/* decomp.c - Character decomposition.

 *

 *  Copyright (C) 1999, 2000 Tom Tromey

 *  Copyright 2000 Red Hat, Inc.

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

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

 * along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include <stdlib.h>

#include "gunicode.h"

#include "gunidecomp.h"

#include "gmem.h"

#include "gunicomp.h"

#include "gunicodeprivate.h"

#define CC_PART1(Page, Char) \

  ((combining_class_table_part1[Page] >= G_UNICODE_MAX_TABLE_INDEX) \

   ? (combining_class_table_part1[Page] - G_UNICODE_MAX_TABLE_INDEX) \

   : (cclass_data[combining_class_table_part1[Page]][Char]))

#define CC_PART2(Page, Char) \

  ((combining_class_table_part2[Page] >= G_UNICODE_MAX_TABLE_INDEX) \

   ? (combining_class_table_part2[Page] - G_UNICODE_MAX_TABLE_INDEX) \

   : (cclass_data[combining_class_table_part2[Page]][Char]))

#define COMBINING_CLASS(Char) \

  (((Char) <= G_UNICODE_LAST_CHAR_PART1) \

   ? CC_PART1 ((Char) >> 8, (Char) & 0xff) \

   : (((Char) >= 0xe0000 && (Char) <= G_UNICODE_LAST_CHAR) \

      ? CC_PART2 (((Char) - 0xe0000) >> 8, (Char) & 0xff) \

      : 0))

/**

 * g_unichar_combining_class:

 * @uc: a Unicode character

 * 

 * Determines the canonical combining class of a Unicode character.

 * 

 * Returns: the combining class of the character

 *

 * Since: 2.14

 **/

gint

g_unichar_combining_class (gunichar uc)

{

  return COMBINING_CLASS (uc);

}

/* constants for hangul syllable [de]composition */

#define SBase 0xAC00 

#define LBase 0x1100 

#define VBase 0x1161 

#define TBase 0x11A7

#define LCount 19 

#define VCount 21

#define TCount 28

#define NCount (VCount * TCount)

#define SCount (LCount * NCount)

/**

 * g_unicode_canonical_ordering:

 * @string: (array length=len) (element-type gunichar): a UCS-4 encoded string.

 * @len: the maximum length of @string to use.

 *

 * Computes the canonical ordering of a string in-place.  

 * This rearranges decomposed characters in the string 

 * according to their combining classes.  See the Unicode 

 * manual for more information. 

 **/

void

g_unicode_canonical_ordering (gunichar *string,

            gsize     len)

{

  gsize i;

  int swap = 1;

  while (swap)

    {

      int last;

      swap = 0;

      last = COMBINING_CLASS (string[0]);

      for (i = 0; i < len - 1; ++i)

  {

    int next = COMBINING_CLASS (string[i + 1]);

    if (next != 0 && last > next)

      {

        gsize j;

        /* Percolate item leftward through string.  */

        for (j = i + 1; j > 0; --j)

    {

      gunichar t;

      if (COMBINING_CLASS (string[j - 1]) <= next)

        break;

      t = string[j];

      string[j] = string[j - 1];

      string[j - 1] = t;

      swap = 1;

    }

        /* We're re-entering the loop looking at the old

     character again.  */

        next = last;

      }

    last = next;

  }

    }

}

/* http://www.unicode.org/unicode/reports/tr15/#Hangul

 * r should be null or have sufficient space. Calling with r == NULL will

 * only calculate the result_len; however, a buffer with space for three

 * characters will always be big enough. */

static void

decompose_hangul (gunichar s,

                  gunichar *r,

                  gsize *result_len)

{

  gint SIndex = s - SBase;

  gint TIndex = SIndex % TCount;

  if (r)

    {

      r[0] = LBase + SIndex / NCount;

      r[1] = VBase + (SIndex % NCount) / TCount;

    }

  if (TIndex)

    {

      if (r)

  r[2] = TBase + TIndex;

      *result_len = 3;

    }

  else

    *result_len = 2;

}

/* returns a pointer to a null-terminated UTF-8 string */

static const gchar *

find_decomposition (gunichar ch,

        gboolean compat)

{

  int start = 0;

  int end = G_N_ELEMENTS (decomp_table);

  if (ch >= decomp_table[start].ch &&

      ch <= decomp_table[end - 1].ch)

