer, msg_t &&req) {
  OPTION_ITEM options[2] {};

  auto &seqn           = options[0];
  auto &session_option = options[1];

  seqn.option = const_cast<char *>("CSeq");

  auto seqn_str = to_string(req->sequenceNumber);
  seqn.content  = const_cast<char *>(seqn_str.c_str());

  std::string_view target { req->message.request.target };
  auto begin = std::find(std::begin(target), std::end(target), '=') + 1;
  auto end   = std::find(begin, std::end(target), '/');
  std::string_view type { begin, (size_t)std::distance(begin, end) };

  if(type == "audio"sv) {
    seqn.next = &session_option;

    session_option.option  = const_cast<char *>("Session");
    session_option.content = const_cast<char *>("DEADBEEFCAFE;timeout = 90");
  }
  else if(type != "video"sv && type != "control"sv) {
    cmd_not_found(server->host(), peer, std::move(req));

    return;
  }

  respond(server->host(), peer, &seqn, 200, "OK", req->sequenceNumber, {});
}

void cmd_announce(rtsp_server_t *server, net::peer_t peer, msg_t &&req) {
  OPTION_ITEM option {};

  // I know these string literals will not be modified
  option.option = const_cast<char *>("CSeq");

  auto seqn_str  = to_string(req->sequenceNumber);
  option.content = const_cast<char *>(seqn_str.c_str());

  if(!server->launch_event.peek()) {
    // /launch has not been used

    respond(server->host(), peer, &option, 503, "Service Unavailable", req->sequenceNumber, {});
    return;
  }
  auto launch_session { server->launch_event.pop() };

  std::string_view payload { req->payload, (size_t)req->payloadLength };

  std::vector<std::string_view> lines;

  auto whitespace = [](char ch) {
    return ch == '\n' || ch == '\r';
  };

  {
    auto pos   = std::begin(payload);
    auto begin = pos;
    while(pos != std::end(payload)) {
      if(whitespace(*pos++)) {
        lines.emplace_back(begin, pos - begin - 1);

        while(pos != std::end(payload) && whitespace(*pos)) { ++pos; }
        begin = pos;
      }
    }
  }

  std::string_view client;
  std::unordered_map<std::string_view, std::string_view> args;

  for(auto line : lines) {
    auto type = line.substr(0, 2);
    if(type == "s="sv) {
      client = line.substr(2);
    }
    else if(type == "a=") {
      auto pos = line.find(':');

      auto name = line.substr(2, pos - 2);
      auto val  = line.substr(pos + 1);

      if(val[val.size() - 1] == ' ') {
        val = val.substr(0, val.size() - 1);
      }
      args.emplace(name, val);
    }
  }

  // Initialize any omitted parameters to defaults
  args.try_emplace("x-nv-video[0].encoderCscMode"sv, "0"sv);
  args.try_emplace("x-nv-vqos[0].bitStreamFormat"sv, "0"sv);
  args.try_emplace("x-nv-video[0].dynamicRangeMode"sv, "0"sv);
  args.try_emplace("x-nv-aqos.packetDuration"sv, "5"sv);

  config_t config;

  config.audio.flags[audio::config_t::HOST_AUDIO] = launch_session->host_audio;
  try {
    config.audio.channels       = util::from_view(args.at("x-nv-audio.surround.numChannels"sv));
    config.audio.mask           = util::from_view(args.at("x-nv-audio.surround.channelMask"sv));
    config.audio.packetDuration = util::from_view(args.at("x-nv-aqos.packetDuration"sv));

    config.audio.flags[audio::config_t::HIGH_QUALITY] =
      util::from_view(args.at("x-nv-audio.surround.AudioQuality"sv));

    config.packetsize = util::from_view(args.at("x-nv-video[0].packetSize"sv));

    config.monitor.height         = util::from_view(args.at("x-nv-video[0].clientViewportHt"sv));
    config.monitor.width          = util::from_view(args.at("x-nv-video[0].clientViewportWd"sv));
    config.monitor.framerate      = util::from_view(args.at("x-nv-video[0].maxFPS"sv));
    config.monitor.bitrate        = util::from_view(args.at("x-nv-vqos[0].bw.maximumBitrateKbps"sv));
    config.monitor.slicesPerFrame = util::from_view(args.at("x-nv-video[0].videoEncoderSlicesPerFrame"sv));
    config.monitor.numRefFrames   = util::from_view(args.at("x-nv-video[0].maxNumReferenceFrames"sv));
    config.monitor.encoderCscMode = util::from_view(args.at("x-nv-video[0].encoderCscMode"sv));
    config.monitor.videoFormat    = util::from_view(args.at("x-nv-vqos[0].bitStreamFormat"sv));
    config.monitor.dynamicRange   = util::from_view(args.at("x-nv-video[0].dynamicRangeMode"sv));
  }
  catch(std::out_of_range &) {

