//! Simulate the Minecraft world, currently only used for tests.

use std::sync::Arc;

use azalea_client::{
    ClientMovementState, interact::BlockStatePredictionHandler, local_player::LocalGameMode,
    mining::MineBundle,
};
use azalea_core::{
    entity_id::MinecraftEntityId, game_type::GameMode, position::Vec3, tick::GameTick,
};
use azalea_entity::{
    Attributes, LookDirection, Physics, Position, dimensions::EntityDimensions,
    inventory::Inventory,
};
use azalea_registry::builtin::EntityKind;
use azalea_world::{ChunkStorage, PartialWorld, World, WorldName, Worlds};
use bevy_app::App;
use bevy_ecs::prelude::*;
use parking_lot::RwLock;
use uuid::Uuid;

#[derive(Bundle, Clone)]
pub struct SimulatedPlayerBundle {
    pub position: Position,
    pub physics: Physics,
    pub physics_state: ClientMovementState,
    pub look_direction: LookDirection,
    pub attributes: Attributes,
    pub inventory: Inventory,
}

impl SimulatedPlayerBundle {
    pub fn new(position: Vec3) -> Self {
        let dimensions = EntityDimensions::from(EntityKind::Player);

        SimulatedPlayerBundle {
            position: Position::new(position),
            physics: Physics::new(&dimensions, position),
            physics_state: ClientMovementState::default(),
            look_direction: LookDirection::default(),
            attributes: Attributes::new(EntityKind::Player),
            inventory: Inventory::default(),
        }
    }
}

fn simulation_world_name() -> WorldName {
    WorldName::new("azalea:simulation")
}

fn create_simulation_world(chunks: ChunkStorage) -> (App, Arc<RwLock<World>>) {
    let world_name = simulation_world_name();

    let world = Arc::new(RwLock::new(World {
        chunks,
        ..Default::default()
    }));

    let mut app = App::new();
    // we don't use all the default azalea plugins because we don't need all of them
    app.add_plugins((
        azalea_physics::PhysicsPlugin,
        azalea_entity::EntityPlugin,
        azalea_client::movement::MovementPlugin,
        super::PathfinderPlugin,
        crate::bot::BotPlugin,
        azalea_client::task_pool::TaskPoolPlugin::default(),
        // for mining
        azalea_client::inventory::InventoryPlugin,
        azalea_client::mining::MiningPlugin,
        azalea_client::interact::InteractPlugin,
        azalea_client::loading::PlayerLoadedPlugin,
    ))
    .insert_resource(Worlds {
        map: [(world_name.clone(), Arc::downgrade(&world.clone()))]
            .iter()
            .cloned()
            .collect(),
    });

    app.edit_schedule(bevy_app::Main, |schedule| {
        schedule.set_executor_kind(bevy_ecs::schedule::ExecutorKind::SingleThreaded);
    });

    app.finish();

    (app, world)
}

fn create_simulation_player_complete_bundle(
    world: Arc<RwLock<World>>,
    player: &SimulatedPlayerBundle,
) -> impl Bundle {
    let world_name = simulation_world_name();

    (
        MinecraftEntityId(0),
        azalea_entity::LocalEntity,
        azalea_entity::metadata::PlayerMetadataBundle::default(),
        azalea_entity::EntityBundle::new(
            Uuid::nil(),
            *player.position,
            EntityKind::Player,
            world_name,
        ),
        azalea_client::local_player::WorldHolder {
            // the partial world is never actually used by the pathfinder, so we can leave it empty
            partial: Arc::new(RwLock::new(PartialWorld::default())),
            shared: world.clone(),
        },
        Inventory::default(),
        LocalGameMode::from(GameMode::Survival),
        MineBundle::default(),
        BlockStatePredictionHandler::default(),
        azalea_client::local_player::PermissionLevel::default(),
        azalea_entity::PlayerAbilities::default(),
    )
}

pub fn create_simulation_player(
    ecs: &mut bevy_ecs::world::World,
    world: Arc<RwLock<World>>,
    player: SimulatedPlayerBundle,
) -> Entity {
    let mut entity = ecs.spawn(create_simulation_player_complete_bundle(world, &player));
    entity.insert(player);
    entity.id()
}

/// Simulate the Minecraft world to see if certain movements would be possible.
pub struct Simulation {
    pub app: App,
    pub entity: Entity,
    pub world: Arc<RwLock<World>>,
}

impl Simulation {
    pub fn new(chunks: ChunkStorage, player: SimulatedPlayerBundle) -> Self {
        let (mut app, world) = create_simulation_world(chunks);
        let entity = create_simulation_player(app.world_mut(), world.clone(), player);
        Self { app, entity, world }
    }

    /// Despawn the old simulated player and create a new one.
    ///
    /// This is cheaper than creating a new [`Simulation`] from scratch.
    pub fn reset(&mut self, player: SimulatedPlayerBundle) {
        self.app.world_mut().despawn(self.entity);
        let entity = create_simulation_player(self.app.world_mut(), self.world.clone(), player);
        self.entity = entity;
    }

    pub fn tick(&mut self) {
        self.run_update_schedule();
        self.run_gametick_schedule();
    }

    pub fn run_update_schedule(&mut self) {
        self.app.update();
    }
    pub fn run_gametick_schedule(&mut self) {
        self.app.world_mut().run_schedule(GameTick);
    }

    pub fn component<T: Component + Clone>(&self) -> T {
        self.app.world().get::<T>(self.entity).unwrap().clone()
    }
    pub fn get_component<T: Component + Clone>(&self) -> Option<T> {
        self.app.world().get::<T>(self.entity).cloned()
    }
    pub fn position(&self) -> Vec3 {
        *self.component::<Position>()
    }
    pub fn physics(&self) -> Physics {
        self.component::<Physics>().clone()
    }
    pub fn is_mining(&self) -> bool {
        // return true if the component is present and Some
        self.get_component::<azalea_client::mining::MineBlockPos>()
            .and_then(|c| *c)
            .is_some()
    }
}

/// A set of simulations, useful for efficiently doing multiple simulations.
pub struct SimulationSet {
    pub app: App,
    world: Arc<RwLock<World>>,
}
impl SimulationSet {
    pub fn new(chunks: ChunkStorage) -> Self {
        let (app, world) = create_simulation_world(chunks);
        Self { app, world }
    }
    pub fn tick(&mut self) {
        self.app.update();
        self.app.world_mut().run_schedule(GameTick);
    }

    pub fn spawn(&mut self, player: SimulatedPlayerBundle) -> Entity {
        create_simulation_player(self.app.world_mut(), self.world.clone(), player)
    }
    pub fn despawn(&mut self, entity: Entity) {
        self.app.world_mut().despawn(entity);
    }

    pub fn position(&self, entity: Entity) -> Vec3 {
        **self.app.world().get::<Position>(entity).unwrap()
    }
}