/*

 * Copyright © 2011,2012  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-khmer-machine.hh"

#include "hb-ot-shaper-indic.hh"

#include "hb-ot-layout.hh"

/*

 * Khmer shaper.

 */

static const hb_ot_map_feature_t

khmer_features[] =

{

  /*

   * Basic features.

   * These features are applied all at once, before reordering, constrained

   * to the syllable.

   */

  {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},

  {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},

  {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},

  {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS | F_PER_SYLLABLE},

  {HB_TAG('c','f','a','r'), F_MANUAL_JOINERS | F_PER_SYLLABLE},

  /*

   * Other features.

   * These features are applied all at once after clearing syllables.

   */

  {HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS},

  {HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS},

  {HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS},

  {HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS},

};

/*

 * Must be in the same order as the khmer_features array.

 */

enum {

  KHMER_PREF,

  KHMER_BLWF,

  KHMER_ABVF,

  KHMER_PSTF,

  KHMER_CFAR,

  _KHMER_PRES,

  _KHMER_ABVS,

  _KHMER_BLWS,

  _KHMER_PSTS,

  KHMER_NUM_FEATURES,

  KHMER_BASIC_FEATURES = _KHMER_PRES, /* Don't forget to update this! */

};

static inline void

set_khmer_properties (hb_glyph_info_t &info)

{

  hb_codepoint_t u = info.codepoint;

  unsigned int type = hb_indic_get_categories (u);

  info.khmer_category() = (khmer_category_t) (type & 0xFFu);

}

static bool

setup_syllables_khmer (const hb_ot_shape_plan_t *plan,

           hb_font_t *font,

           hb_buffer_t *buffer);

static bool

reorder_khmer (const hb_ot_shape_plan_t *plan,

         hb_font_t *font,

         hb_buffer_t *buffer);

static void

collect_features_khmer (hb_ot_shape_planner_t *plan)

{

  hb_ot_map_builder_t *map = &plan->map;

  /* Do this before any lookups have been applied. */

  map->add_gsub_pause (setup_syllables_khmer);

  map->add_gsub_pause (reorder_khmer);

  /* Testing suggests that Uniscribe does NOT pause between basic

   * features.  Test with KhmerUI.ttf and the following three

   * sequences:

   *

   *   U+1789,U+17BC

   *   U+1789,U+17D2,U+1789

   *   U+1789,U+17D2,U+1789,U+17BC

   *

   * https://github.com/harfbuzz/harfbuzz/issues/974

   */

  map->enable_feature (HB_TAG('l','o','c','l'), F_PER_SYLLABLE);

  map->enable_feature (HB_TAG('c','c','m','p'), F_PER_SYLLABLE);

  unsigned int i = 0;

  for (; i < KHMER_BASIC_FEATURES; i++)

    map->add_feature (khmer_features[i]);

  /* https://github.com/harfbuzz/harfbuzz/issues/3531 */

  map->add_gsub_pause (hb_syllabic_clear_var); // Don't need syllables anymore, use stop to free buffer var

  for (; i < KHMER_NUM_FEATURES; i++)

    map->add_feature (khmer_features[i]);

}

static void

override_features_khmer (hb_ot_shape_planner_t *plan)

{

  hb_ot_map_builder_t *map = &plan->map;

  /* Khmer spec has 'clig' as part of required shaping features:

   * "Apply feature 'clig' to form ligatures that are desired for

   * typographical correctness.", hence in overrides... */

  map->enable_feature (HB_TAG('c','l','i','g'));

  /* Uniscribe does not apply 'kern' in Khmer. */

  if (hb_options ().uniscribe_bug_compatible)

  {

    map->disable_feature (HB_TAG('k','e','r','n'));

  }

  map->disable_feature (HB_TAG('l','i','g','a'));

}

struct khmer_shape_plan_t

{

  hb_mask_t mask_array[KHMER_NUM_FEATURES];

};

static void *

data_create_khmer (const hb_ot_shape_plan_t *plan)

{

  khmer_shape_plan_t *khmer_plan = (khmer_shape_plan_t *) hb_calloc (1, sizeof (khmer_shape_plan_t));

  if (unlikely (!khmer_plan))

    return nullptr;

  for (unsigned int i = 0; i < ARRAY_LENGTH (khmer_plan->mask_array); i++)

    khmer_plan->mask_array[i] = (khmer_features[i].flags & F_GLOBAL) ?

         0 : plan->map.get_1_mask (khmer_features[i].tag);

  return khmer_plan;

}

static void

data_destroy_khmer (void *data)

{

  hb_free (data);

}

static void

setup_masks_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,

       hb_buffer_t              *buffer,

       hb_font_t                *font HB_UNUSED)

{

  HB_BUFFER_ALLOCATE_VAR (buffer, khmer_category);

  /* We cannot setup masks here.  We save information about characters

   * and setup masks later on in a pause-callback. */

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

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

    set_khmer_properties (info[i]);

}

static bool

setup_syllables_khmer (const hb_ot_shape_plan_t *plan HB_UNUSED,

           hb_font_t *font HB_UNUSED,

           hb_buffer_t *buffer)

{

  HB_BUFFER_ALLOCATE_VAR (buffer, syllable);

  find_syllables_khmer (buffer);

  foreach_syllable (buffer, start, end)

    buffer->unsafe_to_break (start, end);

  return false;

}

/* Rules from:

 * https://docs.microsoft.com/en-us/typography/script-development/devanagari */

static void

reorder_consonant_syllable (const hb_ot_shape_plan_t *plan,

          hb_face_t *face HB_UNUSED,

          hb_buffer_t *buffer,

          unsigned int start, unsigned int end)

{

  const khmer_shape_plan_t *khmer_plan = (const khmer_shape_plan_t *) plan->data;

  hb_glyph_info_t *info = buffer->info;

  /* Setup masks. */

  {

    /* Post-base */

    hb_mask_t mask = khmer_plan->mask_array[KHMER_BLWF] |

         khmer_plan->mask_array[KHMER_ABVF] |

         khmer_plan->mask_array[KHMER_PSTF];

    for (unsigned int i = start + 1; i < end; i++)

      info[i].mask  |= mask;

  }

  unsigned int num_coengs = 0;

  for (unsigned int i = start + 1; i < end; i++)

  {

    /* """

     * When a COENG + (Cons | IndV) combination are found (and subscript count

     * is less than two) the character combination is handled according to the

     * subscript type of the character following the COENG.

