/*

 * Copyright © 2013  Google, Inc.

 *

 *  This is part of HarfBuzz, a text shaping library.

 *

 * Permission is hereby granted, without written agreement and without

 * license or royalty fees, to use, copy, modify, and distribute this

 * software and its documentation for any purpose, provided that the

 * above copyright notice and the following two paragraphs appear in

 * all copies of this software.

 *

 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

 * DAMAGE.

 *

 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 *

 * Google Author(s): Behdad Esfahbod

 */

#include "hb.hh"

#ifndef HB_NO_OT_SHAPE

#include "hb-ot-shaper.hh"

/* Hangul shaper */

/* Same order as the feature array below */

enum {

  _JMO,

  LJMO,

  VJMO,

  TJMO,

  FIRST_HANGUL_FEATURE = LJMO,

  HANGUL_FEATURE_COUNT = TJMO + 1

};

static const hb_tag_t hangul_features[HANGUL_FEATURE_COUNT] =

{

  HB_TAG_NONE,

  HB_TAG('l','j','m','o'),

  HB_TAG('v','j','m','o'),

  HB_TAG('t','j','m','o')

};

static void

collect_features_hangul (hb_ot_shape_planner_t *plan)

{

  hb_ot_map_builder_t *map = &plan->map;

  for (unsigned int i = FIRST_HANGUL_FEATURE; i < HANGUL_FEATURE_COUNT; i++)

    map->add_feature (hangul_features[i]);

}

static void

override_features_hangul (hb_ot_shape_planner_t *plan)

{

  /* Uniscribe does not apply 'calt' for Hangul, and certain fonts

   * (Noto Sans CJK, Source Han Sans, etc) apply all of jamo lookups

   * in calt, which is not desirable.

   *

   * Rather than disabling 'calt' for the entire run, which also turns

   * it off for any other characters in the run, allocate a mask for it

   * and clear that mask on jamo only (in setup_masks_hangul).  That

   * keeps jamo out of reach of such lookups while letting the rest of

   * the run shape with 'calt' as usual.

   *

   * https://github.com/harfbuzz/harfbuzz/discussions/4853 */

  plan->map.add_feature (HB_TAG('c','a','l','t'));

}

struct hangul_shape_plan_t

{

  hb_mask_t mask_array[HANGUL_FEATURE_COUNT];

  hb_mask_t calt_mask;

};

static void *

data_create_hangul (const hb_ot_shape_plan_t *plan)

{

  hangul_shape_plan_t *hangul_plan = (hangul_shape_plan_t *) hb_calloc (1, sizeof (hangul_shape_plan_t));

  if (unlikely (!hangul_plan))

    return nullptr;

  for (unsigned int i = 0; i < HANGUL_FEATURE_COUNT; i++)

    hangul_plan->mask_array[i] = plan->map.get_1_mask (hangul_features[i]);

  hangul_plan->calt_mask = plan->map.get_1_mask (HB_TAG('c','a','l','t'));

  return hangul_plan;

}

static void

data_destroy_hangul (void *data)

{

  hb_free (data);

}

/* Constants for algorithmic hangul syllable [de]composition. */

#define LBase 0x1100u

#define VBase 0x1161u

#define TBase 0x11A7u

#define LCount 19u

#define VCount 21u

#define TCount 28u

#define SBase 0xAC00u

#define NCount (VCount * TCount)

#define SCount (LCount * NCount)

#define isCombiningL(u) (hb_in_range<hb_codepoint_t> ((u), LBase, LBase+LCount-1))

#define isCombiningV(u) (hb_in_range<hb_codepoint_t> ((u), VBase, VBase+VCount-1))

#define isCombiningT(u) (hb_in_range<hb_codepoint_t> ((u), TBase+1, TBase+TCount-1))

#define isCombinedS(u) (hb_in_range<hb_codepoint_t> ((u), SBase, SBase+SCount-1))

