/*

 * 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-fallback-private.hh"

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

static unsigned int

recategorize_combining_class (hb_codepoint_t u,

                              unsigned int klass)

{

  if (klass >= 200)

    return klass;

  /* Thai / Lao need some per-character work. */

  if ((u & ~0xFF) == 0x0E00u)

  {

    if (unlikely (klass == 0))

    {

      switch (u)

      {

        case 0x0E31u:

        case 0x0E34u:

        case 0x0E35u:

        case 0x0E36u:

        case 0x0E37u:

        case 0x0E47u:

        case 0x0E4Cu:

        case 0x0E4Du:

        case 0x0E4Eu:

          klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;

          break;

        case 0x0EB1u:

        case 0x0EB4u:

        case 0x0EB5u:

        case 0x0EB6u:

        case 0x0EB7u:

        case 0x0EBBu:

        case 0x0ECCu:

        case 0x0ECDu:

          klass = HB_UNICODE_COMBINING_CLASS_ABOVE;

          break;

        case 0x0EBCu:

          klass = HB_UNICODE_COMBINING_CLASS_BELOW;

          break;

      }

    } else {

      /* Thai virama is below-right */

      if (u == 0x0E3Au)

        klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;

    }

  }

  switch (klass)

  {

    /* Hebrew */

    case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */

    case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */

    case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */

    case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */

    case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */

    case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */

    case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */

    case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */

    case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */

    case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */

    case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */

      return HB_UNICODE_COMBINING_CLASS_BELOW;

    case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */

      return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;

    case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */

      return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;

    case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */

    case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */

      return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;

    case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */

      return HB_UNICODE_COMBINING_CLASS_ABOVE;

    case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */

      break;

    /* Arabic and Syriac */

    case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */

    case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */

    case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */

    case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */

    case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */

    case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */

    case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */

    case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */

      return HB_UNICODE_COMBINING_CLASS_ABOVE;

    case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */

    case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */

      return HB_UNICODE_COMBINING_CLASS_BELOW;

    /* Thai */

    case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */

      return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;

    case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */

      return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;

    /* Lao */

    case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */

      return HB_UNICODE_COMBINING_CLASS_BELOW;

    case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */

      return HB_UNICODE_COMBINING_CLASS_ABOVE;

    /* Tibetan */

    case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */

      return HB_UNICODE_COMBINING_CLASS_BELOW;

    case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/

      return HB_UNICODE_COMBINING_CLASS_ABOVE;

    case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */

      return HB_UNICODE_COMBINING_CLASS_BELOW;

  }

  return klass;

}

void

_hb_ot_shape_fallback_position_recategorize_marks (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_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {

      unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);

      combining_class = recategorize_combining_class (info[i].codepoint, combining_class);

      _hb_glyph_info_set_modified_combining_class (&info[i], combining_class);

    }

}

static void

zero_mark_advances (hb_buffer_t *buffer,

                    unsigned int start,

                    unsigned int end)

{

  hb_glyph_info_t *info = buffer->info;

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

    if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)

    {

      buffer->pos[i].x_advance = 0;

      buffer->pos[i].y_advance = 0;

    }

}

static inline void

position_mark (const hb_ot_shape_plan_t *plan,

               hb_font_t *font,

               hb_buffer_t  *buffer,

               hb_glyph_extents_t &base_extents,

               unsigned int i,

               unsigned int combining_class)

{

  hb_glyph_extents_t mark_extents;

  if (!font->get_glyph_extents (buffer->info[i].codepoint,

                                &mark_extents))

    return;

  hb_position_t y_gap = font->y_scale / 16;

  hb_glyph_position_t &pos = buffer->pos[i];

  pos.x_offset = pos.y_offset = 0;

  /* X positioning */

  switch (combining_class)

  {

    case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:

    case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:

      if (buffer->props.direction == HB_DIRECTION_LTR) {

        pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;

        break;

      } else if (buffer->props.direction == HB_DIRECTION_RTL) {

        pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;

        break;

      }

      HB_FALLTHROUGH;

    default:

