use crate::{inspector::HideFromInspector, prelude::*};
use bevy::tasks::{block_on, futures_lite::future, AsyncComputeTaskPool, Task};
// use bevy::{
//     ecs::world::CommandQueue,
//     tasks::{AsyncComputeTaskPool, Task},
// };
use bevy_ecs_tilemap::prelude::*;
use rand::prelude::*;
use rand_pcg::Pcg64;
use rand_seeder::Seeder;

#[derive(Component, Debug)]
pub struct Tilemap;

#[derive(Component, Debug)]
pub struct TileLoader(Task<()>);

#[derive(Event)]
pub struct TileLoadEvent(TileBundle);

pub fn init(
    mut commands: Commands,
    assets: Res<AssetServer>,
    mut loads: EventWriter<TileLoadEvent>,
) {
    // TODO: I'm pretty determined to not have this sieze up the game despite the large number of entities being added. Should work with a "loading" screen and doing this in the background?

    let mut rng: Pcg64 = Seeder::from("default_seed").make_rng();
    let size = TilemapSize::new(1024, 1024);
    let tile_size = TilemapTileSize::new(16., 16.);
    let grid_size = TilemapGridSize::new(16., 16.);
    let map_type = TilemapType::Square;
    let texture = TilemapTexture::Single(assets.load("img/Tileset Grass.png"));
    let storage = TileStorage::empty(size);

    let tilemap = commands
        .spawn((
            Tilemap,
            Name::new("Tilemap"),
            TilemapBundle {
                grid_size,
                map_type,
                size,
                storage,
                texture,
                tile_size,
                transform: get_tilemap_center_transform(&size, &grid_size, &map_type, f32::MIN),
                ..Default::default()
            },
        ))
        .id();

    let pool = AsyncComputeTaskPool::get();
    let task = pool.spawn(async move {
        for x in 0..size.x {
            for y in 0..size.y {
                let position = TilePos::new(x, y);
                let texture_index = TileTextureIndex(if rng.gen_range(0..1000) > 925 {
                    rng.gen_range(0..(16 * 8))
                } else {
                    0
                });
                loads.send(TileLoadEvent(TileBundle {
                    position,
                    tilemap_id: TilemapId(tilemap),
                    texture_index,
                    ..default()
                }));
            }
        }

        return ();
    });

    commands.entity(tilemap).insert(TileLoader(task));
}

pub fn tile_loaders(
    mut commands: Commands,
    mut storage: Query<&mut TileStorage>,
    mut tasks: Query<&mut TileLoader>,
    mut loads: EventReader<TileLoadEvent>,
) {
    // TODO: to avoid locking up the universe we only want to handle a certain number per iteration (Update)
    let mut storage = storage.single_mut();
    for ev in loads.read() {
        let ref_position = &ev.0.position;
        let tile = commands.spawn((HideFromInspector, ev.0)).id();
        storage.set(ref_position, tile);
    }

    for mut task in &mut tasks {
        if block_on(future::poll_once(&mut task.0)).is_some() {
            // TODO: transition to game?
        }
    }
}

pub fn exit(mut commands: Commands, q: Query<Entity, With<Tilemap>>) {
    for id in q.iter() {
        commands.entity(id).despawn_recursive();
    }
}