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

fn to_moves(line: String) -> (i32, i32) {
    let mut parts = line.split(" ");
    let dir = parts.nth(0).unwrap();
    let arg: i32 = parts.nth(0).unwrap().parse().unwrap();

    match dir {
        "up" => (0, -arg),
        "down" => (0, arg),
        "forward" => (arg, 0),
        _ => panic!("Unsupported Direction: {}", dir),
    }
}

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 moves: Vec<(i32, i32)> = lines.map(|l| to_moves(l)).collect();
    let pos = moves
        .iter()
        .fold((0, 0), |(ax, ay), (bx, by)| (ax + bx, ay + by));

    println!("Answer1: {}", pos.0 * pos.1);

    let pos = moves.iter().fold((0, 0, 0), |(x, y, aim), (mx, maim)| {
        (x + mx, y + mx * (maim + aim), aim + maim)
    });

    println!("Answer2: {}", pos.0 * pos.1);

    Ok(())
}