import java.awt.Graphics;
import java.awt.Color;


/**Defines a circular ball(implements interface circle) that has a name, color, mass, velocity, radius, x, and y coordinates.*/
public class Ball extends MoveableObject implements Circle
{
  private double x_location;
  private double y_location;
  private double radius;
  private boolean willCollideWithWallThisTimeStep = false;
  private boolean willCollideWithBallThisTimeStep = false;
  private Ball collidingBallObject;
  private StationaryObject collidingStationaryObject;
  private MyMathOperations operation; 
  
  public Ball() //default constructor 
  {
    super();
    x_location = 0;
    y_location = 0;
    radius = 0;
    operation = new MyMathOperations();
  }
  /**Creates a ball. The coordinates are at the center of the circular ball.
   * @param (name, color, mass, velocity)
   * @param x  x-coordinate
   * @param y  y-coordinate*/
  
  public Ball(String name, Color color, double mass, double xVelocity, double yVelocity, double x, double y, double r)
  {
    super(name, color, mass, xVelocity, yVelocity);
    setCoordinates(x, y, radius);
  }
  
  public void setCoordinates(double newX_location, double newY_location, double newRadius)
  {
    x_location = (newX_location);
    y_location = (newY_location);
    radius = newRadius;
  }
  
  
  public void setCoordinates(double newX_location, double newY_location)
  {
   x_location = (newX_location);
   y_location = (newY_location);
  }
  
  public void setRadius(double newRadius)
  {
   radius = newRadius;
  }
  
  public double getXCoordinate()
  {
    return x_location;
  }
  public double getYCoordinate()
  {
    return y_location;
  }
  public double getRadius()
  {
    return radius;
  }
  
  
  public void updatePosition(double dt)//velocity must be constant
  {
    //dt = operation.truncate(dt);
    //x_location = operation.truncate(x_location + (super.getXVelocity())*dt);
    x_location = (x_location + (super.getXVelocity())*dt);
    //y_location = operation.truncate(y_location + (super.getYVelocity())*dt);
    y_location = (y_location + (super.getYVelocity())*dt);
  }
  
  public double timeToCollision(Ball that)
  {
    if (this == that) return 1.0/0.0;
    double dx = that.getXCoordinate() - this.getXCoordinate(), dy = that.getYCoordinate() - this.getYCoordinate();
    double dvx = that.getXVelocity() - this.getXVelocity();
    double dvy = that.getYVelocity() - this.getYVelocity();
    double dvdr = dx*dvx + dy*dvy;
    if(dvdr >= 0) return 1.0/0.0;
    double dvdv = dvx*dvx + dvy*dvy;
    if(dvdv == 0) return 1.0/0.0;
    double drdr = dx*dx + dy*dy;
    double sigma = this.getRadius() + that.getRadius();
    double d = (dvdr*dvdr) - dvdv * (drdr - sigma*sigma);
    if (d < 0) return 1.0/0.0;
    return -(dvdr + Math.sqrt(d)) / dvdv;
  }
  
