#pragma once

#ifdef _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#include <ws2bth.h>
#include <ws2def.h>
#include <windows.h>
#define in_addr_t ULONG
#elif __linux__
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/eventfd.h>
#define SOCKET int
#define INVALID_SOCKET -1
#define SOCKET_ERROR -1
#else
#error "이 플랫폼은 지원되지 않습니다."
#endif

#include <chrono>

void err_quit(const char *msg) {
  char *msgbuf = strerror(errno);
  fprintf(stderr, "[%s] %s\n", msg, msgbuf);
  exit(1);
}

void err_display(const char *msg) {
  char *msgbuf = strerror(errno);
  fprintf(stderr, "[%s] %s\n", msg, msgbuf);
}

#define LISTENIP "::"
#define LISTENPORT 9010
#define BUFSIZE 100

int main(int argc, char *argv[]) {
  WSADATA wsa;
  if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0) {
    err_quit("WSAStartup()");
    return EXIT_FAILURE;
  }
  SOCKET listenSocket = socket(AF_INET6, SOCK_STREAM, 0);
  if (listenSocket == INVALID_SOCKET) err_quit("socket()");

  struct sockaddr_in6 serverAddr;
  memset(&serverAddr, 0, sizeof(serverAddr));
  serverAddr.sin6_family = AF_INET6;
  inet_pton(AF_INET6, LISTENIP, &serverAddr.sin6_addr);
  serverAddr.sin6_port = htons(LISTENPORT);

  if (SOCKET_ERROR ==
      bind(listenSocket, (struct sockaddr *)&serverAddr, sizeof(serverAddr)))
    err_quit("bind()");
  if (SOCKET_ERROR == listen(listenSocket, SOMAXCONN)) err_quit("listen()");

  SOCKET client_sock;
  struct sockaddr_in6 client_addr;
  socklen_t addr_len;

  addr_len = sizeof(client_addr);
  printf("Waiting for connection...\n");
  client_sock =
      accept(listenSocket, (struct sockaddr *)&client_addr, &addr_len);
  if (client_sock == INVALID_SOCKET) err_quit("accept()");
  printf("Connection established!\n");

  char buf[BUFSIZE + 1];

  while (2) {
    int retVal = recv(client_sock, buf, BUFSIZE, 0);
    if (retVal == SOCKET_ERROR)
      err_display("recv()");
    else if (retVal == 0)
      break;

    char ipv6str[INET6_ADDRSTRLEN];
    inet_ntop(AF_INET6, &client_addr, ipv6str, sizeof(ipv6str));
    buf[retVal] = '\0';
    printf("[TCP/%s:%d] %s\n", ipv6str, ntohs(client_addr.sin6_port), buf);

    if (SOCKET_ERROR == send(client_sock, buf, BUFSIZE, 0))
      err_display("send()");
  }

  WSACleanup();
}