use crate::{inspector::HideFromInspector, prelude::*};
use bevy::{
    ecs::{system::SystemState, world::CommandQueue},
    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)]
struct MapGenTask(Task<CommandQueue>);

#[derive(Resource, Deref, DerefMut)]
struct TileStorageHandle(TileStorage);

pub fn spawn(mut commands: Commands, assets: Res<AssetServer>) {
    // 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 tilemap = commands.spawn((Tilemap, Name::new("Tilemap"))).id();
    commands.insert_resource(TileStorageHandle(TileStorage::empty(size)));
    let pool = AsyncComputeTaskPool::get();
    // this task is for generating tilebundles
    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
            });
            let task = pool.spawn(async move {
                let mut command_queue = CommandQueue::default();
                command_queue.push(move |world: &mut World| {
                    let mut state = SystemState::<ResMut<TileStorageHandle>>::new(world);
                    let entity = world
                        .spawn((
                            HideFromInspector,
                            TileBundle {
                                position,
                                tilemap_id: TilemapId(tilemap),
                                texture_index,
                                ..Default::default()
                            },
                        ))
                        .id();

                    let mut storage = state.get_mut(world);
                    storage.set(&position, entity);
                });
                command_queue
            });
            commands.entity(tilemap).insert(MapGenTask(task));
        }
    }
}

fn load(mut commands: Commands, mut tasks: Query<&mut MapGenTask>) {
    // to avoid locking up the universe we only want to handle a certain number per iteration (Update)
    for mut task in &mut tasks {
        if let Some(mut commands_queue) = block_on(future::poll_once(&mut task.0)) {
            // append the returned command queue to have it execute later
            commands.append(&mut commands_queue);
        }
    }
}

pub fn finalize(
    // mut commands: Commands,
    // mut storage: Res<TileStorageHandle>,
    // tilemap: Query<Entity, With<Tilemap>>,
    // assets: Res<AssetServer>,
    world: &mut World,
) {
    let storage = world.remove_resource::<TileStorageHandle>().unwrap();

    // TODO: dedupe with load
    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 storage = storage.0;
    let mut query = world.query_filtered::<Entity, With<Tilemap>>();
    let tilemap = query.single(world);
    let assets = world.resource::<AssetServer>();
    let texture = TilemapTexture::Single(assets.load("img/Tileset Grass.png"));
    let mut commands = world.commands();
    commands.entity(tilemap).insert(TilemapBundle {
        grid_size,
        map_type,
        size,
        storage,
        texture,
        tile_size,
        transform: get_tilemap_center_transform(&size, &grid_size, &map_type, f32::MIN),
        ..Default::default()
    });
}

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