// Oldham, Jeffrey D.
// 2000Feb01
// CS3352

// CS3352 Monte Carlo Repeater Program

// This program runs another program P a specified number n of times.
// It collects the one integer output of P, printing the output.

// To run the program, type
//   repeater number-of-trials P [P's command line arguments]
// where
//  "number-of-trials" is an integer indicating how many times program 
//     P should be run
//  "P" is the name of the program that generates one trial
//     It should print one number to the standard output.
//  command-line arguments for P can be specified


#include <iostream.h>
#include <stdlib.h>		// has EXIT_SUCCESS
#include <stdio.h>
#include <string>
#include <limits.h>		// has ULONG_MAX


// Run a specified program.
// input <- argv[0] (for printing error messages)
//	    command line to run program
// output-> integer returned by the program
int runP(const char cmd[], const string & commandLine) {
  FILE * output;
  // Start up the program P.
  if ((output = popen(commandLine.c_str(), "r")) == static_cast<FILE *>(NULL)) {
    cerr << cmd << ": failed to run " << commandLine << "\n";
    throw "failed to run";
  }

  int response;
  if (fscanf(output, "%i", &response) != 1) {
    cerr << cmd << ": failed to read response from " << commandLine << "\n";
    throw "failed to read from program";
  }

  if (pclose(output) != EXIT_SUCCESS) {
    cerr << cmd << ": " << commandLine << " failed execution\n";
    throw "program failed to run";
  }
  return response;
}


int main(int argc, char *argv[])
{
  if (argc < 3) {
    cerr << argv[0] << ": number-of-trials program-to-run [command-line-arguments]\n";
    throw "illegal command line arguments";
  }

  unsigned long nuTrials = strtoul(argv[1], static_cast<char **>(0), 0);
  if (nuTrials == ULONG_MAX) {
    cerr << argv[0] << ": number-of-trials out of range\n";
    throw "illegal number of trials";
  }

  // Construct P's command line.
  string commandLine = argv[2];	// command line to run P
  for (int argCounter = 3; argCounter < argc; ++argCounter) {
    commandLine += " ";
    commandLine += argv[argCounter];
  }

  // Run the program P.
  for (; nuTrials > 0; --nuTrials)
    cout << runP(argv[0], commandLine) << endl;

  return EXIT_SUCCESS;
}