#![allow(clippy::precedence)]
#![allow(clippy::too_many_arguments)]

pub use crate::filters::*;

use crate::AppState;

use bevy::{
	ecs::system::EntityCommands,
	input::{keyboard::KeyCode, Input},
	prelude::{shape::Quad, *},
	sprite::Mesh2dHandle,
};
use bevy_rapier2d::prelude::*;

pub enum AudioMsg {
	Color([f32; 3]),
	Fusion,
	Jump,
	Switch,
}

#[derive(Clone, Copy, Eq, Hash, PartialEq)]
pub struct LevelId(pub u32);

pub struct GamePlugin;

impl Plugin for GamePlugin {
	fn build(&self, app: &mut App) {
		app.add_event::<LevelStartupEvent>()
			.init_resource::<CharacterMeshes>()
			.insert_resource(CurrentLevel(None))
			.add_system_set(SystemSet::on_enter(AppState::Game).with_system(setup))
			.add_system_set(SystemSet::on_enter(AppState::Win).with_system(win_setup))
			.add_system_set(
				SystemSet::on_exit(AppState::Win).with_system(crate::levels::despawn_level),
			)
			.add_system_set(
				SystemSet::on_update(AppState::Game)
					.with_system(crate::levels::post_setup_level)
					.with_system(change_character_system)
					.with_system(player_movement_system)
					.with_system(move_camera)
					.with_system(character_particle_effect_system),
			)
			.add_system_set(
				SystemSet::on_update(AppState::Win)
					.with_system(player_movement_system)
					.with_system(move_camera)
					.with_system(character_particle_effect_system),
			)
			.add_system_to_stage(CoreStage::PostUpdate, collision_event_system);
	}
}

// Events

pub struct LevelStartupEvent(pub Entity);

// Resources

pub struct CurrentLevel(pub Option<LevelId>);

pub struct CharacterMeshes {
	square: Mesh2dHandle,
}

impl FromWorld for CharacterMeshes {
	fn from_world(world: &mut World) -> Self {
		let mut meshes = world.get_resource_mut::<Assets<Mesh>>().unwrap();
		Self {
			square: meshes
				.add(Mesh::from(Quad {
					size: Vec2 { x: 64.0, y: 64.0 },
					flip: false,
				}))
				.into(),
		}
	}
}

// Components

#[derive(Component)]
pub struct Level;

#[derive(Clone, Component, PartialEq)]
pub struct CharacterColor(pub Color);

#[derive(Component)]
pub struct Player;

// Systems

fn setup(
	mut commands: Commands,
	mut current_level: ResMut<CurrentLevel>,
	mut level_startup_event: EventWriter<LevelStartupEvent>,
	mut camera_query: Query<&mut Transform, With<Camera>>,
) {
	let level_id = LevelId(current_level.0.map_or(0, |level_id| level_id.0 + 1));
	crate::levels::setup_level(
		&mut commands,
		&mut current_level,
		&mut level_startup_event,
		&mut camera_query,
		level_id,
	);
}

pub fn spawn_characters<I: IntoIterator<Item = (Transform, Color)>>(
	commands: &mut Commands,
	character_meshes: &Res<CharacterMeshes>,
	materials: &mut ResMut<Assets<ColorMaterial>>,
	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,

	characters: I,
) {
	for (i, (transform, color)) in characters.into_iter().enumerate() {
		spawn_character(
			commands,
			character_meshes,
			materials,
			audio,
			transform,
			color,
			i == 0,
		);
	}
}

pub fn spawn_character(
	commands: &mut Commands,
	character_meshes: &Res<CharacterMeshes>,
	materials: &mut ResMut<Assets<ColorMaterial>>,
	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
	mut transform: Transform,
	color: Color,
	is_player: bool,
) {
	transform.translation.z = transform.translation.z.max(1.0);

	let color_mesh_2d_bundle: ColorMesh2dBundle = ColorMesh2dBundle {
		mesh: character_meshes.square.clone(),
		material: materials.add(ColorMaterial::from(color)),
		transform,
		..default()
	};

	let mut entity_commands: EntityCommands = commands.spawn_bundle(color_mesh_2d_bundle);

	entity_commands
		.insert(Level)
		.insert(CharacterColor(color))
		.insert(RigidBody::Dynamic)
		.insert(Collider::cuboid(32., 32.))
		.insert(ExternalForce::default())
		.insert(Velocity::default())
		.insert(GravityScale(10.0))
		.insert(LockedAxes::ROTATION_LOCKED)
		.insert(Friction::new(0.8))
		.insert(Damping {
			linear_damping: 0.5,
			angular_damping: 0.5,
		})
		.insert(ExternalImpulse::default())
		.insert(ActiveEvents::COLLISION_EVENTS);

	if is_player {
		entity_commands.insert(Player);
		audio
			.send(AudioMsg::Color([color.r(), color.g(), color.b()]))
			.ok();
	}
}

fn collision_event_system(
	mut commands: Commands,
	character_meshes: Res<CharacterMeshes>,
	mut materials: ResMut<Assets<ColorMaterial>>,
	mut collision_events: EventReader<CollisionEvent>,
	character_query: Query<(&CharacterColor, &Transform, Option<&Player>)>,
	mut app_state: ResMut<State<AppState>>,
	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
) {
	for collision_event in collision_events.iter() {
		if let CollisionEvent::Started(e1, e2, flags) = collision_event {
			if flags.is_empty() {
				if let (
					Ok((c1_color, c1_transform, c1_player)),
					Ok((c2_color, c2_transform, c2_player)),
				) = (character_query.get(*e1), character_query.get(*e2))
				{
					commands.entity(*e1).despawn_recursive();
					commands.entity(*e2).despawn_recursive();

					let new_color = (Vec4::from(c1_color.0) + Vec4::from(c2_color.0))
						.clamp(Vec4::ZERO, Vec4::ONE);

