#include "sass.hpp"

#include <string>

#include <vector>

#include <cstdlib>

#include <cmath>

#include "utf8.h"

namespace Sass {

  namespace UTF_8 {

    using std::string;

    // naming conventions:

    // offset: raw byte offset (0 based)

    // position: code point offset (0 based)

    // index: code point offset (1 based or negative)

    // function that will count the number of code points (utf-8 characters) from the given beginning to the given end

    size_t code_point_count(const string& str, size_t start, size_t end) {

      return utf8::distance(str.begin() + start, str.begin() + end);

    }

    size_t code_point_count(const string& str) {

      return utf8::distance(str.begin(), str.end());

    }

    // function that will return the byte offset at a code point position

    size_t offset_at_position(const string& str, size_t position) {

      string::const_iterator it = str.begin();

      utf8::advance(it, position, str.end());

      return distance(str.begin(), it);

    }

    // function that returns number of bytes in a character at offset

    size_t code_point_size_at_offset(const string& str, size_t offset) {

      // get iterator from string and forward by offset

      string::const_iterator stop = str.begin() + offset;

      // check if beyond boundary

      if (stop == str.end()) return 0;

      // advance by one code point

      utf8::advance(stop, 1, str.end());

      // calculate offset for code point

      return  stop - str.begin() - offset;

    }

    // function that will return a normalized index, given a crazy one

    size_t normalize_index(int index, size_t len) {

      long signed_len = static_cast<long>(len);

      // assuming the index is 1-based

      // we are returning a 0-based index

      if (index > 0 && index <= signed_len) {

        // positive and within string length

        return index-1;

      }

      else if (index > signed_len) {

        // positive and past string length

        return len;

      }

      else if (index == 0) {

        return 0;

      }

      else if (std::abs((double)index) <= signed_len) {

        // negative and within string length

        return index + signed_len;

      }

      else {

        // negative and past string length

        return 0;

      }

    }

    #ifdef _WIN32

    // utf16 functions

    using std::wstring;

    // convert from utf16/wide string to utf8 string

    string convert_from_utf16(const wstring& utf16)

    {

      string utf8;

      // pre-allocate expected memory

      utf8.reserve(sizeof(utf16)/2);

      utf8::utf16to8(utf16.begin(), utf16.end(),

                     back_inserter(utf8));

      return utf8;

    }

    // convert from utf8 string to utf16/wide string

    wstring convert_to_utf16(const string& utf8)

    {

      wstring utf16;

      // pre-allocate expected memory

      utf16.reserve(code_point_count(utf8)*2);

      utf8::utf8to16(utf8.begin(), utf8.end(),

                     back_inserter(utf16));

      return utf16;

    }

    #endif

  }

}