use crate::constants::ITILE_SIZE;
use crate::entities::shared_components::Ambulatory;
use bevy::prelude::*;
use rustc_hash::FxHashMap;

#[derive(Resource, Default)]
pub struct TileOccupancy {
    pub counts: FxHashMap<(i32, i32), u8>,
}

impl TileOccupancy {
    #[inline]
    pub fn count_at(&self, world_pos: Vec3) -> u8 {
        let tx = (world_pos.x as i32) / ITILE_SIZE;
        let ty = (world_pos.y as i32) / ITILE_SIZE;
        *self.counts.get(&(tx, ty)).unwrap_or(&0)
    }
}

pub fn rebuild_tile_occupancy(
    mut occupancy: ResMut<TileOccupancy>,
    query: Query<&Transform, With<Ambulatory>>,
) {
    occupancy.counts.clear();
    for transform in query.iter() {
        let tx = (transform.translation.x as i32) / ITILE_SIZE;
        let ty = (transform.translation.y as i32) / ITILE_SIZE;
        let count = occupancy.counts.entry((tx, ty)).or_insert(0);
        if *count < 255 {
            *count += 1;
        }
    }
}