use hashbrown::HashMap;
use itertools::Itertools;
use md5::{Digest, Md5};

pub fn part_one(input: &str) -> Option<String> {
    let key = input.trim().as_bytes();
    let mut hasher = Md5::new();
    let mut count = 0;
    let mut res = String::new();

    for x in 0..std::u64::MAX {
        hasher.update(key);
        hasher.update(x.to_string().as_bytes());
        let output = hasher.finalize_reset();

        if output.starts_with(&[0, 0]) && output[2] <= 0x0F {
            count += 1;
            res.push_str(&format!("{:02x}", output[2])[1..]);
        }

        if count == 8 {
            break;
        }
    }

    Some(res)
}
pub fn part_two(input: &str) -> Option<String> {
    let key = input.trim().as_bytes();
    let mut hasher = Md5::new();
    let mut res = HashMap::new();

    for x in 0..std::u64::MAX {
        hasher.update(key);
        hasher.update(x.to_string().as_bytes());
        let output = hasher.finalize_reset();

        if output.starts_with(&[0, 0]) && output[2] <= 0x0F {
            let (p, c) = format!("{:02x}{:02x}", output[2], output[3])[1..3]
                .chars()
                .next_tuple()
                .unwrap();
            if ('0'..='7').contains(&p) && !res.contains_key(&p) {
                res.insert(p, c);
            }
        }

        if res.len() == 8 {
            break;
        }
    }

    Some(
        res.iter()
            .sorted_by(|a, b| a.0.cmp(b.0))
            .map(|(_, v)| v)
            .collect(),
    )
}
fn main() {
    let input = &aoc::read_file("inputs", 5);
    aoc::solve!(1, part_one, input);
    aoc::solve!(2, part_two, input);
}
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_part_one() {
        let input = aoc::read_file("examples", 5);
        assert_eq!(part_one(&input), Some("18f47a30".to_string()));
    }
    #[test]
    fn test_part_two() {
        let input = aoc::read_file("examples", 5);
        assert_eq!(part_two(&input), Some("05ace8e3".to_string()));
    }
}