/*

 * Copyright © 2018  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): Garret Rieger, Rod Sheeter, Behdad Esfahbod

 */

#include "hb.hh"

#include "hb-open-type.hh"

#include "hb-subset.hh"

#include "hb-subset-glyf.hh"

#include "hb-open-file.hh"

#include "hb-ot-cmap-table.hh"

#include "hb-ot-glyf-table.hh"

#include "hb-ot-hdmx-table.hh"

#include "hb-ot-head-table.hh"

#include "hb-ot-hhea-table.hh"

#include "hb-ot-hmtx-table.hh"

#include "hb-ot-maxp-table.hh"

#include "hb-ot-os2-table.hh"

#include "hb-ot-post-table.hh"

#include "hb-ot-cff1-table.hh"

#include "hb-ot-cff2-table.hh"

#include "hb-ot-vorg-table.hh"

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

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

static unsigned int

_plan_estimate_subset_table_size (hb_subset_plan_t *plan,

                                  unsigned int table_len)

{

  unsigned int src_glyphs = plan->source->get_num_glyphs ();

  unsigned int dst_glyphs = plan->glyphset->get_population ();

  if (unlikely (!src_glyphs))

    return 512 + table_len;

  return 512 + (unsigned int) (table_len * sqrt ((double) dst_glyphs / src_glyphs));

}

template<typename TableType>

static bool

_subset2 (hb_subset_plan_t *plan)

{

  hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);

  const TableType *table = source_blob->as<TableType> ();

  hb_tag_t tag = TableType::tableTag;

  hb_bool_t result = false;

  if (source_blob->data)

  {

    hb_vector_t<char> buf;

    unsigned int buf_size = _plan_estimate_subset_table_size (plan, source_blob->length);

    DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);

    if (unlikely (!buf.alloc (buf_size)))

    {

      DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c failed to allocate %u bytes.", HB_UNTAG (tag), buf_size);

      return false;

    }

  retry:

    hb_serialize_context_t serializer ((void *) buf, buf_size);

    hb_subset_context_t c (plan, &serializer);

    result = table->subset (&c);

    if (serializer.in_error ())

    {

      buf_size += (buf_size >> 1) + 32;

      DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (tag), buf_size);

      if (unlikely (!buf.alloc (buf_size)))

      {

        DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c failed to reallocate %u bytes.", HB_UNTAG (tag), buf_size);

        return false;

      }

      goto retry;

    }

    if (result)

    {

      hb_blob_t *dest_blob = serializer.copy_blob ();

      DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length);

      result = c.plan->add_table (tag, dest_blob);

      hb_blob_destroy (dest_blob);

    }

    else

    {

      DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset table subsetted to empty.", HB_UNTAG (tag));

      result = true;

    }

  }

  else

    DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));

  hb_blob_destroy (source_blob);

  DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!");

  return result;

}

template<typename TableType>

static bool

_subset (hb_subset_plan_t *plan)

{

  hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);

  const TableType *table = source_blob->as<TableType> ();

  hb_tag_t tag = TableType::tableTag;

  hb_bool_t result = false;

  if (source_blob->data)

    result = table->subset (plan);

  else

    DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));

  hb_blob_destroy (source_blob);

  DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c::subset %s", HB_UNTAG (tag), result ? "success" : "FAILED!");

  return result;

}

static bool

_subset_table (hb_subset_plan_t *plan,

               hb_tag_t          tag)

{

  DEBUG_MSG(SUBSET, nullptr, "begin subset %c%c%c%c", HB_UNTAG (tag));

  bool result = true;

  switch (tag) {

    case HB_OT_TAG_glyf:

      result = _subset<const OT::glyf> (plan);

      break;

    case HB_OT_TAG_hdmx:

      result = _subset<const OT::hdmx> (plan);

      break;

    case HB_OT_TAG_head:

      // TODO that won't work well if there is no glyf

      DEBUG_MSG(SUBSET, nullptr, "skip head, handled by glyf");

      result = true;

      break;

    case HB_OT_TAG_hhea:

      DEBUG_MSG(SUBSET, nullptr, "skip hhea handled by hmtx");

      return true;

    case HB_OT_TAG_hmtx:

      result = _subset<const OT::hmtx> (plan);

      break;

    case HB_OT_TAG_vhea:

      DEBUG_MSG(SUBSET, nullptr, "skip vhea handled by vmtx");

      return true;

    case HB_OT_TAG_vmtx:

      result = _subset<const OT::vmtx> (plan);

      break;

    case HB_OT_TAG_maxp:

      result = _subset<const OT::maxp> (plan);

      break;

    case HB_OT_TAG_loca:

      DEBUG_MSG(SUBSET, nullptr, "skip loca handled by glyf");

      return true;

    case HB_OT_TAG_cmap:

      result = _subset<const OT::cmap> (plan);

      break;

    case HB_OT_TAG_OS2:

      result = _subset<const OT::OS2> (plan);

      break;

    case HB_OT_TAG_post:

      result = _subset<const OT::post> (plan);

      break;

    case HB_OT_TAG_cff1:

      result = _subset<const OT::cff1> (plan);

      break;

    case HB_OT_TAG_cff2:

      result = _subset<const OT::cff2> (plan);

      break;

    case HB_OT_TAG_VORG:

      result = _subset<const OT::VORG> (plan);

      break;

    case HB_OT_TAG_GDEF:

      result = _subset2<const OT::GDEF> (plan);

      break;

    case HB_OT_TAG_GSUB:

      result = _subset2<const OT::GSUB> (plan);

      break;

    case HB_OT_TAG_GPOS:

      result = _subset2<const OT::GPOS> (plan);

      break;

    default:

      hb_blob_t *source_table = hb_face_reference_table (plan->source, tag);

      if (likely (source_table))

        result = plan->add_table (tag, source_table);

      else

        result = false;

      hb_blob_destroy (source_table);

      break;

  }

  DEBUG_MSG(SUBSET, nullptr, "subset %c%c%c%c %s", HB_UNTAG (tag), result ? "ok" : "FAILED");

  return result;

}

static bool

_should_drop_table (hb_subset_plan_t *plan, hb_tag_t tag)

{

  switch (tag) {

    case HB_TAG ('c', 'v', 'a', 'r'): /* hint table, fallthrough */

    case HB_TAG ('c', 'v', 't', ' '): /* hint table, fallthrough */

    case HB_TAG ('f', 'p', 'g', 'm'): /* hint table, fallthrough */

    case HB_TAG ('p', 'r', 'e', 'p'): /* hint table, fallthrough */

    case HB_TAG ('h', 'd', 'm', 'x'): /* hint table, fallthrough */

    case HB_TAG ('V', 'D', 'M', 'X'): /* hint table, fallthrough */

      return plan->drop_hints;

    // Drop Layout Tables if requested.

    case HB_OT_TAG_GDEF:

    case HB_OT_TAG_GPOS:

    case HB_OT_TAG_GSUB:

      return plan->drop_layout;

    // Drop these tables below by default, list pulled

    // from fontTools:

    case HB_TAG ('B', 'A', 'S', 'E'):

    case HB_TAG ('J', 'S', 'T', 'F'):

    case HB_TAG ('D', 'S', 'I', 'G'):

    case HB_TAG ('E', 'B', 'D', 'T'):

    case HB_TAG ('E', 'B', 'L', 'C'):

    case HB_TAG ('E', 'B', 'S', 'C'):

    case HB_TAG ('S', 'V', 'G', ' '):

    case HB_TAG ('P', 'C', 'L', 'T'):

    case HB_TAG ('L', 'T', 'S', 'H'):

    // Graphite tables:

    case HB_TAG ('F', 'e', 'a', 't'):

    case HB_TAG ('G', 'l', 'a', 't'):

    case HB_TAG ('G', 'l', 'o', 'c'):

    case HB_TAG ('S', 'i', 'l', 'f'):

    case HB_TAG ('S', 'i', 'l', 'l'):

    // Colour

    case HB_TAG ('s', 'b', 'i', 'x'):

      return true;

    default:

      return false;

  }

}

/**

 * hb_subset:

 * @source: font face data to be subset.

 * @input: input to use for the subsetting.

 *

 * Subsets a font according to provided input.

 **/

hb_face_t *

hb_subset (hb_face_t *source,

           hb_subset_input_t *input)

{

  if (unlikely (!input || !source)) return hb_face_get_empty ();

  hb_subset_plan_t *plan = hb_subset_plan_create (source, input);

  hb_tag_t table_tags[32];

  unsigned int offset = 0, count;

  bool success = true;

  do {

    count = ARRAY_LENGTH (table_tags);

    hb_face_get_table_tags (source, offset, &count, table_tags);

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

    {

      hb_tag_t tag = table_tags[i];

      if (_should_drop_table (plan, tag))

      {

        DEBUG_MSG(SUBSET, nullptr, "drop %c%c%c%c", HB_UNTAG (tag));

        continue;

      }

      success = success && _subset_table (plan, tag);

    }

    offset += count;

  } while (success && count == ARRAY_LENGTH (table_tags));

  hb_face_t *result = success ? hb_face_reference (plan->dest) : hb_face_get_empty ();

  hb_subset_plan_destroy (plan);

  return result;

}