/*

 * Copyright © 2010,2012  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-arabic-private.hh"

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

/* buffer var allocations */

#define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */

/*

 * Joining types:

 */

/*

 * Bits used in the joining tables

 */

enum hb_arabic_joining_type_t {

  JOINING_TYPE_U                = 0,

  JOINING_TYPE_L                = 1,

  JOINING_TYPE_R                = 2,

  JOINING_TYPE_D                = 3,

  JOINING_TYPE_C                = JOINING_TYPE_D,

  JOINING_GROUP_ALAPH           = 4,

  JOINING_GROUP_DALATH_RISH     = 5,

  NUM_STATE_MACHINE_COLS        = 6,

  JOINING_TYPE_T = 7,

  JOINING_TYPE_X = 8  /* means: use general-category to choose between U or T. */

};

#include "hb-ot-shape-complex-arabic-table.hh"

static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)

{

  unsigned int j_type = joining_type(u);

  if (likely (j_type != JOINING_TYPE_X))

    return j_type;

  return (FLAG_SAFE(gen_cat) &

          (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) |

           FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) |

           FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))

         ) ?  JOINING_TYPE_T : JOINING_TYPE_U;

}

#define FEATURE_IS_SYRIAC(tag) hb_in_range<unsigned char> ((unsigned char) (tag), '2', '3')

static const hb_tag_t arabic_features[] =

{

  HB_TAG('i','s','o','l'),

  HB_TAG('f','i','n','a'),

  HB_TAG('f','i','n','2'),

  HB_TAG('f','i','n','3'),

  HB_TAG('m','e','d','i'),

  HB_TAG('m','e','d','2'),

  HB_TAG('i','n','i','t'),

  HB_TAG_NONE

};

/* Same order as the feature array */

enum {

  ISOL,

  FINA,

  FIN2,

  FIN3,

  MEDI,

  MED2,

  INIT,

  NONE,

  ARABIC_NUM_FEATURES = NONE

};

static const struct arabic_state_table_entry {

        uint8_t prev_action;

        uint8_t curr_action;

        uint16_t next_state;

} arabic_state_table[][NUM_STATE_MACHINE_COLS] =

{

  /*   jt_U,          jt_L,          jt_R,          jt_D,          jg_ALAPH,      jg_DALATH_RISH */

  /* State 0: prev was U, not willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },

  /* State 1: prev was R or ISOL/ALAPH, not willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },

  /* State 2: prev was D/L in ISOL form, willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },

  /* State 3: prev was D in FINA form, willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },

  /* State 4: prev was FINA ALAPH, not willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },

  /* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },

  /* State 6: prev was DALATH/RISH, not willing to join. */

  { {NONE,NONE,0}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }

};

static void

nuke_joiners (const hb_ot_shape_plan_t *plan,

              hb_font_t *font,

              hb_buffer_t *buffer);

static void

arabic_fallback_shape (const hb_ot_shape_plan_t *plan,

                       hb_font_t *font,

                       hb_buffer_t *buffer);

static void

collect_features_arabic (hb_ot_shape_planner_t *plan)

{

  hb_ot_map_builder_t *map = &plan->map;

  /* We apply features according to the Arabic spec, with pauses

   * in between most.

   *

   * The pause between init/medi/... and rlig is required.  See eg:

   * https://bugzilla.mozilla.org/show_bug.cgi?id=644184

   *

   * The pauses between init/medi/... themselves are not necessarily

   * needed as only one of those features is applied to any character.

   * The only difference it makes is when fonts have contextual

   * substitutions.  We now follow the order of the spec, which makes

   * for better experience if that's what Uniscribe is doing.

   *

   * At least for Arabic, looks like Uniscribe has a pause between

   * rlig and calt.  Otherwise the IranNastaliq's ALLAH ligature won't

   * work.  However, testing shows that rlig and calt are applied

   * together for Mongolian in Uniscribe.  As such, we only add a

   * pause for Arabic, not other scripts.

   */

  map->add_gsub_pause (nuke_joiners);

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

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

  map->add_gsub_pause (NULL);

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

  {

    bool has_fallback = plan->props.script == HB_SCRIPT_ARABIC && !FEATURE_IS_SYRIAC (arabic_features[i]);

    map->add_feature (arabic_features[i], 1, has_fallback ? F_HAS_FALLBACK : F_NONE);

    map->add_gsub_pause (NULL);

  }

  map->add_feature (HB_TAG('r','l','i','g'), 1, F_GLOBAL|F_HAS_FALLBACK);

  if (plan->props.script == HB_SCRIPT_ARABIC)

    map->add_gsub_pause (arabic_fallback_shape);

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

  map->add_gsub_pause (NULL);

  /* The spec includes 'cswh'.  Earlier versions of Windows

   * used to enable this by default, but testing suggests

   * that Windows 8 and later do not enable it by default,

   * and spec now says 'Off by default'.

   * We disabled this in ae23c24c32.

   * Note that IranNastaliq uses this feature extensively

   * to fixup broken glyph sequences.  Oh well...

