#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h>

// receives results from the workers and displays them on the console 
// usage: 
//    a.out portno
//          number of the port for the result socket 

#define MAXHOSTNAME 80  

int main(int argc, char * argv[]) {
        int s,si, retcode, i;
        unsigned int salen; 
        struct sockaddr_in sa,sai;
        char hostname[MAXHOSTNAME];

        si = socket(AF_INET,SOCK_STREAM,0);     // socket to receive the results
        if(si == -1) {
                perror("while opening socket"); return -1;}
        sai.sin_family = AF_INET;
        sai.sin_port = htons(atoi(argv[1]));
        gethostname(hostname,MAXHOSTNAME);
        memcpy(&sai.sin_addr, (gethostbyname(hostname)->h_addr), 
                sizeof(sa.sin_addr));
        retcode = bind(si,(struct sockaddr *) & sai, sizeof(sai));
        if(retcode == -1) { 
                perror("while binding socket to addr"); return -1; }
        retcode = listen(si,1); 
        if(retcode == -1) { 
                perror("while calling listen"); return -1; }

        while(1==1) {
          salen = sizeof(sa);
          printf("Accepting connections\n");
          s = accept(si,(struct sockaddr *)&sa,&salen); // accept a connection
          if(s == 1) {
                  perror("while accepting a connection"); return -1;
          }
          retcode = read(s,&i,sizeof(int));// read a res from one of the Worker
          if(retcode == -1) {
                perror("while reading a result"); return -1; }
          if(i==(-1)) { 
                printf("EOS -> terminating\n");
                break;
          }
          printf("Read result: %d ",i); fflush(stdout); // and print it on console
          close(s);
        }
        close(si);
        return 0; 
}