/*

 * 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

 */

/* Thai / Lao shaper */

/* PUA shaping */

enum thai_consonant_type_t

{

  NC,

  AC,

  RC,

  DC,

  NOT_CONSONANT,

  NUM_CONSONANT_TYPES = NOT_CONSONANT

};

static thai_consonant_type_t

get_consonant_type (hb_codepoint_t u)

{

  if (u == 0x0E1Bu || u == 0x0E1Du || u == 0x0E1Fu/* || u == 0x0E2Cu*/)

    return AC;

  if (u == 0x0E0Du || u == 0x0E10u)

    return RC;

  if (u == 0x0E0Eu || u == 0x0E0Fu)

    return DC;

  if (hb_in_range<hb_codepoint_t> (u, 0x0E01u, 0x0E2Eu))

    return NC;

  return NOT_CONSONANT;

}

enum thai_mark_type_t

{

  AV,

  BV,

  T,

  NOT_MARK,

  NUM_MARK_TYPES = NOT_MARK

};

static thai_mark_type_t

get_mark_type (hb_codepoint_t u)

{

  if (u == 0x0E31u || hb_in_range<hb_codepoint_t> (u, 0x0E34u, 0x0E37u) ||

      u == 0x0E47u || hb_in_range<hb_codepoint_t> (u, 0x0E4Du, 0x0E4Eu))

    return AV;

  if (hb_in_range<hb_codepoint_t> (u, 0x0E38u, 0x0E3Au))

    return BV;

  if (hb_in_range<hb_codepoint_t> (u, 0x0E48u, 0x0E4Cu))

    return T;

  return NOT_MARK;

}

enum thai_action_t

{

  NOP,

  SD,  /* Shift combining-mark down */

  SL,  /* Shift combining-mark left */

  SDL, /* Shift combining-mark down-left */

  RD   /* Remove descender from base */

};

static hb_codepoint_t

thai_pua_shape (hb_codepoint_t u, thai_action_t action, hb_font_t *font)

{

  struct thai_pua_mapping_t {

    hb_codepoint_t u;

    hb_codepoint_t win_pua;

    hb_codepoint_t mac_pua;

  } const *pua_mappings = nullptr;

  static const thai_pua_mapping_t SD_mappings[] = {

    {0x0E48u, 0xF70Au, 0xF88Bu}, /* MAI EK */

    {0x0E49u, 0xF70Bu, 0xF88Eu}, /* MAI THO */

    {0x0E4Au, 0xF70Cu, 0xF891u}, /* MAI TRI */

    {0x0E4Bu, 0xF70Du, 0xF894u}, /* MAI CHATTAWA */

    {0x0E4Cu, 0xF70Eu, 0xF897u}, /* THANTHAKHAT */

    {0x0E38u, 0xF718u, 0xF89Bu}, /* SARA U */

    {0x0E39u, 0xF719u, 0xF89Cu}, /* SARA UU */

    {0x0E3Au, 0xF71Au, 0xF89Du}, /* PHINTHU */

    {0x0000u, 0x0000u, 0x0000u}

  };

  static const thai_pua_mapping_t SDL_mappings[] = {

    {0x0E48u, 0xF705u, 0xF88Cu}, /* MAI EK */

    {0x0E49u, 0xF706u, 0xF88Fu}, /* MAI THO */

    {0x0E4Au, 0xF707u, 0xF892u}, /* MAI TRI */

    {0x0E4Bu, 0xF708u, 0xF895u}, /* MAI CHATTAWA */

    {0x0E4Cu, 0xF709u, 0xF898u}, /* THANTHAKHAT */

    {0x0000u, 0x0000u, 0x0000u}

  };

  static const thai_pua_mapping_t SL_mappings[] = {

    {0x0E48u, 0xF713u, 0xF88Au}, /* MAI EK */

    {0x0E49u, 0xF714u, 0xF88Du}, /* MAI THO */

    {0x0E4Au, 0xF715u, 0xF890u}, /* MAI TRI */

    {0x0E4Bu, 0xF716u, 0xF893u}, /* MAI CHATTAWA */

    {0x0E4Cu, 0xF717u, 0xF896u}, /* THANTHAKHAT */

    {0x0E31u, 0xF710u, 0xF884u}, /* MAI HAN-AKAT */

    {0x0E34u, 0xF701u, 0xF885u}, /* SARA I */

    {0x0E35u, 0xF702u, 0xF886u}, /* SARA II */

    {0x0E36u, 0xF703u, 0xF887u}, /* SARA UE */

    {0x0E37u, 0xF704u, 0xF888u}, /* SARA UEE */

    {0x0E47u, 0xF712u, 0xF889u}, /* MAITAIKHU */

    {0x0E4Du, 0xF711u, 0xF899u}, /* NIKHAHIT */

    {0x0000u, 0x0000u, 0x0000u}

  };

