// Copyright (c) 2022 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "UICanvas.hpp"
#include "game/DawnGame.hpp"
#include "UIComponent.hpp"

using namespace Dawn;

std::shared_ptr<UICanvas> UICanvas::create(Scene *scene) {
  auto item = scene->createSceneItem();
  return item->addComponent<UICanvas>();
}

UICanvas::UICanvas(std::weak_ptr<SceneItem> item) :
  SceneItemComponent(item),
  camera(nullptr)
{
}

void UICanvas::rebufferShaderParameters() {
  struct UICanvasShaderBufferData data;

  switch(this->drawType) {
    case UI_DRAW_TYPE_WORLD_ABSOLUTE:
      data.projection = camera->getProjection();
      data.view = camera->item.lock()->getWorldTransform();
      break;

    case UI_DRAW_TYPE_WORLD_CAMERA_RELATIVE:
      data.projection = glm::ortho(
        0.0f,
        camera->getRenderTarget()->getWidth() / this->getScale(),
        camera->getRenderTarget()->getHeight() / this->getScale(),
        0.0f
      );
      data.view = glm::mat4(1.0f);
      break;

    default:
      assertUnreachable("UICanvas::rebufferShaderParameters: Unknown draw type");
  }

  this->shaderBuffer.buffer(&data);
}

float_t UICanvas::getScale() {
  return this->camera->getRenderTarget()->getScale();
}

float_t UICanvas::getWidth() {
  return w;
}

float_t UICanvas::getHeight() {
  return h;
}

float_t UICanvas::getContentWidth() {
  return this->getWidth();
}

float_t UICanvas::getContentHeight() {
  return this->getHeight();
}

float_t UICanvas::getChildOffsetX() {
  return 0.0f;
}

float_t UICanvas::getChildOffsetY() {
  return 0.0f;
}

void UICanvas::onStart() {
  if(camera == nullptr) camera = getScene()->findComponent<Camera>();

  this->shaderBuffer.init();
  this->rebufferShaderParameters();

  useEffectWithTeardown([&]{
    if(camera == nullptr) return evtRenderResize = [&] {};
    this->w = camera->getRenderTarget()->getWidth() / this->getScale();
    this->h = camera->getRenderTarget()->getHeight() / this->getScale();
    this->rebufferShaderParameters();

    return evtRenderResize = useEvent([&](float_t w, float_t h){
      this->w = w / this->getScale();
      this->h = h / this->getScale();
      this->rebufferShaderParameters();
      
      auto comps = this->item.lock()->findChildren<UIComponent>();
      auto itComps = comps.begin();
      while(itComps != comps.end()) {
        (*itComps)->alignmentNeedsUpdating = true;
        ++itComps;
      }
    }, camera->eventRenderTargetResized);
  }, camera)();
}

void UICanvas::onDispose() {
}