// File: TankApp2.java
// author: David Fleming
// created: 7/13/96

import java.awt.*;
import java.applet.*;

public class TankApplet2 extends Applet
{
   Tank tank;
   Graphics g;
   Button go;
   Choice incDec;
   Choice amt;
   Label by;
   Label gallons;
   TextField text_Field;
   float overFlowCheck;
   float underFlowCheck;


   public TankApplet2()
   {
      // create tank object
      tank = new Tank( 0.0f );
      // create "GO" button
      go = new Button("GO");
      // create inc/dec choice box w/ choices of "Inc" and "Dec"
      incDec = new Choice();
      incDec.addItem("Inc");
      incDec.addItem("Dec");
      // create amount choice box w/ choices from "1" to "10"
      amt = new Choice();
      amt.addItem("1");
      amt.addItem("2");
      amt.addItem("3");
      amt.addItem("4");
      amt.addItem("5");
      amt.addItem("6");
      amt.addItem("7");
      amt.addItem("8");
      amt.addItem("9");
      amt.addItem("10");
      // create text box for gallon read out
      text_Field = new TextField(20);
      // create "by" label
      by = new Label("by");
      gallons = new Label("gallons");
   }

   public void init()
   {
      setLayout( new BorderLayout() );
      Panel p = new Panel();
      p.setLayout(new FlowLayout());
      p.add(incDec);
      p.add(by);
      p.add(amt);
      p.add(gallons);
      p.add(go);

      add("North", text_Field);
      add("West", p);
      add("South", tank);

      updateDisplay();
   }

   private void updateDisplay()
   {
      text_Field.setText(String.valueOf(tank.howFull()));
      text_Field.paint(g);
      Graphics g = this.getGraphics();
      paint(g);
   }

   public boolean action(Event evt, Object arg)
   {
      Float amtToChange;
      amtToChange=new Float(amt.getSelectedItem());
      if("GO".equals(arg))
      {
          if( incDec.getSelectedItem() == "Inc" )
          {
              overFlowCheck=tank.howFull() + amtToChange.floatValue();
              if(overFlowCheck <= tank.tankCapacity() )
              {
                  tank.addFluid(amtToChange.floatValue());
                  updateDisplay();
                  return true;
              }
              else
              {
                  text_Field.setText("Tank is Full!");
                  text_Field.paint(g);
                  return false;
              };

          }
          else if( incDec.getSelectedItem() == "Dec" )
          {
              underFlowCheck=tank.howFull()-amtToChange.floatValue();
              if(underFlowCheck >= 0.0)
              {
                  tank.removeFluid(amtToChange.floatValue());
                  add("South",tank);
                  updateDisplay();
                  return true;
              }
              else
              {
                  text_Field.setText("Tank is Empty");
                  text_Field.paint(g);
                  return false;
              };
          }
          else
          {
             return false;
          };
      }
      else
      {
          return false;
      };
   }                        
}