import java.awt.*;
import java.util.*;

/**
 * A small ball object that wanders randomly around a bounded area.
 *
 * CSE143 lecture demo  Au01, Sp03, Sp04
 * 
 * @author Hal Perkins 
 * @version 10/18/01, 4/16/03, 4/12/04, 1/21/05
 */
public class Ball implements SimThing {
  // instance variables
  private int x, y;           // current coordinates of this Ball
  private int dx, dy;         // current motion direction in x and y
                              //    (sign gives direction, magnitude
                              //    gives speed)
  private Color color;        // color of this ball
  private int diameter;       // size of this ball
  private int maxx, maxy;     // max x and y coordiantes
  
  
  /**
   * Construct a new Ball with the given coordinates, initial direction, and model.
   * @param x initial x coordinate of center of the ball
   * @param y initial y coordinate of center of the ball
   * @param dx initial change in x value on each simulation cycle
   * @param dy initial change in y value on each simulation cycle
   * @param c color of the ball
   * @param diameter diameter of the ball
   * @param model the model that this Ball is a part of
   */
  public Ball(int x, int y, int dx, int dy, 
              Color c, int diameter, SimModel model) {
    this.x = x;
    this.y = y;
    this.dx = dx;
    this.dy = dy;
    this.color = c;
    this.diameter = diameter;
    this.maxx = model.getWidth();
    this.maxy = model.getHeight();
  }
  
  /**
   * Return the current horizontal location of the center of this Ball
   * @return the current x coordinate of the ball
   */
  public int getX() { return x; }
  
  /**
   * Return the current vertical location of the center of this Ball
   * @return the current y coordinate of the ball
   */
  public int getY() { return y; }

  
  /**
   * Perform an appropriate action on each cycle of the simulation,
   * in this case advancing by dx,dy and reversing either direction
   * if we hit an edge of the simulation.
   */
  public void action() {
    x = x + dx;
    if (x < diameter/2 || x > maxx - diameter/2) {
      dx = -dx;
    }
    y = y + dy;
    if (y < diameter/2 || y > maxy - diameter/2) {
      dy = -dy;
    }
  }

  /**
   * Draw a graphical representation of this ball at the given coordinates.
   * @param g Graphics context where the drawing should occur
   * @param h Horizontal screen coordinate where the center of this SimThing should appear
   * @param v Vertical screen coordinate where the center of this SimThing should appear
   */
  public void render(Graphics g, int h, int v) {
    g.setColor(color);
    g.fillOval(h-diameter/2, v-diameter/2, diameter, diameter);
  }
}