use grid::*;

fn main() {
    let mut input = include_str!("../input.txt").lines().peekable();
    let width = input.peek().unwrap().len();
    let mut grid = Grid::from_vec(input.flat_map(|l| l.chars()).collect(), width);

    let time = std::time::Instant::now();

    let mut sum = 0;

    for i in 0..width * grid.rows() {
        let x = (i % width) as i16;
        let y = (i / width) as i16;

        let cell = grid[(y as usize, x as usize)];

        if cell == '#' {
            continue;
        }

        let mut cells = Vec::new();
        let perimeter = explore(x, y, cell, &mut grid, &mut cells);

        sum += cells.len() as u32 * perimeter;
    }

    println!("Time: {:?}", time.elapsed());
    println!("🪵 answer: {:#?}", sum);
}

fn explore(
    x: i16,
    y: i16,
    cell: char,
    grid: &mut Grid<char>,
    cells: &mut Vec<(u16, u16)>,
) -> u32 {
    if cells.iter().any(|&(cy, cx)| cy as i16 == y && cx as i16 == x) {
        return 0;
    }

    if let Some(other) = grid.get(y, x) {
        if *other == cell {
            cells.push((y as u16, x as u16));
            grid[(y as usize, x as usize)] = '#';

            let val = explore(x, y - 1, cell, grid, cells) +
                explore(x + 1, y, cell, grid, cells) +
                explore(x, y + 1, cell, grid, cells) +
                explore(x - 1, y, cell, grid, cells);

            return val;

        } else {
            return 1;
        }
    }

    1 // no cell means edge. That adds 1 perimeter
}