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:

    case HB_UNICODE_COMBINING_CLASS_BELOW:

    case HB_UNICODE_COMBINING_CLASS_ABOVE:

      /* Center align. */

      pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;

      break;

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:

    case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:

    case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:

      /* Left align. */

      pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;

      break;

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:

    case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:

    case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:

      /* Right align. */

      pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;

      break;

  }

  /* Y positioning */

  switch (combining_class)

  {

    case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:

    case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:

    case HB_UNICODE_COMBINING_CLASS_BELOW:

    case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:

      /* Add gap, fall-through. */

      base_extents.height -= y_gap;

      HB_FALLTHROUGH;

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:

      pos.y_offset = base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;

      /* Never shift up "below" marks. */

      if ((y_gap > 0) == (pos.y_offset > 0))

      {

        base_extents.height -= pos.y_offset;

        pos.y_offset = 0;

      }

      base_extents.height += mark_extents.height;

      break;

    case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:

    case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:

    case HB_UNICODE_COMBINING_CLASS_ABOVE:

    case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:

      /* Add gap, fall-through. */

      base_extents.y_bearing += y_gap;

      base_extents.height -= y_gap;

      HB_FALLTHROUGH;

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:

    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:

      pos.y_offset = base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);

      /* Don't shift down "above" marks too much. */

      if ((y_gap > 0) != (pos.y_offset > 0))

      {

        unsigned int correction = -pos.y_offset / 2;

        base_extents.y_bearing += correction;

        base_extents.height -= correction;

        pos.y_offset += correction;

      }

      base_extents.y_bearing -= mark_extents.height;

      base_extents.height += mark_extents.height;

      break;

  }

}

static inline void

position_around_base (const hb_ot_shape_plan_t *plan,

                      hb_font_t *font,

                      hb_buffer_t  *buffer,

                      unsigned int base,

                      unsigned int end)

{

  hb_direction_t horiz_dir = HB_DIRECTION_INVALID;

  hb_glyph_extents_t base_extents;

  if (!font->get_glyph_extents (buffer->info[base].codepoint,

                                &base_extents))

  {

    /* If extents don't work, zero marks and go home. */

    zero_mark_advances (buffer, base + 1, end);

    return;

  }

  base_extents.x_bearing += buffer->pos[base].x_offset;

  base_extents.y_bearing += buffer->pos[base].y_offset;

  unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[base]);

  unsigned int num_lig_components = _hb_glyph_info_get_lig_num_comps (&buffer->info[base]);

  hb_position_t x_offset = 0, y_offset = 0;

  if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {

    x_offset -= buffer->pos[base].x_advance;

    y_offset -= buffer->pos[base].y_advance;

  }

  hb_glyph_extents_t component_extents = base_extents;

  unsigned int last_lig_component = (unsigned int) -1;

  unsigned int last_combining_class = 255;

  hb_glyph_extents_t cluster_extents = base_extents; /* Initialization is just to shut gcc up. */

  hb_glyph_info_t *info = buffer->info;

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

    if (_hb_glyph_info_get_modified_combining_class (&info[i]))

    {

      if (num_lig_components > 1) {

        unsigned int this_lig_id = _hb_glyph_info_get_lig_id (&info[i]);

        unsigned int this_lig_component = _hb_glyph_info_get_lig_comp (&info[i]) - 1;

        /* Conditions for attaching to the last component. */

        if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)

          this_lig_component = num_lig_components - 1;

        if (last_lig_component != this_lig_component)

        {

          last_lig_component = this_lig_component;

          last_combining_class = 255;

          component_extents = base_extents;

          if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {

            if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))

              horiz_dir = plan->props.direction;

            else

              horiz_dir = hb_script_get_horizontal_direction (plan->props.script);

          }

          if (horiz_dir == HB_DIRECTION_LTR)

            component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;

          else

            component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;

          component_extents.width /= num_lig_components;

        }

      }

      unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&info[i]);

      if (last_combining_class != this_combining_class)

      {

        last_combining_class = this_combining_class;

        cluster_extents = component_extents;

      }

      position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);

      buffer->pos[i].x_advance = 0;

      buffer->pos[i].y_advance = 0;

      buffer->pos[i].x_offset += x_offset;

      buffer->pos[i].y_offset += y_offset;

