#ifndef OT_LAYOUT_GPOS_PAIRPOSFORMAT2_HH

#define OT_LAYOUT_GPOS_PAIRPOSFORMAT2_HH

#include "ValueFormat.hh"

namespace OT {

namespace Layout {

namespace GPOS_impl {

template <typename Types>

struct PairPosFormat2_4 : ValueBase

{

  protected:

  HBUINT16      format;                 /* Format identifier--format = 2 */

  typename Types::template OffsetTo<Coverage>

                coverage;               /* Offset to Coverage table--from

                                         * beginning of subtable */

  ValueFormat   valueFormat1;           /* ValueRecord definition--for the

                                         * first glyph of the pair--may be zero

                                         * (0) */

  ValueFormat   valueFormat2;           /* ValueRecord definition--for the

                                         * second glyph of the pair--may be

                                         * zero (0) */

  typename Types::template OffsetTo<ClassDef>

                classDef1;              /* Offset to ClassDef table--from

                                         * beginning of PairPos subtable--for

                                         * the first glyph of the pair */

  typename Types::template OffsetTo<ClassDef>

                classDef2;              /* Offset to ClassDef table--from

                                         * beginning of PairPos subtable--for

                                         * the second glyph of the pair */

  HBUINT16      class1Count;            /* Number of classes in ClassDef1

                                         * table--includes Class0 */

  HBUINT16      class2Count;            /* Number of classes in ClassDef2

                                         * table--includes Class0 */

  ValueRecord   values;                 /* Matrix of value pairs:

                                         * class1-major, class2-minor,

                                         * Each entry has value1 and value2 */

  public:

  DEFINE_SIZE_ARRAY (10 + 3 * Types::size, values);

  bool sanitize (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    if (!(c->check_struct (this)

       && coverage.sanitize (c, this)

       && classDef1.sanitize (c, this)

       && classDef2.sanitize (c, this))) return_trace (false);

    unsigned int len1 = valueFormat1.get_len ();

    unsigned int len2 = valueFormat2.get_len ();

    unsigned int stride = HBUINT16::static_size * (len1 + len2);

    unsigned int count = (unsigned int) class1Count * (unsigned int) class2Count;

    return_trace (c->check_range ((const void *) values,

                                  count,

                                  stride) &&

      (c->lazy_some_gpos ||

       (valueFormat1.sanitize_values_stride_unsafe (c, this, &values[0], count, stride) &&

        valueFormat2.sanitize_values_stride_unsafe (c, this, &values[len1], count, stride))));

  }

  bool intersects (const hb_set_t *glyphs) const

  {

    return (this+coverage).intersects (glyphs) &&

           (this+classDef2).intersects (glyphs);

  }

  void closure_lookups (hb_closure_lookups_context_t *c) const {}

  void collect_variation_indices (hb_collect_variation_indices_context_t *c) const

  {

    if (!intersects (c->glyph_set)) return;

    if ((!valueFormat1.has_device ()) && (!valueFormat2.has_device ())) return;

    hb_set_t klass1_glyphs, klass2_glyphs;

    if (!(this+classDef1).collect_coverage (&klass1_glyphs)) return;

    if (!(this+classDef2).collect_coverage (&klass2_glyphs)) return;

    hb_set_t class1_set, class2_set;

    for (const unsigned cp : + c->glyph_set->iter () | hb_filter (this + coverage))

    {

      if (!klass1_glyphs.has (cp)) class1_set.add (0);

      else

      {

        unsigned klass1 = (this+classDef1).get (cp);

        class1_set.add (klass1);

      }

    }

    class2_set.add (0);

    for (const unsigned cp : + c->glyph_set->iter () | hb_filter (klass2_glyphs))

    {

      unsigned klass2 = (this+classDef2).get (cp);

      class2_set.add (klass2);

    }

    if (class1_set.is_empty ()

        || class2_set.is_empty ()

        || (class2_set.get_population() == 1 && class2_set.has(0)))

      return;

    unsigned len1 = valueFormat1.get_len ();

    unsigned len2 = valueFormat2.get_len ();

    const hb_array_t<const Value> values_array = values.as_array ((unsigned)class1Count * (unsigned) class2Count * (len1 + len2));

    for (const unsigned class1_idx : class1_set.iter ())

    {

      for (const unsigned class2_idx : class2_set.iter ())

      {

        unsigned start_offset = (class1_idx * (unsigned) class2Count + class2_idx) * (len1 + len2);

        if (valueFormat1.has_device ())

          valueFormat1.collect_variation_indices (c, this, values_array.sub_array (start_offset, len1));

        if (valueFormat2.has_device ())

          valueFormat2.collect_variation_indices (c, this, values_array.sub_array (start_offset+len1, len2));

      }

    }

  }

  void collect_glyphs (hb_collect_glyphs_context_t *c) const

  {

    if (unlikely (!(this+coverage).collect_coverage (c->input))) return;

    if (unlikely (!(this+classDef2).collect_coverage (c->input))) return;

