/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup overlay
 */

#pragma once

#include "DNA_world_types.h"

#include "draw_cache.hh"

#include "overlay_base.hh"

namespace blender::draw::overlay {

/**
 * Draw background color .
 */
class Background : Overlay {
 private:
  PassSimple bg_ps_ = {"Background"};

  GPUFrameBuffer *framebuffer_ref_ = nullptr;

 public:
  void begin_sync(Resources &res, const State &state) final
  {
    DRWState pass_state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_BACKGROUND;
    float4 color_override(0.0f, 0.0f, 0.0f, 0.0f);
    int background_type;

    if (state.is_viewport_image_render && !state.draw_background) {
      background_type = BG_SOLID;
      color_override[3] = 1.0f;
    }
    else if (state.is_space_image()) {
      background_type = BG_SOLID_CHECKER;
    }
    else if (state.is_space_node()) {
      background_type = BG_MASK;
      pass_state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_MUL;
    }
    else if (!state.draw_background) {
      background_type = BG_CHECKER;
    }
    else if (state.v3d->shading.background_type == V3D_SHADING_BACKGROUND_WORLD &&
             state.scene->world)
    {
      background_type = BG_SOLID;
      /* TODO(fclem): this is a scene referred linear color. we should convert
       * it to display linear here. */
      color_override = float4(UNPACK3(&state.scene->world->horr), 1.0f);
    }
    else if (state.v3d->shading.background_type == V3D_SHADING_BACKGROUND_VIEWPORT &&
             state.v3d->shading.type <= OB_SOLID)
    {
      background_type = BG_SOLID;
      color_override = float4(UNPACK3(state.v3d->shading.background_color), 1.0f);
    }
    else {
      switch (UI_GetThemeValue(TH_BACKGROUND_TYPE)) {
        case TH_BACKGROUND_GRADIENT_LINEAR:
          background_type = BG_GRADIENT;
          break;
        case TH_BACKGROUND_GRADIENT_RADIAL:
          background_type = BG_RADIAL;
          break;
        default:
        case TH_BACKGROUND_SINGLE_COLOR:
          background_type = BG_SOLID;
          break;
      }
    }

    bg_ps_.init();
    bg_ps_.framebuffer_set(&framebuffer_ref_);

    if ((state.clipping_plane_count != 0) && (state.rv3d) && (state.rv3d->clipbb)) {
      Span<float3> bbox(reinterpret_cast<float3 *>(state.rv3d->clipbb->vec[0]), 8);

      bg_ps_.state_set(DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ALPHA | DRW_STATE_CULL_BACK);
      bg_ps_.shader_set(res.shaders->background_clip_bound.get());
      bg_ps_.push_constant("ucolor", res.theme.colors.clipping_border);
      bg_ps_.push_constant("boundbox", bbox.data(), 8);
      bg_ps_.draw(res.shapes.cube_solid.get());
    }

    bg_ps_.state_set(pass_state);
    bg_ps_.shader_set(res.shaders->background_fill.get());
    bg_ps_.bind_ubo(OVERLAY_GLOBALS_SLOT, &res.globals_buf);
    bg_ps_.bind_ubo(DRW_CLIPPING_UBO_SLOT, &res.clip_planes_buf);
    bg_ps_.bind_texture("color_buffer", &res.color_render_tx);
    bg_ps_.bind_texture("depth_buffer", &res.depth_tx);
    bg_ps_.push_constant("color_override", color_override);
    bg_ps_.push_constant("bg_type", background_type);
    bg_ps_.draw_procedural(GPU_PRIM_TRIS, 1, 3);
  }

  void draw_output(Framebuffer &framebuffer, Manager &manager, View &view) final
  {
    framebuffer_ref_ = framebuffer;
    manager.submit(bg_ps_, view);
  }
};

}  // namespace blender::draw::overlay