  static const thai_pua_mapping_t RD_mappings[] = {

    {0x0E0Du, 0xF70Fu, 0xF89Au}, /* YO YING */

    {0x0E10u, 0xF700u, 0xF89Eu}, /* THO THAN */

    {0x0000u, 0x0000u, 0x0000u}

  };

  switch (action) {

    case NOP: return u;

    case SD:  pua_mappings = SD_mappings; break;

    case SDL: pua_mappings = SDL_mappings; break;

    case SL:  pua_mappings = SL_mappings; break;

    case RD:  pua_mappings = RD_mappings; break;

  }

  for (; pua_mappings->u; pua_mappings++)

    if (pua_mappings->u == u)

    {

      hb_codepoint_t glyph;

      if (hb_font_get_glyph (font, pua_mappings->win_pua, 0, &glyph))

        return pua_mappings->win_pua;

      if (hb_font_get_glyph (font, pua_mappings->mac_pua, 0, &glyph))

        return pua_mappings->mac_pua;

      break;

    }

  return u;

}

static enum thai_above_state_t

{     /* Cluster above looks like: */

  T0, /*  ⣤                      */

  T1, /*     ⣼                   */

  T2, /*        ⣾                */

  T3, /*           ⣿             */

  NUM_ABOVE_STATES

} thai_above_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =

{

  T0, /* NC */

  T1, /* AC */

  T0, /* RC */

  T0, /* DC */

  T3, /* NOT_CONSONANT */

};

static const struct thai_above_state_machine_edge_t {

  thai_action_t action;

  thai_above_state_t next_state;

} thai_above_state_machine[NUM_ABOVE_STATES][NUM_MARK_TYPES] =

{        /*AV*/    /*BV*/    /*T*/

/*T0*/ {{NOP,T3}, {NOP,T0}, {SD, T3}},

/*T1*/ {{SL, T2}, {NOP,T1}, {SDL,T2}},

/*T2*/ {{NOP,T3}, {NOP,T2}, {SL, T3}},

/*T3*/ {{NOP,T3}, {NOP,T3}, {NOP,T3}},

};

static enum thai_below_state_t

{

  B0, /* No descender */

  B1, /* Removable descender */

  B2, /* Strict descender */

  NUM_BELOW_STATES

} thai_below_start_state[NUM_CONSONANT_TYPES + 1/* For NOT_CONSONANT */] =

{

  B0, /* NC */

  B0, /* AC */

  B1, /* RC */

  B2, /* DC */

  B2, /* NOT_CONSONANT */

};

static const struct thai_below_state_machine_edge_t {

  thai_action_t action;

  thai_below_state_t next_state;

} thai_below_state_machine[NUM_BELOW_STATES][NUM_MARK_TYPES] =

{        /*AV*/    /*BV*/    /*T*/

/*B0*/ {{NOP,B0}, {NOP,B2}, {NOP, B0}},

/*B1*/ {{NOP,B1}, {RD, B2}, {NOP, B1}},

/*B2*/ {{NOP,B2}, {SD, B2}, {NOP, B2}},

};

static void

do_thai_pua_shaping (const hb_ot_shape_plan_t *plan HB_UNUSED,

                     hb_buffer_t              *buffer,

                     hb_font_t                *font)

{

  thai_above_state_t above_state = thai_above_start_state[NOT_CONSONANT];

  thai_below_state_t below_state = thai_below_start_state[NOT_CONSONANT];

  unsigned int base = 0;

  hb_glyph_info_t *info = buffer->info;

  unsigned int count = buffer->len;

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

  {

    thai_mark_type_t mt = get_mark_type (info[i].codepoint);

    if (mt == NOT_MARK) {

      thai_consonant_type_t ct = get_consonant_type (info[i].codepoint);

      above_state = thai_above_start_state[ct];

      below_state = thai_below_start_state[ct];

      base = i;

      continue;

    }

    const thai_above_state_machine_edge_t &above_edge = thai_above_state_machine[above_state][mt];

    const thai_below_state_machine_edge_t &below_edge = thai_below_state_machine[below_state][mt];

    above_state = above_edge.next_state;

    below_state = below_edge.next_state;

    /* At least one of the above/below actions is NOP. */

    thai_action_t action = above_edge.action != NOP ? above_edge.action : below_edge.action;

    buffer->unsafe_to_break (base, i);

    if (action == RD)

      info[base].codepoint = thai_pua_shape (info[base].codepoint, action, font);

    else

      info[i].codepoint = thai_pua_shape (info[i].codepoint, action, font);

  }

}

static void

preprocess_text_thai (const hb_ot_shape_plan_t *plan,

                      hb_buffer_t              *buffer,

                      hb_font_t                *font)

{

  /* This function implements the shaping logic documented here:

   *

   *   https://linux.thai.net/~thep/th-otf/shaping.html

   *

   * The first shaping rule listed there is needed even if the font has Thai

   * OpenType tables.  The rest do fallback positioning based on PUA codepoints.

