/**
 * Creates a frame and draws some random circles in it
 * @author harrchen
 * @version 1.0
 * Last Modified 04/24/02
 */

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

public class DrawCircles extends Frame {
    // We declare some constants here (the size of the frame)
    public static final int height=500;
    public static final int width=500;
    
    // These are the "Draw" and "Quit" buttons
    protected Button draw;
    protected Button quit;

    // This is for our random number generation
    protected Random randomGen;

    /**
     * This class listens to triggers of the "Draw" button
     */
    protected class DrawButtonListener implements ActionListener {
        /**
         * Tells the frame to repaint on an action event
         * @param e The ActionEvent corresponding to the action
         */
        public void actionPerformed(ActionEvent e) {
            repaint();
        }
    }

    /**
     * This class listens to triggers of the "Quit" button
     */
    protected class QuitButtonListener implements ActionListener {
        /**
         * Terminates the application on an action event
         * @param e The ActionEvent corresponding to the action
         */
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    }

    /**
     * main function - creates the DrawCircles frame
     * @param args Command line arguments
     */
    public static void main(String[] args) {
        // Create a DrawCircles frame and display it
        DrawCircles drawCircles = new DrawCircles();
        drawCircles.show();
    }

    /**
     * Creates and initializes a DrawCircles fram with some defaults
     */
    protected DrawCircles() {
        // Initialize the frame's details
        setSize(height,width);
        setTitle("DrawCircles Application");
        setLayout(new FlowLayout());

        // We create the buttons and make event handlers for them
        draw=new Button("Draw");
        quit=new Button("Quit");
        draw.addActionListener(new DrawButtonListener());
        quit.addActionListener(new QuitButtonListener());
        add(draw);
        add(quit);

        // Create the random number generator
        randomGen=new Random();
    }

    /**
     * Returns the number of circles that should be drawn
     */
    public int numberOfCircles() {
        // Return a default 20 for now
        return 20;
    }

    /**
     * Returns the minimum diameter of a circle to draw
     */
    public int minCircleDiameter() {
        // Return a default 10 for now
        return 10;
    }

    /**
     * Returns the maximum diameter of a circle to draw
     */
    public int maxCircleDiameter() {
        // Return a default 30 for now
        return 30;
    }
    
    /**
     * Returns the color of a circle to draw
     */
    public Color circleColor() {
        // Returns a color with random RGB components
        return new Color(randomGen.nextFloat(),
                         randomGen.nextFloat(),
                         randomGen.nextFloat());
    }
    
    /**
     * Does the actual drawing of the circles
     */
    public void paint(Graphics g) {
        int diameter;
        // Store locally the range of diameters for code readability
        int range=maxCircleDiameter()-minCircleDiameter();
        // This clears the window
        g.clearRect(0,0,width,height);
        // This draws the circles
        for (int i=0; i<numberOfCircles(); i++) {
            // Randomly generate a new diameter from minCircleDiameter()
            // to maxCircleDiameter()-1 (inclusive)
            diameter=randomGen.nextInt(range)+minCircleDiameter();
            g.setColor(circleColor());
            // We also get a random (x,y) position when we draw the oval
            g.fillOval(randomGen.nextInt(width),randomGen.nextInt(height),
                       diameter,diameter);
        }
    }
}