#include <SFML/Graphics.hpp>
#include <math.h>
using namespace sf;

int main()
{
  RenderWindow app(VideoMode(640, 480), "Car Racing Game!");
  app.setFramerateLimit(60);

  Texture t1, t2;
  t1.loadFromFile("/Users/alleyuan/code-snippets/16_games/07 Top Down Racing/images/background.png");
  t2.loadFromFile("/Users/alleyuan/code-snippets/16_games/07 Top Down Racing/images/car.png");

  Sprite sBackground(t1), sCar(t2);
  sCar.setPosition(300, 300);
  sCar.setOrigin(22,22);

  float x=300, y=300;
  float speed = 0, angle = 0; // initial speed/angle (angle=direciton from car center)
  float maxSpeed = 12.0;
  float acc = 0.2, dec = 0.3; // acceleration.deceleration
  float turnSpeed = 0.08; // angular velocity when turning

  int offsetX = 0, offsetY = 0;



  while (app.isOpen())
  {
    Event e;
    while (app.pollEvent(e))
    {
      if (e.type == Event::Closed)
        app.close();
    }

    // set directions
    bool Up = 0, Right = 0, Down = 0, Left = 0;
    if (Keyboard::isKeyPressed(Keyboard::Up)) Up = 1;
    if (Keyboard::isKeyPressed(Keyboard::Right)) Right = 1;
    if (Keyboard::isKeyPressed(Keyboard::Down)) Down = 1;
    if (Keyboard::isKeyPressed(Keyboard::Left)) Left = 1;

    // CAR MOVEMENT
    // positive speed
    if (Up && speed < maxSpeed)
    {
      if (speed < 0) speed += dec;
      else speed += acc;
    }

    // negative speed
    if (Down && speed > -maxSpeed)
    {
      if (speed > 0) speed -= dec;
      else speed -= acc;
    }

    // friction
    if (!Up && !Down)
    {
      if (speed - dec > 0) speed -= dec;
      else if (speed + dec < 0) speed += dec;
      else speed = 0;
    }

    // angle
    if (Right && speed != 0) angle += turnSpeed * speed/maxSpeed;
    if (Left && speed != 0) angle -= turnSpeed * speed/maxSpeed;

    // set new position and orientation
    x += sin(angle) * speed;
    y -= cos(angle) * speed;

    if (x > 320) offsetX = x - 320;
    if (y > 240) offsetY = y - 240;

    app.clear(Color::White);
    sBackground.setPosition(-offsetX, -offsetY); // follow the car w/ the camera
    app.draw(sBackground);

    sCar.setPosition(x - offsetX, y - offsetY);
    sCar.setRotation(angle*180/3.141592);

    sCar.setColor(Color::Red);
    app.draw(sCar);

    app.display();
  }

  return 0;
}