use std::collections::HashSet;

use aoc_runner_derive::{aoc, aoc_generator};
use itertools::Itertools;

#[aoc_generator(day6, part1)]
fn parse(input: &str) -> Vec<usize> {
    input.split("\n\n")
    .map(|group| {
        group.chars()
            .filter(|char| !char.is_ascii_whitespace())
            .collect::<HashSet<_>>().len()
        }).collect_vec()
}

#[aoc(day6, part1)]
fn part1(input: &Vec<usize>) -> usize {
    input.iter().sum()
}

#[aoc_generator(day6, part2)]
fn parse2(input: &str) -> Vec<usize> {
    input.split("\n\n")
    .map(|group| {
        let people = group.lines().collect_vec();
        let mut first = people[0].chars().collect_vec();
        for person in &people[1..] {
            first = first.iter()
                .cloned()
                .filter(|question| person.contains(*question))
                .collect_vec()
        }
        first.len()
    }).collect_vec()
}

#[aoc(day6, part2)]
fn part2(input: &Vec<usize>) -> usize {
    input.iter().sum()
}


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

const EX: &str = r"abc

a
b
c

ab
ac

a
a
a
a

b";

    #[test]
    fn part1_example() {
        assert_eq!(part1(&parse(EX)), 11);
    }

    #[test]
    fn part2_example() {
        assert_eq!(part2(&parse2(EX)), 6);
    }
}