#![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::*;
use rapier2d::geometry::CollisionEventFlags;
use std::collections::BTreeSet;

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

pub struct FirstLevel(pub LevelId);

#[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))
			.init_resource::<CharacterList>()
			.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(level_keyboard_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(level_keyboard_system)
					.with_system(move_camera)
					.with_system(character_particle_effect_system)
					.with_system(move_win_text_system),
			)
			.add_system_to_stage(CoreStage::PostUpdate, char_char_collision_event_system)
			.add_system_to_stage(CoreStage::PostUpdate, char_airbound_event_system)
			.add_system_to_stage(CoreStage::PostUpdate, collision_event_system);
	}
}

// Events

pub struct LevelStartupEvent;

// Resources

pub struct CurrentLevel(pub Option<LevelId>);

#[derive(Default)]
pub struct CharacterList(pub BTreeSet<Entity>);

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;

#[derive(Component)]
pub struct Platform;

#[derive(Component)]
pub struct Airbound(bool);

#[derive(Component)]
pub struct Melty(pub Color);

#[derive(Component)]
pub struct WinText;

// Systems

fn setup(
	first_level: Res<FirstLevel>,
	mut current_level: ResMut<CurrentLevel>,
	mut level_startup_event: EventWriter<LevelStartupEvent>,
	mut camera_query: Query<&mut Transform, With<Camera>>,
) {
	if current_level.0.is_none() {
		current_level.0 = Some(first_level.0);
	}

	crate::levels::setup_level(&mut level_startup_event, &mut camera_query);
}

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>>,
	character_list: &mut ResMut<CharacterList>,

	characters: I,
) {
	for (i, (transform, color)) in characters.into_iter().enumerate() {
		spawn_character(
			commands,
			character_meshes,
			materials,
			audio,
			character_list,
			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>>,
	character_list: &mut ResMut<CharacterList>,
	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(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(ActiveEvents::COLLISION_EVENTS)
		.with_children(|c| {
			c.spawn_bundle(TransformBundle::from_transform(Transform::from_xyz(
				0., -33., 0.,
			)))
			.insert(Sensor)
			.insert(Collider::cuboid(30., 0.5))
			.insert(ActiveEvents::COLLISION_EVENTS)
			.insert(Airbound(true));
		});

	character_list.0.insert(entity_commands.id());

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

pub fn spawn_platforms<I: IntoIterator<Item = (Transform, Vec2)>>(
	commands: &mut Commands,
	meshes: &mut ResMut<Assets<Mesh>>,
	materials: &mut ResMut<Assets<ColorMaterial>>,

	platforms: I,
) {
	for (transform, size) in platforms.into_iter() {
		spawn_platform(commands, meshes, materials, transform, size);
	}
}

pub fn spawn_platform(
	commands: &mut Commands,
	meshes: &mut ResMut<Assets<Mesh>>,
	materials: &mut ResMut<Assets<ColorMaterial>>,

	transform: Transform,
	size: Vec2,
) {
	commands
		.spawn_bundle(ColorMesh2dBundle {
			mesh: meshes.add(Mesh::from(Quad { size, flip: false })).into(),
			material: materials.add(ColorMaterial::from(Color::GRAY)),
			transform,
			..default()
		})
		.insert(Collider::cuboid(size.x / 2., size.y / 2.))
		.insert(Level)
		.insert(Platform);
}

pub fn spawn_melty_platform(
	commands: &mut Commands,
	meshes: &mut ResMut<Assets<Mesh>>,
	materials: &mut ResMut<Assets<ColorMaterial>>,
	asset_server: &Res<AssetServer>,

	transform: Transform,
	color: Color,
) {
	commands
		.spawn_bundle(ColorMesh2dBundle {
			mesh: meshes
				.add(Mesh::from(Quad {
					size: Vec2 { x: 96., y: 16. },
					flip: false,
				}))
				.into(),
			material: materials.add(ColorMaterial::from(color)),
			transform,
			..default()
		})
		.insert(Collider::cuboid(48., 8.))
		.insert(Melty(color))
		.insert(Level)
		.with_children(|c| {
			c.spawn_bundle(SpriteBundle {
				texture: asset_server.get_handle("melty.png"),
				transform: Transform::from_xyz(0., 0., 0.5),
				..default()
			});
		});
}

fn char_char_collision_event_system(
	mut commands: Commands,

	mut collision_events: EventReader<CollisionEvent>,
	character_query: Query<(
		&mut CharacterColor,
		&Transform,
		&mut Handle<ColorMaterial>,
		Option<&Player>,
	)>,

	mut character_list: ResMut<CharacterList>,
	mut app_state: ResMut<State<AppState>>,
	character_meshes: Res<CharacterMeshes>,
	audio: Res<crossbeam_channel::Sender<AudioMsg>>,
	mut materials: ResMut<Assets<ColorMaterial>>,
) {
	for collision_event in collision_events.iter() {
        if let CollisionEvent::Started(e1, e2, _flags) =  collision_event {
			if let (
				Ok((c1_color, c1_transform, _c1_material, c1_player)),
				Ok((c2_color, c2_transform, _c2_material, c2_player)),
			) = (character_query.get(*e1), character_query.get(*e2)) {
				character_list.0.remove(e1);
				character_list.0.remove(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 && new_color.min_element() >= 0.9 {
					app_state.replace(AppState::Win).ok();
				}

				// position character based on current player location
				spawn_character(
					&mut commands,
					&character_meshes,
					&mut materials,
					&audio,
					&mut character_list,
					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) * 0.5,
						)
					},
					new_color.into(),
					c1_player.is_some() || c2_player.is_some(),
				);

