#include <stdio.h>  /* printf */
#include <stdlib.h>  /*exit*/
#include <string.h> /* memcpy*/
#include <netdb.h>

void reusePort(int sock);   

int main( int argc, char *argv[] ) {
  int s;
  struct sockaddr_in server;
  struct sockaddr_in from[3];
  int fromlen;
  int length;
  fd_set readfds, readfdsCopy;
  int n,i;
  int sockList[3], lastSock=0;

  server.sin_family = AF_INET;
  server.sin_addr.s_addr = htonl(INADDR_ANY);
  server.sin_port = htons(atoi(argv[1])); 
  s = socket (AF_INET,SOCK_STREAM,0); 
  reusePort(s);
  if ( bind( s, (struct sockaddr *)&server, sizeof(server) ) ) {
    close(s);
    perror("binding name to stream socket");
    exit(-1);
  }
  listen(s,4);
  fromlen = sizeof(from);
  FD_ZERO(&readfdsCopy);
  FD_SET(s,&readfdsCopy);
  for(;;){
    memcpy(&readfds, &readfdsCopy, sizeof(fd_set));
    n = select(FD_SETSIZE, &readfds, (fd_set *) 0, (fd_set *) 0, NULL);
    if (n > 0) {
      if (FD_ISSET(s, &readfds)) {
        printf("Accepting a new connection...\n");
        sockList[lastSock] = accept(s, (struct sockaddr *)&(from[lastSock]),
                                      &fromlen);
        FD_SET(sockList[lastSock], &readfdsCopy);
        lastSock++;
      }
      for (i=0; i < lastSock; i++) {
        if (FD_ISSET(sockList[i], &readfds))
          if (distribuyaMensaje(sockList, i, from, lastSock) < 0) {
            FD_CLR(sockList[i], &readfdsCopy);
            close (sockList[i]);
            sockList[i] = sockList[--lastSock];
            i--;
            printf("Number of current clients: %d\n", lastSock);
          }
      }
    }
  }
}

int distribuyaMensaje(int *sockList, int i, struct sockaddr_in *from, int lastSock){
  char buf[512];
  int rc,j;
  
  if( (rc=read(sockList[i], buf, sizeof(buf))) < 0)
    perror("receiving stream  message");
  if (rc > 0){
    buf[rc]='\0';
    printf("%s:%d  %s\n", inet_ntoa(from[i].sin_addr),
           ntohs(from[i].sin_port), buf);
    for (j=0; j<lastSock; j++)
      if (j!=i)
        if (send(sockList[j], buf, rc, 0) <0 )
          perror("sending stream message");
    return(1);           
  }
  else {
    printf("Disconnected..\n");
    return(-1);
  }
}

void reusePort(int s){
  int one=1;

  if ( setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *) &one,sizeof(one)) == -1 ){
    printf("error in setsockopt,SO_REUSEPORT \n");
    exit(-1);
  }
}