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

pub use crate::audio::AudioMsg;

use crate::AppState;

use bevy::{
	input::{keyboard::KeyCode, Input},
	prelude::{shape::Quad, *},
	sprite::Mesh2dHandle,
};
use bevy_rapier2d::prelude::*;
use std::collections::BTreeSet;

#[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(keyboard_input_system)
					.with_system(move_camera)
					.with_system(character_particle_effect_system),
			)
			.add_system_set(
				SystemSet::on_update(AppState::Win)
					.with_system(keyboard_input_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, Copy, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub struct CharacterId(pub u32);

#[derive(Clone, Component, Copy, Eq, Hash, PartialEq)]
pub struct SelectedCharacterId(pub Option<CharacterId>);

#[derive(Component)]
pub struct CharacterIdList(pub BTreeSet<CharacterId>);

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

// 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_character(
	commands: &mut Commands,
	character_meshes: &Res<CharacterMeshes>,
	materials: &mut ResMut<Assets<ColorMaterial>>,
	selected_character_id: &mut Mut<SelectedCharacterId>,
	character_id_list: &mut Mut<CharacterIdList>,
	audio: &Res<crossbeam_channel::Sender<AudioMsg>>,
	mut transform: Transform,
	color: Color,
) {
	transform.translation.z = transform.translation.z.max(1.0);

	let character_id = CharacterId(
		character_id_list
			.0
			.iter()
			.last()
			.map_or(0, |last_character_id| last_character_id.0 + 1),
	);
	character_id_list.0.insert(character_id);

	commands
		.spawn_bundle(ColorMesh2dBundle {
			mesh: character_meshes.square.clone(),
			material: materials.add(ColorMaterial::from(color)),
			transform,
			..default()
		})
		.insert(Level)
		.insert(character_id)
		.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 no character is selected, then select this one
	if selected_character_id.0.is_none() {
		selected_character_id.0 = Some(character_id);
		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<(&CharacterId, &CharacterColor, &Transform)>,
	mut level_query: Query<(&mut SelectedCharacterId, &mut CharacterIdList)>,
	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_id, c1_color, c1_transform)), Ok((c2_id, c2_color, _c2_transform))) =
					(character_query.get(*e1), character_query.get(*e2))
				{
					let (mut selected_character_id, mut character_id_list) =
						level_query.single_mut();
					character_id_list.0.remove(c1_id);
					character_id_list.0.remove(c2_id);
					selected_character_id.0 = None;

					// TODO completely remove particles
					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();
					}

					spawn_character(
						&mut commands,
						&character_meshes,
						&mut materials,
						&mut selected_character_id,
						&mut character_id_list,
						&audio,
						*c1_transform,
						new_color.into(),
					);
				}
			}
		}
	}
}

fn keyboard_input_system(
	keyboard_input: Res<Input<KeyCode>>,
	mut characters: Query<(&CharacterId, &mut Velocity, &CharacterColor)>,
	mut level_query: Query<(&mut SelectedCharacterId, &CharacterIdList)>,
	mut app_state: ResMut<State<AppState>>,
	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
) {
	if let Ok((mut selected_character_id, character_id_list)) = level_query.get_single_mut() {
		if keyboard_input.just_pressed(KeyCode::Tab) {
			let selected = if let Some(selected_character_id) = &mut selected_character_id.0 {
				*selected_character_id = *character_id_list
					.0
					.range(*selected_character_id..)
					.nth(1)
					.unwrap_or_else(|| character_id_list.0.iter().next().unwrap());
				*selected_character_id
			} else {
				selected_character_id.0 = Some(CharacterId(0));
				CharacterId(0)
			};

			if let Some((_character_id, _velocity, color)) = characters
				.iter_mut()
				.find(|(character_id, _velocity, _color)| **character_id == selected)
			{
				audio
					.send(AudioMsg::Color([color.0.r(), color.0.g(), color.0.b()]))
					.ok();
			}
		}

		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);

		if let Some(selected_character_id) = &selected_character_id.0 {
			if let Some((_character_id, mut velocity, _color)) = characters
				.iter_mut()
				.find(|(character_id, _velocity, _color)| *character_id == selected_character_id)
			{
				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(
	mut characters: Query<(&CharacterId, &Transform, &CharacterColor)>,
	mut particle_effect: ResMut<crate::particle_effect::ParticleEffectResource>,
	mut level_query: Query<&SelectedCharacterId>,
) {
	if let Ok(selected_character_id) = level_query.get_single_mut() {
		if let Some(selected_character_id) = &selected_character_id.0 {
			if let Some((_character_id, transform, color)) = characters
				.iter_mut()
				.find(|(character_id, _transform, _color)| *character_id == selected_character_id)
			{
				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<(&CharacterId, &Transform), Without<Camera>>,
	level_query: Query<&SelectedCharacterId>,
	time: Res<Time>,
) {
	const MARGIN: f32 = 300.0;
	const FOLLOW_SPEED: f32 = std::f32::consts::PI;

	if let Ok(selected_character_id) = level_query.get_single() {
		if let Some(selected_character_id) = &selected_character_id.0 {
			if let Some((_character_id, transform)) = characters
				.iter()
				.find(|(character_id, _transform)| *character_id == selected_character_id)
			{
				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(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);
				camera_transform.translation.z = 999.0;
			}
		}
	}
}