use itertools::Itertools;
use std::error::Error;
use std::fs::File;
use std::io::{self, BufRead};
use std::vec::Vec;

const WIN_LEN: usize = 25;

fn main() -> Result<(), Box<dyn Error>> {
    let file = File::open("inputs/day9.txt")?;
    let lines = io::BufReader::new(file).lines().map(|l| l.unwrap());

    let numbers: Vec<u64> = lines.map(|l| l.parse().unwrap()).collect();

    let mut target = 0;

    for win in numbers.windows(WIN_LEN + 1) {
        target = win[WIN_LEN];
        let canidates = &win[0..WIN_LEN];
        let mut valid = false;

        for pair in canidates.iter().combinations(2) {
            //println!("{} + {} = {}", pair[0], pair[1], pair[0] + pair[1]);
            if pair[0] + pair[1] == target {
                valid = true;
                break;
            }
        }

        if !valid {
            break;
        }
    }

    println!("Invalid Number: {}", target);
    let invalid_pos = numbers.iter().position(|n| *n == target).unwrap();

    println!("Target is at: {}", invalid_pos);
    'sum_outer: for len in 2..invalid_pos {
        for win in numbers.windows(len) {
            let sum = win.iter().fold(0, |x, acc| x + acc);
            if sum == target {
                println!("Set: {:?}", win);
                let min = win
                    .iter()
                    .fold(*win.first().unwrap(), |x, acc| u64::min(x, *acc));

                let max = win
                    .iter()
                    .fold(*win.first().unwrap(), |x, acc| u64::max(x, *acc));

                println!("Answer: {}", min + max);

                break 'sum_outer;
            }
        }
    }

    Ok(())
}