use std::{cmp::Ordering, collections::HashMap};

pub fn day5() {
    let full_input = crate::input(5);
    let input_parts: Vec<&str> = full_input.split("\n\n").collect();
    let order_rules: Vec<Vec<u64>> = input_parts[0]
        .lines()
        .filter(|line| !line.is_empty())
        .map(|line| line.split("|").map(|x| x.parse::<u64>().unwrap()).collect())
        .collect();
    let page_sets: Vec<Vec<u64>> = input_parts[1]
        .lines()
        .filter(|line| !line.is_empty())
        .map(|line| line.split(",").map(|x| x.parse::<u64>().unwrap()).collect())
        .collect();

    let mut order_map: HashMap<u64, Vec<u64>> = HashMap::new();
    for rule in order_rules.iter() {
        let entry = order_map.entry(rule[0]).or_insert(Vec::new());
        entry.push(rule[1]);
    }

    let sort = |a: &u64, b: &u64| {
        if order_map.get(&a).unwrap_or(&vec![]).contains(&b) {
            Ordering::Less
        } else if order_map.get(&b).unwrap_or(&vec![]).contains(&a) {
            Ordering::Greater
        } else {
            Ordering::Equal
        }
    };
    let is_sorted = |l: &Vec<u64>| {
        l.windows(2)
            .all(|w| (sort)(&w[0], &w[1]) != Ordering::Greater)
    };

    let (correct, mut incorrect): (Vec<Vec<u64>>, Vec<Vec<u64>>) =
        page_sets.into_iter().partition(is_sorted);

    incorrect.iter_mut().for_each(|set| set.sort_by(sort));

    let sum_correct: u64 = correct.iter().map(|set| set[set.len() / 2]).sum();
    let sum_fixed: u64 = incorrect.iter().map(|set| set[set.len() / 2]).sum();

    println!("Sum of Correct Middle Pages: {}", sum_correct);
    println!("Sum of Fixed Middle Pages: {}", sum_fixed);
}