   * Test case: U+0643,U+0640,U+0631. */

  //map->add_global_bool_feature (HB_TAG('c','s','w','h'));

  map->add_global_bool_feature (HB_TAG('m','s','e','t'));

}

#include "hb-ot-shape-complex-arabic-fallback.hh"

struct arabic_shape_plan_t

{

  ASSERT_POD ();

  /* The "+ 1" in the next array is to accommodate for the "NONE" command,

   * which is not an OpenType feature, but this simplifies the code by not

   * having to do a "if (... < NONE) ..." and just rely on the fact that

   * mask_array[NONE] == 0. */

  hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];

  bool do_fallback;

  arabic_fallback_plan_t *fallback_plan;

};

void *

data_create_arabic (const hb_ot_shape_plan_t *plan)

{

  arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) calloc (1, sizeof (arabic_shape_plan_t));

  if (unlikely (!arabic_plan))

    return NULL;

  arabic_plan->do_fallback = plan->props.script == HB_SCRIPT_ARABIC;

  for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {

    arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);

    arabic_plan->do_fallback = arabic_plan->do_fallback &&

                               (FEATURE_IS_SYRIAC (arabic_features[i]) ||

                                plan->map.needs_fallback (arabic_features[i]));

  }

  return arabic_plan;

}

void

data_destroy_arabic (void *data)

{

  arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) data;

  arabic_fallback_plan_destroy (arabic_plan->fallback_plan);

  free (data);

}

static void

arabic_joining (hb_buffer_t *buffer)

{

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  unsigned int prev = (unsigned int) -1, state = 0;

  /* Check pre-context */

  for (unsigned int i = 0; i < buffer->context_len[0]; i++)

  {

    unsigned int this_type = get_joining_type (buffer->context[0][i], buffer->unicode->general_category (buffer->context[0][i]));

    if (unlikely (this_type == JOINING_TYPE_T))

      continue;

    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];

    state = entry->next_state;

    break;

  }

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

  {

    unsigned int this_type = get_joining_type (info[i].codepoint, _hb_glyph_info_get_general_category (&info[i]));

    if (unlikely (this_type == JOINING_TYPE_T)) {

      info[i].arabic_shaping_action() = NONE;

      continue;

    }

    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];

    if (entry->prev_action != NONE && prev != (unsigned int) -1)

      info[prev].arabic_shaping_action() = entry->prev_action;

    info[i].arabic_shaping_action() = entry->curr_action;

    prev = i;

    state = entry->next_state;

  }

  for (unsigned int i = 0; i < buffer->context_len[1]; i++)

  {

    unsigned int this_type = get_joining_type (buffer->context[1][i], buffer->unicode->general_category (buffer->context[1][i]));

    if (unlikely (this_type == JOINING_TYPE_T))

      continue;

    const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];

    if (entry->prev_action != NONE && prev != (unsigned int) -1)

      info[prev].arabic_shaping_action() = entry->prev_action;

    break;

  }

}

static void

mongolian_variation_selectors (hb_buffer_t *buffer)

{

  /* Copy arabic_shaping_action() from base to Mongolian variation selectors. */

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  for (unsigned int i = 1; i < count; i++)

    if (unlikely (hb_in_range (info[i].codepoint, 0x180Bu, 0x180Du)))

      info[i].arabic_shaping_action() = info[i - 1].arabic_shaping_action();

}

void

setup_masks_arabic_plan (const arabic_shape_plan_t *arabic_plan,

                         hb_buffer_t               *buffer,

                         hb_script_t                script)

{

  HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);

  arabic_joining (buffer);

  if (script == HB_SCRIPT_MONGOLIAN)

    mongolian_variation_selectors (buffer);

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

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

    info[i].mask |= arabic_plan->mask_array[info[i].arabic_shaping_action()];

  HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);

}

static void

setup_masks_arabic (const hb_ot_shape_plan_t *plan,

                    hb_buffer_t              *buffer,

                    hb_font_t                *font HB_UNUSED)

{

  const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;

  setup_masks_arabic_plan (arabic_plan, buffer, plan->props.script);

}

static void

nuke_joiners (const hb_ot_shape_plan_t *plan HB_UNUSED,

              hb_font_t *font HB_UNUSED,

              hb_buffer_t *buffer)

{

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

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

    if (_hb_glyph_info_is_zwj (&info[i]))

      _hb_glyph_info_flip_joiners (&info[i]);

}

static void

arabic_fallback_shape (const hb_ot_shape_plan_t *plan,

                       hb_font_t *font,

                       hb_buffer_t *buffer)

{

  const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;

  if (!arabic_plan->do_fallback)

    return;

retry:

  arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) hb_atomic_ptr_get (&arabic_plan->fallback_plan);

  if (unlikely (!fallback_plan))

  {

    /* This sucks.  We need a font to build the fallback plan... */

    fallback_plan = arabic_fallback_plan_create (plan, font);

    if (unlikely (!hb_atomic_ptr_cmpexch (&(const_cast<arabic_shape_plan_t *> (arabic_plan))->fallback_plan, NULL, fallback_plan))) {

      arabic_fallback_plan_destroy (fallback_plan);

      goto retry;

    }

  }

  arabic_fallback_plan_shape (fallback_plan, font, buffer);

}

const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =

{

  "arabic",

  collect_features_arabic,

  NULL, /* override_features */

  data_create_arabic,

  data_destroy_arabic,

  NULL, /* preprocess_text_arabic */

  HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,

  NULL, /* decompose */

  NULL, /* compose */

  setup_masks_arabic,

  HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,

  true, /* fallback_position */

};