use crate::View;
use crate::{inspector::HideFromInspector, prelude::*};
use bevy::ecs::system::SystemState;
use bevy::ecs::world::CommandQueue;
use bevy::tasks::{block_on, futures_lite::future, AsyncComputeTaskPool, Task};
use bevy_ecs_tilemap::prelude::*;
use rand::prelude::*;
use rand_pcg::Pcg64;
use rand_seeder::Seeder;
use std::sync::mpsc::{channel, Receiver};
use std::sync::Mutex;

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

#[derive(Component, Debug)]
pub struct TileChan(Mutex<Receiver<TileBundle>>);

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

pub fn init(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 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 (tx, rx) = channel::<TileBundle>();
    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
                });
                tx.send(TileBundle {
                    position,
                    tilemap_id: TilemapId(tilemap),
                    texture_index,
                    ..Default::default()
                })
                .unwrap();
            }
        }
        return ();
    });

    commands
        .entity(tilemap)
        .insert((TileLoaderTask(task), TileChan(Mutex::new(rx))));
}

const MAX_TILES_TO_LOAD_IN_ONE_UPDATE: usize = 5_000;
pub fn tile_loaders(
    world: &mut World,
    tilemap: QueryState<Entity, With<Tilemap>>,
    storage: &mut QueryState<&mut TileStorage, With<Tilemap>>,
    chan: QueryState<&TileChan, With<Tilemap>>,
    task: QueryState<&mut TileLoaderTask, With<Tilemap>>,
    params: &mut SystemState<ResMut<NextState<View>>>,
) {
    // TODO: this state should maybe be converted to a resource or something?
    let mut tiles_done = false;
    let mut task_done = false;
    type AddingTile = (HideFromInspector, TileBundle);
    type AddedTile<'a> = (Entity, &'a TilePos);
    let mut tiles_to_add: Vec<AddingTile> = Vec::with_capacity(MAX_TILES_TO_LOAD_IN_ONE_UPDATE);
    let mut added_tiles: Vec<AddedTile> = Vec::with_capacity(MAX_TILES_TO_LOAD_IN_ONE_UPDATE);

    // let mut task = task;

    // {
    //     task_done = true;
    //     let mut task = task_query.get_single();
    //     if let Ok(task) = task {
    //         let poll = future::poll_once(task.0);
    //         if block_on(poll).is_some() {
    //             task_done = true;
    //             // task is done, remove it so we don't poll it again
    //             world.entity_mut(tilemap).remove::<TileLoaderTask>();
    //         }
    //     } else {
    //         next_view.set(View::InGame)
    //     }

    //     let (tilemap, mut storage) = entity_query.single_mut();
    //     let tiles: Vec<TileBundle> = vec![];
    //     if let Ok(channel) = channel_query.get_single_mut() {
    //         let channel = channel.0.lock().unwrap();
    //         tiles_done = false;
    //         let mut counter = 0;
    //         loop {
    //             match channel.recv() {
    //                 Ok(tile) => {
    //                     let position = &tile.position;
    //                     let tile = world.spawn((HideFromInspector, tile)).id();
    //                     storage.set(position, tile);
    //                     counter += 1;
    //                     if counter >= MAX_TILES_TO_LOAD_IN_ONE_UPDATE {
    //                         info!("Finished {}!", counter);
    //                         break;
    //                     }
    //                 }
    //                 Err(_) => {
    //                     world.entity_mut(tilemap).remove::<TileChan>();
    //                     if counter > 0 {
    //                         info!("Finished {counter}! Probably finishing mapgen soon...");
    //                     }
    //                     // the channel is likely closed, so let's note that and be done
    //                     tiles_done = true;
    //                     break;
    //                 }
    //             }
    //         }
    //     }

    for tile in tiles_to_add {
        added_tiles.push((id, &tile.1.position));
        let id = world.spawn(tile).id();
    }

    //     world.spawn_batch(
    //         tiles
    //             .into_iter()
    //             .map(|t| (HideFromInspector, t))
    //             .into_iter(),
    //     );

    {
        let mut storage = storage.single_mut(world);
        // storage.set(&
        let mut next_view = params.get_mut(world);
        if task_done && tiles_done {
            next_view.set(View::InGame)
        }
    }
}

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