CheckerboardKarel

/*
 * File: CheckerboardKarel.java
 * ----------------------------
 * When you finish writing it, the CheckerboardKarel class should draw
 * a checkerboard using beepers, as described in Assignment 1.  You
 * should make sure that your program works for all of the sample
 * worlds supplied in the starter folder.
 */

import stanford.karel.*;

public class CheckerboardKarel extends SuperKarel {

    public void run() {
        while (facingEast()){
            fillRow();
            moveBack();
            moveToNextLine();
        }
    }
    private void fillRow(){
        determinePattern();
    }
    private void determinePattern(){
        if (facingEast()){
            turnRight();
            if (frontIsClear()){
                move();
                if (beepersPresent()){
                    turnAround();
                    move();
                    turnRight();
                    putPattern2();
                } else {
                    turnAround();
                    move();
                    turnRight();
                    putPattern1();
                }
            } else {
                turnLeft();
                putPattern1();
            }
        }
    }
    private void putPattern1(){
        putBeeper();
        while (frontIsClear()){
            move();
            if (frontIsClear()){
                move();
                putBeeper();
            }
        }
    }
    private void putPattern2(){
        if (frontIsClear()){
            move();
            while (frontIsClear()){
                putBeeper();
                move();
                if (frontIsClear()){
                    move();
                }
            }
            checkIfBeeperNeeded();
        } else {
            moveToNextLine();
            determinePattern();
        }
    }
    private void moveBack(){
        turnAround();
        while (frontIsClear()){
            move();
        }
        turnAround();
    }
    private void moveToNextLine(){
        turnLeft();
        if (frontIsClear()){
            move();
            turnRight();
        } else {
            turnLeft();
        }
    }
    private void checkIfBeeperNeeded(){
        if (frontIsBlocked()){
            turnRight();
            move();
            if (beepersPresent()) {
                turnAround();
                move();
                turnRight();
            } else {
                turnAround();
                move();
                putBeeper();
                turnRight();
            }
        }
    }
}