/************************************************************************
 *     Routines to download random seed value from www.random.org       *
 *     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~       *
 ************************************************************************
 ************************************************************************
 * Writen by:                                                           *
 *    Laszlo BALOGH                                                     *
 *       e-mail: blaci947@yahoo.co.uk                                   *
 *       Ph.D. student @ Dep. of Theor. Phys., BUTE, Budapest, Hungary  *
 *       2011.                                                          *
 ************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <gsl/gsl_rng.h>

#include "downloadseed.h"

int DownloadSeed(unsigned long int *seed_, unsigned long int *warmup_)
// seed + warm up
// download integers (3 x 16 bits) from http://www.random.org
//  * it OWERWRITES the "random.org.txt" file,
//  * it will USE THE WGET software,
//  * it will CONNECT TO THE INTERNET
// return value: 1,    if no error occured,
//               zero, if an error occured (cannot open "random.org" file,
//                       the wget is not installed,
//                       the random.org server is unavailable,
//                       or the free quota is exceeded)
// To check your free quota, visit: http://www.random.org/quota/
// or type: wget -O /dev/stdout -q "http://www.random.org/quota/?format=plain"

{
  unsigned long int a,b,c;
  int sys;
  char cmd[]="wget \"http://www.random.org/integers/?num=3&min=0&max=65535&col=5&base=10&format=plain&rnd=new\" -O random.org.txt -q -T 3";
  FILE* rnd = NULL;
  
  //open (and erase) "random.org.txt" file
  rnd = fopen("random.org.txt", "wt");
  if (!rnd) {
    fprintf(stderr, "Cannot open \"random.org.txt\" for writing\n");
    return 0;
  }
  fclose(rnd);
  
  // downloading 3 x 16 bits of integer into "random.org"
  sys = system(cmd);
  if (sys) {
    fprintf(stderr, "An error accoured while downloading random numbers from http://www.random.org. Please check:\n");
    fprintf(stderr, "  * is wget installed?\n");
    fprintf(stderr, "  * can you access the http://www.random.org website?\n");
    fprintf(stderr, "  * is not your free download quota exceeded?\n");
    return 0;
  }

  //open (and read) "random.org.txt" file
  rnd = fopen("random.org.txt", "rt");
  if (!rnd) {
    fprintf(stderr, "Cannot open \"random.org.txt\" for reading\n");
    return 0;
  }
  if (fscanf(rnd, "%lu %lu %lu", &a, &b, &c) != 3) {
    fprintf(stderr, "Wrong format in \"random.org.txt\" file\n");
    fclose(rnd);
    return 0;
  }
  fclose(rnd);
  
  *seed_ = (a << 16) | b;
  *warmup_ = 65535 + c;
  
  return 1;
}

int RNGSeedWarmupGiven(gsl_rng* rng_, const unsigned long int s_, const unsigned long int w_)
// * initializes the Randon Number Generator with the given value
// * gets some the given amount of random numbers - "warming up" the generator
{
  unsigned long int i;
  gsl_rng_set(rng_, s_);
  for (i=0; i<w_; i++) {
    gsl_rng_get(rng_);
  }
  return 1;
}

int RNGSeedWarmup(gsl_rng* rng_)
// * initializes the Randon Number Generator with a random value (zero excluded)
// * gets some (undefined) amount of random numbers - "warming up" the generator
{
  unsigned long int s, w;
  
  do {
    if ( !DownloadSeed(&s, &w) ) {
      return 0;
    }
  }
  while (s == 0);
  
  return RNGSeedWarmupGiven(rng_, s, w);
}