/*

 * 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-private.hh"

#include "hb-ot-layout-private.hh"

/*

 * Khmer shaper.

 */

struct feature_list_t {

  hb_tag_t tag;

  hb_ot_map_feature_flags_t flags;

};

static const feature_list_t

khmer_features[] =

{

  /*

   * Basic features.

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

   */

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

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

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

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

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

  /*

   * Other features.

   * These features are applied all at once, after final_reordering.

   * Default Bengali font in Windows for example has intermixed

   * lookups for init,pres,abvs,blws features.

   */

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

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

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

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

  /* Positioning features, though 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

initial_reordering (const hb_ot_shape_plan_t *plan,

                    hb_font_t *font,

                    hb_buffer_t *buffer);

static void

final_reordering (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_global_bool_feature (HB_TAG('l','o','c','l'));

  /* The Indic specs do not require ccmp, but we apply it here since if

   * there is a use of it, it's typically at the beginning. */

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

  unsigned int i = 0;

  map->add_gsub_pause (initial_reordering);

  for (; i < KHMER_BASIC_FEATURES; i++) {

    map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);

    map->add_gsub_pause (nullptr);

  }

  map->add_gsub_pause (final_reordering);

  for (; i < KHMER_NUM_FEATURES; i++) {

    map->add_feature (khmer_features[i].tag, 1, khmer_features[i].flags | F_MANUAL_ZWJ | F_MANUAL_ZWNJ);

  }

  map->add_global_bool_feature (HB_TAG('c','a','l','t'));

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

  map->add_gsub_pause (clear_syllables);

}

static void

override_features_khmer (hb_ot_shape_planner_t *plan)

{

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

  if (hb_options ().uniscribe_bug_compatible)

  {

    plan->map.add_feature (HB_TAG('k','e','r','n'), 0, F_GLOBAL);

  }

  plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);

}

struct would_substitute_feature_t

{

  inline 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);

  }

  inline 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

{

  ASSERT_POD ();

  inline 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);

  HB_BUFFER_ALLOCATE_VAR (buffer, khmer_position);

  /* 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);

}

static int

compare_khmer_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)

{

  int a = pa->khmer_position();

  int b = pb->khmer_position();

  return a < b ? -1 : a == b ? 0 : +1;

}

/* Rules from:

static void

initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,

                                       hb_face_t *face,

                                       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;

  /* 1. Khmer shaping assumes that a syllable will begin with a Cons, IndV, or Number. */

  /* The first consonant is always the base. */

  unsigned int base = start;

  info[base].khmer_position() = POS_BASE_C;

  /* Mark all subsequent consonants as below. */

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

    if (is_consonant_or_vowel (info[i]))

      info[i].khmer_position() = POS_BELOW_C;

  /* Mark final consonants.  A final consonant is one appearing after a matra,

   * like in Khmer. */

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

    if (info[i].khmer_category() == OT_M) {

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

        if (is_consonant_or_vowel (info[j])) {

          info[j].khmer_position() = POS_FINAL_C;

          break;

        }

      break;

    }

  /* Attach misc marks to previous char to move with them. */

  {

    khmer_position_t last_pos = POS_START;

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

    {

      if ((FLAG_UNSAFE (info[i].khmer_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | FLAG (OT_Coeng))))

      {

        info[i].khmer_position() = last_pos;

                      info[i].khmer_position() == POS_PRE_M))

        {

          /*

           * Uniscribe doesn't move the Halant with Left Matra.

           * TEST: U+092B,U+093F,U+094DE

           * We follow.  This is important for the Sinhala

           * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA

           * where U+0DD9 is a left matra and U+0DCA is the virama.

           * We don't want to move the virama with the left matra.

           * TEST: U+0D9A,U+0DDA

           */

          for (unsigned int j = i; j > start; j--)

            if (info[j - 1].khmer_position() != POS_PRE_M) {

              info[i].khmer_position() = info[j - 1].khmer_position();

              break;

            }

        }

      } else if (info[i].khmer_position() != POS_SMVD) {

        last_pos = (khmer_position_t) info[i].khmer_position();

      }

    }

  }

  /* For post-base consonants let them own anything before them

   * since the last consonant or matra. */

  {

    unsigned int last = base;

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

      if (is_consonant_or_vowel (info[i]))

      {

        for (unsigned int j = last + 1; j < i; j++)

          if (info[j].khmer_position() < POS_SMVD)

            info[j].khmer_position() = info[i].khmer_position();

        last = i;

      } else if (info[i].khmer_category() == OT_M)

        last = i;

  }

  {

    /* Use syllable() for sort accounting temporarily. */

    unsigned int syllable = info[start].syllable();

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

      info[i].syllable() = i - start;

    /* Sit tight, rock 'n roll! */

    hb_stable_sort (info + start, end - start, compare_khmer_order);

    /* Find base again */

    base = end;

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

      if (info[i].khmer_position() == POS_BASE_C)

      {

        base = i;

        break;

      }

    /* Note!  syllable() is a one-byte field. */

    for (unsigned int i = base; i < end; i++)

      if (info[i].syllable() != 255)

      {

        unsigned int max = i;

        unsigned int j = start + info[i].syllable();

        while (j != i)

        {

          max = MAX (max, j);

          unsigned int next = start + info[j].syllable();

          info[j].syllable() = 255; /* So we don't process j later again. */

          j = next;

        }

        if (i != max)

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

      }

    /* Put syllable back in. */

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

      info[i].syllable() = syllable;

  }

  /* Setup masks now */

  {

    hb_mask_t mask;

    /* Post-base */

    mask = khmer_plan->mask_array[BLWF] | khmer_plan->mask_array[ABVF] | khmer_plan->mask_array[PSTF];

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

      info[i].mask  |= mask;

  }

  unsigned int pref_len = 2;

  if (khmer_plan->mask_array[PREF] && base + pref_len < end)

  {

    /* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */

    for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {

      hb_codepoint_t glyphs[2];

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

        glyphs[j] = info[i + j].codepoint;

      if (khmer_plan->pref.would_substitute (glyphs, pref_len, face))

      {

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

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

        /* 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 (; i < end; i++)

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

        break;

      }

    }

  }

}

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:

     initial_reordering_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;

  {

    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. */

             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

initial_reordering (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);

}

static void