use std::fs::File;
use std::io;
use std::io::BufRead;
use std::io::BufReader;

pub fn part1() -> io::Result<u32> {
    let file = File::open("input/day1")?;
    let reader = BufReader::new(file);

    let mut first = true;
    let mut previous = 0;
    let mut count = 0;

    for line in reader.lines() {
        let num: u32 = line?.parse().unwrap();

        if !first && num > previous {
            count += 1;
        }

        previous = num;
        first = false;
    }

    Ok(count)
}

pub fn part2() -> io::Result<u32> {
    let file = File::open("input/day1")?;
    let reader = BufReader::new(file);

    let mut vals: [u32; 3] = [0, 0, 0];
    let mut count = 0;

    for (i, line) in reader.lines().enumerate() {
        let num: u32 = line?.parse().unwrap();

        if i < 3 {
            vals[i] = num;
        } else {
            // Calculate the previous sum
            let sum = vals[0] + vals[1] + vals[2];

            // Shift the values
            vals[0] = vals[1];
            vals[1] = vals[2];
            vals[2] = num;

            let new_sum = vals[0] + vals[1] + vals[2];

            if new_sum > sum {
                count += 1;
            }
        }
    }

    Ok(count)
}