use std::{
    fs::File,
    io::{prelude::*, BufReader},
};
fn main() {
    let input = read_input("input.txt");
    println!("part one: {}", part_one(&input));
}
fn read_input(filename: &str) -> Vec<Vec<char>> {
    let file = File::open(filename).expect("no such file");
    let buf = BufReader::new(file);
    buf.lines()
        .map(|l| -> Vec<char> {l.expect("Could not parse line").chars().collect()})
        .collect()
}
fn part_one(input: &Vec<Vec<char>>) -> u32 {
    let mut x = 0;
    let mut y = 0;
    let mut collisions = 0;
    let width = input[0].len();
    while y < input.len() {
        if x >= width {
            x = x - width;
        }
        if input[y][x] == '#' {
            collisions += 1;
        }
        x += 3;
        y += 1;
    }
    collisions
}
#[test]
fn test_read_input() {
    let input = read_input("test_input.txt");
    let first_char = input[0][0];
    assert_eq!(first_char, '.')
}
#[test]
fn test_part_one() {
    let input = read_input("test_input.txt");
    assert_eq!(part_one(&input), 7)
}

[package]
name = "three"
version = "0.1.0"
authors = ["David Mynors <hello@davidmyno.rs>"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]

# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
[[package]]
name = "three"
version = "0.1.0"