    {

      while (TRUE)

  {

    int half = (start + end) / 2;

    if (ch == decomp_table[half].ch)

      {

        int offset;

        if (compat)

    {

      offset = decomp_table[half].compat_offset;

      if (offset == G_UNICODE_NOT_PRESENT_OFFSET)

        offset = decomp_table[half].canon_offset;

    }

        else

    {

      offset = decomp_table[half].canon_offset;

      if (offset == G_UNICODE_NOT_PRESENT_OFFSET)

        return NULL;

    }

        return &(decomp_expansion_string[offset]);

      }

    else if (half == start)

      break;

    else if (ch > decomp_table[half].ch)

      start = half;

    else

      end = half;

  }

    }

  return NULL;

}

/**

 * g_unicode_canonical_decomposition:

 * @ch: a Unicode character.

 * @result_len: location to store the length of the return value.

 *

 * Computes the canonical decomposition of a Unicode character.  

 * 

 * Returns: a newly allocated string of Unicode characters.

 *   @result_len is set to the resulting length of the string.

 *

 * Deprecated: 2.30: Use the more flexible g_unichar_fully_decompose()

 *   instead.

 **/

gunichar *

g_unicode_canonical_decomposition (gunichar ch,

           gsize   *result_len)

{

  const gchar *decomp;

  const gchar *p;

  gunichar *r;

  /* Hangul syllable */

  if (ch >= SBase && ch < SBase + SCount)

    {

      decompose_hangul (ch, NULL, result_len);

      r = g_malloc (*result_len * sizeof (gunichar));

      decompose_hangul (ch, r, result_len);

    }

  else if ((decomp = find_decomposition (ch, FALSE)) != NULL)

    {

      /* Found it.  */

      int i;

      *result_len = g_utf8_strlen (decomp, -1);

      r = g_malloc (*result_len * sizeof (gunichar));

      for (p = decomp, i = 0; *p != '\0'; p = g_utf8_next_char (p), i++)

        r[i] = g_utf8_get_char (p);

    }

  else

    {

      /* Not in our table.  */

      r = g_malloc (sizeof (gunichar));

      *r = ch;

      *result_len = 1;

    }

  return r;

}

/* L,V => LV and LV,T => LVT  */

static gboolean

combine_hangul (gunichar a,

                gunichar b,

                gunichar *result)

{

  gint LIndex = a - LBase;

  gint SIndex = a - SBase;

  gint VIndex = b - VBase;

  gint TIndex = b - TBase;

  if (0 <= LIndex && LIndex < LCount

      && 0 <= VIndex && VIndex < VCount)

    {

      *result = SBase + (LIndex * VCount + VIndex) * TCount;

      return TRUE;

    }

  else if (0 <= SIndex && SIndex < SCount && (SIndex % TCount) == 0

           && 0 < TIndex && TIndex < TCount)

    {

      *result = a + TIndex;

      return TRUE;

    }

  return FALSE;

}

#define CI(Page, Char) \

  ((compose_table[Page] >= G_UNICODE_MAX_TABLE_INDEX) \

   ? (compose_table[Page] - G_UNICODE_MAX_TABLE_INDEX) \

   : (compose_data[compose_table[Page]][Char]))

#define COMPOSE_INDEX(Char) \

     (((Char >> 8) > (COMPOSE_TABLE_LAST)) ? 0 : CI((Char) >> 8, (Char) & 0xff))

static gboolean

combine (gunichar  a,

   gunichar  b,

   gunichar *result)

{

  gushort index_a, index_b;

  if (combine_hangul (a, b, result))

    return TRUE;

  index_a = COMPOSE_INDEX(a);

  if (index_a >= COMPOSE_FIRST_SINGLE_START && index_a < COMPOSE_SECOND_START)

    {

      if (b == compose_first_single[index_a - COMPOSE_FIRST_SINGLE_START][0])

  {

    *result = compose_first_single[index_a - COMPOSE_FIRST_SINGLE_START][1];

    return TRUE;

  }

      else

        return FALSE;

    }

  index_b = COMPOSE_INDEX(b);

  if (index_b >= COMPOSE_SECOND_SINGLE_START)

