//  animation-simulation applet:  hungry being and food
//  See program assignment for labs meeting Nov. 10, 15, 16, 20, 21.
//  Prepared by A. Biermann, November 2000.

import java.awt.*;
import awb.*;
import java.awt.event.*;


public class CA6 extends java.applet.Applet 
                           implements ActionListener
{
     Graphics g;
     Canvas c;
     Button b1,b2;
     HuOne h1;                      //  This declares one hungry being
     Foo f1 [];                     //  This declares an array of food objects
     int FooMax, lifetime;
     int x, y, boxsize;
     IntField xF, yF, lifetimeF;

     public void init()             //  Initialize program
     {
         f1 = new Foo[15];          //  15 food objects
	 boxsize = 200;
         c = new Canvas();
         c.setSize(200,200);
         add(c);
         g = c.getGraphics();
         b1 = new Button("Initialize");
         b1.addActionListener(this);
         b2 = new Button("Go");
         b2.addActionListener(this);
	 xF = new IntField(10);
	 xF.setLabel("x-coord");
         yF = new IntField(10);
         yF.setLabel("y-coord");
         lifetimeF = new IntField(10);
         lifetimeF.setLabel("lifetime");
	 x = xF.getInt();
         y = yF.getInt();
         add(b1);  add(b2);  add(xF); add(yF); add(lifetimeF); 
     }

     public void actionPerformed(ActionEvent event)
     {
        Object cause = event.getSource();

        if (cause == b1)                    //  Initialize screen
	{
           g.setColor(Color.white);
           g.fillRect(0,0,200,200);
	   x = xF.getInt();
	   y = yF.getInt();
           lifetime = 0;
           lifetimeF.setInt(lifetime);
	   h1 = new HuOne(x, y, g);         //  Create and draw hungry being
	   h1.draw();
           f1[0] = new Foo(40,30,g);    //  Create and scatter 15 food objects
           f1[0].draw();
           f1[1] = new Foo(30,70,g);
           f1[1].draw();
           f1[2] = new Foo(50,120,g);
           f1[2].draw();
           f1[3] = new Foo(70,170,g);
           f1[3].draw();
           f1[4] = new Foo(90,120,g);
           f1[4].draw();
           f1[5] = new Foo(110,70,g);
           f1[5].draw();
           f1[6] = new Foo(130,20,g);
           f1[6].draw();
           f1[7] = new Foo(15,70,g);
           f1[7].draw();
           f1[8] = new Foo(170,120,g);
           f1[8].draw();
           f1[9] = new Foo(190,170,g);
           f1[9].draw();
           f1[10] = new Foo(20,150,g);
           f1[10].draw();
           f1[11] = new Foo(40,90,g);
           f1[11].draw();
           f1[12] = new Foo(60,180,g);
           f1[12].draw();
           f1[13] = new Foo(80,60,g);
           f1[13].draw();
           f1[14] = new Foo(120,140,g);
           f1[14].draw();
           FooMax = 14;                  //  Maximum number of food objects
        }
        if (cause == b2)        //  Advance the simulation one time interval
	{
            lifetime = lifetime + 1;
            lifetimeF.setInt(lifetime);
	    h1.advance();
	}
     }

     public class HuOne                 //  Hungry being class
	                                //  It goes looking for food
	                                //  It eats what it finds
     {
         protected int xc,yc,diameter;
         protected Graphics hg;

         public HuOne(int x, int y, Graphics h)
         {
	      diameter = 20;           //  The being will be a filled circle
              xc = x;
              yc = y;
              hg = h;
         }

         public void draw()
         {
           hg.setColor(Color.blue);
           hg.fillOval(xc,yc,diameter,diameter);
         }

         public void erase()
         {
           hg.setColor(Color.white);
	   hg.fillOval(xc,yc,diameter,diameter);
         }

         public void advance()            //  Advance the being through 
	                                  //  one time interval
         {
	   int d, distance, mindist, closest, j;
           int xtarget, ytarget;
           erase();
           diameter = diameter - 1;       //  Being gets thinner

           if (diameter > 0)              //  If being still exists
	   {
               xc = xc + 10;              //  Move 10 pixels right
               yc = yc + 10;              //  Move 10 pixels down
	                                  //  This is a dumb strategy
                                          //  You can do better than this

               if (xc > (boxsize-diameter))   //  Bounce off right side
	       {
	           d = xc - (boxsize-diameter);
                   xc = xc - 2*d;
	       }
               if (xc < 0)                    //  Bounce off left side
	       {
	           xc = -xc;
	       }
               if (yc > (boxsize-diameter))   //  Bounce off bottom
	       {
	           d = yc - (boxsize-diameter);
                   yc = yc - 2*d;
	       }
               if (yc < 0)                    //  Bounce off top
	       {
	           yc = -yc;
	       }
	                                    //  Is there food near at hand?
                                            //  Find closest food
               j = 1;
               mindist = f1[0].FooDist(xc,yc);
               closest = 0;
               while(j <= FooMax)
	       {
                   distance = f1[j].FooDist(xc,yc);
	           if (distance < mindist)
	           {
		       mindist = distance;
                       closest = j;
                   }
                   j = j + 1;
               }
               xtarget = f1[closest].FooX();  //  Closest food x-coord
               ytarget = f1[closest].FooY();  //  Closest food y-coord

	                                    //  If food is near, eat it.
               if (((xc-xtarget)*(xc-xtarget) + 
                            (yc-ytarget)*(yc-ytarget))  < 200)
	       {
                   f1[closest].eat();
                   diameter = diameter + 2;    //  Being gets fatter
               }
               draw();
           }
         }      
     }

    public class Foo         //  This is the food class
	                     //  We scatter these around
	                     //  The being searches for them 
	                     //  and eats them
     {
	 protected int fx, fy, foolife;    //  foolife is 1 until it is eaten
	                                   //  then foolife is 0
         protected Graphics fg;

         public Foo(int x, int y, Graphics h)
         {
              fx = x;
              fy = y;
              foolife = 1;
              fg = h;
         }

         public int FooDist(int xx, int yy)   //  Finds the distance to food
	                                      //  (squared)
         {
             if (foolife==1)
	     {    
                  return ( (xx-fx)*(xx-fx) + (yy-fy)*(yy-fy) );
             }
             else
	     {
		 return 1000000;             //  If foolife is zero,
		                             //  distance is very far
             }
         }

         public int FooX()            //  Finds the x-coord of the food
         {
             return fx;
	 }

	 public int FooY()            //  Finds the y-coord of the food
	 {
	     return fy;
	 }

         public void draw()
         {
             fg.setColor(Color.green);
             fg.fillRect(fx,fy,10,10);
         }

         public void eat()
         {
             foolife = 0;
             fg.setColor(Color.white);
             fg.fillRect(fx,fy,10,10);
         }
     }            
}