    respond(server->host(), peer, &option, 400, "BAD REQUEST", req->sequenceNumber, {});
    return;
  }

  if(config.monitor.videoFormat != 0 && config::video.hevc_mode == 1) {
    BOOST_LOG(warning) << "HEVC is disabled, yet the client requested HEVC"sv;

    respond(server->host(), peer, &option, 400, "BAD REQUEST", req->sequenceNumber, {});
    return;
  }

  auto session = session::alloc(config, launch_session->gcm_key, launch_session->iv);

  auto slot = server->accept(session);
  if(!slot) {
    BOOST_LOG(info) << "Ran out of slots for client from ["sv << ']';

    respond(server->host(), peer, &option, 503, "Service Unavailable", req->sequenceNumber, {});
    return;
  }

  if(session::start(*session, platf::from_sockaddr((sockaddr *)&peer->address.address))) {
    BOOST_LOG(error) << "Failed to start a streaming session"sv;

    server->clear(slot);
    respond(server->host(), peer, &option, 500, "Internal Server Error", req->sequenceNumber, {});
    return;
  }

  respond(server->host(), peer, &option, 200, "OK", req->sequenceNumber, {});
}

void cmd_play(rtsp_server_t *server, net::peer_t peer, msg_t &&req) {
  OPTION_ITEM option {};

  // I know these string literals will not be modified
  option.option = const_cast<char *>("CSeq");

  auto seqn_str  = to_string(req->sequenceNumber);
  option.content = const_cast<char *>(seqn_str.c_str());

  respond(server->host(), peer, &option, 200, "OK", req->sequenceNumber, {});
}

void rtpThread() {
  auto shutdown_event           = mail::man->event<bool>(mail::shutdown);
  auto broadcast_shutdown_event = mail::man->event<bool>(mail::broadcast_shutdown);

  server.map("OPTIONS"sv, &cmd_option);
  server.map("DESCRIBE"sv, &cmd_describe);
  server.map("SETUP"sv, &cmd_setup);
  server.map("ANNOUNCE"sv, &cmd_announce);

  server.map("PLAY"sv, &cmd_play);

  if(server.bind(RTSP_SETUP_PORT)) {
    BOOST_LOG(fatal) << "Couldn't bind RTSP server to port ["sv << RTSP_SETUP_PORT << "], likely another process already bound to the port"sv;
    shutdown_event->raise(true);

    return;
  }

  while(!shutdown_event->peek()) {
    server.iterate(std::min(500ms, config::stream.ping_timeout));

    if(broadcast_shutdown_event->peek()) {
      server.clear();
    }
    else {
      // cleanup all stopped sessions
      server.clear(false);
    }
  }

  server.clear();
}

void print_msg(PRTSP_MESSAGE msg) {
  std::string_view type = msg->type == TYPE_RESPONSE ? "RESPONSE"sv : "REQUEST"sv;

  std::string_view payload { msg->payload, (size_t)msg->payloadLength };
  std::string_view protocol { msg->protocol };
  auto seqnm = msg->sequenceNumber;
  std::string_view messageBuffer { msg->messageBuffer };

  BOOST_LOG(debug) << "type ["sv << type << ']';
  BOOST_LOG(debug) << "sequence number ["sv << seqnm << ']';
  BOOST_LOG(debug) << "protocol :: "sv << protocol;
  BOOST_LOG(debug) << "payload :: "sv << payload;

  if(msg->type == TYPE_RESPONSE) {
    auto &resp = msg->message.response;

    auto statuscode = resp.statusCode;
    std::string_view status { resp.statusString };

    BOOST_LOG(debug) << "statuscode :: "sv << statuscode;
    BOOST_LOG(debug) << "status :: "sv << status;
  }
  else {
    auto &req = msg->message.request;

    std::string_view command { req.command };
    std::string_view target { req.target };

    BOOST_LOG(debug) << "command :: "sv << command;
    BOOST_LOG(debug) << "target :: "sv << target;
  }

  for(auto option = msg->options; option != nullptr; option = option->next) {
    std::string_view content { option->content };
    std::string_view name { option->option };

    BOOST_LOG(debug) << name << " :: "sv << content;
  }

  BOOST_LOG(debug) << "---Begin MessageBuffer---"sv << std::endl
                   << messageBuffer << std::endl
                   << "---End MessageBuffer---"sv << std::endl;
}
} // namespace stream