use std::{
    fs::File,
    io::{BufRead, BufReader},
    path::Path,
};

pub fn solve(input: &Path) -> anyhow::Result<()> {
    println!("part one: {}", part_one(input)?);
    println!("part two: {}", part_two(input)?);

    Ok(())
}

fn part_one(input: &Path) -> anyhow::Result<i32> {
    let reader = BufReader::new(File::open(input)?);

    let mut first: Vec<i32> = vec![];
    let mut second: Vec<i32> = vec![];
    for line in reader.lines() {
        let line = line?;
        let mut numbers = line.split_whitespace();
        first.push(numbers.next().unwrap().parse()?);
        second.push(numbers.next().unwrap().parse()?);
    }
    first.sort();
    second.sort();
    let mut answer = 0;
    for (i, f) in first.into_iter().enumerate() {
        answer += (f - second[i]).abs();
    }

    Ok(answer)
}

fn part_two(input: &Path) -> anyhow::Result<i32> {
    let reader = BufReader::new(File::open(input)?);

    let mut first: Vec<i32> = vec![];
    let mut second: Vec<i32> = vec![];
    for line in reader.lines() {
        let line = line?;
        let mut numbers = line.split_whitespace();
        first.push(numbers.next().unwrap().parse()?);
        second.push(numbers.next().unwrap().parse()?);
    }
    let mut answer = 0;
    for f in first {
        let amount = second
            .clone()
            .into_iter()
            .filter(|&s| s == f)
            .collect::<Vec<i32>>()
            .len();
        answer += f * amount as i32;
    }

    Ok(answer)
}