#include "RayTracer.h"
#include "HitRecord.h"
#include "Output.h"
#include "Parser.h"
#include "Progress.h"
#include "Ray.h"

#include <Eigen/Core>
#include <cmath>
#include <iostream>
#include <queue>

using std::priority_queue;

void RayTracer::parse() {
  for (auto i = json["output"].begin(); i != json["output"].end(); ++i)
    scenes.push_back(Parser::getScene(*i));

  for (auto i = json["geometry"].begin(); i != json["geometry"].end(); ++i)
    geometries.push_back(Parser::getGeometry(*i));

  for (auto i = json["light"].begin(); i != json["light"].end(); ++i)
    lights.push_back(Parser::getLight(*i));
}

Ray getRay(int x, int y, const Vector3f &camPos, const Vector3f &pxUpperLeft,
           const Vector3f &du, const Vector3f &dv) {
  return Ray(camPos, pxUpperLeft + x * du + y * dv - camPos);
}

void RayTracer::calculateColor(const HitRecord &hit, int i) {
  Vector3f result(0, 0, 0);
  for (auto light : lights)
    result += light->isUse() ? light->illumination(hit, geometries)
                             : Vector3f::Zero();

  result = result.cwiseMax(0.0f).cwiseMin(1.0f);
  Output::current->r(i, result.x());
  Output::current->g(i, result.y());
  Output::current->b(i, result.z());
}

void RayTracer::render() {
  int width = Scene::current->width();
  int height = Scene::current->height();
  Vector3f cameraPos = Scene::current->center();
  Vector3f lookAt = Scene::current->lookAt();
  float vpHeight =
      2 * tan(Scene::current->fov() / 180 * M_PI / 2) * lookAt.norm();
  float vpWidth = vpHeight * width / height;
  Vector3f u = Vector3f(vpWidth, 0, 0);
  Vector3f v = Vector3f(0, -vpHeight, 0);
  Vector3f du = u / width;
  Vector3f dv = v / height;

  Vector3f vpUpperLeft = cameraPos + lookAt - u / 2.0 - v / 2.0;
  Vector3f pxUpperLeft = vpUpperLeft + (du + dv) / 2.0;

  Output::current = new Output(Scene::current->backgroundColor(),
                               Scene::current->name(), width, height);

  int gridWidth = 1, gridHeight = 1, rpp = 1;
  Eigen::VectorXi raysPerPixel = Scene::current->raysPerPixel();

  if (raysPerPixel.size() == 2) {
    gridWidth = gridHeight = raysPerPixel.x();
    rpp = raysPerPixel.y();
  } else if (raysPerPixel.size() == 3) {
    gridWidth = raysPerPixel.x();
    gridHeight = raysPerPixel.y();
    rpp = raysPerPixel.z();
  }

  for (int y = 0; y < height; ++y) {
    utils::Progress::of((y + 1.0f) / height);
    for (int x = 0; x < width; ++x)
      for (int j = 0; j < gridHeight; ++j)
        for (int i = 0; i < gridWidth; ++i) {
          Ray ray = getRay(x, y, cameraPos, pxUpperLeft, du, dv);
          priority_queue<HitRecord> records;
          for (auto g : geometries) {
            Optional<float> t = g->intersect(ray);
            if (t.hasValue())
              records.push(HitRecord(t.value(), ray, g));
          }

          if (!records.empty()) {
            HitRecord hit = records.top();
            hit.calcNormal();
            calculateColor(hit, y * width + x);
          }
        }
  }

  std::cout << std::endl;
}

void RayTracer::run() {
  parse();

  for (auto scene : scenes) {
    Scene::current = scene;
    render();
    Output::current->write();
  }
}