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 {

    // You fill in this part
    public void run() {
        // for vertical lines
        if (frontIsBlocked()) {
            putBeeper();
            turnLeft();
            while (frontIsClear()) {
                patternNorth();
            }
        }

        // for squares
        while (frontIsClear()) {
            patternEast();
            checkCeilingFromEast(); // checks ceiling from east AND moves to next row
            patternWest();
            checkCeilingFromWest(); // checks ceiling from west AND moves to next row
        }

        // removes beeper when ending on east side since patterWest()
        // adds a beeper there
        if (rightIsBlocked()) {
            pickBeeper();
        }

    }

    private void patternEast() {
        putBeeper();

        while (facingEast()) {
            skipCornerAndPutBeeper();
            checkEastWall();
        }
    }

    private void skipCornerAndPutBeeper() {
        if (frontIsClear()) {
            move();
            if (frontIsClear()) {
                move();
                putBeeper();
            }
        }
    }

    private void checkEastWall() {
        if (frontIsBlocked()) {
            turnLeft();
        }
    }

    private void checkCeilingFromEast() {
        if (frontIsClear()) {
            toWestRow();
        }
    }


    private void toWestRow() {
        if (beepersPresent()) {
            move();
            turnLeft();
            move();
        } else {
            move();
            turnLeft();
        }
    }

    private void patternWest() {
        putBeeper();

        while (facingWest()) {
            skipCornerAndPutBeeper();
            checkWestWall();
        }
    }

    private void checkWestWall() {
        if (frontIsBlocked()) {
            turnRight();
        }
    }

    private void checkCeilingFromWest() {
        if (frontIsClear()) {
            toEastRow();
        }
    }

    private void toEastRow() {
        if (beepersPresent()) {
            move();
            turnRight();
            move();
        } else {
            move();
            turnRight();
        }
    }

    private void patternNorth() {
        skipCornerAndPutBeeper();
    }

}