    {

      if (a == compose_second_single[index_b - COMPOSE_SECOND_SINGLE_START][0])

  {

    *result = compose_second_single[index_b - COMPOSE_SECOND_SINGLE_START][1];

    return TRUE;

  }

      else

        return FALSE;

    }

  if (index_a >= COMPOSE_FIRST_START && index_a < COMPOSE_FIRST_SINGLE_START &&

      index_b >= COMPOSE_SECOND_START && index_b < COMPOSE_SECOND_SINGLE_START)

    {

      gunichar res = compose_array[index_a - COMPOSE_FIRST_START][index_b - COMPOSE_SECOND_START];

      if (res)

  {

    *result = res;

    return TRUE;

  }

    }

  return FALSE;

}

gunichar *

_g_utf8_normalize_wc (const gchar    *str,

          gssize          max_len,

          GNormalizeMode  mode)

{

  gsize n_wc;

  gunichar *wc_buffer;

  const char *p;

  gsize last_start;

  gboolean do_compat = (mode == G_NORMALIZE_NFKC ||

      mode == G_NORMALIZE_NFKD);

  gboolean do_compose = (mode == G_NORMALIZE_NFC ||

       mode == G_NORMALIZE_NFKC);

  n_wc = 0;

  p = str;

  while ((max_len < 0 || p < str + max_len) && *p)

    {

      const gchar *decomp;

      const char *next, *between;

      gunichar wc;

      next = g_utf8_next_char (p);

      /* Avoid reading truncated multibyte characters

         which run past the end of the buffer */

      if (max_len < 0)

        {

          /* Does the character contain a NUL terminator? */

          for (between = &p[1]; between < next; between++)

            {

              if (G_UNLIKELY (!*between))

                return NULL;

            }

        }

      else

        {

          if (G_UNLIKELY (next > str + max_len))

            return NULL;

        }

      wc = g_utf8_get_char (p);

      if (G_UNLIKELY (wc == (gunichar) -1))

        {

          return NULL;

        }

      else if (wc >= SBase && wc < SBase + SCount)

        {

          gsize result_len;

          decompose_hangul (wc, NULL, &result_len);

          n_wc += result_len;

        }

      else 

        {

          decomp = find_decomposition (wc, do_compat);

          if (decomp)

            n_wc += g_utf8_strlen (decomp, -1);

          else

            n_wc++;

        }

      p = next;

    }

  wc_buffer = g_new (gunichar, n_wc + 1);

  last_start = 0;

  n_wc = 0;

  p = str;

  while ((max_len < 0 || p < str + max_len) && *p)

    {

      gunichar wc = g_utf8_get_char (p);

      const gchar *decomp;

      int cc;

      gsize old_n_wc = n_wc;

      if (wc >= SBase && wc < SBase + SCount)

        {

          gsize result_len;

          decompose_hangul (wc, wc_buffer + n_wc, &result_len);

          n_wc += result_len;

        }

      else

        {

          decomp = find_decomposition (wc, do_compat);

          if (decomp)

            {

              const char *pd;

              for (pd = decomp; *pd != '\0'; pd = g_utf8_next_char (pd))

                wc_buffer[n_wc++] = g_utf8_get_char (pd);

            }

          else

            wc_buffer[n_wc++] = wc;

        }

      if (n_wc > 0)

  {

    cc = COMBINING_CLASS (wc_buffer[old_n_wc]);

    if (cc == 0)

      {

        g_unicode_canonical_ordering (wc_buffer + last_start, n_wc - last_start);

        last_start = old_n_wc;

      }

  }

      p = g_utf8_next_char (p);

    }

  if (n_wc > 0)

    {

      g_unicode_canonical_ordering (wc_buffer + last_start, n_wc - last_start);

      last_start = n_wc;

      (void) last_start;

    }

  wc_buffer[n_wc] = 0;

  /* All decomposed and reordered */ 

  if (do_compose && n_wc > 0)

    {

      gsize i, j;

      int last_cc = 0;

      last_start = 0;

      for (i = 0; i < n_wc; i++)

  {

    int cc = COMBINING_CLASS (wc_buffer[i]);

    if (i > 0 &&

        (last_cc == 0 || last_cc < cc) &&

        combine (wc_buffer[last_start], wc_buffer[i],

           &wc_buffer[last_start]))

      {

        for (j = i + 1; j < n_wc; j++)

    wc_buffer[j-1] = wc_buffer[j];

        n_wc--;

        i--;

        if (i == last_start)

    last_cc = 0;

        else

    last_cc = COMBINING_CLASS (wc_buffer[i-1]);

        continue;

      }

    if (cc == 0)

      last_start = i;

    last_cc = cc;

  }

    }

  wc_buffer[n_wc] = 0;

  return wc_buffer;

}

/**

 * g_utf8_normalize:

 * @str: a UTF-8 encoded string.

