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

fn main(){
    println!("Advent of Code #2!\n");

    let path = Path::new("./2.txt");
    let display = path.display();

    let file = match File::open(&path) {
        Err(why) => panic!("Couldn't open {}: {}", display, why),
        Ok(file) => file,
    };

    let lines = io::BufReader::new(file).lines();
    let mut instructions = Vec::<(String, u32)>::new();

    for line in lines {
        if let Ok(l) = line {
            let mut words_iter = l.split_whitespace();
            let direction = words_iter.next().unwrap().to_string();
            let distance = words_iter.next().unwrap().parse::<u32>().unwrap();

            instructions.push((direction, distance));
        }
    }

    let mut depth = 0;
    let mut position = 0;
    for (direction, distance) in &instructions {
        match direction.as_str() {
            "forward" => position += distance,
            "up" => depth -= distance,
            "down" => depth += distance,
            s => println!("Stumbled upon unknown input: {}", s),
        }
    }

    println!("Position of {} * depth of {} equals {}", position, depth, position * depth);

    
    // Now for the second part of day 2
    // So instead of just adding to the depth immediately through the up and down commands, we now use
    // a so-called aim

    depth = 0;
    position = 0;
    let mut aim = 0;

    for (direction, distance) in &instructions {
        match direction.as_str() {
            "forward" => {
                depth += aim * distance;
                position += distance
            },
            "up" => aim -= distance,
            "down" => aim += distance,
            s => println!("Stumbled upon unknown input: {}", s),
        }
    }

    println!("Position of {} * depth of {} equals {}", position, depth, position * depth);
}