#include <cstddef>
#include <cstdio>
#include <chrono>
#include <sys/select.h>
#include <cstring>
#include <thread>
#include <vector>
#include <fcntl.h>
#include <signal.h>

#include "bettola/network/tcpsocket.h"
#include "bettola/network/udpsocket.h"
#include "bettola/network/net_common.h"
#include "bettola/network/message.h"
#include "bettola/network/player_input_message.h"
#include "game/game.h"

int main(void) {
  Game game;
  std::vector<BettolaLib::Network::TCPSocket*> client_sockets;

  signal(SIGPIPE, SIG_IGN);

  printf("=== Bettola Server: Starting ===\n");

  BettolaLib::Network::TCPSocket server_socket; /* For TCP connections. */
  BettolaLib::Network::UDPSocket udp_socket;    /* For UDP traffic. */

  /* Create and bind TCP socket. */
  if(!server_socket.create()) {
    printf("Bettola Server: Failed to create socket.\n");
    return 1;
  }

  if(!server_socket.bind(BettolaLib::Network::DEFAULT_PORT)) {
    printf("Bettola Server: Failed to bind socket to port %hu.\n",
           BettolaLib::Network::DEFAULT_PORT);
    server_socket.close();
    return 1;
  }

  if(!server_socket.listen()) {
    printf("Bettola Server: Failed to listen on socket.\n");
    server_socket.close();
    return 1;
  }

  printf("Bettola Server: TCP Listening on port %hu...\n", BettolaLib::Network::DEFAULT_PORT);

  /* Create and bind UDP socket. */
  if(!udp_socket.create()) {
    printf("Bettola Server: Failed to create UDP socket.\n");
    return 1;
  }

  if(!udp_socket.bind(BettolaLib::Network::DEFAULT_PORT)) {
    printf("Bettola Server: Failed to bind UDP Socket to port %hu.\n",
           BettolaLib::Network::DEFAULT_PORT);
    udp_socket.close();
    return 1;
  }

  printf("Bettola Server: UDP Listening on port %hu...\n", BettolaLib::Network::DEFAULT_PORT);

  /* Set the server socket to non-blocking. */
  int flags = fcntl(server_socket.get_sockfd(), F_GETFL, 0);
  if(flags == -1) {
    perror("fcntl F_GETFL, failed.");
    return 1;
  }
  fcntl(server_socket.get_sockfd(), F_SETFL, flags | O_NONBLOCK);

  int udp_flags = fcntl(udp_socket.get_sockfd(), F_GETFL, 0);
  fcntl(udp_socket.get_sockfd(), F_SETFL, udp_flags | O_NONBLOCK);

  auto last_time = std::chrono::high_resolution_clock::now();

  /* Main server loop. */
  while(true) {
    fd_set read_fds;
    FD_ZERO(&read_fds);
    FD_SET(server_socket.get_sockfd(), &read_fds);
    FD_SET(udp_socket.get_sockfd(), &read_fds);

    int max_fd = std::max(server_socket.get_sockfd(), udp_socket.get_sockfd());

    for(const auto& client : client_sockets) {
    FD_SET(client->get_sockfd(), &read_fds);
      if(client->get_sockfd() > max_fd) {
        max_fd = client->get_sockfd();
      }
    }

    struct timeval tv;
    tv.tv_sec = 0;
    tv.tv_usec = 1000; /* 1ms */

    int activity = select(max_fd+1, &read_fds, nullptr, nullptr, &tv);

    if(activity > 0) {
      /* Handle new TCP connections. */
      if(FD_ISSET(server_socket.get_sockfd(), &read_fds)) {
        BettolaLib::Network::TCPSocket* client_socket = server_socket.accept();
        if(client_socket != nullptr) {
          Player* new_player = game.add_player(client_socket);
          printf("Bettola Server: Client connected! Player ID: %u\n", new_player->get_id());

          BettolaLib::Network::MessageHeader header;
          header.type = BettolaLib::Network::MessageType::PlayerId;
          header.size = sizeof(unsigned int);
          client_socket->send(&header, sizeof(header));
          unsigned int id = new_player->get_id();
          client_socket->send(&id, sizeof(id));

          int client_flags = fcntl(client_socket->get_sockfd(), F_GETFL, 0);
          fcntl(client_socket->get_sockfd(), F_SETFL, client_flags | O_NONBLOCK);

          client_sockets.push_back(client_socket);
        }
      }

      /* Handle UDP messages. */
      if(FD_ISSET(udp_socket.get_sockfd(), &read_fds)) {
        char buffer[1024];
        sockaddr_in from_addr;
        ssize_t bytes_received;

        while((bytes_received = udp_socket.recv_from(buffer, sizeof(buffer), from_addr)) > 0) {
          game.process_udp_message(buffer, bytes_received, from_addr);
        }
      }

      /* Handle TCP messages from clients. */
      for(auto it = client_sockets.begin(); it != client_sockets.end();) {
        BettolaLib::Network::TCPSocket* client = *it;
        if(FD_ISSET(client->get_sockfd(), &read_fds)) {
          bool client_disconnected = false;
          while (true) {
            BettolaLib::Network::MessageHeader header;
            ssize_t bytes_received = client->recv(&header, sizeof(header));

            if(bytes_received == 0) {
              client_disconnected = true;
              break;
            }

            if(bytes_received < 0) {
              break;
            }
          }

          if(client_disconnected) {
            Player* player = game.get_player_by_socket(client);
            if(player) game.remove_player(player->get_id());
            it = client_sockets.erase(it);
            delete client;
          } else {
            ++it;
          }
        } else {
          ++it;
        }
      }
    }

    /* Update dynamic game state, like chunk loading for players. */
    game.update_player_chunks();

    /* Broadcase game state. */
    game.broadcast_game_state(udp_socket);

    /* Sleep for a short time to avoid busy-waiting. */
    std::this_thread::sleep_for(std::chrono::milliseconds(10));
  }

  server_socket.close(); /* Shouldn't reach here. */
  printf("=== Bettola Server: Shutting Down ===\n");
  return 0;
}