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

public class Raindrops
{
    static final int XSIZE = 600;
    static final int YSIZE = 600;
    static final int NDROPS = 50; 
    static final int DEFAULTMAXHEIGHT = 8; 
    static final int MAXRADIUS = 120; 

    public int dropX[];
    public int dropY[];
    public int dropZ[]; 
    public int dropR[];
    public int dropStatus[];
    int maxheight;
    Boolean clicked = Boolean.FALSE;

    public Raindrops()         // constructor
    {
	dropX = new int[NDROPS];
	dropY = new int[NDROPS];
	dropZ = new int[NDROPS];
	dropR = new int[NDROPS];
	maxheight = DEFAULTMAXHEIGHT;

	nextTimeStep(); 
    }

    public void nextTimeStep() {
	int i;
	for (i = 0; i < NDROPS; i++) {
	    if (dropZ[i] == 0 && dropR[i] == 0) { // create a new raindrop
		dropX[i] = (int) (Math.random() * XSIZE);
		dropY[i] = (int) (Math.random() * YSIZE);
		dropZ[i] = (int) (Math.random() * maxheight);
		dropR[i] = 0;
	    }
	    else if (dropZ[i] > 0) { // let the raindrop fall a little
		dropZ[i] --; 
		if (dropZ[i] == 0) { 
		    // it's hit the ground
		    dropR[i] = 1;}
	    }
	    else if (dropR[i] > 0) { // let the splash spread
		dropR[i] +=6;
		if (dropR[i] >= MAXRADIUS) {
		    // the splash has dissipated
		    dropR[i] = 0; }
	    }
	}
    }

    void resetDrops() {  // mark each raindrop as uninitialized
	int i; 
	for (i = 0; i < NDROPS; i++) {
	    dropZ[i] = 0; dropR[i] = 0;
	} }

    public void setIndicator() {
	clicked = Boolean.TRUE; 
    }

    public void handleKey(KeyEvent e) {
	int kc = e.getKeyCode();
	switch (kc) {
	case KeyEvent.VK_R:
	    resetDrops();
	    break;
	default: 
	    System.out.println("unknown keypress");
	} }
	
    public void drawRain(Graphics2D graphics2D) {
	if (clicked) {
	    graphics2D.setColor(Color.blue); 
	    graphics2D.fillRect(0, 10, XSIZE, 5);}
	int i, centerX, centerY, circleR, topLeftX, topLeftY, grayLightness;
	for (i = 0; i < NDROPS; i++) {
	    if  (dropR[i] > 0) {
		centerX = dropX[i];
		centerY = dropY[i];
		for (circleR = 0; circleR < dropR[i]; circleR += 10) {
		    //graphics2D.setColor(Color.red); 
		    grayLightness = (int) (255 * (float) dropR[i] / MAXRADIUS);
		    graphics2D.setColor(new Color(grayLightness, grayLightness, grayLightness));
		    topLeftX = centerX - circleR/2;
		    topLeftY = centerY - circleR/2;
		    graphics2D.drawOval(topLeftX, topLeftY, circleR, circleR);
		} } } 
    }
}