#include "renderer.h"

#include <glm/mat4x4.hpp>
#include <glm/trigonometric.hpp>
#include <glm/ext/matrix_clip_space.hpp>

namespace engine {

Renderer::Renderer(const char* app_name, const char* app_version,
                   SDL_Window* window, gfx::GraphicsSettings settings) {
  device_ =
      std::make_unique<GFXDevice>(app_name, app_version, window, settings);

  // sort out descriptor set layouts:
  std::vector<gfx::DescriptorSetLayoutBinding> globalSetBindings;
  {
    auto& binding0 = globalSetBindings.emplace_back();
    binding0.descriptor_type = gfx::DescriptorType::kUniformBuffer;
    binding0.stage_flags = gfx::ShaderStageFlags::kVertex;
  }
  global_uniform.layout = device_->CreateDescriptorSetLayout(globalSetBindings);
  global_uniform.set = device_->AllocateDescriptorSet(global_uniform.layout);
  global_uniform.uniform_buffer_data.data = glm::mat4{1.0f};
  global_uniform.uniform_buffer =
      device_->CreateUniformBuffer(sizeof(global_uniform.uniform_buffer_data),
                                   &global_uniform.uniform_buffer_data);
  device_->UpdateDescriptorUniformBuffer(
      global_uniform.set, 0, global_uniform.uniform_buffer, 0,
      sizeof(global_uniform.uniform_buffer_data));

  std::vector<gfx::DescriptorSetLayoutBinding> frameSetBindings;
  {
    auto& binding0 = frameSetBindings.emplace_back();
    binding0.descriptor_type = gfx::DescriptorType::kUniformBuffer;
    binding0.stage_flags = gfx::ShaderStageFlags::kVertex;
  }
  frame_uniform.layout = device_->CreateDescriptorSetLayout(frameSetBindings);
  frame_uniform.set = device_->AllocateDescriptorSet(frame_uniform.layout);
  frame_uniform.uniform_buffer_data.data = glm::mat4{1.0f};
  frame_uniform.uniform_buffer =
      device_->CreateUniformBuffer(sizeof(frame_uniform.uniform_buffer_data),
                                   &frame_uniform.uniform_buffer_data);
  device_->UpdateDescriptorUniformBuffer(
      frame_uniform.set, 0, frame_uniform.uniform_buffer, 0,
      sizeof(frame_uniform.uniform_buffer_data));

  std::vector<gfx::DescriptorSetLayoutBinding> materialSetBindings;
  {
    auto& binding0 = materialSetBindings.emplace_back();
    binding0.descriptor_type = gfx::DescriptorType::kCombinedImageSampler;
    binding0.stage_flags = gfx::ShaderStageFlags::kFragment;
  }
  material_set_layout = device_->CreateDescriptorSetLayout(materialSetBindings);
};

Renderer::~Renderer() {
  for (const auto& [info, sampler] : samplers) {
    device_->DestroySampler(sampler);
  }
  device_->DestroyDescriptorSetLayout(material_set_layout);

  device_->DestroyUniformBuffer(frame_uniform.uniform_buffer);
  device_->DestroyDescriptorSetLayout(frame_uniform.layout);

  device_->DestroyUniformBuffer(global_uniform.uniform_buffer);
  device_->DestroyDescriptorSetLayout(global_uniform.layout);
}

void Renderer::PreRender(bool window_is_resized, glm::mat4 camera_transform) {
  if (window_is_resized) {
    uint32_t w, h;
    device_->GetViewportSize(&w, &h);
    viewport_aspect_ratio_ = (float)w / (float)h;
    const glm::mat4 proj_matrix = glm::perspectiveZO(
        camera_settings_.vertical_fov_radians, viewport_aspect_ratio_,
        camera_settings_.clip_near, camera_settings_.clip_far);
    /* update SET 0 (rarely changing uniforms)*/
    global_uniform.uniform_buffer_data.data = proj_matrix;
    device_->WriteUniformBuffer(global_uniform.uniform_buffer, 0,
                                sizeof(global_uniform.uniform_buffer_data),
                                &global_uniform.uniform_buffer_data);
  }

  // set camera view matrix uniform
  /* update SET 1 (per frame uniforms) */
  const glm::mat4 view_matrix = glm::inverse(camera_transform);
  frame_uniform.uniform_buffer_data.data = view_matrix;
  device_->WriteUniformBuffer(frame_uniform.uniform_buffer, 0,
                              sizeof(frame_uniform.uniform_buffer_data),
                              &frame_uniform.uniform_buffer_data);
}

void Renderer::Render(const RenderList& static_list,
                      const RenderList& dynamic_list) {
  last_bound_pipeline_ = nullptr;

  gfx::DrawBuffer* draw_buffer = device_->BeginRender();

  if (!static_list.empty()) {
    DrawRenderList(draw_buffer, static_list);
  }
  if (!dynamic_list.empty()) {
    DrawRenderList(draw_buffer, dynamic_list);
  }

  device_->FinishRender(draw_buffer);
}

void Renderer::DrawRenderList(gfx::DrawBuffer* draw_buffer,
                              const RenderList& render_list) {
  // if a pipeline hasn't been bound yet at all
  if (last_bound_pipeline_ == nullptr) {
    const gfx::Pipeline* first_pipeline = render_list.begin()->pipeline;
    // these bindings persist between all pipelines
    device_->CmdBindDescriptorSet(draw_buffer, first_pipeline,
                                  global_uniform.set, 0);
    device_->CmdBindDescriptorSet(draw_buffer, first_pipeline,
                                  frame_uniform.set, 1);
    device_->CmdBindPipeline(draw_buffer, first_pipeline);
    last_bound_pipeline_ = first_pipeline;
  }

  for (const auto& entry : render_list) {
    if (entry.pipeline != last_bound_pipeline_) {
      device_->CmdBindPipeline(draw_buffer, entry.pipeline);
      last_bound_pipeline_ = entry.pipeline;
    }
    device_->CmdBindDescriptorSet(draw_buffer, entry.pipeline,
                                  entry.base_colour_texture, 2);
    device_->CmdPushConstants(draw_buffer, entry.pipeline, 0,
                              sizeof(entry.model_matrix), &entry.model_matrix);
    device_->CmdBindVertexBuffer(draw_buffer, 0, entry.vertex_buffer);
    device_->CmdBindIndexBuffer(draw_buffer, entry.index_buffer);
    device_->CmdDrawIndexed(draw_buffer, entry.index_count, 1, 0, 0, 0);
  }
}

}  // namespace engine