  public void bounce(Ball that) 
  {
    //double energy = (0.5*(this.getMass()*(Math.pow(this.getXVelocity(), 2) + Math.pow(this.getYVelocity(), 2)) 
                              //+ that.getMass()*(Math.pow(that.getXVelocity(), 2) + Math.pow(that.getYVelocity(), 2))));
      //System.out.println("Energy = " + energy);
  double dx = that.getXCoordinate() - this.getXCoordinate(), dy = that.getYCoordinate() - this.getYCoordinate();
  double dvx = that.getXVelocity() - this.getXVelocity();
  double dvy = that.getYVelocity() - this.getYVelocity();
  double dvdr = dx*dvx + dy*dvy;
  double dist = this.getRadius() + that.getRadius();
  double J = (2 * this.getMass() * that.getMass() * dvdr) / ((this.getMass() + that.getMass()) * dist);
  //double J = (2 * this.getMass() * dvdr) / (((this.getMass()/that.getMass()) + 1.0) * dist);
  double Jx = (J * dx) / dist;
  double Jy = (J * dy) / dist;
  //this.setVelocity(operation.truncate(this.getXVelocity() + (Jx / (this.getMass()))), operation.truncate(this.getYVelocity() + (Jy / (this.getMass()))));
  this.setVelocity((this.getXVelocity() + (Jx / (this.getMass()))), (this.getYVelocity() + (Jy / (this.getMass()))));
  //that.setVelocity(operation.truncate(that.getXVelocity() - (Jx / (that.getMass()))), operation.truncate(that.getYVelocity() - (Jy / (that.getMass()))));
  that.setVelocity((that.getXVelocity() - (Jx / (that.getMass()))), (that.getYVelocity() - (Jy / (that.getMass()))));
   //energy = (0.5*(this.getMass()*(Math.pow(this.getXVelocity(), 2) + Math.pow(this.getYVelocity(), 2)) 
                              //+ that.getMass()*(Math.pow(that.getXVelocity(), 2) + Math.pow(that.getYVelocity(), 2))));
    //System.out.println("energy after = " + energy);
}
  public double ballEnergy()
  {
    double energy = (0.5*(this.getMass()*(Math.pow(this.getXVelocity(), 2)))) + (0.5*(this.getMass()*(Math.pow(this.getYVelocity(), 2))));
    return energy;
  }
  
  
  public void bounce(StationaryObject that)
  {
    double u1x = this.getXVelocity();
    double u1y = this.getYVelocity();
    double m1 = this.getMass();
    double m2 = that.getMass();
    double u2x = that.getXVelocity();
    double u2y = that.getYVelocity();

    double v1x = (u1x*(m1 - m2) + 2*m2*u2x) / (m1 + m2);
    double v2x = (u2x*(m2 - m1) + 2*m1*u1x) / (m1 + m2);

    double v1y = (u1y*(m1 - m2) + 2*m2*u2y) / (m1 + m2);
    double v2y = (u2y*(m1 - m2) + 2*m2*u1y) / (m1 + m2);

    this.setVelocity(v1x, v1y);
    //System.out.println(v1x + ", " + v1y);
    //there is no set method for the stationary object because the stationary object does not change velocity. 
  }
  
  public void setWillCollideWithWallThisTimeStep(boolean expression)
  {
   willCollideWithWallThisTimeStep = expression;
  }
  
  public boolean getCollisionWallAnswer()
  {
    return willCollideWithWallThisTimeStep;
  }
  
  public void setWillCollideWithBallThisTimeStep(boolean expression)
  {
   willCollideWithBallThisTimeStep = expression;
  }
  
  public boolean getCollisionBallAnswer()
  {
    return willCollideWithBallThisTimeStep;
  }
  
  public void setCollidingBallObject(Ball that)
  {
    collidingBallObject = that;
  }
  
  public void setCollidingStationaryObject(StationaryObject that)
  {
    collidingStationaryObject = that;
  }
  
  public Ball getCollidingBallObject()
  {
    return collidingBallObject;
  }
  
  public StationaryObject getCollidingStationaryObject()
  {
    return collidingStationaryObject;
  }
  
  
  
    
  
  /**Draws the ball onto the canvas at x coordinate - radius, and y coordinate - radius. 
   * The coordinates defined the center of the circle, but the Graphics paint method inscribes the circle in a square,
   * and defines the upper left corner as the coordinates.*/
  public void draw(Graphics canvas)
  {
      canvas.setColor(super.getColor());
      //System.out.println("I'm in Ball.draw" + x_location + "\t" + y_location + (getColor()).toString());
      canvas.fillOval(((int)x_location) - (int)radius, ((int)y_location) - (int)radius, 2*(int)radius, 2*(int)radius);
  }
    
 }