#define isL(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1100u, 0x115Fu, 0xA960u, 0xA97Cu))

#define isV(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x1160u, 0x11A7u, 0xD7B0u, 0xD7C6u))

#define isT(u) (hb_in_ranges<hb_codepoint_t> ((u), 0x11A8u, 0x11FFu, 0xD7CBu, 0xD7FBu))

#define isHangulTone(u) (hb_in_range<hb_codepoint_t> ((u), 0x302Eu, 0x302Fu))

/* buffer var allocations */

#define hangul_shaping_feature() ot_shaper_var_u8_auxiliary() /* hangul jamo shaping feature */

static bool

is_zero_width_char (hb_font_t *font,

        hb_codepoint_t unicode)

{

  hb_codepoint_t glyph;

  return hb_font_get_glyph (font, unicode, 0, &glyph) && hb_font_get_glyph_h_advance (font, glyph) == 0;

}

static void

preprocess_text_hangul (const hb_ot_shape_plan_t *plan HB_UNUSED,

      hb_buffer_t              *buffer,

      hb_font_t                *font)

{

  HB_BUFFER_ALLOCATE_VAR (buffer, hangul_shaping_feature);

  /* Hangul syllables come in two shapes: LV, and LVT.  Of those:

   *

   *   - LV can be precomposed, or decomposed.  Lets call those

   *     <LV> and <L,V>,

   *   - LVT can be fully precomposed, partially precomposed, or

   *     fully decomposed.  Ie. <LVT>, <LV,T>, or <L,V,T>.

   *

   * The composition / decomposition is mechanical.  However, not

   * all <L,V> sequences compose, and not all <LV,T> sequences

   * compose.

   *

   * Here are the specifics:

   *

   *   - <L>: U+1100..115F, U+A960..A97F

   *   - <V>: U+1160..11A7, U+D7B0..D7C7

   *   - <T>: U+11A8..11FF, U+D7CB..D7FB

   *

   *   - Only the <L,V> sequences for some of the U+11xx ranges combine.

   *   - Only <LV,T> sequences for some of the Ts in U+11xx range combine.

   *

   * Here is what we want to accomplish in this shaper:

   *

   *   - If the whole syllable can be precomposed, do that,

   *   - Otherwise, fully decompose and apply ljmo/vjmo/tjmo features.

   *   - If a valid syllable is followed by a Hangul tone mark, reorder the tone

   *     mark to precede the whole syllable - unless it is a zero-width glyph, in

   *     which case we leave it untouched, assuming it's designed to overstrike.

   *

   * That is, of the different possible syllables:

   *

   *   <L>

   *   <L,V>

   *   <L,V,T>

   *   <LV>

   *   <LVT>

   *   <LV, T>

   *

   * - <L> needs no work.

   *

   * - <LV> and <LVT> can stay the way they are if the font supports them, otherwise we

   *   should fully decompose them if font supports.

   *

   * - <L,V> and <L,V,T> we should compose if the whole thing can be composed.

   *

   * - <LV,T> we should compose if the whole thing can be composed, otherwise we should

   *   decompose.

   */

  buffer->clear_output ();

  unsigned int start = 0, end = 0; /* Extent of most recently seen syllable;

            * valid only if start < end

            */

  unsigned int count = buffer->len;

  for (buffer->idx = 0; buffer->idx < count && buffer->successful;)

  {

    hb_codepoint_t u = buffer->cur().codepoint;

    if (isHangulTone (u))

    {

      /*

       * We could cache the width of the tone marks and the existence of dotted-circle,

       * but the use of the Hangul tone mark characters seems to be rare enough that

       * I didn't bother for now.

