// Copyright (c) 2023 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "assert/assert.hpp"
#include "RenderPipeline.hpp"
#include "game/Game.hpp"
#include "scene/Scene.hpp"
#include "component/display/Camera.hpp"
#include "component/display/IRenderableComponent.hpp"

using namespace Dawn;

RenderPipeline::RenderPipeline() {
  
}

void RenderPipeline::render(
  const std::shared_ptr<Game> game
) {
  assertNotNull(game, "Game cannot be null");
  
  auto scene = game->getCurrentScene();
  if(!scene) return;

  this->renderScene(game, scene);
}

void RenderPipeline::renderScene(
  const std::shared_ptr<Game> game,
  const std::shared_ptr<Scene> scene
) {
  assertNotNull(game, "Game cannot be null");
  assertNotNull(scene, "Scene cannot be null");

  // TODO: Render Subscenes First

  // Get a list of all cameras in the scene
  auto cameras = scene->findComponents<Camera>();
  auto backBuffer = scene->getGame()->renderHost.getBackBufferRenderTarget();

  std::shared_ptr<Camera> backbufferCamera = nullptr;
  for(auto camera : cameras) {
    auto rt = camera->getRenderTarget();
    // Is this camera the backbuffer camera?
    if(rt == backBuffer) {
      backbufferCamera = camera;
      continue;
    }

    // Render scene with this camera
    renderSceneCamera(game, scene, camera, rt);
  }

  if(backbufferCamera) {
    // Render the backbuffer camera
    renderSceneCamera(game, scene, backbufferCamera, backBuffer);
  }
}

void RenderPipeline::renderSceneCamera(
  const std::shared_ptr<Game> game,
  const std::shared_ptr<Scene> scene,
  const std::shared_ptr<Camera> camera,
  const std::shared_ptr<RenderTarget> renderTarget
) {
  assertNotNull(game, "Game cannot be null");
  assertNotNull(scene, "Scene cannot be null"); 
  assertNotNull(camera, "Camera cannot be null");
  assertNotNull(renderTarget, "RenderTarget cannot be null");

  struct RenderPassContext ctx = {
    game,
    scene,
    camera,
    renderTarget
  };

  // Get list of renderables
  std::vector<std::shared_ptr<IRenderPass>> renderPasses;
  auto renderables = scene->findComponents<IRenderableComponent>();
  for(auto renderable : renderables) {
    auto rp = renderable->getPasses(ctx);
    renderPasses.insert(renderPasses.end(), rp.begin(), rp.end());
  }

  auto rp = renderPasses[0];
  rp->bind();
  
  // TODO: Make clearing the buffers editable!
  renderTarget->bind();
  renderTarget->clear(
    RENDER_TARGET_CLEAR_COLOR |
    RENDER_TARGET_CLEAR_DEPTH
  );

  rp->bind();
  
  for(auto renderPass : renderPasses) {
    renderPass->bind();
    renderPass->setData();
    renderPass->upload();
    renderPass->draw();
  }
}

RenderPipeline::~RenderPipeline() {

}