use color_eyre::{eyre::eyre, Result};

pub fn solve() -> Result<()> {
  let input_data = include_str!("../../data/day_07.txt").trim();
  println!("Day 07 Part 1: {}", part_1(input_data)?);
  println!("Day 07 Part 2: {}", part_2(input_data)?);
  Ok(())
}

fn parse_crabs(input: &str) -> Result<(Vec<isize>, isize)> {
  let crabs = input
    .split(",")
    .map(str::parse)
    .collect::<Result<Vec<_>, _>>()?;

  let highest_crab = *crabs
    .iter()
    .max()
    .ok_or(eyre!("Unable to find highest crab"))?;

  Ok((crabs, highest_crab))
}

fn part_1(input: &str) -> Result<isize> {
  let (crabs, highest_crab) = parse_crabs(input)?;
  (0..=highest_crab)
    .map(|target_position| {
      crabs
        .iter()
        .map(|crab| (target_position - crab).abs())
        .sum()
    })
    .min()
    .ok_or(eyre!("Unable to find lowest fuel"))
}

fn part_2(input: &str) -> Result<isize> {
  let (crabs, highest_crab) = parse_crabs(input)?;
  (0..=highest_crab)
    .map(|target_position| {
      crabs
        .iter()
        .map(|crab| (target_position - crab).abs())
        .map(|steps| (steps * (steps + 1)) / 2)
        .sum()
    })
    .min()
    .ok_or(eyre!("Unable to find lowest fuel"))
}