use std::{collections::HashSet, fs::read_to_string};

use color_eyre::{eyre::*, Result};
use itertools::Itertools;

fn priority(item: &char) -> usize {
    ('a'..='z')
        .position(|c| *item == c)
        .map(|i| i + 1)
        .or_else(|| ('A'..='Z').position(|c| *item == c).map(|i| i + 27))
        .unwrap_or(0)
}

fn initial(input: &str) -> (usize, usize) {
    let output1 = input
        .lines()
        .map(|line| {
            let (compartment1, compartment2) = line.split_at(line.len() / 2);
            let compartment1 = compartment1.chars().collect::<HashSet<_>>();
            let compartment2 = compartment2.chars().collect::<HashSet<_>>();
            compartment1
                .intersection(&compartment2)
                .map(priority)
                .sum::<usize>()
        })
        .sum();
    let output2 = input
        .lines()
        .chunks(3)
        .into_iter()
        .map(|group| {
            group
                .map(|line| line.chars().collect::<HashSet<_>>())
                .coalesce(|a, b| Ok(a.intersection(&b).copied().collect()))
                .map(|set| set.iter().map(priority).sum::<usize>())
                .sum::<usize>()
        })
        .sum();
    (output1, output2)
}

fn main() -> Result<()> {
    let input = read_to_string("input.txt").wrap_err("reading input.txt")?;
    let output = initial(&input);
    println!("output: {output:?}");
    Ok(())
}