       */

      if (start < end && end == buffer->out_len)

      {

  /* Tone mark follows a valid syllable; move it in front, unless it's zero width. */

  buffer->unsafe_to_break_from_outbuffer (start, buffer->idx);

  if (unlikely (!buffer->next_glyph ())) break;

  if (!is_zero_width_char (font, u))

  {

    buffer->merge_out_clusters (start, end + 1);

    hb_glyph_info_t *info = buffer->out_info;

    hb_glyph_info_t tone = info[end];

    memmove (&info[start + 1], &info[start], (end - start) * sizeof (hb_glyph_info_t));

    info[start] = tone;

  }

      }

      else

      {

  /* No valid syllable as base for tone mark; try to insert dotted circle. */

  if (!(buffer->flags & HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE) &&

      font->has_glyph (0x25CCu))

  {

    hb_codepoint_t chars[2];

    if (!is_zero_width_char (font, u))

    {

      chars[0] = u;

      chars[1] = 0x25CCu;

    } else

    {

      chars[0] = 0x25CCu;

      chars[1] = u;

    }

    (void) buffer->replace_glyphs (1, 2, chars);

  }

  else

  {

    /* No dotted circle available in the font; just leave tone mark untouched. */

    (void) buffer->next_glyph ();

  }

      }

      start = end = buffer->out_len;

      continue;

    }

    start = buffer->out_len; /* Remember current position as a potential syllable start;

            * will only be used if we set end to a later position.

            */

    if (isL (u) && buffer->idx + 1 < count)

    {

      hb_codepoint_t l = u;

      hb_codepoint_t v = buffer->cur(+1).codepoint;

      if (isV (v))

      {

  /* Have <L,V> or <L,V,T>. */

  hb_codepoint_t t = 0;

  unsigned int tindex = 0;

  if (buffer->idx + 2 < count)

  {

    t = buffer->cur(+2).codepoint;

    if (isT (t))

      tindex = t - TBase; /* Only used if isCombiningT (t); otherwise invalid. */

    else

      t = 0; /* The next character was not a trailing jamo. */

  }

  buffer->unsafe_to_break (buffer->idx, buffer->idx + (t ? 3 : 2));

  /* We've got a syllable <L,V,T?>; see if it can potentially be composed. */

  if (isCombiningL (l) && isCombiningV (v) && (t == 0 || isCombiningT (t)))

  {

    /* Try to compose; if this succeeds, end is set to start+1. */

    hb_codepoint_t s = SBase + (l - LBase) * NCount + (v - VBase) * TCount + tindex;

    if (font->has_glyph (s))

    {

      (void) buffer->replace_glyphs (t ? 3 : 2, 1, &s);

      end = start + 1;

      continue;

    }

  }

  /* We didn't compose, either because it's an Old Hangul syllable without a

   * precomposed character in Unicode, or because the font didn't support the

   * necessary precomposed glyph.

   * Set jamo features on the individual glyphs, and advance past them.

   */

  buffer->cur().hangul_shaping_feature() = LJMO;

  (void) buffer->next_glyph ();

  buffer->cur().hangul_shaping_feature() = VJMO;

  (void) buffer->next_glyph ();

  if (t)

  {

    buffer->cur().hangul_shaping_feature() = TJMO;

    (void) buffer->next_glyph ();

    end = start + 3;

  }

  else

    end = start + 2;

  if (unlikely (!buffer->successful))

    break;

  buffer->merge_out_grapheme_clusters (start, end);

  continue;

      }

    }

    else if (isCombinedS (u))

    {

      /* Have <LV>, <LVT>, or <LV,T> */

      hb_codepoint_t s = u;

      bool has_glyph = font->has_glyph (s);

      unsigned int lindex = (s - SBase) / NCount;

      unsigned int nindex = (s - SBase) % NCount;

      unsigned int vindex = nindex / TCount;

      unsigned int tindex = nindex % TCount;

      if (!tindex &&

    buffer->idx + 1 < count &&

    isCombiningT (buffer->cur(+1).codepoint))

