// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.

#include "unicode.h"

#include <cassert>
#include <cstdlib>

namespace fsa {

const unsigned int Unicode::_BadUTF8Char;
const unsigned int Unicode::_EOF;


char* Unicode::utf8copy(char *dst, const ucs4_t *src)
{
  ucs4_t i;
  char *p;

  p = dst;
  while ((i = *src++) != 0) {
    if (i < 128)
      *p++ = i;
    else if (i < 0x800) {
      *p++ = (i >> 6) | 0xc0;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x10000) {
      *p++ = (i >> 12) | 0xe0;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x200000) {
      *p++ = (i >> 18) | 0xf0;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x4000000) {
      *p++ = (i >> 24) | 0xf8;
      *p++ = ((i >> 18) & 63) | 0x80;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else {
      *p++ = (i >> 30) | 0xfc;
      *p++ = ((i >> 24) & 63) | 0x80;
      *p++ = ((i >> 18) & 63) | 0x80;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    }
  }
  *p = 0;
  return p;
}

char* Unicode::utf8ncopy(char *dst, const ucs4_t *src,
    int maxdst, int maxsrc)
{
  ucs4_t i = 0;
  char * p = dst;
  char * edst = dst + maxdst;
  const ucs4_t * esrc = src + maxsrc;

  while (src < esrc && (i = *src++) != 0 && p < edst) {
    if (i < 128)
      *p++ = i;
    else if (i < 0x800) {
      if (p + 1 >= edst)
	break;
      *p++ = (i >> 6) | 0xc0;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x10000) {
      if (p + 2 >= edst)
	break;
      *p++ = (i >> 12) | 0xe0;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x200000) {
      if (p + 3 >= edst)
	break;
      *p++ = (i >> 18) | 0xf0;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else if (i < 0x4000000) {
      if (p + 4 >= edst)
	break;
      *p++ = (i >> 24) | 0xf8;
      *p++ = ((i >> 18) & 63) | 0x80;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    } else {
      if (p + 5 >= edst)
	break;
      *p++ = (i >> 30) | 0xfc;
      *p++ = ((i >> 24) & 63) | 0x80;
      *p++ = ((i >> 18) & 63) | 0x80;
      *p++ = ((i >> 12) & 63) | 0x80;
      *p++ = ((i >> 6) & 63) | 0x80;
      *p++ = (i & 63) | 0x80;
    }
  }
  if (p < edst)
    *p = 0;
  return p;
}


int Unicode::utf8cmp(const char *s1, const ucs4_t *s2)
{
  ucs4_t i1;
  ucs4_t i2;

  const unsigned char *ps1 = reinterpret_cast<const unsigned char *>(s1);
  do {
    i1 = getUTF8Char(ps1);
    i2 = *s2++;
  } while (i1 != 0 && i1 == i2);
  if (i1 > i2)
    return 1;
  if (i1 < i2)
    return -1;
  return 0;
}


int Unicode::utf8casecmp(const char *s1, const ucs4_t *s2)
{
  ucs4_t i1, i2;

  const unsigned char *ps1 = reinterpret_cast<const unsigned char *>(s1);
  do {
    i1 = toLower(getUTF8Char(ps1));
    i2 = toLower(*s2++);
  } while (i1 != 0 && i1 == i2);
  if (i1 > i2)
    return 1;
  if (i1 < i2)
    return -1;
  return 0;
}

size_t Unicode::utf8len(const ucs4_t *str)
{
  ucs4_t i;
  size_t res;

  res = 0;
  while ((i = *str++) != 0) {
    if (i < 128)
      res += 1;
    else if (i < 0x800)
      res += 2;
    else if (i < 0x10000)
      res += 3;
    else if (i < 0x200000)
      res += 4;
    else if (i < 0x4000000)
      res += 5;
    else
      res += 6;
  }
  return res;
}

size_t Unicode::utf8nlen(const ucs4_t *str, int maxsrc)
{
  ucs4_t i;
  size_t res;
  int n;

  n = 0;
  res = 0;
  while ((i = *str++) != 0 && n < maxsrc) {
    if (i < 128)
      res += 1;
    else if (i < 0x800)
      res += 2;
    else if (i < 0x10000)
      res += 3;
    else if (i < 0x200000)
      res += 4;
    else if (i < 0x4000000)
      res += 5;
    else
      res += 6;

    n++;
  }
  return res;
}

size_t Unicode::ucs4strlen(const ucs4_t *str)
{
  const ucs4_t *p = str;
  while (*p++ != 0) {
    /* Do nothing */
  }
  return p - 1 - str;
}

size_t Unicode::ucs4len(const char *str)
{
  ucs4_t i;
  size_t res;
  const unsigned char *pstr = reinterpret_cast<const unsigned char *>(str);

