#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>

#include "task.h"

// receives results from the workers and displays them on the console 
// usage: 
//    a.out portno emitterhost emitterport
//          number of the port for the result socket 
//          then address of emitter (to send feedbacks on task completion)

#define MAXHOSTNAME 80  

int main(int argc, char * argv[]) {
        int s, ei, si, retcode, i;
        RESULT result;
        unsigned int salen; 
        struct sockaddr_in sa,sai,eai;
        char hostname[MAXHOSTNAME];
        char * emitterhost = argv[2];
        int emitter_port = atoi(argv[3]); 

        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(sai.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) {
          SERVICE feedback; 
          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;
          }
          // read a res from one of the Worker 
          retcode = read(s,&result,sizeof(RESULT));
          if(retcode != sizeof(RESULT)) {  // AGAIN, should be corrected 
                perror("while reading a result"); return -1; }
          if(result.tag < 0) { 
                printf("EOS -> terminating\n");
                break;
          }
          printf("Read result: <%d,%d> ",result.v,result.tag); 
          fflush(stdout); // and print it on console
          close(s);
          // now send a feedback to emitter process with the tag of the 
          // received task: in case it was selected for re-scheduling
          // it will be removed, otherwise it will be rescheduled after
          // completing "normal" tasks
          ei = socket(AF_INET,SOCK_STREAM,0);   // socket to receive the results
          if(ei == -1) {
                  perror("while opening socket"); return -1;}
          eai.sin_family = AF_INET;
          eai.sin_port = htons(emitter_port);
          memcpy(&eai.sin_addr, (gethostbyname(emitterhost)->h_addr), 
                  sizeof(eai.sin_addr));
          retcode = connect(ei,(struct sockaddr *)&eai,sizeof(eai));
          if(retcode == -1) {
                perror("while connecting to emitter"); return(-1);}
          // send feedback on computed task     
          feedback.tag = TAG_COMPLETED; 
          feedback.v   = result.tag; 
          retcode = write(ei,&feedback,sizeof(SERVICE));
          if(retcode != sizeof(SERVICE)) {
                perror("while writing feedback to emitter"); return (-1); }
          close(ei); // one shot: TODO use permanent connection on dedicated ss 
        }
        close(si);
        return 0; 
}