#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pvm3.h"

#define EXEC "neighbours-2"
#define GROUP "neighbours"
#define BUFF 100

int main(int argc, char **argv){
  int cc=0,*tids, mytid, ptid, ntask, i, me;
  char buf[BUFF];

  if((argc != 2) || ((ntask = atoi(argv[1])) == 0)){
    fprintf(stderr,"Usage: %s <ntask>\n", argv[0]);
    exit(0);
  }

  if((mytid = pvm_mytid()) < 0){
    fprintf(stderr, "Error in pvm_mytid\n");
    pvm_exit();
    exit(0);
  }

  ptid = pvm_parent();

  if(ptid == PvmNoParent){
    tids = (int*)calloc(sizeof(int), ntask);

    for(i=0;i<ntask;i++){
      char host[BUFF];
      sprintf(host, "b%d",i+1);
      if(pvm_spawn(EXEC, &argv[1], 0, host, 1, &tids[i]) == 0){
	fprintf(stderr, "Failed to spawn on host %s\n", host);
      }
      cc++;
    }

    if(cc < ntask){
      fprintf(stderr, "Spawning failed with the following tid array:\n");
      for(i=0;i<ntask;i++){
	fprintf(stderr, "tids[%d]=%d\n",i,tids[i]);
      }
    }

    for(i=0;i<ntask;i++){
      if((cc = pvm_recv(-1, -1)) < 0){
	fprintf(stderr, "Error in pvm_recv\n");
	pvm_exit();
	exit(0);
      }
      if(pvm_bufinfo(cc, (int*)0, (int*)0, &tids[i]) < 0){
	fprintf(stderr, "Error in pvm_bufinfo\n");
	pvm_exit();
	exit(0);
      }
      if(pvm_upkstr(buf) < 0){
	fprintf(stderr, "Error in pvm_upkstr\n");
	pvm_exit();
	exit(0);
      }
      fprintf(stderr,"from t%x: %s\n", tids[i], buf);
    }
  }
  else{
    me = pvm_joingroup(GROUP);
    pvm_barrier(GROUP,ntask);

    sprintf(buf, "me=%d size=%d left=%d, right=%d, im from ", 
	    mytid, pvm_gsize(GROUP),
	    pvm_gettid(GROUP, (me == 0 ? ntask - 1 : me - 1)), 
	    pvm_gettid(GROUP, (me == ntask - 1 ? 0 : me + 1)));

    gethostname(buf + strlen(buf), 64);
    if(pvm_initsend(PvmDataDefault) < 0){
      fprintf(stderr, "Error in pvm_initsend\n");
      pvm_lvgroup(GROUP);
      pvm_exit();
      exit(0);
    }
    if(pvm_pkstr(buf) < 0){
      fprintf(stderr, "Error in pvm_pkstr\n");
      pvm_lvgroup(GROUP);
      pvm_exit();
      exit(0);
    }
    if(pvm_send(ptid, 1) < 0){
      fprintf(stderr, "Error in pvm_pkstr\n");

      pvm_exit();
      exit(0);
    }
    pvm_barrier(GROUP,ntask);
    pvm_lvgroup(GROUP);
  }

  pvm_exit();
  exit(0);
}