#[path = "../lib.rs"]
mod lib;

fn parse_input() -> ([Vec<(usize, usize)>; 256], usize, usize) {
    let mut x = 0;
    let mut y = 0;
    let mut antennas = core::array::from_fn(|_| vec![]);
    for line in lib::iter_input() {
        x = 0;
        for b in line.bytes() {
            if b != b'.' {
                antennas[b as usize].push((x, y));
            }
            x += 1;
        }
        y += 1;
    }
    return (antennas, x, y);
}

fn gcd(a: usize, b: usize) -> usize {
    let mut x = a.max(b);
    let mut y = a.min(b);
    while y > 0 {
        (x, y) = (y, x % y);
    }
    return x;
}

fn main() {
    let mut sum1 = 0;
    let mut sum2 = 0;

    let (antennas, w, h) = parse_input();
    let mut points1 = vec![vec![false; w]; h];
    let mut points2 = vec![vec![false; w]; h];

    for set in antennas.iter() {
        for i in 0..set.len() {
            for j in 0..set.len() {
                if i != j {
                    let (x1, y1) = set[i];
                    let (x2, y2) = set[j];

                    if 2 * x1 >= x2 && 2 * x1 < w + x2 && 2 * y1 >= y2 && 2 * y1 < h + y2 {
                        // p3 = (1 - (-1)) * p1 + (-1) * p2
                        let x3 = 2 * x1 - x2;
                        let y3 = 2 * y1 - y2;
                        if !points1[y3][x3] {
                            points1[y3][x3] = true;
                            sum1 += 1;
                        }
                    }

                    let d = gcd(x1.abs_diff(x2), y1.abs_diff(y2));
                    for t in 0.. {
                        if (d + t) * x1 < t * x2
                            || (d + t) * y1 < t * y2
                            || (d + t) * x1 >= w * d + t * x2
                            || (d + t) * y1 >= h * d + t * y2
                        {
                            break;
                        }

                        // p3 = (1 - (-t/d)) * p1 + (-t/d) * p2
                        let x3 = ((d + t) * x1 - t * x2) / d;
                        let y3 = ((d + t) * y1 - t * y2) / d;
                        if !points2[y3][x3] {
                            points2[y3][x3] = true;
                            sum2 += 1;
                        }
                    }
                }
            }
        }
    }

    println!("part1: {}", sum1);
    println!("part2: {}", sum2);
}