public class Turtle {
  private Page page;
  private Pen pen;
  private int x = 0, y = 0;
  public boolean penDown = true;

  public Turtle(Page page, Pen pen) {
    this.page = page;
    this.pen = pen;
  }

  public void setPen(Pen pen) {
    this.pen = pen;
  }

  public void penUp() {
    this.penDown = false;
  }

  public void penDown() {
    this.penDown = true;
  }

  public boolean isPenDown() {
    if (this.penDown == true) {
      return true;
    }
    return false;
  }

  public void move(Direction direction, int distance) {
    assert distance > 0;
    switch (direction) {
      case NORTH:
        for (int i = 0; i < distance; i++) {
          if (this.x > 0) {
            this.x--;
          } else {
            this.x = 0;
          }
          if (this.isPenDown()) {
            this.makeMark();
          }
        }

      case EAST:
        for (int i = 0; i < distance; i++) {
          if (this.y > 0) {
            this.y--;
          } else {
            this.y = 0;
          }
          if (this.isPenDown()) {
            this.makeMark();
          }
        }

      case SOUTH:
        for (int i = 0; i < distance; i++) {
          if (this.x < (page.size() - 1)) {
            this.x++;
          } else {
            this.x = 0;
          }
          if (this.isPenDown()) {
            this.makeMark();
          }
        }

      case WEST:
        for (int i = 0; i < distance; i++) {
          if (this.y < (page.size() - 1)) {
            this.y++;
          } else {
            this.y = 0;
          }
          if (this.isPenDown()) {
            this.makeMark();
          }
        }
    }
  }

  private void makeMark() {
    page.draw(this.x, this.y, pen);
  }

  private void move(int deltaI, int deltaJ, int distance) {
    this.y += distance * deltaI;
    this.x += distance * deltaJ;
  }
}