enum Direction {
  Left,
  Up,
  Right,
  Down
}

fn spiral_iter() -> impl Iterator<Item = [i32; 2]> {
    let mut curr = [0, 0];
    let mut dir = Direction::Left;
    let mut len = 1;
    let mut remaining = 1;

    std::iter::from_fn(move || {
        let rv = curr;

        remaining -= 1;

        match dir {
            Direction::Left => {
                curr[0] += 1;
                if remaining == 0 {
                    dir = Direction::Up;
                    remaining = len;
                }
            }
            Direction::Up => {
                curr[1] -= 1;
                if remaining == 0 {
                    dir = Direction::Right;
                    len += 1;
                    remaining = len;
                }
            }
            Direction::Right => {
                curr[0] -= 1;
                if remaining == 0 {
                    dir = Direction::Down;
                    remaining = len;
                }
            }
            Direction::Down => {
                curr[1] += 1;
                if remaining == 0 {
                    dir = Direction::Left;
                    len += 1;
                    remaining = len;
                }
            }
        }

        Some(rv)
    })
}

fn main() {
  let mult_values: Vec<[i32;2]> = spiral_iter().take(23).collect();
  println!("{:?}", mult_values);
}