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

fn update_signal(cycle: i32, register: i32, signal: i32) -> i32 {
    match cycle % 40 {
        20 => signal + register * cycle,
        _ => signal
    }
}

fn main() {
    let file_path = String::from("input");
    let mut cycle: i32 = 0;
    let mut register: i32 = 1;
    let mut signal: i32 = 0;

    println!("In file {}", file_path);

    if let Ok(lines) = read_lines(file_path) {
        // Consumes the iterator, returns an (Optional) String
        for line in lines {
            if let Ok(ip) = line {
                let split: Vec<&str> = ip.split(" ").collect();
                let v = split.get(1).unwrap_or(&"").parse::<i32>();
                match v {
                    Ok(n) => {
                        cycle += 1;
                        signal = update_signal(cycle, register, signal);
                        cycle += 1;
                        signal = update_signal(cycle, register, signal);
                        register += n;
                    },
                    Err(_) => {
                        cycle += 1;
                        signal = update_signal(cycle, register, signal);
                    },
                }
            }
        }
    }

    println!("signal {}", signal);
}

fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where P: AsRef<Path>, {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}