use std::fs::{File, OpenOptions};
use std::io::{BufRead, BufReader, Error, Write};

#[derive(Debug)]
pub struct Input {
  a: u64,
  b: u64,
}

#[derive(Debug)]
pub struct Output {
  sum: u64,
}

pub fn read_input(filepath: &str) -> Input {
  let reader = match File::open(filepath) {
    Ok(f) => BufReader::new(f),
    Err(e) => panic!("Failed opening input file: {}", e.to_string()),
  };

  let input = reader
    .lines()
    .into_iter()
    .map(|r| r.map(|s| s.parse().unwrap()))
    .collect::<Vec<Result<u64, Error>>>();

  match input.as_slice() {
    [Ok(a), Ok(b)] => Input { a: *a, b: *b },
    _ => panic!("Ill formatted input file"),
  }
}

pub fn write_output(filepath: &str, output: &Output) {
  let mut file = OpenOptions::new()
    .write(true)
    .truncate(true)
    .create(true)
    .open(filepath)
    .expect("Failed opening output file");

  file
    .write(&output.sum.to_string().as_bytes())
    .expect("Failed writing to output file");
}

pub fn solve(input: Input) -> Output {
  Output { sum: input.a + input.b }
}
fn main() {
  let input = read_input("adunare.in");
  write_output("adunare.out", &solve(input));
}