use aoc_runner_derive::{aoc, aoc_generator};
use grid::Grid;

#[aoc_generator(day4)]
fn parse(input: &str) -> Grid<u8> {
    input.parse().unwrap()
}

#[aoc(day4, part1)]
fn part1(input: &Grid<u8>) -> u64 {
    (0..input.height() * input.width())
        .filter(|i| *input.get(&input.coord(*i as i64).unwrap()).unwrap() == b'@')
        .map(|i| input.neighbours_count(input.coord(i as i64).unwrap(), |c| *c == b'@'))
        .filter(|n| *n < 4)
        .count() as u64
}

#[aoc(day4, part2)]
fn part2(input: &Grid<u8>) -> u64 {
    input.width() as u64
}

#[cfg(test)]
mod tests {
    use super::*;

    const EXAMPLE: &str = "..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.";

    #[test]
    fn part1_example() {
        assert_eq!(part1(&parse(EXAMPLE)), 13);
    }

    #[test]
    fn part2_example() {
        assert_eq!(part2(&parse(EXAMPLE)), 0);
    }
}