#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define NPROCS 7  /*Number of processes to be created*/
#define MSGLEN 9  /*Length of messages sent to each process*/

int main(){

   int fd[NPROCS][2], i, myID = 0, parent, rng, j, num;
   char msg[MSGLEN];


   for(i = 0; i < NPROCS; i++){   /*Create pipes*/
      if(pipe(fd[i]) == -1){
         perror("Piping error");
         exit(-1);
      }
   }

   for(i = 1; i < NPROCS; i++){  /*Create processes*/
      switch(parent = fork()){
         case -1:
            perror("Forking error");
            exit(-1);
         case 0:
            myID = i;

      }
      if(parent){
         break;
      }
   }

   /*COMMON CODE*/

   close(fd[myID][1]);           /*Close current process's write end to pipe*/


   for(i = 0; i < NPROCS; i++){  /*Close all read ends from other processes*/
      if(i != myID){
         close(fd[i][0]);
      }
   }

   sprintf(msg, "process%d", myID);

   int count = 0;

   srand(71913173*myID);
   rng = RAND_MAX/NPROCS;           /*Generate random numbers, write to 13 random processes*/
   rng *= NPROCS;
   for(i = 0; i < 13; i++){
      do{
         num = rand();
         j = num % NPROCS;
      } while(num >= rng || myID==j);
     count++;
     printf("myID: %d, j: %d, count: %d\n", myID, j, count);
     if(write(fd[j][1], msg, MSGLEN) != MSGLEN){
         perror("Write error");
         exit(-1);
     }
   }

   for(i = 0; i < NPROCS; i++){ /*Close all write ends*/
      if(i != myID){
         close(fd[i][1]);
      }
   }

   msg[MSGLEN] = '\0';
   while(read(fd[myID][0], msg, MSGLEN) == MSGLEN){
      printf("process%d has received a message from %s\n", myID, msg);
   }





   close(fd[myID][0]);
   exit(0);
}