public class Crab extends Animal
{
    private GreenfootImage image1;
    private GreenfootImage image2;
    private int wormsEaten;
    private int energyBurnRate;  //BORDERS: Rate at which the crab burns one worm. This code satisifies requirement R7.
    private int numberOfSteps; //BORDERS: Stores the number of steps the crab takes. This code satisfies requirement R7.
    
    /**
     * Create a crab and initialize its two images.
     */
    public Crab()
    {
        image1 = new GreenfootImage("crab.png");
        image2 = new GreenfootImage("crab2.png");
        setImage(image1);
        wormsEaten = Greenfoot.getRandomNumber(16) + 5; //BORDERS: Sets the initial wormsEaten from 5 to 20. This code satisfies
                                                        //BORDERS: requirement R5.
        numberOfSteps = 0;
        energyBurnRate = 20;
    }
        
    /** 
     * Act - do whatever the crab wants to do. This method is called whenever
     *  the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act()
    {
        turnAtEdge();
        randomTurn();
        move();
        lookForWorm();
        switchImage();
    }
    
    /**
     * Alternate the crab's image between image1 and image2.
     */
    public void switchImage()
    {
        if (getImage() == image1) 
        {
            setImage(image2);
        }
        else
        {
            setImage(image1);
        }
    }
    
    /**
     * BORDERS: Check whether we are at the edge of the world. If we are, turn a bit.
     * If not, do nothing.
     */
    public void turnAtEdge()
    {
        if (atWorldEdge())
        {
            turn(17);
        }
    }
    
    /**
     * BORDERS: Randomly decide to turn from the current direction, or not. If we
     * turn, turn a bit left or right by a random degree.
     */
    public void randomTurn()
    {
        if (Greenfoot.getRandomNumber(100) > 90)
        {
            turn(Greenfoot.getRandomNumber(90)-45);
        }
    }
    
    /**
     * Check whether we have stumbled upon a worm.
     * If we have, eat it. If not, do nothing.
     */
    public void lookForWorm()
    {
        if (canSee(Worm.class))
        {
            eat(Worm.class);
            
            wormsEaten = wormsEaten + 1;
            if (wormsEaten == 10) //BORDERS: This code satisfies requirement R6.
            {
                return;
            }
        }
        if (wormsEaten <= 0) //BORDERS: This code satisfies requirement R8.
        {
            getWorld().removeObject(this);
            return;
        }
    }
    
    /**
     * BORDERS: Count the number of steps by incrementing the numberOfSteps property by one every time the crab moves. This code
     * satisfies requirement R7. 
     */
    public void countSteps()
    {
        numberOfSteps = numberOfSteps + 1;
    }
    
    /**
     * BORDERS: Tell how many steps the crab has moved. This code satisfies requirement R7.
     */
    public int  getNumberOfSteps()
    {
       return numberOfSteps;        
    }    
    
    /**
     * BORDERS: This method simulates the energy that the crab burns when it moves by subtracting one worm every so many steps
     * given by the burningRate parameter. This code satisfies requirement R7.
     */
    public void burnEnergy(int burningRate)
    {
        if (numberOfSteps >= burningRate)
        {
            numberOfSteps = 0;
            wormsEaten = wormsEaten - 1;
        }
    }    
}