#ifndef OT_GLYF_PATH_BUILDER_HH

#define OT_GLYF_PATH_BUILDER_HH

#include "../../hb.hh"

namespace OT {

namespace glyf_impl {

struct path_builder_t

{

  hb_font_t *font;

  hb_draw_session_t *draw_session;

  struct optional_point_t

  {

    optional_point_t () {}

    optional_point_t (float x_, float y_) : has_data (true), x (x_), y (y_) {}

    operator bool () const { return has_data; }

    bool has_data = false;

    float x;

    float y;

    optional_point_t mid (optional_point_t p)

    { return optional_point_t ((x + p.x) * 0.5f, (y + p.y) * 0.5f); }

  } first_oncurve, first_offcurve, first_offcurve2, last_offcurve, last_offcurve2;

  path_builder_t (hb_font_t *font_, hb_draw_session_t &draw_session_) :

    font (font_), draw_session (&draw_session_) {}

  /* based on https://github.com/RazrFalcon/ttf-parser/blob/4f32821/src/glyf.rs#L287

     See also:

     * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM01/Chap1.html

     * https://stackoverflow.com/a/20772557

     *

     * Cubic support added. */

  HB_ALWAYS_INLINE

  void consume_point (const contour_point_t &point)

  {

    bool is_on_curve = point.flag & glyf_impl::SimpleGlyph::FLAG_ON_CURVE;

#ifdef HB_NO_CUBIC_GLYF

    constexpr bool is_cubic = false;

#else

    bool is_cubic = !is_on_curve && (point.flag & glyf_impl::SimpleGlyph::FLAG_CUBIC);

#endif

    optional_point_t p (font->em_fscalef_x (point.x), font->em_fscalef_y (point.y));

    if (unlikely (!first_oncurve))

    {

      if (is_on_curve)

      {

  first_oncurve = p;

  draw_session->move_to (p.x, p.y);

      }

      else

      {

  if (is_cubic && !first_offcurve2)

  {

    first_offcurve2 = first_offcurve;

    first_offcurve = p;

  }

  else if (first_offcurve)

  {

    optional_point_t mid = first_offcurve.mid (p);

    first_oncurve = mid;

    last_offcurve = p;

    draw_session->move_to (mid.x, mid.y);

  }

  else

    first_offcurve = p;

      }

    }

    else

    {

      if (last_offcurve)

      {

  if (is_on_curve)

  {

    if (last_offcurve2)

    {

      draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,

            last_offcurve.x, last_offcurve.y,

            p.x, p.y);

      last_offcurve2 = optional_point_t ();

    }

    else

      draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,

               p.x, p.y);

    last_offcurve = optional_point_t ();

  }

  else

  {

    if (is_cubic && !last_offcurve2)

    {

      last_offcurve2 = last_offcurve;

      last_offcurve = p;

    }

    else

    {

      optional_point_t mid = last_offcurve.mid (p);

      if (is_cubic)

      {

        draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,

              last_offcurve.x, last_offcurve.y,

              mid.x, mid.y);

        last_offcurve2 = optional_point_t ();

      }

      else

        draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,

           mid.x, mid.y);

      last_offcurve = p;

    }

  }

      }

      else

      {

  if (is_on_curve)

    draw_session->line_to (p.x, p.y);

  else

    last_offcurve = p;

      }

    }

  }

  void contour_end ()

  {

    if (first_offcurve && last_offcurve)

    {

      optional_point_t mid = last_offcurve.mid (first_offcurve2 ?

            first_offcurve2 :

            first_offcurve);

      if (last_offcurve2)

  draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,

        last_offcurve.x, last_offcurve.y,

        mid.x, mid.y);

      else

  draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,

           mid.x, mid.y);

      last_offcurve = optional_point_t ();

    }

    /* now check the rest */

    if (first_offcurve && first_oncurve)

    {

      if (first_offcurve2)

  draw_session->cubic_to (first_offcurve2.x, first_offcurve2.y,

        first_offcurve.x, first_offcurve.y,

        first_oncurve.x, first_oncurve.y);

      else

  draw_session->quadratic_to (first_offcurve.x, first_offcurve.y,

           first_oncurve.x, first_oncurve.y);

    }

    else if (last_offcurve && first_oncurve)

    {

      if (last_offcurve2)

  draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,

        last_offcurve.x, last_offcurve.y,

        first_oncurve.x, first_oncurve.y);

      else

  draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,

           first_oncurve.x, first_oncurve.y);

    }

    else if (first_oncurve)

      draw_session->line_to (first_oncurve.x, first_oncurve.y);

    else if (first_offcurve)

    {

      float x = first_offcurve.x, y = first_offcurve.y;

      draw_session->move_to (x, y);

      draw_session->quadratic_to (x, y, x, y);

    }

    /* Getting ready for the next contour */

    first_oncurve = first_offcurve = last_offcurve = last_offcurve2 = optional_point_t ();

    draw_session->close_path ();

  }

  void points_end () {}

  bool is_consuming_contour_points () { return true; }

  contour_point_t *get_phantoms_sink () { return nullptr; }

};

} /* namespace glyf_impl */

} /* namespace OT */

#endif /* OT_GLYF_PATH_BUILDER_HH */