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 /*

  * 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-private.hh"

 /* 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 == 0x0E1B || u == 0x0E1D || u == 0x0E1F/* || u == 0x0E2C*/)

     return AC;

   if (u == 0x0E0D || u == 0x0E10)

     return RC;

   if (u == 0x0E0E || u == 0x0E0F)

     return DC;

   if (hb_in_range<hb_codepoint_t> (u, 0x0E01, 0x0E2E))

     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 == 0x0E31 || hb_in_range<hb_codepoint_t> (u, 0x0E34, 0x0E37) ||

       u == 0x0E47 || hb_in_range<hb_codepoint_t> (u, 0x0E4D, 0x0E4E))

     return AV;

   if (hb_in_range<hb_codepoint_t> (u, 0x0E38, 0x0E3A))

     return BV;

   if (hb_in_range<hb_codepoint_t> (u, 0x0E48, 0x0E4C))

     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 = NULL;

   static const thai_pua_mapping_t SD_mappings[] = {

     {0x0E48, 0xF70A, 0xF88B}, /* MAI EK */

     {0x0E49, 0xF70B, 0xF88E}, /* MAI THO */

     {0x0E4A, 0xF70C, 0xF891}, /* MAI TRI */

     {0x0E4B, 0xF70D, 0xF894}, /* MAI CHATTAWA */

     {0x0E4C, 0xF70E, 0xF897}, /* THANTHAKHAT */

     {0x0E38, 0xF718, 0xF89B}, /* SARA U */

     {0x0E39, 0xF719, 0xF89C}, /* SARA UU */

     {0x0E3A, 0xF71A, 0xF89D}, /* PHINTHU */

     {0x0000, 0x0000, 0x0000}

   };

   static const thai_pua_mapping_t SDL_mappings[] = {

     {0x0E48, 0xF705, 0xF88C}, /* MAI EK */

     {0x0E49, 0xF706, 0xF88F}, /* MAI THO */

     {0x0E4A, 0xF707, 0xF892}, /* MAI TRI */

     {0x0E4B, 0xF708, 0xF895}, /* MAI CHATTAWA */

     {0x0E4C, 0xF709, 0xF898}, /* THANTHAKHAT */

     {0x0000, 0x0000, 0x0000}

   };

   static const thai_pua_mapping_t SL_mappings[] = {

     {0x0E48, 0xF713, 0xF88A}, /* MAI EK */

     {0x0E49, 0xF714, 0xF88D}, /* MAI THO */

     {0x0E4A, 0xF715, 0xF890}, /* MAI TRI */

     {0x0E4B, 0xF716, 0xF893}, /* MAI CHATTAWA */

     {0x0E4C, 0xF717, 0xF896}, /* THANTHAKHAT */

     {0x0E31, 0xF710, 0xF884}, /* MAI HAN-AKAT */

     {0x0E34, 0xF701, 0xF885}, /* SARA I */

     {0x0E35, 0xF702, 0xF886}, /* SARA II */

     {0x0E36, 0xF703, 0xF887}, /* SARA UE */

     {0x0E37, 0xF704, 0xF888}, /* SARA UEE */

     {0x0E47, 0xF712, 0xF889}, /* MAITAIKHU */

     {0x0E4D, 0xF711, 0xF899}, /* NIKHAHIT */

     {0x0000, 0x0000, 0x0000}

   };

   static const thai_pua_mapping_t RD_mappings[] = {

     {0x0E0D, 0xF70F, 0xF89A}, /* YO YING */

     {0x0E10, 0xF700, 0xF89E}, /* THO THAN */

     {0x0000, 0x0000, 0x0000}

   };

   switch (action) {

     default: assert (false); /* Fallthrough */

     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;

     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:

    *

    *   http://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) & ~0x0080) == 0x0E33)

 #define NIKHAHIT_FROM_SARA_AM(x) ((x) - 0xE33 + 0xE4D)

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

 #define IS_TONE_MARK(x) (hb_in_ranges<hb_codepoint_t> ((x) & ~0x0080, 0x0E34, 0x0E37, 0x0E47, 0x0E4E, 0x0E31, 0x0E31))

   buffer->clear_output ();

   unsigned int count = buffer->len;

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

   {

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

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

       buffer->next_glyph ();

       continue;

     }

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

     hb_codepoint_t decomposed[2] = {hb_codepoint_t (NIKHAHIT_FROM_SARA_AM (u)),

 				    hb_codepoint_t (SARA_AA_FROM_SARA_AM (u))};

     buffer->replace_glyphs (1, 2, decomposed);

     if (unlikely (buffer->in_error))

       return;

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

     unsigned int end = buffer->out_len;

     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->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 =

 {

   "thai",

   NULL, /* collect_features */

   NULL, /* override_features */

   NULL, /* data_create */

   NULL, /* data_destroy */

   preprocess_text_thai,

   HB_OT_SHAPE_NORMALIZATION_MODE_DEFAULT,

   NULL, /* decompose */

   NULL, /* compose */

   NULL, /* setup_masks */

   HB_OT_SHAPE_ZERO_WIDTH_MARKS_DEFAULT,

   false,/* fallback_position */

 };