 * @len: length of @str, in bytes, or -1 if @str is nul-terminated.

 * @mode: the type of normalization to perform.

 *

 * Converts a string into canonical form, standardizing

 * such issues as whether a character with an accent

 * is represented as a base character and combining

 * accent or as a single precomposed character. The

 * string has to be valid UTF-8, otherwise %NULL is

 * returned. You should generally call g_utf8_normalize()

 * before comparing two Unicode strings.

 *

 * The normalization mode %G_NORMALIZE_DEFAULT only

 * standardizes differences that do not affect the

 * text content, such as the above-mentioned accent

 * representation. %G_NORMALIZE_ALL also standardizes

 * the "compatibility" characters in Unicode, such

 * as SUPERSCRIPT THREE to the standard forms

 * (in this case DIGIT THREE). Formatting information

 * may be lost but for most text operations such

 * characters should be considered the same.

 *

 * %G_NORMALIZE_DEFAULT_COMPOSE and %G_NORMALIZE_ALL_COMPOSE

 * are like %G_NORMALIZE_DEFAULT and %G_NORMALIZE_ALL,

 * but returned a result with composed forms rather

 * than a maximally decomposed form. This is often

 * useful if you intend to convert the string to

 * a legacy encoding or pass it to a system with

 * less capable Unicode handling.

 *

 * Returns: (nullable): a newly allocated string, that

 *   is the normalized form of @str, or %NULL if @str

 *   is not valid UTF-8.

 **/

gchar *

g_utf8_normalize (const gchar    *str,

      gssize          len,

      GNormalizeMode  mode)

{

  gunichar *result_wc = _g_utf8_normalize_wc (str, len, mode);

  gchar *result = NULL;

  if (G_LIKELY (result_wc != NULL))

    {

      result = g_ucs4_to_utf8 (result_wc, -1, NULL, NULL, NULL);

      g_free (result_wc);

    }

  return result;

}

static gboolean

decompose_hangul_step (gunichar  ch,

                       gunichar *a,

                       gunichar *b)

{

  gint SIndex, TIndex;

  if (ch < SBase || ch >= SBase + SCount)

    return FALSE;  /* not a hangul syllable */

  SIndex = ch - SBase;

  TIndex = SIndex % TCount;

  if (TIndex)

    {

      /* split LVT -> LV,T */

      *a = ch - TIndex;

      *b = TBase + TIndex;

    }

  else

    {

      /* split LV -> L,V */

      *a = LBase + SIndex / NCount;

      *b = VBase + (SIndex % NCount) / TCount;

    }

  return TRUE;

}

/**

 * g_unichar_decompose:

 * @ch: a Unicode character

 * @a: (out) (not optional): return location for the first component of @ch

 * @b: (out) (not optional): return location for the second component of @ch

 *

 * Performs a single decomposition step of the

 * Unicode canonical decomposition algorithm.

 *

 * This function does not include compatibility

 * decompositions. It does, however, include algorithmic

 * Hangul Jamo decomposition, as well as 'singleton'

 * decompositions which replace a character by a single

 * other character. In the case of singletons *@b will

 * be set to zero.

 *

 * If @ch is not decomposable, *@a is set to @ch and *@b

 * is set to zero.

 *

 * Note that the way Unicode decomposition pairs are

 * defined, it is guaranteed that @b would not decompose

 * further, but @a may itself decompose.  To get the full

 * canonical decomposition for @ch, one would need to

 * recursively call this function on @a.  Or use

 * g_unichar_fully_decompose().

 *

 * See

 * [UAX#15](http://unicode.org/reports/tr15/)

 * for details.