     *

     * ...

     *

     * Subscript Type 2 - The COENG + RO characters are reordered to immediately

     * before the base glyph. Then the COENG + RO characters are assigned to have

     * the 'pref' OpenType feature applied to them.

     * """

     */

    if (info[i].khmer_category() == K_Cat(H) && num_coengs <= 2 && i + 1 < end)

    {

      num_coengs++;

      if (info[i + 1].khmer_category() == K_Cat(Ra))

      {

  for (unsigned int j = 0; j < 2; j++)

    info[i + j].mask |= khmer_plan->mask_array[KHMER_PREF];

  /* Move the Coeng,Ro sequence to the start. */

  buffer->merge_clusters (start, i + 2);

  hb_glyph_info_t t0 = info[i];

  hb_glyph_info_t t1 = info[i + 1];

  memmove (&info[start + 2], &info[start], (i - start) * sizeof (info[0]));

  info[start] = t0;

  info[start + 1] = t1;

  /* Mark the subsequent stuff with 'cfar'.  Used in Khmer.

   * Read the feature spec.

   * This allows distinguishing the following cases with MS Khmer fonts:

   * U+1784,U+17D2,U+179A,U+17D2,U+1782

   * U+1784,U+17D2,U+1782,U+17D2,U+179A

   */

  if (khmer_plan->mask_array[KHMER_CFAR])

    for (unsigned int j = i + 2; j < end; j++)

      info[j].mask |= khmer_plan->mask_array[KHMER_CFAR];

  num_coengs = 2; /* Done. */

      }

    }

    /* Reorder left matra piece. */

    else if (info[i].khmer_category() == K_Cat(VPre))

    {

      /* Move to the start. */

      buffer->merge_clusters (start, i + 1);

      hb_glyph_info_t t = info[i];

      memmove (&info[start + 1], &info[start], (i - start) * sizeof (info[0]));

      info[start] = t;

    }

  }

}

static void

reorder_syllable_khmer (const hb_ot_shape_plan_t *plan,

      hb_face_t *face,

      hb_buffer_t *buffer,

      unsigned int start, unsigned int end)

{

  khmer_syllable_type_t syllable_type = (khmer_syllable_type_t) (buffer->info[start].syllable() & 0x0F);

  switch (syllable_type)

  {

    case khmer_broken_cluster: /* We already inserted dotted-circles, so just call the consonant_syllable. */

    case khmer_consonant_syllable:

     reorder_consonant_syllable (plan, face, buffer, start, end);

     break;

    case khmer_non_khmer_cluster:

      break;

  }

}

static bool

reorder_khmer (const hb_ot_shape_plan_t *plan,

         hb_font_t *font,

         hb_buffer_t *buffer)

{

  bool ret = false;

  if (buffer->message (font, "start reordering khmer"))

  {

    if (hb_syllabic_insert_dotted_circles (font, buffer,

             khmer_broken_cluster,

             K_Cat(DOTTEDCIRCLE),

             (unsigned) -1))

      ret = true;

    foreach_syllable (buffer, start, end)

      reorder_syllable_khmer (plan, font->face, buffer, start, end);

    (void) buffer->message (font, "end reordering khmer");

  }

  HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);

  return ret;

}

static bool

decompose_khmer (const hb_ot_shape_normalize_context_t *c,

     hb_codepoint_t  ab,

     hb_codepoint_t *a,

     hb_codepoint_t *b)

{

  switch (ab)

  {

    /*

     * Decompose split matras that don't have Unicode decompositions.

     */

    /* Khmer */

    case 0x17BEu  : *a = 0x17C1u; *b= 0x17BEu; return true;

    case 0x17BFu  : *a = 0x17C1u; *b= 0x17BFu; return true;

    case 0x17C0u  : *a = 0x17C1u; *b= 0x17C0u; return true;

    case 0x17C4u  : *a = 0x17C1u; *b= 0x17C4u; return true;

    case 0x17C5u  : *a = 0x17C1u; *b= 0x17C5u; return true;

  }

  return (bool) c->unicode->decompose (ab, a, b);

}

static bool

compose_khmer (const hb_ot_shape_normalize_context_t *c,

         hb_codepoint_t  a,

         hb_codepoint_t  b,

         hb_codepoint_t *ab)

{

  /* Avoid recomposing split matras. */

  if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))

    return false;

  return (bool) c->unicode->compose (a, b, ab);

}

const hb_ot_shaper_t _hb_ot_shaper_khmer =

{

  collect_features_khmer,

  override_features_khmer,

  data_create_khmer,

  data_destroy_khmer,

  nullptr, /* preprocess_text */

  nullptr, /* postprocess_glyphs */

  decompose_khmer,

  compose_khmer,

  setup_masks_khmer,

  nullptr, /* reorder_marks */

  HB_TAG_NONE, /* gpos_tag */

  HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,

  HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,

  false, /* fallback_position */

};

#endif