/*

 * Copyright © 2018  Ebrahim Byagowi

 * 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): Behdad Esfahbod

 */

#ifndef HB_AAT_LAYOUT_TRAK_TABLE_HH

#define HB_AAT_LAYOUT_TRAK_TABLE_HH

#include "hb-aat-layout-common.hh"

#include "hb-ot-layout.hh"

#include "hb-open-type.hh"

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

/*

 * trak -- Tracking

 * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6trak.html

 */

#define HB_AAT_TAG_trak HB_TAG('t','r','a','k')

namespace AAT {

struct TrackTableEntry

{

  friend struct TrackData;

  float get_track_value () const { return track.to_float (); }

  float interpolate_at (unsigned int idx,

      float ptem,

      const void *base,

      hb_array_t<const F16DOT16> size_table) const

  {

    const FWORD *values = (base+valuesZ).arrayZ;

    float s0 = size_table[idx].to_float ();

    float s1 = size_table[idx + 1].to_float ();

    int v0 = values[idx];

    int v1 = values[idx + 1];

    // Deal with font bugs.

    if (unlikely (s1 < s0))

    { hb_swap (s0, s1); hb_swap (v0, v1); }

    if (unlikely (ptem < s0)) return v0;

    if (unlikely (ptem > s1)) return v1;

    if (unlikely (s0 == s1)) return (v0 + v1) * 0.5f;

    float t = (ptem - s0) / (s1 - s0);

    return v0 + t * (v1 - v0);

  }

  float get_value (float ptem,

       const void *base,

       hb_array_t<const F16DOT16> size_table) const

  {

    const FWORD *values = (base+valuesZ).arrayZ;

    unsigned int n_sizes = size_table.length;

    /*

     * Choose size.

     */

    if (!n_sizes) return 0.f;

    if (n_sizes == 1) return values[0];

    // At least two entries.

    unsigned i;

    for (i = 0; i < n_sizes; i++)

      if (size_table[i].to_float () >= ptem)

  break;

    // Boundary conditions.

    if (i == 0)       return values[0];

    if (i == n_sizes) return values[n_sizes - 1];

    // Exact match.

    if (size_table[i].to_float () == ptem) return values[i];

    // Interpolate.

    return interpolate_at (i - 1, ptem, base, size_table);

  }

  public:

  bool sanitize (hb_sanitize_context_t *c,

     const void *base,

     unsigned int n_sizes) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        (valuesZ.sanitize (c, base, n_sizes))));

  }

  protected:

  F16DOT16  track;    /* Track value for this record. */

  OT::NameID  trackNameID;  /* The 'name' table index for this track.

         * (a short word or phrase like "loose"

         * or "very tight") */

  NNOffset16To<UnsizedArrayOf<FWORD>>

    valuesZ;  /* Offset from start of tracking table to

         * per-size tracking values for this track. */

  public:

  DEFINE_SIZE_STATIC (8);

};

struct TrackData

{

  float get_tracking (const void *base, float ptem, float track = 0.f) const

  {

    unsigned count = nTracks;

    hb_array_t<const F16DOT16> size_table = (base+sizeTable).as_array (nSizes);

    if (!count) return 0.f;

    if (count == 1) return trackTable[0].get_value (ptem, base, size_table);

    // At least two entries.

    unsigned i = 0;

    unsigned j = count - 1;

    // Find the two entries that track is between.

    while (i + 1 < count && trackTable[i + 1].get_track_value () <= track)

      i++;

    while (j > 0 && trackTable[j - 1].get_track_value () >= track)

      j--;

    // Exact match.

    if (i == j) return trackTable[i].get_value (ptem, base, size_table);

    // Interpolate.

    float t0 = trackTable[i].get_track_value ();

    float t1 = trackTable[j].get_track_value ();

    float t = (track - t0) / (t1 - t0);

    float a = trackTable[i].get_value (ptem, base, size_table);

    float b = trackTable[j].get_value (ptem, base, size_table);

    return a + t * (b - a);

  }

  bool sanitize (hb_sanitize_context_t *c, const void *base) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        hb_barrier () &&

        sizeTable.sanitize (c, base, nSizes) &&

        trackTable.sanitize (c, nTracks, base, nSizes)));

  }

  protected:

  HBUINT16  nTracks;  /* Number of separate tracks included in this table. */

  HBUINT16  nSizes;   /* Number of point sizes included in this table. */

  NNOffset32To<UnsizedArrayOf<F16DOT16>>

    sizeTable;  /* Offset from start of the tracking table to

         * Array[nSizes] of size values.. */

  UnsizedArrayOf<TrackTableEntry>

    trackTable; /* Array[nTracks] of TrackTableEntry records. */

  public:

  DEFINE_SIZE_ARRAY (8, trackTable);

};

struct trak

{

  static constexpr hb_tag_t tableTag = HB_AAT_TAG_trak;

  bool has_data () const { return version.to_int (); }

  hb_position_t get_h_tracking (hb_font_t *font, float track = 0.f) const

  {

    float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;

    return font->em_scalef_x ((this+horizData).get_tracking (this, ptem, track));

  }

  hb_position_t get_v_tracking (hb_font_t *font, float track = 0.f) const

  {

    float ptem = font->ptem > 0.f ? font->ptem : HB_CORETEXT_DEFAULT_FONT_SIZE;

    return font->em_scalef_y ((this+vertData).get_tracking (this, ptem, track));

  }

  hb_position_t get_tracking (hb_font_t *font, hb_direction_t dir, float track = 0.f) const

  {

#ifndef HB_NO_STYLE

    if (!font->face->table.STAT->has_data ())

      return 0;

    return HB_DIRECTION_IS_HORIZONTAL (dir) ?

      get_h_tracking (font, track) :

      get_v_tracking (font, track);

#else

    return 0;

#endif

  }

  bool apply (hb_aat_apply_context_t *c, float track = 0.f) const

  {

    TRACE_APPLY (this);

    float ptem = c->font->ptem;

    if (unlikely (ptem <= 0.f))

    {

      /* https://developer.apple.com/documentation/coretext/1508745-ctfontcreatewithgraphicsfont */

      ptem = HB_CORETEXT_DEFAULT_FONT_SIZE;

    }

    hb_buffer_t *buffer = c->buffer;

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

    {

      hb_position_t advance_to_add = get_h_tracking (c->font, track);

      foreach_grapheme (buffer, start, end)

  buffer->pos[start].x_advance += advance_to_add;

    }

    else

    {

      hb_position_t advance_to_add = get_v_tracking (c->font, track);

      foreach_grapheme (buffer, start, end)

  buffer->pos[start].y_advance += advance_to_add;

    }

    return_trace (true);

  }

  bool sanitize (hb_sanitize_context_t *c) const

  {

    TRACE_SANITIZE (this);

    return_trace (likely (c->check_struct (this) &&

        hb_barrier () &&

        version.major == 1 &&

        horizData.sanitize (c, this, this) &&

        vertData.sanitize (c, this, this)));

  }

  protected:

  FixedVersion<>version;  /* Version of the tracking table

         * (0x00010000u for version 1.0). */

  HBUINT16  format;   /* Format of the tracking table (set to 0). */

  Offset16To<TrackData>

    horizData;  /* Offset from start of tracking table to TrackData

         * for horizontal text (or 0 if none). */

  Offset16To<TrackData>

    vertData; /* Offset from start of tracking table to TrackData

         * for vertical text (or 0 if none). */

  HBUINT16  reserved; /* Reserved. Set to 0. */

  public:

  DEFINE_SIZE_STATIC (12);

};

} /* namespace AAT */

#endif /* HB_AAT_LAYOUT_TRAK_TABLE_HH */