// ireland.java resource based potato famine in Ireland
// adapted from a program in basic by H.T. Odum & E. Odum, 1994
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

public class ireland extends Applet implements ActionListener
{
 Label      lb01, lb02, lb03, lb04, lb05, lb06, lb07, lb08, lb09, lb10;
 TextField  tf01, tf02, tf03, tf04, tf05, tf06, tf07, tf08, tf09, tf10;
 Button bt;
 double q, n, s2, c,t0;         //variaveis globais

 public void init()
 {
	lb01 = new Label("Alim. Q:");   tf01 = new TextField("0.15",2); add(lb01);add(tf01);
	lb02 = new Label("Pop.  N:");   tf02 = new TextField("0.95",3); add(lb02);add(tf02);
	lb03 = new Label("E.solar:");   tf03 = new TextField("2500",4); add(lb03);add(tf03);
	lb04 = new Label("Fator C:");   tf04 = new TextField("0.30",3); add(lb04);add(tf04);
	lb05 = new Label("Fator T0:");  tf05 = new TextField("0.100",3);add(lb05);add(tf05);
	bt = new Button("Plotar"); add(bt); bt.addActionListener(this);
 }

 public void actionPerformed(ActionEvent e)
 {
   if (e.getSource()==bt)
   {
      q  = Double.valueOf(tf01.getText()).doubleValue();
	  n  = Double.valueOf(tf02.getText()).doubleValue();
	  s2 = Double.valueOf(tf03.getText()).doubleValue();
	  c  = Double.valueOf(tf04.getText()).doubleValue();
	  t0 = Double.valueOf(tf05.getText()).doubleValue();
	  repaint();
   }
 }

 public void paint(Graphics g)
 {
   double c, t,dt,dq,dn,  s0,q0,n0;
   double f,d,p, r,s,s1,w,x,y,z;
   double k0,k1,k2,k3,k4,k5,k6,k7,k8,k9;

   g.drawRect(0, 90,320,300);
   g.drawLine(0,190,320,190);
   g.drawLine(0,290,320,290);

   dt=1;  // dt=1
   t=0;   s0 = 0.0067;  q0 = 2.5;	   n0 = 33; w = 1;
   k0 = 18.8;	   k1 = 0.0022;  k2 = 0.002;   k3 = 0.007;	 k4 = 2;
   k5 = 0.0000081; k6 = 1.6E-07; k7 = 0.00006; k8 = 0.0025; k9 = 0.000002;
   d=0; 	s=0; 	y=0; 	z=0; // zerar variaveis

   do
   {
  	 g.setColor(Color.blue); 	 g.drawOval((int)(t*t0),(int)(390-q*q0),1,1);//alimento
	 g.setColor(Color.green);	 g.drawOval((int)(t*t0),(int)(290-n*n0),1,1);//populaçãp
	 g.setColor(Color.red);  	 g.drawOval((int)(t*t0),(int)(190-s*s0),1,1);//e.solar

     c = 0.3; //perda de energia solar
	 if (t<1180) c=1; // pleno sol
	 if (t>2010) c=1; // pleno sol

	 s1 = c * (800 + 2000*Math.sin(t/60));
	 if (s1<0) s1=0;
	 s = s1 + 200;
	 r = s / (1 + k0*n);

	 if (d>110)
	 {
		 if (s2 < 1500) y=1;  // nuvens causam doença na batata
		 if (s2 > 2000) y=0;  // sem  causam doença na batata
     }
	 else
	 if (d>100)
	 {
	   s2 = s;
       if (s2 < 1500) y=1;  // nuvens causam doença na batata
	   if (s2 > 2000) y=0;  // sem  causam doença na batata
     }
	 f=q/n;

	 if (f<5) x=1;// com fome
	 else x=0;    // sem fome

	 if (x==1) w=0;//crescimento populacional alto
	 if (x==1) z=1;//crescimento populacional moderado com emigração

	 p  = (k1*r*n)/(1+y*k4);
	 dq = p - k2*q - k3*(q/n)*n;
	 dn = w*k5*(q/n)*n - k6*r*n - k7*n - x*k8*n*n + z*k9*(q/n)*n;

	 q  = q + dq*dt;
	 n  = n + dn*dt;
	 d  = d + dt;
	 if (d>365) d=0;
	 t  = t + dt; //dt

	 }while ((t)<3200); //t*t0 320
 }
}
// Camila Duarte & E. Ortega. January 24th, 2001