    } else {

      if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {

        x_offset -= buffer->pos[i].x_advance;

        y_offset -= buffer->pos[i].y_advance;

      } else {

        x_offset += buffer->pos[i].x_advance;

        y_offset += buffer->pos[i].y_advance;

      }

    }

}

static inline void

position_cluster (const hb_ot_shape_plan_t *plan,

                  hb_font_t *font,

                  hb_buffer_t  *buffer,

                  unsigned int start,

                  unsigned int end)

{

  if (end - start < 2)

    return;

  /* Find the base glyph */

  hb_glyph_info_t *info = buffer->info;

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

    if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))

    {

      /* Find mark glyphs */

      unsigned int j;

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

        if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[j])))

          break;

      position_around_base (plan, font, buffer, i, j);

      i = j - 1;

    }

}

void

_hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,

                                hb_font_t *font,

                                hb_buffer_t  *buffer)

{

  _hb_buffer_assert_gsubgpos_vars (buffer);

  unsigned int start = 0;

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

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

    if (likely (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))) {

      position_cluster (plan, font, buffer, start, i);

      start = i;

    }

  position_cluster (plan, font, buffer, start, count);

}

/* Performs old-style TrueType kerning. */

void

_hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,

                            hb_font_t *font,

                            hb_buffer_t  *buffer)

{

  if (!plan->has_kern) return;

  OT::hb_apply_context_t c (1, font, buffer);

  c.set_lookup_mask (plan->kern_mask);

  c.set_lookup_props (OT::LookupFlag::IgnoreMarks);

  OT::hb_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;

  skippy_iter.init (&c);

  unsigned int count = buffer->len;

  hb_glyph_info_t *info = buffer->info;

  hb_glyph_position_t *pos = buffer->pos;

  for (unsigned int idx = 0; idx < count;)

  {

    skippy_iter.reset (idx, 1);

    if (!skippy_iter.next ())

    {

      idx++;

      continue;

    }

    hb_position_t x_kern, y_kern;

    font->get_glyph_kerning_for_direction (info[idx].codepoint,

                                           info[skippy_iter.idx].codepoint,

                                           buffer->props.direction,

                                           &x_kern, &y_kern);

    if (x_kern)

    {

      hb_position_t kern1 = x_kern >> 1;

      hb_position_t kern2 = x_kern - kern1;

      pos[idx].x_advance += kern1;

      pos[skippy_iter.idx].x_advance += kern2;

      pos[skippy_iter.idx].x_offset += kern2;

    }

    if (y_kern)

    {

      hb_position_t kern1 = y_kern >> 1;

      hb_position_t kern2 = y_kern - kern1;

      pos[idx].y_advance += kern1;

      pos[skippy_iter.idx].y_advance += kern2;

      pos[skippy_iter.idx].y_offset += kern2;

    }

    idx = skippy_iter.idx;

  }

}

/* Adjusts width of various spaces. */

void

_hb_ot_shape_fallback_spaces (const hb_ot_shape_plan_t *plan,

                              hb_font_t *font,

                              hb_buffer_t  *buffer)

{

  if (!HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))

    return;

  hb_glyph_info_t *info = buffer->info;

  hb_glyph_position_t *pos = buffer->pos;

  unsigned int count = buffer->len;

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

    if (_hb_glyph_info_is_unicode_space (&info[i]) && !_hb_glyph_info_ligated (&info[i]))

    {

      hb_unicode_funcs_t::space_t space_type = _hb_glyph_info_get_unicode_space_fallback_type (&info[i]);

      hb_codepoint_t glyph;

      typedef hb_unicode_funcs_t t;

      switch (space_type)

      {

        case t::NOT_SPACE: /* Shouldn't happen. */

        case t::SPACE:

          break;

        case t::SPACE_EM:

        case t::SPACE_EM_2:

        case t::SPACE_EM_3:

        case t::SPACE_EM_4:

        case t::SPACE_EM_5:

        case t::SPACE_EM_6:

        case t::SPACE_EM_16:

          pos[i].x_advance = (font->x_scale + ((int) space_type)/2) / (int) space_type;

          break;