// Written by Larry Landwehr 12/95

import java.util.*;
import java.awt.*;
import java.applet.Applet;

//--------------------------------------------------
class kaboomPanel extends Panel implements Runnable {
    KaBoom kaboom;
    Thread thread;

    int nlines;
    Line lines[] = new Line[100];
    Bomb bomb = new Bomb();

    Object pick;
    Image offscreen;
    boolean explode = false;
    Dimension offscreensize;
    Graphics offgraphics;

    //----
    kaboomPanel(KaBoom kaboom) {
        this.kaboom = kaboom;
    }

    //----
    int addLine(int x, int y, int p, int q) {
        Line n = new Line();
        n.set(x, y, p, q);
        lines[nlines] = n;
        return nlines++;
    }

    //----
    void addBomb(int x, int y) {
        bomb.set(x, y);
    }

    //----
    public void run() {
        while (true) {
            repaint();
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                break;
            }
        }
    }

    //----
    public void paintLine(Graphics g, Line n) {
        g.setColor(Color.blue);
        g.drawLine(n.x, n.y, n.p, n.q);
    }

    //----
    public void paintBomb(Graphics g, Bomb b) {
        g.setColor(Color.red);
        g.fillRect(b.x, b.y, 5, 5);
    }

    //----
    public synchronized void update(Graphics g) {

        Dimension d = size();

        if ((offscreen == null) || (d.width != offscreensize.width) ||
                (d.height != offscreensize.height)) {
            offscreen = createImage(d.width, d.height);
            offscreensize = d;
            offgraphics = offscreen.getGraphics();
            offgraphics.setFont(getFont());
        }

        if (explode == true) {
            for (int i=0; i<3; i++) {
                offgraphics.setColor(Color.red);
                offgraphics.fillRect(0, 0, d.width, d.height);
                g.drawImage(offscreen, 0, 0, null);
                offgraphics.setColor(Color.yellow);
                offgraphics.fillRect(0, 0, d.width, d.height);
                g.drawImage(offscreen, 0, 0, null);
            }
            for (int i=0; i<nlines; i++) lines[i].calcDelta(bomb.x, bomb.y);
            for (int i=0; i<80; i++) {
                offgraphics.setColor(getBackground());
                offgraphics.fillRect(0, 0, d.width, d.height);
                for (int j=0; j<nlines; j++) {
                    lines[j].domx();
                    paintLine(offgraphics, lines[j]);
                }
                paintBomb(offgraphics, bomb);
                g.drawImage(offscreen, 0, 0, null);
            }

            explode = false;
            for (int i=0; i<nlines; i++) lines[i].restore();
            bomb.restore();
        }

        offgraphics.setColor(getBackground());
        offgraphics.fillRect(0, 0, d.width, d.height);
        for (int i=0; i<nlines; i++) {
            paintLine(offgraphics, lines[i]);
        }
        paintBomb(offgraphics, bomb);
        g.drawImage(offscreen, 0, 0, null);
    }

    //----
    public synchronized boolean mouseDown(Event evt, int x, int y) {
        double dist, bestdist=Double.MAX_VALUE;

        for (int i=0; i<nlines; i++) {
            Line n = lines[i];
            dist = n.dist(x, y);
            if (dist < bestdist) {
                pick = n;
                bestdist = dist;
            }
        }
        dist = bomb.dist(x, y);
        if (dist < bestdist) pick = bomb;

        if (pick == bomb) ((Bomb)pick).move(x, y);
        else ((Line)pick).move(x, y);

        repaint();
        return true;
    }

    //----
    public synchronized boolean mouseDrag(Event evt, int x, int y) {
        if (pick == bomb) ((Bomb)pick).move(x, y);
        else ((Line)pick).move(x, y);
        repaint();
        return true;
    }

    //----
    public synchronized boolean mouseUp(Event evt, int x, int y) {
        if (pick == bomb) ((Bomb)pick).move(x, y);
        else ((Line)pick).move(x, y);
        pick = null;
        repaint();
        return true;
    }

    //----
    public void start() {
        thread = new Thread(this);
        thread.start();
    }

    //----
    public void stop() {
        thread.stop();
    }
}

//--------------------------------------------------
public class KaBoom extends Applet {
    kaboomPanel panel;

    //----
    public void init() {
        setLayout(new BorderLayout());
        resize(500,250);
        panel = new kaboomPanel(this);
        add("Center", panel);
        Panel p = new Panel();
        add("South", p);
        p.add(new Button("KaBoom!"));

