mod model;
mod parsing;

use aoc_runner_derive::{aoc, aoc_generator};
pub use model::CrabSub;
pub use parsing::parse_crab_sub_swarm;
use yap::IntoTokens;

#[aoc_generator(day7)]
pub fn parse_input(input: &str) -> Vec<CrabSub> {
    parse_crab_sub_swarm(&mut input.into_tokens())
}

#[aoc(day7, part1)]
pub fn part1(input: &[CrabSub]) -> usize {
    solve(input, &|x| x)
}

fn bounds(input: &[CrabSub]) -> (usize, usize) {
    let locations: Vec<usize> = input.iter().map(|sub| sub.location).collect();
    (
        *locations.iter().min().unwrap(),
        *locations.iter().max().unwrap(),
    )
}

pub fn solve(input: &[CrabSub], fuel_calc: &dyn Fn(usize) -> usize) -> usize {
    let mut req_fuel = usize::MAX;
    let (min, max) = bounds(input);
    for i in min..=max {
        let mut new_req_fuel = 0;
        for sub in input.iter() {
            new_req_fuel += fuel_calc((i as isize - sub.location as isize).abs() as usize);
        }
        if req_fuel > new_req_fuel {
            req_fuel = new_req_fuel;
        }
    }
    req_fuel
}

#[aoc(day7, part2)]
pub fn part2(input: &[CrabSub]) -> usize {
    solve(input, &|distance| (1..=distance).sum())
}

#[cfg(test)]
mod test {
    const EXAMPLE_INPUT: &str = "16,1,2,0,4,2,7,1,2,14";
    const RESULT_PART_1: usize = 37;
    const RESULT_PART_2: usize = 168;

    #[test]
    fn part1_example() {
        let result = super::part1(&super::parse_input(EXAMPLE_INPUT));
        assert_eq!(result, RESULT_PART_1);
    }

    #[test]
    fn part2_example() {
        let result = super::part2(&super::parse_input(EXAMPLE_INPUT));
        assert_eq!(result, RESULT_PART_2);
    }

    #[test]
    fn parse_example() {
        let example = super::parse_input(EXAMPLE_INPUT);
        assert_eq!(example.len(), 10);
    }
}