#include <cstdio>
#include <cmath>
#include "helpers.h"

char * strip_eol (char * str) {
  char * ptr = str;
  for (;;) {
    const char c = * ptr;
    if (c == '\0') break;
    else if (c == '\r') * ptr = '\0';
    else if (c == '\n') * ptr = '\0';
    ptr++;
  }
  return str;
}
std::string ing_fmt (const double par, const unsigned dnum) {
  const char * suffixes [] = {"a", "f", "p", "n", "μ", "m", " ", "k", "M", "G", "T", "P", "E"};
  bool sign = false;
  double value = par;
  if (par < 0.0) {
    value = - par;
    sign  = true;
  }
  if (value < 1.0e-18) return std::string ("0");
  if (value > 1.0e+18) return std::string ("hafo");
  
  const double dlog = log10 (value) + 18.0;
  double fractional, integer;
  fractional = modf (dlog, & integer);
  const double mult = pow (10.0, double (dnum - 1));
  double avgf = pow (10.0, fractional);       // do mezí 1.0 až 9.9999...
  avgf *= mult;
  avgf  = round (avgf);                       // a teď zaokrouhli
  avgf /= mult;
  div_t dt = div (int(integer), 3);
  avgf *= pow (10.0, double (dt.rem));
  // printf("%g:%g (%f) [%d:%d]{%s}\n", integer, fractional, avgf, dt.quot, dt.rem, suffixes[dt.quot]);
  
  const unsigned buflen = 64;
  char buffer [buflen];
  const int r = snprintf(buffer, buflen, "%g%s", avgf, suffixes [dt.quot]);
  buffer [r] = '\0';

  std::string result (buffer, r);
  if (sign) result = std::string("-") + result;
  return result;
}