        Dimension d = size();
        int x, y, w=95, h=95, z=25;
        x = (d.width-w)/2;
        y = (d.height+h+w)/2 - 50;
        panel.addLine(x, y, x+w, y);
        panel.addLine(x, y, x, y-h);
        panel.addLine(x+w, y-h, x+w, y);
        panel.addLine(x+w, y-h, x, y-h);
        panel.addLine(x+w, y-h, x+w/2, y-h-z);
        panel.addLine(x, y-h, x+w/2, y-h-z);
        panel.addLine(x+w/5, y-3*h/5, x+w/5, y-4*h/5);
        panel.addLine(x+2*w/5, y-3*h/5, x+2*w/5, y-4*h/5);
        panel.addLine(x+w/5, y-3*h/5, x+2*w/5, y-3*h/5);
        panel.addLine(x+w/5, y-4*h/5, x+2*w/5, y-4*h/5);
        panel.addLine(x+3*w/5, y-3*h/5, x+3*w/5, y-4*h/5);
        panel.addLine(x+4*w/5, y-3*h/5, x+4*w/5, y-4*h/5);
        panel.addLine(x+3*w/5, y-3*h/5, x+4*w/5, y-3*h/5);
        panel.addLine(x+3*w/5, y-4*h/5, x+4*w/5, y-4*h/5);
        panel.addLine(x+1*w/5, y-h/5, x+4*w/5, y-h/5);
        panel.addLine(x+1*w/5, y-2*h/5, x+4*w/5, y-2*h/5);
        panel.addLine(x+1*w/5, y-h/5, x+1*w/5, y-2*h/5);
        panel.addLine(x+4*w/5, y-h/5, x+4*w/5, y-2*h/5);
        panel.addBomb(x+w/2, y-h/2);
    }

    //----
    public void start() {
        panel.start();
    }

    //----
    public void stop() {
        panel.stop();
    }

    //----
    public boolean action(Event evt, Object arg) {
        //String s = "KaBoom!";
        //showStatus(s);
        if ("KaBoom!".equals(arg)) {
            panel.explode = true;
            return true;
        }
        return false;
    }

    //----
    public static void main(String args[]) {
        kaboomFrame k = new kaboomFrame();
        KaBoom kaboom = new KaBoom();
        kaboom.init();
        kaboom.start();
        k.add("Center", kaboom);
        k.resize(500, 250);
        k.show();
    }
}

//--------------------------------------------------
class kaboomFrame extends Frame {

    public kaboomFrame() {
	super("KaBoom");
    }

    public boolean handleEvent(Event e) {
	if (e.id == Event.WINDOW_DESTROY) System.exit(0);
	return false;
    }
}

//--------------------------------------------------
class Line {
    int x, y, p, q, cx, cy;
    int ox, oy, op, oq;
    double mx, my;

    public void set(int x, int y, int p, int q) {
        this.x = x;
        this.y = y;
        this.p = p;
        this.q = q;
        this.cx = (x+p)/2;
        this.cy = (y+q)/2;
        // save original position
        this.ox = x;
        this.oy = y;
        this.op = p;
        this.oq = q;
    }

    public void restore() {
        this.x = this.ox;
        this.y = this.oy;
        this.p = this.op;
        this.q = this.oq;
        this.cx = (this.x+this.p)/2;
        this.cy = (this.y+this.q)/2;
    }

    public void move(int cx, int cy) {
        int dx, dy;

        dx = this.cx - cx;
        dy = this.cy - cy;
        this.x = this.x - dx;
        this.y = this.y - dy;
        this.p = this.p - dx;
        this.q = this.q - dy;
        this.cx = cx;
        this.cy = cy;
    }

    public void domx() {
        this.move((int)(this.cx+this.mx), (int)(this.cy+this.my));
    }

    public double dist(int x, int y) {
        double dist;
        dist = (this.cx - x) * (this.cx - x) + (this.cy - y) * (this.cy - y);
        return(dist);
    }

    public void calcDelta(int x, int y) {
        int dx, dy;
        double s;

        dx = this.cx - x;
        dy = this.cy - y;
        if (dx == 0) {
            this.mx = 0;
            if (dy == 0) {
                this.my = 0;
            } else {
                this.my = (dy>0) ? 3.0 : -3.0;
            }
            return;
        }
        s = (double)dy / (double)dx;
        this.mx = 3.0 / Math.sqrt(1.0 + s*s);
        this.my = Math.abs(s * this.mx);
        if (dx<0) this.mx = -this.mx;
        if (dy<0) this.my = -this.my;
    }
}

//--------------------------------------------------
class Bomb {
    int x, y;
    int ox, oy;

    public void set(int x, int y) {
        this.x = x;
        this.y = y;
        this.ox = x;
        this.oy = y;
    }

    public void restore() {
        this.x = this.ox;
        this.y = this.oy;
    }

    public void move(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public double dist(int x, int y) {
        double dist;
        dist = (this.x - x) * (this.x - x) + (this.y - y) * (this.y - y);
        return(dist);
    }
}