 *

 * Returns: %TRUE if the character could be decomposed

 *

 * Since: 2.30

 */

gboolean

g_unichar_decompose (gunichar  ch,

                     gunichar *a,

                     gunichar *b)

{

  gint start = 0;

  gint end = G_N_ELEMENTS (decomp_step_table);

  if (decompose_hangul_step (ch, a, b))

    return TRUE;

  /* TODO use bsearch() */

  if (ch >= decomp_step_table[start].ch &&

      ch <= decomp_step_table[end - 1].ch)

    {

      while (TRUE)

        {

          gint half = (start + end) / 2;

          const decomposition_step *p = &(decomp_step_table[half]);

          if (ch == p->ch)

            {

              *a = p->a;

              *b = p->b;

              return TRUE;

            }

          else if (half == start)

            break;

          else if (ch > p->ch)

            start = half;

          else

            end = half;

        }

    }

  *a = ch;

  *b = 0;

  return FALSE;

}

/**

 * g_unichar_compose:

 * @a: a Unicode character

 * @b: a Unicode character

 * @ch: (out) (not optional): return location for the composed character

 *

 * Performs a single composition step of the

 * Unicode canonical composition algorithm.

 *

 * This function includes algorithmic Hangul Jamo composition,

 * but it is not exactly the inverse of g_unichar_decompose().

 * No composition can have either of @a or @b equal to zero.

 * To be precise, this function composes if and only if

 * there exists a Primary Composite P which is canonically

 * equivalent to the sequence <@a,@b>.  See the Unicode

 * Standard for the definition of Primary Composite.

 *

 * If @a and @b do not compose a new character, @ch is set to zero.

 *

 * See

 * [UAX#15](http://unicode.org/reports/tr15/)

 * for details.

 *

 * Returns: %TRUE if the characters could be composed

 *

 * Since: 2.30

 */

gboolean

g_unichar_compose (gunichar  a,

                   gunichar  b,

                   gunichar *ch)

{

  if (combine (a, b, ch))

    return TRUE;

  *ch = 0;

  return FALSE;

}

/**

 * g_unichar_fully_decompose:

 * @ch: a Unicode character.

 * @compat: whether perform canonical or compatibility decomposition

 * @result: (optional) (out caller-allocates): location to store decomposed result, or %NULL

 * @result_len: length of @result

 *

 * Computes the canonical or compatibility decomposition of a

 * Unicode character.  For compatibility decomposition,

 * pass %TRUE for @compat; for canonical decomposition

 * pass %FALSE for @compat.

 *

 * The decomposed sequence is placed in @result.  Only up to

 * @result_len characters are written into @result.  The length

 * of the full decomposition (irrespective of @result_len) is

 * returned by the function.  For canonical decomposition,

 * currently all decompositions are of length at most 4, but

 * this may change in the future (very unlikely though).

 * At any rate, Unicode does guarantee that a buffer of length

 * 18 is always enough for both compatibility and canonical

 * decompositions, so that is the size recommended. This is provided

 * as %G_UNICHAR_MAX_DECOMPOSITION_LENGTH.

 *

 * See

 * [UAX#15](http://unicode.org/reports/tr15/)

 * for details.

 *

 * Returns: the length of the full decomposition.

 *

 * Since: 2.30

 **/

gsize

g_unichar_fully_decompose (gunichar  ch,

         gboolean  compat,

         gunichar *result,

         gsize     result_len)

{

  const gchar *decomp;

  const gchar *p;

  /* Hangul syllable */

  if (ch >= SBase && ch < SBase + SCount)

    {

      gsize len, i;

      gunichar buffer[3];

      decompose_hangul (ch, result ? buffer : NULL, &len);

      if (result)

        for (i = 0; i < len && i < result_len; i++)

    result[i] = buffer[i];

      return len;

    }

  else if ((decomp = find_decomposition (ch, compat)) != NULL)

    {

      /* Found it.  */

      gsize len, i;

      len = g_utf8_strlen (decomp, -1);

      for (p = decomp, i = 0; i < len && i < result_len; p = g_utf8_next_char (p), i++)

        result[i] = g_utf8_get_char (p);

      return len;

    }

  /* Does not decompose */

  if (result && result_len >= 1)

    *result = ch;

  return 1;

}