#include "FilenameEncode.h"
#include <set>
#include <sstream>

std::set< char > unchangedChars;
bool init = false;

void initUnchangedChars()
{
  if(init)
    return;
  for (char c = 'A'; c <= 'Z'; c++)
    unchangedChars.insert(c);
  for (char c = 'a'; c <= 'z'; c++)
    unchangedChars.insert(c);
  for (char c = '0'; c <= '9'; c++)
    unchangedChars.insert(c);
  unchangedChars.insert('.');
  init = true;
}

std::string encodeFilename(std::string s)
{
  initUnchangedChars();
  std::stringstream ss;
  char a, b;

  for (unsigned int i = 0; i < s.size(); i++)
  {
    if (unchangedChars.count(s[i]) == 0)
    {
      a = s[i] / 16;
      if (a < 10)
        a += '0';
      else
        a += 'A' - 10;
      b = s[i] % 16;
      if (b < 10)
        b += '0';
      else
        b += 'A' - 10;
      ss << '_' << a << b;;
    }
    else
    {
      ss << s[i];
    }
  }
  return ss.str();
}