					// If color approximately white
					if app_state.current() == &AppState::Game
						&& 4. - new_color.length_squared() < 0.1
					{
						app_state.replace(AppState::Win).ok();
					}

					// position character based on current player location
					spawn_character(
						&mut commands,
						&character_meshes,
						&mut materials,
						&audio,
						if c1_player.is_some() {
							*c1_transform
						} else if c2_player.is_some() {
							*c2_transform
						} else {
							Transform::identity().with_translation(
								(c1_transform.translation + c2_transform.translation) / 2.,
							)
						},
						new_color.into(),
						c1_player.is_some() || c2_player.is_some(),
					);

					audio.send(AudioMsg::Fusion).ok();
				}
			}
		}
	}
}

fn change_character_system(
	mut commands: Commands,

	keyboard_input: Res<Input<KeyCode>>,
	characters: Query<(Entity, &CharacterColor, Option<&Player>)>,
	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
) {
	if !keyboard_input.just_pressed(KeyCode::Tab) {
		return;
	}

	let mut player_idx: usize = 0;
	let mut player_count: usize = 0;

	// find player idx
	for (_entity, _color, player) in characters.iter() {
		if player.is_some() {
			player_idx = player_count;
		}
		player_count += 1;
	}

	// calculate next player index
	let next_player_idx = (player_idx + 1) % player_count;
	player_count = 0;

	// exchange `Player` component from old `player_idx` to new `next_player_idx`
	for (entity, color, _player) in characters.iter() {
		if player_count == player_idx {
			commands.entity(entity).remove::<Player>();
		}

		if player_count == next_player_idx {
			commands.entity(entity).insert(Player);
			audio
				.send(AudioMsg::Color([color.0.r(), color.0.g(), color.0.b()]))
				.ok();
			audio.send(AudioMsg::Switch).ok();
		}

		player_count += 1;
	}
}

fn player_movement_system(
	keyboard_input: Res<Input<KeyCode>>,
	mut characters: Query<&mut Velocity, With<Player>>,
	mut app_state: ResMut<State<AppState>>,
	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
) {
	let right_pressed: bool =
		keyboard_input.pressed(KeyCode::Right) || keyboard_input.pressed(KeyCode::D);
	let left_pressed: bool =
		keyboard_input.pressed(KeyCode::Left) || keyboard_input.pressed(KeyCode::A);

	for mut velocity in characters.iter_mut() {
		velocity.linvel.x = 200. * (right_pressed as i8 - left_pressed as i8) as f32;

		if keyboard_input.just_pressed(KeyCode::Space) {
			audio.send(AudioMsg::Jump).ok();
			velocity.linvel.y = 500.;
		}
	}

	if app_state.current() == &AppState::Win && keyboard_input.just_pressed(KeyCode::Return) {
		app_state.replace(AppState::Game).unwrap();
	}
}

fn character_particle_effect_system(
	characters: Query<(&Transform, &CharacterColor), With<Player>>,
	mut particle_effect: ResMut<crate::particle_effect::ParticleEffectResource>,
) {
	for (transform, color) in characters.iter() {
		particle_effect.translation = transform.translation;
		particle_effect.color = color.0;
	}
}

fn win_setup(mut commands: Commands, asset_server: Res<AssetServer>) {
	let font = asset_server.get_handle("UacariLegacy-Thin.ttf");
	commands
		.spawn_bundle(Text2dBundle {
			text: Text::from_section(
				"Press ENTER to level up",
				TextStyle {
					font,
					font_size: 32.0,
					color: Color::WHITE,
				},
			)
			.with_alignment(TextAlignment::CENTER),
			..Default::default()
		})
		.insert(Level);
}

fn move_camera(
	mut camera_query: Query<(&Camera, &mut Transform)>,
	characters: Query<&Transform, (Without<Camera>, With<Player>)>,
	time: Res<Time>,
) {
	const MARGIN: f32 = 300.0;
	const FOLLOW_SPEED: f32 = std::f32::consts::PI;

	for character_transform in characters.iter() {
		let (camera, mut camera_transform) = camera_query.single_mut();

		let size: Vec2 = camera.logical_viewport_size().unwrap();
		let half_height: f32 = size.y * 0.5;
		camera_transform.translation = camera_transform.translation.lerp(
			character_transform.translation,
			time.delta_seconds() * FOLLOW_SPEED,
		);

		// prevent camera from going too low
		camera_transform.translation.y = camera_transform.translation.y.max(half_height - MARGIN);
		// always make sure that camera is away from the object in order to render them
		camera_transform.translation.z = 999.0;
	}
}