use std::error::Error;
use std::fs::File;
use std::io::{self, BufRead};
use std::vec::Vec;

fn is_valid(line: &Vec<String>) -> bool {
    let pos1: usize = line[0].parse().unwrap();
    let pos2: usize = line[1].parse().unwrap();
    let policy_char = line[2].chars().nth(0).unwrap();

    let char1 = line[3].chars().nth(pos1 - 1);
    let char2 = line[3].chars().nth(pos2 - 1);

    match (char1, char2) {
        (Some(c1), Some(c2)) => (c1 == policy_char) ^ (c2 == policy_char),
        (Some(c), None) => (c == policy_char),
        (None, Some(c)) => (c == policy_char),
        (None, None) => false,
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let file = File::open("inputs/day2.txt")?;
    let lines = io::BufReader::new(file).lines().map(|l| l.unwrap());

    let parts: Vec<Vec<String>> = lines
        .map(|l| {
            l.split(|c| c == ' ' || c == ':' || c == '-')
                .filter(|s| *s != "")
                .map(|s| s.to_string())
                .collect()
        })
        .collect();

    let valid_count = parts
        .iter()
        .map(|p| if is_valid(p) { 1 } else { 0 })
        .fold(0, |acc, x| acc + x);

    println!("Total valid: {}", valid_count);

    Ok(())
}