/* Copyright (c) 2000, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License, version 2.0,

   as published by the Free Software Foundation.

   This program is designed to work with certain software (including

   but not limited to OpenSSL) that is licensed under separate terms,

   as designated in a particular file or component or in included license

   documentation.  The authors of MySQL hereby grant you an additional

   permission to link the program and your derivative works with the

   separately licensed software that they have either included with

   the program or referenced in the documentation.

   Without limiting anything contained in the foregoing, this file,

   which is part of C Driver for MySQL (Connector/C), is also subject to the

   Universal FOSS Exception, version 1.0, a copy of which can be found at

   http://oss.oracle.com/licenses/universal-foss-exception.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "mysql/strings/int2str.h"

#include <array>

#include <cassert>

#include <cstdint>

#include <cstring>

#include <iterator>

#include "dig_vec.h"

#include "integer_digits.h"

/**

  Converts a 64-bit integer value to its character form and moves it to the

  destination buffer followed by a terminating NUL. If radix is -2..-36, val is

  taken to be SIGNED, if radix is 2..36, val is taken to be UNSIGNED. That is,

  val is signed if and only if radix is. All other radixes are treated as bad

  and nothing will be changed in this case.

  For conversion to decimal representation (radix is -10 or 10) one should use

  the optimized #longlong10_to_str() function instead.

  @param val the value to convert

  @param dst the buffer where the string representation should be stored

  @param radix radix of scale of notation

  @param upcase true if we should use upper-case digits

  @return pointer to the ending NUL character, or nullptr if radix is bad

*/

char *ll2str(int64_t val, char *dst, int radix, bool upcase) {

  char buffer[65];

  const char *const dig_vec =

      upcase ? dig_vec_upper.data() : dig_vec_lower.data();

  auto uval = static_cast<uint64_t>(val);

  if (radix < 0) {

    if (radix < -36 || radix > -2) return nullptr;

    if (val < 0) {

      *dst++ = '-';

      /* Avoid integer overflow in (-val) for LLONG_MIN (BUG#31799). */

      uval = 0ULL - uval;

    }

    radix = -radix;

  } else if (radix > 36 || radix < 2) {

    return nullptr;

  }

  char *p = std::end(buffer);

  do {

    *--p = dig_vec[uval % radix];

    uval /= radix;

  } while (uval != 0);

  const size_t length = std::end(buffer) - p;

  memcpy(dst, p, length);

  dst[length] = '\0';

  return dst + length;

}

/**

  Converts a 64-bit integer to its string representation in decimal notation.

  It is optimized for the normal case of radix 10/-10. It takes only the sign of

  radix parameter into account and not its absolute value.

  @param val the value to convert

  @param dst the buffer where the string representation should be stored

  @param radix 10 if val is unsigned, -10 if val is signed

  @return pointer to the ending NUL character

*/

char *longlong10_to_str(int64_t val, char *dst, int radix) {

  assert(radix == 10 || radix == -10);

  auto uval = static_cast<uint64_t>(val);

  if (radix < 0) /* -10 */

  {

    if (val < 0) {

      *dst++ = '-';

      /* Avoid integer overflow in (-val) for LLONG_MIN (BUG#31799). */

      uval = uint64_t{0} - uval;

    }

  }

  char *end = write_digits(uval, count_digits(uval), dst);

  *end = '\0';

  return end;

}