use aoc_runner_derive::aoc;
use itertools::Itertools;
use std::io::BufRead;

// PROBLEM 1 solution
#[aoc(day6, part1)]
fn part1(input: &[u8]) -> u64 {
    let s = input.lines().next().unwrap().unwrap();
    s.as_bytes()
        .windows(4)
        .enumerate()
        .find_map(|(i, window)| {
            if window[1..4].iter().all(|c| *c != window[0])
                && window[2..4].iter().all(|c| *c != window[1])
                && window[2] != window[3]
            {
                println!(
                    "Unique window: {:?} at {}",
                    window.iter().map(|c| *c as char).collect_vec(),
                    i
                );
                Some(i + 4)
            } else {
                None
            }
        })
        .unwrap() as u64
}

// PROBLEM 2 solution
#[aoc(day6, part2)]
fn part2(input: &[u8]) -> u64 {
    let s = input.lines().next().unwrap().unwrap();
    let size = 14;
    s.as_bytes()
        .windows(size)
        .enumerate()
        .find_map(|(i, window)| {
            for i in 1..size {
                let shifted = &window[i..];
                if shifted.iter().enumerate().any(|(j, c)| *c == window[j]) {
                    return None;
                }
            }
            return Some(i + 14);
        })
        .unwrap() as u64
}

#[cfg(test)]
mod tests {
    use crate::day6::*;

    const EXAMPLE1: &[u8] = b"bvwbjplbgvbhsrlpgdmjqwftvncz";
    const EXAMPLE2: &[u8] = b"nppdvjthqldpwncqszvftbrmjlhg";
    const EXAMPLE3: &[u8] = b"nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg";
    const EXAMPLE4: &[u8] = b"zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw";

    #[test]
    fn problem1_example() {
        assert_eq!(part1(EXAMPLE1), 5);
        assert_eq!(part1(EXAMPLE2), 6);
        assert_eq!(part1(EXAMPLE3), 10);
        assert_eq!(part1(EXAMPLE4), 11);
    }

    #[test]
    fn problem2_example() {
        assert_eq!(part2(EXAMPLE1), 23);
        assert_eq!(part2(EXAMPLE2), 23);
        assert_eq!(part2(EXAMPLE3), 29);
        assert_eq!(part2(EXAMPLE4), 26);
    }
}