      {

  /* <LV,T>, try to combine. */

  unsigned int new_tindex = buffer->cur(+1).codepoint - TBase;

  hb_codepoint_t new_s = s + new_tindex;

  if (font->has_glyph (new_s))

  {

    (void) buffer->replace_glyphs (2, 1, &new_s);

    end = start + 1;

    continue;

  }

  else

    buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */

      }

      /* Otherwise, decompose if font doesn't support <LV> or <LVT>,

       * or if having non-combining <LV,T>.  Note that we already handled

       * combining <LV,T> above. */

      if (!has_glyph ||

    (!tindex &&

     buffer->idx + 1 < count &&

     isT (buffer->cur(+1).codepoint)))

      {

  hb_codepoint_t decomposed[3] = {LBase + lindex,

          VBase + vindex,

          TBase + tindex};

  if (font->has_glyph (decomposed[0]) &&

      font->has_glyph (decomposed[1]) &&

      (!tindex || font->has_glyph (decomposed[2])))

  {

    unsigned int s_len = tindex ? 3 : 2;

    (void) buffer->replace_glyphs (1, s_len, decomposed);

    /* If we decomposed an LV because of a non-combining T following,

     * we want to include this T in the syllable.

     */

    if (has_glyph && !tindex)

    {

      (void) buffer->next_glyph ();

      s_len++;

    }

    if (unlikely (!buffer->successful))

      break;

    /* We decomposed S: apply jamo features to the individual glyphs

     * that are now in buffer->out_info.

     */

    hb_glyph_info_t *info = buffer->out_info;

    end = start + s_len;

    unsigned int i = start;

    info[i++].hangul_shaping_feature() = LJMO;

    info[i++].hangul_shaping_feature() = VJMO;

    if (i < end)

      info[i++].hangul_shaping_feature() = TJMO;

    buffer->merge_out_grapheme_clusters (start, end);

    continue;

  }

  else if ((!tindex && buffer->idx + 1 < count && isT (buffer->cur(+1).codepoint)))

    buffer->unsafe_to_break (buffer->idx, buffer->idx + 2); /* Mark unsafe between LV and T. */

      }

      if (has_glyph)

      {

  /* We didn't decompose the S, so just advance past it and fall through. */

  end = start + 1;

      }

    }

    /* Didn't find a recognizable syllable, so we leave end <= start;

     * this will prevent tone-mark reordering happening.

     */

    (void) buffer->next_glyph ();

  }

  buffer->sync ();

}

static void

setup_masks_hangul (const hb_ot_shape_plan_t *plan,

        hb_buffer_t              *buffer,

        hb_font_t                *font HB_UNUSED)

{

  const hangul_shape_plan_t *hangul_plan = (const hangul_shape_plan_t *) plan->data;

  if (likely (hangul_plan))

  {

    unsigned int count = buffer->len;

    hb_glyph_info_t *info = buffer->info;

    for (unsigned int i = 0; i < count; i++, info++)

    {

      info->mask |= hangul_plan->mask_array[info->hangul_shaping_feature()];

      /* Keep 'calt' away from jamo; see override_features_hangul(). */

      hb_codepoint_t u = info->codepoint;

      if (isL (u) || isV (u) || isT (u))

  info->mask &= ~hangul_plan->calt_mask;

    }

  }

  HB_BUFFER_DEALLOCATE_VAR (buffer, hangul_shaping_feature);

}

const hb_ot_shaper_t _hb_ot_shaper_hangul =

{

  collect_features_hangul,

  override_features_hangul,

  data_create_hangul,

  data_destroy_hangul,

  preprocess_text_hangul,

  nullptr, /* postprocess_glyphs */

  nullptr, /* decompose */

  nullptr, /* compose */

  setup_masks_hangul,

  nullptr, /* reorder_marks */

  HB_TAG_NONE, /* gpos_tag */

  HB_OT_SHAPE_NORMALIZATION_MODE_NONE,

  HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,

  true, /* fallback_position */

};

#endif