  }

  const Coverage &get_coverage () const { return this+coverage; }

  struct external_cache_t

  {

    hb_ot_layout_mapping_cache_t coverage;

    hb_ot_layout_mapping_cache_t first;

    hb_ot_layout_mapping_cache_t second;

  };

  void *external_cache_create () const

  {

    external_cache_t *cache = (external_cache_t *) hb_malloc (sizeof (external_cache_t));

    if (likely (cache))

    {

      cache->coverage.clear ();

      cache->first.clear ();

      cache->second.clear ();

    }

    return cache;

  }

  bool apply (hb_ot_apply_context_t *c, void *external_cache) const

  {

    TRACE_APPLY (this);

    hb_buffer_t *buffer = c->buffer;

#ifndef HB_NO_OT_LAYOUT_LOOKUP_CACHE

    external_cache_t *cache = (external_cache_t *) external_cache;

    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint, cache ? &cache->coverage : nullptr);

#else

    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);

#endif

    if (index == NOT_COVERED) return_trace (false);

    auto &skippy_iter = c->iter_input;

    skippy_iter.reset_fast (buffer->idx);

    unsigned unsafe_to;

    if (unlikely (!skippy_iter.next (&unsafe_to)))

    {

      buffer->unsafe_to_concat (buffer->idx, unsafe_to);

      return_trace (false);

    }

#ifndef HB_NO_OT_LAYOUT_LOOKUP_CACHE

    unsigned int klass1 = (this+classDef1).get_class (buffer->cur().codepoint, cache ? &cache->first : nullptr);

    unsigned int klass2 = (this+classDef2).get_class (buffer->info[skippy_iter.idx].codepoint, cache ? &cache->second : nullptr);

#else

    unsigned int klass1 = (this+classDef1).get_class (buffer->cur().codepoint);

    unsigned int klass2 = (this+classDef2).get_class (buffer->info[skippy_iter.idx].codepoint);

#endif

    if (unlikely (klass1 >= class1Count || klass2 >= class2Count))

    {

      buffer->unsafe_to_concat (buffer->idx, skippy_iter.idx + 1);

      return_trace (false);

    }

    unsigned int len1 = valueFormat1.get_len ();

    unsigned int len2 = valueFormat2.get_len ();

    unsigned int record_len = len1 + len2;

    const Value *v = &values[record_len * (klass1 * class2Count + klass2)];

    bool applied_first = false, applied_second = false;

    /* Isolate simple kerning and apply it half to each side.

     * Results in better cursor positioning / underline drawing.

     *

     * Disabled, because causes issues... :-(

     * https://github.com/harfbuzz/harfbuzz/issues/3408

     * https://github.com/harfbuzz/harfbuzz/pull/3235#issuecomment-1029814978

     */

#ifndef HB_SPLIT_KERN

    if (false)

#endif

    {

      if (!len2)

      {

        const hb_direction_t dir = buffer->props.direction;

        const bool horizontal = HB_DIRECTION_IS_HORIZONTAL (dir);

        const bool backward = HB_DIRECTION_IS_BACKWARD (dir);

        unsigned mask = horizontal ? ValueFormat::xAdvance : ValueFormat::yAdvance;

        if (backward)

          mask |= mask >> 2; /* Add eg. xPlacement in RTL. */

        /* Add Devices. */

        mask |= mask << 4;

        if (valueFormat1 & ~mask)

          goto bail;

        /* Is simple kern. Apply value on an empty position slot,

         * then split it between sides. */

        hb_glyph_position_t pos{};

        if (valueFormat1.apply_value (c, this, v, pos))

        {

          hb_position_t *src  = &pos.x_advance;

          hb_position_t *dst1 = &buffer->cur_pos().x_advance;

          hb_position_t *dst2 = &buffer->pos[skippy_iter.idx].x_advance;

          unsigned i = horizontal ? 0 : 1;

          hb_position_t kern  = src[i];

          hb_position_t kern1 = kern >> 1;

          hb_position_t kern2 = kern - kern1;

          if (!backward)

          {

            dst1[i] += kern1;

            dst2[i] += kern2;

            dst2[i + 2] += kern2;

          }

          else

          {

            dst1[i] += kern1;

            dst1[i + 2] += src[i + 2] - kern2;

            dst2[i] += kern2;

          }

          applied_first = applied_second = kern != 0;

          goto success;

        }

        goto boring;

      }

    }

    bail:

    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())

    {

      c->buffer->message (c->font,

        "try kerning glyphs at %u,%u",

        c->buffer->idx, skippy_iter.idx);

    }

    applied_first = len1 && valueFormat1.apply_value (c, this, v, buffer->cur_pos());

    applied_second = len2 && valueFormat2.apply_value (c, this, v + len1, buffer->pos[skippy_iter.idx]);

    if (applied_first || applied_second)

      if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())

