// file: Tank.java
// author: David Fleming
// created 7/1/96

import java.awt.*;

/* This class is a data abstraction representing a tank holding fluid.
   It is capable of adding and removing liquid and can be initialized
   to be of a certain capacity. It also returns messages stating when the
   tank is either empty or full.
*/

public class Tank extends Canvas
{
   private float temp;

   private static final int tankHeight = 100;
   private static final int tankWidth = 225;

   private static final float emptyTank = 0.0f;
   private static final float fullTank = 120.0f;

   private static final Color borderColor = Color.black;
   private static final Color fluidColor = Color.green;

   public Tank( float initial )
   {
      temp = initial;
      resize( tankWidth+5, tankHeight+5 );
   }

   public float howFull()
   {
      return temp;
   }

   public float tankCapacity()
   {
      float capacity = fullTank;
      return capacity;
   }

   public void addFluid( float amount )
   {
      temp = temp + amount;
      Graphics g = this.getGraphics();
      paint(g);

   }

   public void removeFluid( float amount )
   {
      temp = temp - amount;
      Graphics g = this.getGraphics();
      paint(g);
   }

   public void paint( Graphics g )
   {
      g.setColor( borderColor );
      g.drawRect( 0, 0, tankWidth, tankHeight );
      g.setColor( fluidColor );
      int fluidHeight=(int)(((temp - emptyTank)/(fullTank-emptyTank))*tankHeight);
      if ( fluidHeight > tankHeight )
      {
         fluidHeight = tankHeight;
      }
      else
      {
         g.fillRect( 0, tankHeight-fluidHeight, tankWidth, fluidHeight );
      };
   }
}