  res = 0;
  while ((i = getUTF8Char(pstr)) != 0) {
    if (i != _BadUTF8Char)
      res++;
  }
  return res;
}

size_t Unicode::ucs4nlen(const char *str, size_t n)
{
  ucs4_t i;
  size_t res;
  const unsigned char *pstr = reinterpret_cast<const unsigned char *>(str);
  const unsigned char *end_str = pstr + n;

  res = 0;
  while ((pstr < end_str) && (i = getUTF8Char(pstr, end_str-pstr)) != 0) {
    if (i != _BadUTF8Char)
      if (pstr <= end_str)
        res++;
  }
  return res;
}

ucs4_t* Unicode::ucs4copy(ucs4_t *dst, const char *src)
{
  ucs4_t i;
  ucs4_t *p;
  const unsigned char *psrc = reinterpret_cast<const unsigned char *>(src);

  p = dst;
  while ((i = getUTF8Char(psrc)) != 0) {
    if (i != _BadUTF8Char)
      *p++ = i;
  }
  *p = 0;
  return p;
}

ucs4_t* Unicode::ucs4ncopy(ucs4_t *dst, const char *src, int byteLength)
{
  ucs4_t i;
  ucs4_t *p;
  const unsigned char *psrc = reinterpret_cast<const unsigned char *>(src);
  const unsigned char *end_src = psrc + byteLength;

  p = dst;
  while ((psrc < end_src) && (i = getUTF8Char(psrc, end_src-psrc)) != 0) {
    if (i != _BadUTF8Char)
      *p++ = i;
  }
  *p = 0;
  return p;
}


char* Unicode::strdupUTF8(const char *src)
{
  char *res;
  size_t reslen;
  ucs4_t i;
  const unsigned char *p;
  char *q;

  reslen = 0;
  p = reinterpret_cast<const unsigned char *>(src);
  while ((i = getUTF8Char(p)) != 0) {
    if (i != _BadUTF8Char)
      reslen += utf8clen(i);
  }
  res = static_cast<char *>(malloc(reslen + 1));
  p = reinterpret_cast<const unsigned char *>(src);
  q = res;
  while ((i = getUTF8Char(p)) != 0) {
    if (i != _BadUTF8Char)
      q = utf8cput(q, i);
  }
  assert(q == res + reslen);
  *q = 0;
  return res;
}


char* Unicode::strlowdupUTF8(const char *src)
{
  char *res;
  size_t reslen;
  ucs4_t i;
  const unsigned char *p;
  char *q;

  reslen = 0;
  p = reinterpret_cast<const unsigned char *>(src);
  while ((i = getUTF8Char(p)) != 0) {
    if (i != _BadUTF8Char) {
      i = toLower(i);
      if (i != _BadUTF8Char)
	reslen += utf8clen(i);
    }
  }
  res = static_cast<char *>(malloc(reslen + 1));
  p = reinterpret_cast<const unsigned char *>(src);
  q = res;
  while ((i = getUTF8Char(p)) != 0) {
    if (i != _BadUTF8Char) {
      i = toLower(i);
      if (i != _BadUTF8Char)
	q = utf8cput(q, i);
    }
  }
  assert(q == res + reslen);
  *q = 0;
  return res;
}

char* Unicode::strdupLAT1(const char *src)
{
  char *res;
  size_t reslen;
  ucs4_t i;
  const unsigned char *p;
  char *q;

  reslen = 0;
  p = reinterpret_cast<const unsigned char *>(src);
  while ((i = *p++) != 0) {
    reslen += utf8clen(i);
  }
  res = static_cast<char *>(malloc(reslen + 1));
  p = reinterpret_cast<const unsigned char *>(src);
  q = res;
  while ((i = *p++) != 0) {
    q = utf8cput(q, i);
  }
  assert(q == res + reslen);
  *q = 0;
  return res;
}

ucs4_t Unicode::getUTF8Char(unsigned const char *&src,
                              int length /* = -1 */ )
{
  ucs4_t retval;

  if (length != -1) {
    // Check for unfinished UTF8 character sequence
    int bytes = getUTF8ByteLength(*src);
    if (bytes > length) {
      src += bytes;
      return _BadUTF8Char;
    }
  }

