/*

 * Copyright © 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

 */

#ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH

#define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH

#include "hb-private.hh"

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

#include "hb-ot-layout-gsub-table.hh"

/* Features ordered the same as the entries in shaping_table rows,

 * followed by rlig.  Don't change. */

static const hb_tag_t arabic_fallback_features[] =

{

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

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

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

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

  HB_TAG('r','l','i','g'),

};

static OT::SubstLookup *

arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,

                                          hb_font_t *font,

                                          unsigned int feature_index)

{

  OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];

  OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];

  unsigned int num_glyphs = 0;

  /* Populate arrays */

  for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)

  {

    hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];

    hb_codepoint_t u_glyph, s_glyph;

    if (!s ||

        !hb_font_get_glyph (font, u, 0, &u_glyph) ||

        !hb_font_get_glyph (font, s, 0, &s_glyph) ||

        u_glyph == s_glyph ||

        u_glyph > 0xFFFFu || s_glyph > 0xFFFFu)

      continue;

    glyphs[num_glyphs].set (u_glyph);

    substitutes[num_glyphs].set (s_glyph);

    num_glyphs++;

  }

  if (!num_glyphs)

    return nullptr;

  /* Bubble-sort or something equally good!

   * May not be good-enough for presidential candidate interviews, but good-enough for us... */

  hb_stable_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);

  OT::Supplier<OT::GlyphID> glyphs_supplier      (glyphs, num_glyphs);

  OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);

  /* Each glyph takes four bytes max, and there's some overhead. */

  char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];

  OT::hb_serialize_context_t c (buf, sizeof (buf));

  OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();

  bool ret = lookup->serialize_single (&c,

                                       OT::LookupFlag::IgnoreMarks,

                                       glyphs_supplier,

                                       substitutes_supplier,

                                       num_glyphs);

  c.end_serialize ();

  /* TODO sanitize the results? */

  return ret ? c.copy<OT::SubstLookup> () : nullptr;

}

static OT::SubstLookup *

arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,

                                            hb_font_t *font)

{

  OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];

  unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];

  unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];

  unsigned int num_first_glyphs = 0;

  /* We know that all our ligatures are 2-component */

  OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];

  unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];

  OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];

  unsigned int num_ligatures = 0;

  /* Populate arrays */

  /* Sort out the first-glyphs */

  for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)

  {

    hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;

    hb_codepoint_t first_glyph;

    if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))

      continue;

    first_glyphs[num_first_glyphs].set (first_glyph);

    ligature_per_first_glyph_count_list[num_first_glyphs] = 0;

    first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;

    num_first_glyphs++;

  }

  hb_stable_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);

  /* Now that the first-glyphs are sorted, walk again, populate ligatures. */

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

  {

    unsigned int first_glyph_idx = first_glyphs_indirection[i];

    for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)

    {

      hb_codepoint_t second_u   = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;

      hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;

      hb_codepoint_t second_glyph, ligature_glyph;

      if (!second_u ||

          !hb_font_get_glyph (font, second_u,   0, &second_glyph) ||

          !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))

        continue;

      ligature_per_first_glyph_count_list[i]++;

      ligature_list[num_ligatures].set (ligature_glyph);

      component_count_list[num_ligatures] = 2;

      component_list[num_ligatures].set (second_glyph);

      num_ligatures++;

    }

  }

  if (!num_ligatures)

    return nullptr;

  OT::Supplier<OT::GlyphID>   first_glyphs_supplier                      (first_glyphs, num_first_glyphs);

  OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier    (ligature_per_first_glyph_count_list, num_first_glyphs);

  OT::Supplier<OT::GlyphID>   ligatures_supplier                         (ligature_list, num_ligatures);

  OT::Supplier<unsigned int > component_count_supplier                   (component_count_list, num_ligatures);

  OT::Supplier<OT::GlyphID>   component_supplier                         (component_list, num_ligatures);

  /* 16 bytes per ligature ought to be enough... */

  char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];

  OT::hb_serialize_context_t c (buf, sizeof (buf));

  OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();

  bool ret = lookup->serialize_ligature (&c,

                                         OT::LookupFlag::IgnoreMarks,

                                         first_glyphs_supplier,

                                         ligature_per_first_glyph_count_supplier,

                                         num_first_glyphs,

                                         ligatures_supplier,

                                         component_count_supplier,

                                         component_supplier);

  c.end_serialize ();

  /* TODO sanitize the results? */

  return ret ? c.copy<OT::SubstLookup> () : nullptr;

}

static OT::SubstLookup *

arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,

                                   hb_font_t *font,

                                   unsigned int feature_index)

{

  if (feature_index < 4)

    return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);

  else

    return arabic_fallback_synthesize_lookup_ligature (plan, font);

}

#define ARABIC_FALLBACK_MAX_LOOKUPS 5

struct arabic_fallback_plan_t

{

  ASSERT_POD ();

  unsigned int num_lookups;

  bool free_lookups;

  hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];

  OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];

  hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];

};

static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};

#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(HB_NO_WIN1256)

#define HB_WITH_WIN1256

#endif

#ifdef HB_WITH_WIN1256

#include "hb-ot-shape-complex-arabic-win1256.hh"

#endif

struct ManifestLookup {

  OT::Tag tag;

  OT::OffsetTo<OT::SubstLookup> lookupOffset;

};

typedef OT::ArrayOf<ManifestLookup> Manifest;

static bool

arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan,

                                   const hb_ot_shape_plan_t *plan,

                                   hb_font_t *font)

{

#ifdef HB_WITH_WIN1256

  /* Does this font look like it's Windows-1256-encoded? */

  hb_codepoint_t g;

  if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&

        hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&

        hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&

        hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&

        hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))

    return false;

  const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);

  static_assert (sizeof (arabic_win1256_gsub_lookups.manifestData) / sizeof (ManifestLookup)

                 <= ARABIC_FALLBACK_MAX_LOOKUPS, "");

  /* TODO sanitize the table? */

  unsigned j = 0;

  unsigned int count = manifest.len;

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

  {

    fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);

    if (fallback_plan->mask_array[j])

    {

      fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));

      if (fallback_plan->lookup_array[j])

      {

        fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);

        j++;

      }

    }

  }

  fallback_plan->num_lookups = j;

  fallback_plan->free_lookups = false;

  return j > 0;

#else

  return false;

#endif

}

static bool

arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,

                                   const hb_ot_shape_plan_t *plan,

                                   hb_font_t *font)

{

  static_assert ((ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS), "");

  unsigned int j = 0;

  for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)

  {

    fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);

    if (fallback_plan->mask_array[j])

    {

      fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);

      if (fallback_plan->lookup_array[j])

      {

        fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);

        j++;

      }

    }

  }

  fallback_plan->num_lookups = j;

  fallback_plan->free_lookups = true;

  return j > 0;

}

static arabic_fallback_plan_t *

arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,

                             hb_font_t *font)

{

  arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));

  if (unlikely (!fallback_plan))

    return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);

  fallback_plan->num_lookups = 0;

  fallback_plan->free_lookups = false;

  /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,

   * in case the font has cmap entries for the presentation-forms characters. */

  if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))

    return fallback_plan;

  /* See if this looks like a Windows-1256-encoded font.  If it does, use a

   * hand-coded GSUB table. */

  if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))

    return fallback_plan;

  free (fallback_plan);

  return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);

}

static void

arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)

{

  if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)

    return;

  for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)

    if (fallback_plan->lookup_array[i])

    {

      fallback_plan->accel_array[i].fini ();

      if (fallback_plan->free_lookups)

        free (fallback_plan->lookup_array[i]);

    }

  free (fallback_plan);

}

static void

arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,

                            hb_font_t *font,

                            hb_buffer_t *buffer)

{

  OT::hb_apply_context_t c (0, font, buffer);

  for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)

    if (fallback_plan->lookup_array[i]) {

      c.set_lookup_mask (fallback_plan->mask_array[i]);

      hb_ot_layout_substitute_lookup (&c,

                                      *fallback_plan->lookup_array[i],

                                      fallback_plan->accel_array[i]);

    }

}

#endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */