/*

 * Copyright © 2022 Behdad Esfahbod

 *

 *  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.

 */

#ifndef HB_PAINT_EXTENTS_HH

#define HB_PAINT_EXTENTS_HH

#include "hb.hh"

#include "hb-paint.h"

typedef struct hb_extents_t

{

  hb_extents_t () {}

  hb_extents_t (float xmin, float ymin, float xmax, float ymax) :

    xmin (xmin), ymin (ymin), xmax (xmax), ymax (ymax) {}

  bool is_empty () const { return xmin >= xmax || ymin >= ymax; }

  bool is_void () const { return xmin > xmax; }

  void union_ (const hb_extents_t &o)

  {

    xmin = hb_min (xmin, o.xmin);

    ymin = hb_min (ymin, o.ymin);

    xmax = hb_max (xmax, o.xmax);

    ymax = hb_max (ymax, o.ymax);

  }

  void intersect (const hb_extents_t &o)

  {

    xmin = hb_max (xmin, o.xmin);

    ymin = hb_max (ymin, o.ymin);

    xmax = hb_min (xmax, o.xmax);

    ymax = hb_min (ymax, o.ymax);

  }

  void

  add_point (float x, float y)

  {

    if (unlikely (is_void ()))

    {

      xmin = xmax = x;

      ymin = ymax = y;

    }

    else

    {

      xmin = hb_min (xmin, x);

      ymin = hb_min (ymin, y);

      xmax = hb_max (xmax, x);

      ymax = hb_max (ymax, y);

    }

  }

  float xmin = 0.f;

  float ymin = 0.f;

  float xmax = -1.f;

  float ymax = -1.f;

} hb_extents_t;

typedef struct hb_transform_t

{

  hb_transform_t () {}

  hb_transform_t (float xx, float yx,

      float xy, float yy,

      float x0, float y0) :

    xx (xx), yx (yx), xy (xy), yy (yy), x0 (x0), y0 (y0) {}

  void multiply (const hb_transform_t &o)

  {

    /* Copied from cairo, with "o" being "a" there and "this" being "b" there. */

    hb_transform_t r;

    r.xx = o.xx * xx + o.yx * xy;

    r.yx = o.xx * yx + o.yx * yy;

    r.xy = o.xy * xx + o.yy * xy;

    r.yy = o.xy * yx + o.yy * yy;

    r.x0 = o.x0 * xx + o.y0 * xy + x0;

    r.y0 = o.x0 * yx + o.y0 * yy + y0;

    *this = r;

  }

  void transform_distance (float &dx, float &dy) const

  {

    float new_x = xx * dx + xy * dy;

    float new_y = yx * dx + yy * dy;

    dx = new_x;

    dy = new_y;

  }

  void transform_point (float &x, float &y) const

  {

    transform_distance (x, y);

    x += x0;

    y += y0;

  }

  void transform_extents (hb_extents_t &extents) const

  {

    float quad_x[4], quad_y[4];

    quad_x[0] = extents.xmin;

    quad_y[0] = extents.ymin;

    quad_x[1] = extents.xmin;

    quad_y[1] = extents.ymax;

    quad_x[2] = extents.xmax;

    quad_y[2] = extents.ymin;

    quad_x[3] = extents.xmax;

    quad_y[3] = extents.ymax;

    extents = hb_extents_t {};

    for (unsigned i = 0; i < 4; i++)

    {

      transform_point (quad_x[i], quad_y[i]);

      extents.add_point (quad_x[i], quad_y[i]);

    }

  }

  float xx = 1.f;

  float yx = 0.f;

  float xy = 0.f;

  float yy = 1.f;

  float x0 = 0.f;

  float y0 = 0.f;

} hb_transform_t;

typedef struct hb_bounds_t

{

  enum status_t {

    UNBOUNDED,

    BOUNDED,

    EMPTY,

  };

  hb_bounds_t (status_t status) : status (status) {}

  hb_bounds_t (const hb_extents_t &extents) :

    status (extents.is_empty () ? EMPTY : BOUNDED), extents (extents) {}

  void union_ (const hb_bounds_t &o)

  {

    if (o.status == UNBOUNDED)

      status = UNBOUNDED;

    else if (o.status == BOUNDED)

    {

      if (status == EMPTY)

  *this = o;

      else if (status == BOUNDED)

        extents.union_ (o.extents);

    }

  }

  void intersect (const hb_bounds_t &o)

  {

    if (o.status == EMPTY)

      status = EMPTY;

    else if (o.status == BOUNDED)

    {

      if (status == UNBOUNDED)

  *this = o;

      else if (status == BOUNDED)

      {

        extents.intersect (o.extents);

  if (extents.is_empty ())

    status = EMPTY;

      }

    }

  }

  status_t status;

  hb_extents_t extents;

} hb_bounds_t;

typedef struct  hb_paint_extents_context_t hb_paint_extents_context_t;

struct hb_paint_extents_context_t

{

  hb_paint_extents_context_t ()

  {

    transforms.push (hb_transform_t{});

    clips.push (hb_bounds_t{hb_bounds_t::UNBOUNDED});

    groups.push (hb_bounds_t{hb_bounds_t::EMPTY});

  }

  hb_extents_t get_extents ()

  {

    return groups.tail().extents;

  }

  bool is_bounded ()

  {

    return groups.tail().status != hb_bounds_t::UNBOUNDED;

  }

  void push_transform (const hb_transform_t &trans)

  {

    hb_transform_t t = transforms.tail ();

    t.multiply (trans);

    transforms.push (t);

  }

  void pop_transform ()

  {

    transforms.pop ();

  }

  void push_clip (hb_extents_t extents)

  {

    /* Transform extents and push a new clip. */

    const hb_transform_t &t = transforms.tail ();

    t.transform_extents (extents);

    clips.push (hb_bounds_t {extents});

  }

  void pop_clip ()

  {

    clips.pop ();

  }

  void push_group ()

  {

    groups.push (hb_bounds_t {hb_bounds_t::EMPTY});

  }

  void pop_group (hb_paint_composite_mode_t mode)

  {

    const hb_bounds_t src_bounds = groups.pop ();

    hb_bounds_t &backdrop_bounds = groups.tail ();

    // https://learn.microsoft.com/en-us/typography/opentype/spec/colr#format-32-paintcomposite

    switch ((int) mode)

    {

      case HB_PAINT_COMPOSITE_MODE_CLEAR:

  backdrop_bounds.status = hb_bounds_t::EMPTY;

  break;

      case HB_PAINT_COMPOSITE_MODE_SRC:

      case HB_PAINT_COMPOSITE_MODE_SRC_OUT:

  backdrop_bounds = src_bounds;

  break;

      case HB_PAINT_COMPOSITE_MODE_DEST:

      case HB_PAINT_COMPOSITE_MODE_DEST_OUT:

  break;

      case HB_PAINT_COMPOSITE_MODE_SRC_IN:

      case HB_PAINT_COMPOSITE_MODE_DEST_IN:

  backdrop_bounds.intersect (src_bounds);

  break;

      default:

  backdrop_bounds.union_ (src_bounds);

  break;

     }

  }

  void paint ()

  {

    const hb_bounds_t &clip = clips.tail ();

    hb_bounds_t &group = groups.tail ();

    group.union_ (clip);

  }

  protected:

  hb_vector_t<hb_transform_t> transforms;

  hb_vector_t<hb_bounds_t> clips;

  hb_vector_t<hb_bounds_t> groups;

};

HB_INTERNAL hb_paint_funcs_t *

hb_paint_extents_get_funcs ();

#endif /* HB_PAINT_EXTENTS_HH */