/*

 * 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-ot-shape-complex-khmer.hh"

#include "hb-ot-layout.hh"

/*

 * Khmer shaper.

 */

static const hb_ot_map_feature_t

khmer_features[] =

{

  /*

   * Basic features.

   * These features are applied in order, one at a time, after reordering.

   */

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

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

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

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

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

  /*

   * 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},

  /*

   * Positioning features.

   * We don't care about the types.

   */

  {HB_TAG('d','i','s','t'), F_GLOBAL},

  {HB_TAG('a','b','v','m'), F_GLOBAL},

  {HB_TAG('b','l','w','m'), F_GLOBAL},

};

/*

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

 */

enum {

  PREF,

  BLWF,

  ABVF,

  PSTF,

  CFAR,

  _PRES,

  _ABVS,

  _BLWS,

  _PSTS,

  _DIST,

  _ABVM,

  _BLWM,

  KHMER_NUM_FEATURES,

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

};

static void

setup_syllables (const hb_ot_shape_plan_t *plan,

                 hb_font_t *font,

                 hb_buffer_t *buffer);

static void

reorder (const hb_ot_shape_plan_t *plan,

         hb_font_t *font,

         hb_buffer_t *buffer);

static void

clear_syllables (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);

  map->add_gsub_pause (reorder);

  /* 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'));

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

  unsigned int i = 0;

  for (; i < KHMER_BASIC_FEATURES; i++)

    map->add_feature (khmer_features[i]);

  map->add_gsub_pause (clear_syllables);

  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 would_substitute_feature_t

{

  void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)

  {

    zero_context = zero_context_;

    map->get_stage_lookups (0/*GSUB*/,

                            map->get_feature_stage (0/*GSUB*/, feature_tag),

                            &lookups, &count);

  }

  bool would_substitute (const hb_codepoint_t *glyphs,

                         unsigned int          glyphs_count,

                         hb_face_t            *face) const

  {

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

      if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))

        return true;

    return false;

  }

  private:

  const hb_ot_map_t::lookup_map_t *lookups;

  unsigned int count;

  bool zero_context;

};

struct khmer_shape_plan_t

{

  bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const

  {

    hb_codepoint_t glyph = virama_glyph;

    if (unlikely (virama_glyph == (hb_codepoint_t) -1))

    {

      if (!font->get_nominal_glyph (0x17D2u, &glyph))

        glyph = 0;

      /* Technically speaking, the spec says we should apply 'locl' to virama too.

       * Maybe one day... */

      /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph

       * during shape planning...  Instead, overwrite it here.  It's safe.  Don't worry! */

      virama_glyph = glyph;

    }

    *pglyph = glyph;

    return glyph != 0;

  }

  mutable hb_codepoint_t virama_glyph;

  would_substitute_feature_t pref;

  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 *) calloc (1, sizeof (khmer_shape_plan_t));

  if (unlikely (!khmer_plan))

    return nullptr;

  khmer_plan->virama_glyph = (hb_codepoint_t) -1;

  khmer_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), true);

  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)

{

  free (data);

}

enum syllable_type_t {

  consonant_syllable,

  broken_cluster,

  non_khmer_cluster,

};

#include "hb-ot-shape-complex-khmer-machine.hh"

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 void

setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,

                 hb_font_t *font HB_UNUSED,

                 hb_buffer_t *buffer)

{

  find_syllables (buffer);

  foreach_syllable (buffer, start, end)

    buffer->unsafe_to_break (start, end);

}

/* 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[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[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() == OT_Coeng && num_coengs <= 2 && i + 1 < end)

    {

      num_coengs++;

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

      {

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

          info[i + j].mask |= khmer_plan->mask_array[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[CFAR])

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

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

        num_coengs = 2; /* Done. */

      }

    }

    /* Reorder left matra piece. */

    else if (info[i].khmer_category() == OT_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

initial_reordering_syllable (const hb_ot_shape_plan_t *plan,

                             hb_face_t *face,

                             hb_buffer_t *buffer,

                             unsigned int start, unsigned int end)

{

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

  switch (syllable_type)

  {

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

    case consonant_syllable:

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

     break;

    case non_khmer_cluster:

      break;

  }

}

static inline void

insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,

                       hb_font_t *font,

                       hb_buffer_t *buffer)

{

  /* Note: This loop is extra overhead, but should not be measurable. */

  bool has_broken_syllables = false;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

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

    if ((info[i].syllable() & 0x0F) == broken_cluster)

    {

      has_broken_syllables = true;

      break;

    }

  if (likely (!has_broken_syllables))

    return;

  hb_codepoint_t dottedcircle_glyph;

  if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))

    return;

  hb_glyph_info_t dottedcircle = {0};

  dottedcircle.codepoint = 0x25CCu;

  set_khmer_properties (dottedcircle);

  dottedcircle.codepoint = dottedcircle_glyph;

  buffer->clear_output ();

  buffer->idx = 0;

  unsigned int last_syllable = 0;

  while (buffer->idx < buffer->len && buffer->successful)

  {

    unsigned int syllable = buffer->cur().syllable();

    syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);

    if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))

    {

      last_syllable = syllable;

      hb_glyph_info_t ginfo = dottedcircle;

      ginfo.cluster = buffer->cur().cluster;

      ginfo.mask = buffer->cur().mask;

      ginfo.syllable() = buffer->cur().syllable();

      /* TODO Set glyph_props? */

      /* Insert dottedcircle after possible Repha. */

      while (buffer->idx < buffer->len && buffer->successful &&

             last_syllable == buffer->cur().syllable() &&

             buffer->cur().khmer_category() == OT_Repha)

        buffer->next_glyph ();

      buffer->output_info (ginfo);

    }

    else

      buffer->next_glyph ();

  }

  buffer->swap_buffers ();

}

static void

reorder (const hb_ot_shape_plan_t *plan,

         hb_font_t *font,

         hb_buffer_t *buffer)

{

  insert_dotted_circles (plan, font, buffer);

  foreach_syllable (buffer, start, end)

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

  HB_BUFFER_DEALLOCATE_VAR (buffer, khmer_category);

}

static void

clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,

                 hb_font_t *font HB_UNUSED,

                 hb_buffer_t *buffer)

{

  hb_glyph_info_t *info = buffer->info;

  unsigned int count = buffer->len;

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

    info[i].syllable() = 0;

}

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_complex_shaper_t _hb_ot_complex_shaper_khmer =

{

  collect_features_khmer,

  override_features_khmer,

  data_create_khmer,

  data_destroy_khmer,

  nullptr, /* preprocess_text */

  nullptr, /* postprocess_glyphs */

  HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,

  decompose_khmer,

  compose_khmer,

  setup_masks_khmer,

  HB_TAG_NONE, /* gpos_tag */

  nullptr, /* reorder_marks */

  HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,

  false, /* fallback_position */

};