/* SPDX-License-Identifier: GPL-2.0-or-later */

#include "BKE_spline.hh"

#include "node_geometry_util.hh"

namespace blender::nodes::node_geo_curve_primitive_star_cc {

static void node_declare(NodeDeclarationBuilder &b)
{
  b.add_input<decl::Int>(N_("Points"))
      .default_value(8)
      .min(3)
      .max(256)
      .subtype(PROP_UNSIGNED)
      .description(N_("Number of points on each of the circles"));
  b.add_input<decl::Float>(N_("Inner Radius"))
      .default_value(1.0f)
      .min(0.0f)
      .subtype(PROP_DISTANCE)
      .description(N_("Radius of the inner circle; can be larger than outer radius"));
  b.add_input<decl::Float>(N_("Outer Radius"))
      .default_value(2.0f)
      .min(0.0f)
      .subtype(PROP_DISTANCE)
      .description(N_("Radius of the outer circle; can be smaller than inner radius"));
  b.add_input<decl::Float>(N_("Twist"))
      .subtype(PROP_ANGLE)
      .description(N_("The counterclockwise rotation of the inner set of points"));
  b.add_output<decl::Geometry>(N_("Curve"));
  b.add_output<decl::Bool>(N_("Outer Points"))
      .field_source()
      .description(N_("An attribute field with a selection of the outer points"));
}

static std::unique_ptr<CurveEval> create_star_curve(const float inner_radius,
                                                    const float outer_radius,
                                                    const float twist,
                                                    const int points)
{
  std::unique_ptr<CurveEval> curve = std::make_unique<CurveEval>();
  std::unique_ptr<PolySpline> spline = std::make_unique<PolySpline>();
  spline->set_cyclic(true);

  spline->resize(points * 2);
  MutableSpan<float3> positions = spline->positions();
  spline->radii().fill(1.0f);
  spline->tilts().fill(0.0f);

  const float theta_step = (2.0f * M_PI) / float(points);
  for (const int i : IndexRange(points)) {
    const float x = outer_radius * cos(theta_step * i);
    const float y = outer_radius * sin(theta_step * i);
    positions[i * 2] = {x, y, 0.0f};

    const float inner_x = inner_radius * cos(theta_step * i + theta_step * 0.5f + twist);
    const float inner_y = inner_radius * sin(theta_step * i + theta_step * 0.5f + twist);
    positions[i * 2 + 1] = {inner_x, inner_y, 0.0f};
  }

  curve->add_spline(std::move(spline));
  curve->attributes.reallocate(curve->splines().size());

  return curve;
}

static void create_selection_output(CurveComponent &component,
                                    StrongAnonymousAttributeID &r_attribute)
{
  OutputAttribute_Typed<bool> attribute = component.attribute_try_get_for_output_only<bool>(
      r_attribute.get(), ATTR_DOMAIN_POINT);
  MutableSpan<bool> selection = attribute.as_span();
  for (int i : selection.index_range()) {
    selection[i] = i % 2 == 0;
  }
  attribute.save();
}

static void node_geo_exec(GeoNodeExecParams params)
{
  std::unique_ptr<CurveEval> curve = create_star_curve(
      std::max(params.extract_input<float>("Inner Radius"), 0.0f),
      std::max(params.extract_input<float>("Outer Radius"), 0.0f),
      params.extract_input<float>("Twist"),
      std::max(params.extract_input<int>("Points"), 3));
  GeometrySet output = GeometrySet::create_with_curve(curve.release());

  if (params.output_is_required("Outer Points")) {
    StrongAnonymousAttributeID attribute_output("Outer Points");
    create_selection_output(output.get_component_for_write<CurveComponent>(), attribute_output);
    params.set_output("Outer Points",
                      AnonymousAttributeFieldInput::Create<bool>(
                          std::move(attribute_output), params.attribute_producer_name()));
  }
  params.set_output("Curve", std::move(output));
}
}  // namespace blender::nodes::node_geo_curve_primitive_star_cc

void register_node_type_geo_curve_primitive_star()
{
  namespace file_ns = blender::nodes::node_geo_curve_primitive_star_cc;

  static bNodeType ntype;
  geo_node_type_base(&ntype, GEO_NODE_CURVE_PRIMITIVE_STAR, "Star", NODE_CLASS_GEOMETRY);
  ntype.declare = file_ns::node_declare;
  ntype.geometry_node_execute = file_ns::node_geo_exec;
  nodeRegisterType(&ntype);
}