#ifndef RC_UTF8_H_INCLUDED
#define RC_UTF8_H_INCLUDED

#include <string>
#include <algorithm>

std::string rc_utf8_substr(const std::string& str, unsigned int start, unsigned int leng)
{
    if (leng==0) { return ""; }
    unsigned int c, i, ix, q, min=std::string::npos, max=std::string::npos;
    for (q=0, i=0, ix=str.length(); i < ix; i++, q++)
    {
        if (q==start){ min=i; }
        if (q<=start+leng || leng==std::string::npos){ max=i; }

        c = (unsigned char) str[i];
        if      (
                 //c>=0   &&
                 c<=127) i+=0;
        else if ((c & 0xE0) == 0xC0) i+=1;
        else if ((c & 0xF0) == 0xE0) i+=2;
        else if ((c & 0xF8) == 0xF0) i+=3;
        //else if (($c & 0xFC) == 0xF8) i+=4; // 111110bb //byte 5, unnecessary in 4 byte UTF-8
        //else if (($c & 0xFE) == 0xFC) i+=5; // 1111110b //byte 6, unnecessary in 4 byte UTF-8
        else return "";//invalid utf8
    }
    if (q<=start+leng || leng==std::string::npos){ max=i; }
    if (min==std::string::npos || max==std::string::npos) { return ""; }
    return str.substr(min,max-min);
}

std::size_t rc_utf8_length(std::string const &s)
{
  return std::count_if(s.begin(), s.end(),
    [](char c) { return (static_cast<unsigned char>(c) & 0xC0) != 0x80; } );
}

// convert UTF-8 string to wstring
std::wstring utf8_to_wstring (const std::string& str)
{
    std::wstring_convert<std::codecvt_utf8<wchar_t>> myconv;
    return myconv.from_bytes(str);
}

#endif // RC_UTF8_H_INCLUDED