   * We implement that only if there exist no Thai GSUB in the font.

   */

  /* The following is NOT specified in the MS OT Thai spec, however, it seems

   * to be what Uniscribe and other engines implement.  According to Eric Muller:

   *

   * When you have a SARA AM, decompose it in NIKHAHIT + SARA AA, *and* move the

   * NIKHAHIT backwards over any tone mark (0E48-0E4B).

   *

   * <0E14, 0E4B, 0E33> -> <0E14, 0E4D, 0E4B, 0E32>

   *

   * This reordering is legit only when the NIKHAHIT comes from a SARA AM, not

   * when it's there to start with. The string <0E14, 0E4B, 0E4D> is probably

   * not what a user wanted, but the rendering is nevertheless nikhahit above

   * chattawa.

   *

   * Same for Lao.

   *

   * Note:

   *

   * Uniscribe also does some below-marks reordering.  Namely, it positions U+0E3A

   * after U+0E38 and U+0E39.  We do that by modifying the ccc for U+0E3A.

   * See unicode->modified_combining_class ().  Lao does NOT have a U+0E3A

   * equivalent.

   */

  /*

   * Here are the characters of significance:

   *

   *                    Thai    Lao

   * SARA AM:           U+0E33  U+0EB3

   * SARA AA:           U+0E32  U+0EB2

   * Nikhahit:          U+0E4D  U+0ECD

   *

   * Testing shows that Uniscribe reorder the following marks:

   * Thai:      <0E31,0E34..0E37,0E47..0E4E>

   * Lao:       <0EB1,0EB4..0EB7,0EC7..0ECE>

   *

   * Note how the Lao versions are the same as Thai + 0x80.

   */

  /* We only get one script at a time, so a script-agnostic implementation

   * is adequate here. */

#define IS_SARA_AM(x) (((x) & ~0x0080u) == 0x0E33u)

#define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0x0E33u + 0x0E4Du)

#define SARA_AA_FROM_SARA_AM(x) ((x) - 1)

#define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080u, 0x0E34u, 0x0E37u, 0x0E47u, 0x0E4Eu, 0x0E31u, 0x0E31u))

  buffer->clear_output ();

  unsigned int count = buffer->len;

  for (buffer->idx = 0; buffer->idx < count && buffer->successful;)

  {

    hb_codepoint_t u = buffer->cur().codepoint;

    if (likely (!IS_SARA_AM (u))) {

      buffer->next_glyph ();

      continue;

    }

    /* Is SARA AM. Decompose and reorder. */

    if (unlikely (!buffer->successful))

      return;

    /* Make Nikhahit be recognized as a ccc=0 mark when zeroing widths. */

    unsigned int end = buffer->out_len;

    _hb_glyph_info_set_general_category (&buffer->out_info[end - 2], HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK);

    /* Ok, let's see... */

    unsigned int start = end - 2;

    while (start > 0 && IS_TONE_MARK (buffer->out_info[start - 1].codepoint))

      start--;

    if (start + 2 < end)

    {

      /* Move Nikhahit (end-2) to the beginning */

      buffer->merge_out_clusters (start, end);

      hb_glyph_info_t t = buffer->out_info[end - 2];

      memmove (buffer->out_info + start + 1,

               buffer->out_info + start,

               sizeof (buffer->out_info[0]) * (end - start - 2));

      buffer->out_info[start] = t;

    }

    else

    {

      /* Since we decomposed, and NIKHAHIT is combining, merge clusters with the

       * previous cluster. */

      if (start && buffer->cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES)

        buffer->merge_out_clusters (start - 1, end);

    }

  }

  buffer->swap_buffers ();

  /* If font has Thai GSUB, we are done. */

  if (plan->props.script == HB_SCRIPT_THAI && !plan->map.found_script[0])

    do_thai_pua_shaping (plan, buffer, font);

}

const hb_ot_complex_shaper_t _hb_ot_complex_shaper_thai =

{

  nullptr, /* collect_features */

  nullptr, /* override_features */

  nullptr, /* data_create */

  nullptr, /* data_destroy */

  preprocess_text_thai,

  nullptr, /* postprocess_glyphs */

  HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,

  nullptr, /* decompose */

  nullptr, /* compose */

  nullptr, /* setup_masks */

  nullptr, /* reorder_marks */

  HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE,

  false,/* fallback_position */

};