      {

  c->buffer->message (c->font,

          "kerned glyphs at %u,%u",

          c->buffer->idx, skippy_iter.idx);

      }

    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())

    {

      c->buffer->message (c->font,

        "tried kerning glyphs at %u,%u",

        c->buffer->idx, skippy_iter.idx);

    }

    success:

    if (applied_first || applied_second)

      buffer->unsafe_to_break (buffer->idx, skippy_iter.idx + 1);

    else

    boring:

      buffer->unsafe_to_concat (buffer->idx, skippy_iter.idx + 1);

    if (len2)

    {

      skippy_iter.idx++;

      // https://github.com/harfbuzz/harfbuzz/issues/3824

      // https://github.com/harfbuzz/harfbuzz/issues/3888#issuecomment-1326781116

      buffer->unsafe_to_break (buffer->idx, skippy_iter.idx + 1);

    }

    buffer->idx = skippy_iter.idx;

    return_trace (true);

  }

  bool subset (hb_subset_context_t *c) const

  {

    TRACE_SUBSET (this);

    auto *out = c->serializer->start_embed (*this);

    if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

    out->format = format;

    hb_map_t klass1_map;

    out->classDef1.serialize_subset (c, classDef1, this, &klass1_map, true, true, &(this + coverage));

    out->class1Count = klass1_map.get_population ();

    hb_map_t klass2_map;

    out->classDef2.serialize_subset (c, classDef2, this, &klass2_map, true, false);

    out->class2Count = klass2_map.get_population ();

    unsigned len1 = valueFormat1.get_len ();

    unsigned len2 = valueFormat2.get_len ();

    hb_pair_t<unsigned, unsigned> newFormats = hb_pair (valueFormat1, valueFormat2);

    if (c->plan->normalized_coords)

    {

      /* in case of full instancing, all var device flags will be dropped so no

       * need to strip hints here */

      newFormats = compute_effective_value_formats (klass1_map, klass2_map, false, false, &c->plan->layout_variation_idx_delta_map);

    }

    /* do not strip hints for VF */

    else if (c->plan->flags & HB_SUBSET_FLAGS_NO_HINTING)

    {

      hb_blob_t* blob = hb_face_reference_table (c->plan->source, HB_TAG ('f','v','a','r'));

      bool has_fvar = (blob != hb_blob_get_empty ());

      hb_blob_destroy (blob);

      bool strip = !has_fvar;

      /* special case: strip hints when a VF has no GDEF varstore after

       * subsetting*/

      if (has_fvar && !c->plan->has_gdef_varstore)

        strip = true;

      newFormats = compute_effective_value_formats (klass1_map, klass2_map, strip, true);

    }

    out->valueFormat1 = newFormats.first;

    out->valueFormat2 = newFormats.second;

    unsigned total_len = len1 + len2;

    hb_vector_t<unsigned> class2_idxs (+ hb_range ((unsigned) class2Count) | hb_filter (klass2_map));

    for (unsigned class1_idx : + hb_range ((unsigned) class1Count) | hb_filter (klass1_map))

    {

      for (unsigned class2_idx : class2_idxs)

      {

        unsigned idx = (class1_idx * (unsigned) class2Count + class2_idx) * total_len;

        valueFormat1.copy_values (c->serializer, out->valueFormat1, this, &values[idx], &c->plan->layout_variation_idx_delta_map);

        valueFormat2.copy_values (c->serializer, out->valueFormat2, this, &values[idx + len1], &c->plan->layout_variation_idx_delta_map);

      }

    }

    bool ret = out->coverage.serialize_subset(c, coverage, this);

    return_trace (out->class1Count && out->class2Count && ret);

  }

  hb_pair_t<unsigned, unsigned> compute_effective_value_formats (const hb_map_t& klass1_map,

                                                                 const hb_map_t& klass2_map,

                                                                 bool strip_hints, bool strip_empty,

                                                                 const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *varidx_delta_map = nullptr) const

  {

    unsigned len1 = valueFormat1.get_len ();

    unsigned len2 = valueFormat2.get_len ();

    unsigned record_size = len1 + len2;

    unsigned format1 = 0;

    unsigned format2 = 0;

    for (unsigned class1_idx : + hb_range ((unsigned) class1Count) | hb_filter (klass1_map))

    {

      for (unsigned class2_idx : + hb_range ((unsigned) class2Count) | hb_filter (klass2_map))

      {

        unsigned idx = (class1_idx * (unsigned) class2Count + class2_idx) * record_size;

        format1 = format1 | valueFormat1.get_effective_format (&values[idx], strip_hints, strip_empty, this, varidx_delta_map);

        format2 = format2 | valueFormat2.get_effective_format (&values[idx + len1], strip_hints, strip_empty, this, varidx_delta_map);

      }

      if (format1 == valueFormat1 && format2 == valueFormat2)

        break;

    }

    return hb_pair (format1, format2);

  }

};

}

}

}

#endif  // OT_LAYOUT_GPOS_PAIRPOSFORMAT2_HH