Wombats

import greenfoot.*;  // (World, Actor, GreenfootImage, and Greenfoot)

/**
 * Wombat. A Wombat moves forward until it hits the edge of the world, at
 * which point it turns left. If a wombat finds a leaf, it eats it.
 * 
 * @author Michael Kölling
 * @version 2.0
 */
public class Wombat extends Actor
{
    private int leavesEaten;

    public Wombat()
    {
        leavesEaten = 0;
    }

    /**
     * Do whatever the wombat likes to to just now.
     */
    public void act()
    {
        if (foundLeaf()) {
            eatLeaf();
        }
        else if (canMove()) {
            move();
        }
        else {
            turnLeft();
        }
    }

    /**
     * Move one step forward.
     */
    public void move()
    {
        move(1);
    }
    
    /**
     * Turn left by 90 degrees.
     */
    public void turnLeft()
    {
        turn(-90);
    }
       
    /**
     * Check whether there is a leaf in the same cell as we are.
     * Return true, if there is, false otherwise.
     */
    public boolean foundLeaf()
    {
        Actor leaf = getOneObjectAtOffset(0, 0, Leaf.class);
        return leaf != null;
    }
    
    /**
     * Eat a leaf (if there is one in our cell).
     */
    public void eatLeaf()
    {
        Actor leaf = getOneObjectAtOffset(0, 0, Leaf.class);
        if (leaf != null) {
            // eat the leaf...
            getWorld().removeObject(leaf);
            leavesEaten = leavesEaten + 1; 
        }
    }
    
    /**
     * Set the direction we're facing. The 'direction' parameter must
     * be in the range [0..3].
     */
    public void setDirection(int direction)
    {
        if ((direction >= 0) && (direction <= 3)) {
            setRotation(direction * 90);
        }
    }
    
    /**
     * Test if we can move forward. Return true if we can, false otherwise.
     */
    public boolean canMove()
    {
        int rotation = getRotation();
        int x = getX();
        int y = getY();
        boolean facingEdge = false;
        
        switch (rotation) {
            case 0:
                facingEdge = (x == getWorld().getWidth() - 1);
                break;
            case 90:
                facingEdge = (y == getWorld().getHeight() - 1);
                break;
            case 180:
                facingEdge = (x == 0);
                break;
            case 270:
                facingEdge = (y == 0);
                break;
        }
        
        return !facingEdge;
    }

    /**
     * Tell how many leaves we have eaten.
     */
    public int getLeavesEaten()
    {
        return leavesEaten;
    }
}