/* SPDX-FileCopyrightText: 2022 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup draw
 *
 * \brief Simple API to draw debug shapes and log in the viewport.
 *
 * Both CPU and GPU implementation are supported and symmetrical (meaning GPU shader can use it
 * too, see common_draw_lib.glsl).
 *
 * NOTE: CPU logging will overlap GPU logging on screen as it is drawn after.
 */

#pragma once

#include "BLI_math_vector_types.hh"
#include "BLI_vector.hh"
#include "DNA_object_types.h"
#include "DRW_gpu_wrapper.hh"

namespace blender::draw {

/* Shortcuts to avoid boilerplate code and match shader API. */
#define drw_debug_line(...) DRW_debug_get()->draw_line(__VA_ARGS__)
#define drw_debug_polygon(...) DRW_debug_get()->draw_polygon(__VA_ARGS__)
#define drw_debug_bbox(...) DRW_debug_get()->draw_bbox(__VA_ARGS__)
#define drw_debug_sphere(...) DRW_debug_get()->draw_sphere(__VA_ARGS__)
#define drw_debug_point(...) DRW_debug_get()->draw_point(__VA_ARGS__)
#define drw_debug_matrix(...) DRW_debug_get()->draw_matrix(__VA_ARGS__)
#define drw_debug_matrix_as_bbox(...) DRW_debug_get()->draw_matrix_as_bbox(__VA_ARGS__)

class DebugDraw {
 private:
  using DebugDrawBuf = StorageBuffer<DRWDebugDrawBuffer>;

  /** Data buffers containing all verts or chars to draw. */
  DebugDrawBuf cpu_draw_buf_ = {"DebugDrawBuf-CPU"};
  DebugDrawBuf gpu_draw_buf_ = {"DebugDrawBuf-GPU"};
  /** True if the gpu buffer have been requested and may contain data to draw. */
  bool gpu_draw_buf_used = false;
  /** Matrix applied to all points before drawing. Could be a stack if needed. */
  float4x4 model_mat_;
  /** Precomputed shapes verts. */
  Vector<float3> sphere_verts_;
  Vector<float3> point_verts_;

 public:
  DebugDraw();
  ~DebugDraw(){};

  /**
   * Resets all buffers and reset model matrix state.
   * Not to be called by user.
   */
  void init();

  /**
   * Resets model matrix state to identity.
   */
  void modelmat_reset();
  /**
   * Sets model matrix transform to apply to any vertex passed to drawing functions.
   */
  void modelmat_set(const float modelmat[4][4]);

  /**
   * Drawing functions that will draw wire-frames with the given color.
   */
  void draw_line(float3 v1, float3 v2, float4 color = {1, 0, 0, 1});
  void draw_polygon(Span<float3> face_verts, float4 color = {1, 0, 0, 1});
  void draw_bbox(const BoundBox &bbox, const float4 color = {1, 0, 0, 1});
  void draw_sphere(const float3 center, float radius, const float4 color = {1, 0, 0, 1});
  void draw_point(const float3 center, float radius = 0.01f, const float4 color = {1, 0, 0, 1});
  /**
   * Draw a matrix transformation as 3 colored axes.
   */
  void draw_matrix(const float4x4 &m4);
  /**
   * Draw a matrix as a 2 units length bounding box, centered on origin.
   */
  void draw_matrix_as_bbox(const float4x4 &mat, const float4 color = {1, 0, 0, 1});

  /**
   * Will draw all debug shapes and text cached up until now to the current view / frame-buffer.
   * Draw buffers will be emptied and ready for new debug data.
   */
  void display_to_view();

  /**
   * Not to be called by user. Should become private.
   */
  GPUStorageBuf *gpu_draw_buf_get();

 private:
  uint color_pack(float4 color);
  DRWDebugVert vert_pack(float3 pos, uint color);

  void draw_line(float3 v1, float3 v2, uint color);

  void display_lines();
};

}  // namespace blender::draw

/**
 * Ease of use function to get the debug module.
 * TODO(fclem): Should be removed once DRWManager is no longer global.
 * IMPORTANT: Can return nullptr if storage buffer is not supported.
 */
blender::draw::DebugDraw *DRW_debug_get();