  if (*src >= 0x80) {				/* 0x80..0xff */
    if (*src >= 0xc0) {
      if (src[1] < 0x80 || src[1] >= 0xc0) {
        src++;
        return _BadUTF8Char;
      }
      if (*src >= 0xe0) {			/* 0xe0..0xff */
        if (src[2] < 0x80 || src[2] >= 0xc0) {
          src += 2;
          return _BadUTF8Char;
        }
        if (*src >= 0xf0) {			/* 0xf0..0xff */
          if (src[3] < 0x80 || src[3] >= 0xc0) {
            src += 3;
            return _BadUTF8Char;
          }
          if (*src >= 0xf8) {			/* 0xf8..0xff */
            if (src[4] < 0x80 || src[4] >= 0xc0) {
              src += 4;
              return _BadUTF8Char;
            }
            if (*src >= 0xfc) {			/* 0xfc..0xff */
              if (src[5] < 0x80 || src[5] >= 0xc0) {
                src += 5;
                return _BadUTF8Char;
              }
              if (*src >= 0xfe) {		/* 0xfe..0xff: INVALID */
                src += 5;
                return _BadUTF8Char;
              } else {				/* 0xfc..0xfd: 6 bytes */
                retval = ((src[0] & 1) << 30) |
                  ((src[1] & 63) << 24) |
                  ((src[2] & 63) << 18) |
                  ((src[3] & 63) << 12) |
                  ((src[4] & 63) << 6) |
                  (src[5] & 63);
                if (retval < 0x4000000u)	/* 6 bytes: >= 0x4000000 */
                  retval = _BadUTF8Char;
                src += 6;
                return retval;
              }
            } else {				/* 0xf8..0xfb: 5 bytes */
              retval = ((src[0] & 3) << 24) |
                ((src[1] & 63) << 18) |
                ((src[2] & 63) << 12) |
                ((src[3] & 63) << 6) |
                (src[4] & 63);
              if (retval < 0x200000u)		/* 5 bytes: >= 0x200000 */
                retval = _BadUTF8Char;
              src += 5;
              return retval;
            }
          } else {				/* 0xf0..0xf7: 4 bytes */
            retval = ((src[0] & 7) << 18) |
              ((src[1] & 63) << 12) |
              ((src[2] & 63) << 6) |
              (src[3] & 63);
            if (retval < 0x10000)		/* 4 bytes: >= 0x10000 */
              retval = _BadUTF8Char;
            src += 4;
            return retval;
          }
        } else {				/* 0xe0..0xef: 3 bytes */
          retval = ((src[0] & 15) << 12) |
            ((src[1] & 63) << 6) |
            (src[2] & 63);
          if (retval < 0x800)			/* 3 bytes: >= 0x800 */
            retval = _BadUTF8Char;
          src += 3;
          return retval;
        }
      } else {					/* 0xc0..0xdf: 2 bytes */

        retval = ((src[0] & 31) << 6) |
          (src[1] & 63);
        if (retval < 0x80)			/* 2 bytes: >= 0x80 */
          retval = _BadUTF8Char;
        src += 2;
        return retval;
      }
    } else {					/* 0x80..0xbf: INVALID */
      src += 1;
      return _BadUTF8Char;
    }
  } else					/* 0x00..0x7f: 1 byte */
    return *src++;
}




#define UTF8_STARTCHAR(c)  (!((c) & 0x80) || ((c) & 0x40))

  /** Move forwards or backwards a number of characters within an UTF8 buffer
   * Modify pos to yield new position if possible
   * @param start A pointer to the start of the UTF8 buffer
   * @param length The length of the UTF8 buffer
   * @param pos A pointer to the current position within the UTF8 buffer,
   *            updated to reflect new position upon return. @param pos will
   *    point to the start of the offset'th character before or after the character
   *    currently pointed to.
   * @param offset An offset (+/-) in number of UTF8 characters.
   *        Offset 0 consequently yields a move to the start of the current character.
   * @return Number of bytes moved, or -1 if out of range.
   *        If -1 is returned, pos is unchanged.
   */
int Unicode::utf8move(unsigned const char* start, size_t length,
                      unsigned const char*& pos, off_t offset)
{
  int increment = offset > 0 ? 1 : -1;
  unsigned const char* p = pos;

  /* If running backward we first need to get to the start of
   * the current character, that's an extra step.
   * Similarly, if we are running forward an are at the start of a character,
   * we count that character as a step.
   */

  if (increment < 0)
  {
    // Already at start?
    if (p < start) return -1;
    if (!offset)
    {
      if (p > start + length) return -1;
    }
    else if (p == start) return -1;

    // Initially pointing to the first invalid char?
    if (p == start + length)
      p += increment;
    else
      offset += increment;
  }
  else if (p >= start + length)
    return -1;
  else if (UTF8_STARTCHAR(*p))
    offset += increment;


  for (; p >= start && p < start+length; p += increment)
  {
    /** Are we at start of a character? (both highest bits or none of them set) */
    if (UTF8_STARTCHAR(*p))
      offset -= increment; // We have "eaten" another character (independent of dir)
    if (offset == 0) break;
  }

  if (offset != 0)
  {
    offset -= increment;
    if (increment < 0)
      p -= increment;
  }

  if (offset == 0) // Enough room to make it..
  {
    int moved = std::abs(p - pos);
    pos = p;
    return moved;
  }
  else
    return -1;
}

} // namespace fsa