#[derive(Debug)]
enum Instruction {
    Noop,
    AddX(i32),
}

fn main() {
    let contents = std::fs::read_to_string("data.txt").expect("Failed to read file");
    let ops = contents.lines().map(parse).collect::<Vec<Instruction>>();

    let strength = run(&ops);
    println!("total signal strength {:?}", strength);
}

fn parse(line: &str) -> Instruction {
    let parts = line.split(" ").collect::<Vec<&str>>();
    match parts[0] {
        "noop" => Instruction::Noop,
        _ => Instruction::AddX(parts[1].parse().unwrap()),
    }
}

fn run(ops: &Vec<Instruction>) -> i32 {
    let mut x: i32 = 1;
    let mut cycle = 1;
    let mut to_add = None;
    let mut op_idx = 0;
    let mut strength = 0;

    while op_idx < ops.len() {
        let pixel = cycle % 40;
        let diff = (x + 1 - pixel).abs();
        if diff.abs() <= 1 {
            print!("#");
        } else {
            print!(" ");
        }

        match to_add {
            None => {
                match ops[op_idx] {
                    Instruction::Noop => (),
                    Instruction::AddX(v) => {
                        to_add = Some(v);
                    }
                }
                op_idx += 1;
            }
            Some(v) => {
                x += v;
                to_add = None;
            }
        }

        if (cycle + 20) % 40 == 0 {
            strength += x * cycle;
        }

        if cycle % 40 == 0 {
            println!();
        }

        cycle += 1;
    }

    strength
}