#include <netinet/in.h>
#include <poll.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

int main() {
  struct sockaddr_in addr;
  addr.sin_family = AF_INET;         /* IPv4 */
  addr.sin_port = htons(8000);       /* Port */
  addr.sin_addr.s_addr = INADDR_ANY; /* equals to 0.0.0.0 */
  int sfd = socket(AF_INET, SOCK_STREAM, 0);
  if (sfd == -1) {
    perror("could not open socket");
    return 1;
  }
  int opt = 1;
  setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
  int bind_addr = bind(sfd, (struct sockaddr *)&addr, sizeof(addr));
  if (bind_addr == -1) {
    perror("could not bind socket");
    return 1;
  }
  int listen_addr = listen(sfd, 100);
  if (listen_addr == -1) {
    perror("could not listen");
    return 1;
  }
  struct pollfd fds[256];
  fds[0].fd = sfd;        /* socket file descriptor */
  fds[0].events = POLLIN; /* data to read */
  nfds_t nfds = 1;        /* non file descriptor. something with timeout */
  while (1) {
    /* we start the polling here */
    int ready =
        poll(fds, nfds, -1); /* poll to accept many conn simultaneously */
    if (ready == -1) {
      perror("could not run poll");
      return 1;
    }
    if (fds[0].revents & POLLIN) {
      /* we accept the connections */
      int conn = accept(sfd, NULL, NULL);
      if (conn == -1) {
        perror("could not accept connection");
        continue; /* if one client is not able to connect the server shall not
                     die */
      }
      fds[nfds].fd = conn; /* read */
      fds[nfds].events =
          POLLIN; /* check if telnet client has something to say */
      nfds++;
    }
    for (nfds_t i = 1; i < nfds; i++) {
      /* if client has something to say */
      if (fds[i].revents & POLLIN) {
        char buf[1024];
        ssize_t n = read(fds[i].fd, buf,
                         sizeof(buf)); /* read the n which the client sent */
        if (n <= 0) {
          /* close the connection if client disappeared or disconnected */
          close(fds[i].fd);
        } else {
          /* send every n bytes to the other clients */
          for (nfds_t j = 1; j < nfds; j++) {
            if (j != i) {
              write(fds[j].fd, buf, n);
            }
          }
        }
      }
    }
  }
  return 0;
}