use aoc_runner_derive::{aoc,aoc_generator};
pub struct Forest {
    slice: Vec<Vec<bool>>,
}

impl Forest {
    fn get(&self, x: usize,y: usize) -> Option<bool> {
        self.slice.get(y).map(|line| line.get(x%line.len())).flatten().cloned()
    }
}


#[aoc_generator(day3)]
pub fn input_generator(input: &str) -> Forest {
    let slice=input.lines().map(|l| l.chars().map(|c| c=='#').collect()).collect();
    Forest{
        slice
    }
}

#[aoc(day3,part1)]
pub fn solve_part1(input: &Forest) -> usize {
    let mut sum: usize=0;
    let dx=3;
    let dy=1;
    let mut pos=(0,0);
    while let Some(tree) = input.get(pos.0,pos.1) {
        if tree {
            sum+=1;
        }
        pos.0+=dx;
        pos.1+=dy;
    };
    sum
}


#[aoc(day3,part2)]
pub fn solve_part2(input: &Forest) -> usize {
    let mut prod: usize = 1;
    for (dx,dy) in &[(1,1),(3,1),(5,1),(7,1),(1,2)] {
        let mut sum: usize=0;
        let mut pos=(0,0);
        while let Some(tree) = input.get(pos.0,pos.1) {
            if tree {
                sum+=1;
            }
            pos.0+=dx;
            pos.1+=dy;
        };
        prod*=sum;
    }
    prod
}