use std::io;
use std::vec::Vec;
use std::collections::HashSet;

use crate::utils;

pub fn execute() -> Result<(), io::Error> {
    let mut score = 0;
    let mut sacks: Vec<HashSet<u8>> = Vec::new();

    for line in utils::read_lines("input/day03.txt")? {
        let text = line?;
        let (text1, text2) = text.split_at(text.len() / 2);
        let mut pouch1 = HashSet::new();
        let mut pouch2 = HashSet::new();
        for i in 0..text1.len() {
            pouch1.insert(text1.as_bytes()[i]);
            pouch2.insert(text2.as_bytes()[i]);
        }

        let intersect: HashSet<_> = pouch1.intersection(&pouch2).cloned().collect();
        score += get_score(&intersect);

        sacks.push(pouch1.union(&pouch2).cloned().collect());
    }

    let mut score2 = 0;
    for group in sacks.chunks(3) {
        let mut intersect: HashSet<u8> = group[0].intersection(&group[1]).cloned().collect();
        intersect = intersect.intersection(&group[2]).cloned().collect();
        score2 += get_score(&intersect);
    }
    
    utils::print_step(1, &score);
    utils::print_step(2, &score2);
    Ok(())
}

fn get_score(intersect: &HashSet<u8>) -> u64 {
    if intersect.len() > 1 {
        panic!("More than one overlapping item.");
    }

    if let Some(item) = intersect.iter().next() {
        if *item > 0x60 {
            return (*item - 0x60) as u64;
        }

        return ((*item - 0x40) + 26) as u64;
    }

    panic!("No items in intersection.");
}