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

fn char_airbound_event_system(
	mut collision_events: EventReader<CollisionEvent>,
	mut airbound_query: Query<&mut Airbound>,
	platform_query: Query<&Platform>,
) {
	// detect platform + player collisions only
	for collision_event in collision_events.iter() {
        match collision_event {
			CollisionEvent::Started(e1, e2, flags) => {
				if *flags == CollisionEventFlags::SENSOR {
                    if let (Ok(mut airbound), Ok(_)) = (
                        airbound_query.get_mut(*e1),
                        platform_query.get(*e2),
                    ) {
                        airbound.0 = false;
                    } else if let (Ok(mut airbound), Ok(_)) = (
                        airbound_query.get_mut(*e2),
                        platform_query.get(*e1),
                    ) {
                        airbound.0 = false;
                    }
				}
			}

			CollisionEvent::Stopped(e1, e2, flags) => {
				if *flags == CollisionEventFlags::SENSOR {
                    if let (Ok(mut airbound), Ok(_)) = (
                        airbound_query.get_mut(*e1),
                        platform_query.get(*e2),
                    ) {
                        airbound.0 = true;
                    } else if let (Ok(mut airbound), Ok(_)) = (
                        airbound_query.get_mut(*e2),
                        platform_query.get(*e1),
                    ) {
                        airbound.0 = true;
                    }
				}
			}
		}
	}
}

fn collision_event_system(
	mut commands: Commands,
	mut materials: ResMut<Assets<ColorMaterial>>,
	mut collision_events: EventReader<CollisionEvent>,
	mut character_query: Query<(
		&mut CharacterColor,
		&Transform,
		&mut Handle<ColorMaterial>,
		Option<&Player>,
	)>,
	pass_through_filter_query: Query<&PassThroughFilter>,
	melty_query: Query<&Melty>,
	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((c_color, _c_transform, _c_material, _c_player)), Ok(melty)) =
                    (character_query.get_mut(*e1), melty_query.get(*e2))
                {
                    if (Vec4::from(melty.0) - Vec4::from(c_color.0)).max_element() <= 0. {
                        commands.entity(*e2).despawn_recursive();
                    }
                } else if let (Ok((c_color, _c_transform, _c_material, _c_player)), Ok(melty)) =
                    (character_query.get_mut(*e2), melty_query.get(*e1))
                {
                    if (Vec4::from(melty.0) - Vec4::from(c_color.0)).max_element() <= 0. {
                        commands.entity(*e1).despawn_recursive();
                    }
                }
            } else if *flags == CollisionEventFlags::SENSOR {
                if let (Ok((mut c_color, _c_transform, mut c_material, c_player)), Ok(filter)) = (
                    character_query.get_mut(*e1),
                    pass_through_filter_query.get(*e2),
                ) {
                    c_color.0 = filter.apply(c_color.0);
                    *c_material = materials.add(ColorMaterial::from(c_color.0));

                    if c_player.is_some() {
                        audio
                            .send(AudioMsg::Color([
                                c_color.0.r(),
                                c_color.0.g(),
                                c_color.0.b(),
                            ]))
                            .ok();
                        audio.send(AudioMsg::Switch).ok();
                    }
                } else if let (
                    Ok((mut c_color, _c_transform, mut c_material, c_player)),
                    Ok(filter),
                ) = (
                    character_query.get_mut(*e2),
                    pass_through_filter_query.get(*e1),
                ) {
                    c_color.0 = filter.apply(c_color.0);
                    *c_material = materials.add(ColorMaterial::from(c_color.0));

                    if c_player.is_some() {
                        audio
                            .send(AudioMsg::Color([
                                c_color.0.r(),
                                c_color.0.g(),
                                c_color.0.b(),
                            ]))
                            .ok();
                        audio.send(AudioMsg::Switch).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>>,
	character_list: Res<CharacterList>,
) {
	if !keyboard_input.just_pressed(KeyCode::Tab) {
		return;
	}

	if let Some((player_entity, _color, _)) = characters
		.iter()
		.find(|(_entity, _color, player)| player.is_some())
		.or_else(|| characters.iter().next())
	{
		commands.entity(player_entity).remove::<Player>();
		if let Some(new_player_entity) = character_list
			.0
			.range(player_entity..)
			.nth(1)
			.or_else(|| character_list.0.iter().next())
		{
			commands.entity(*new_player_entity).insert(Player);
			if let Ok((_entity, color, _player)) = characters.get(*new_player_entity) {
				audio
					.send(AudioMsg::Color([color.0.r(), color.0.g(), color.0.b()]))
					.ok();
				audio.send(AudioMsg::Switch).ok();
			}
		}
	}
}

fn player_movement_system(
	keyboard_input: Res<Input<KeyCode>>,
	mut characters: Query<(&mut Velocity, &Children), With<Player>>,
	airbound_query: Query<&Airbound>,
	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, children) in characters.iter_mut() {
		velocity.linvel.x = 200. * (right_pressed as i8 - left_pressed as i8) as f32;

		let airbound: &Airbound = airbound_query.get(children[0]).unwrap();
		if keyboard_input.just_pressed(KeyCode::Space) && !airbound.0 {
			audio.send(AudioMsg::Jump).ok();
			velocity.linvel.y = 700.;
		}
	}
}

fn character_particle_effect_system(
	player_character: Query<(&Transform, &CharacterColor), With<Player>>,
	mut particle_effect: ResMut<crate::particle_effect::ParticleEffectResource>,
) {
	if let Ok((transform, color)) = player_character.get_single() {
		particle_effect.translation = transform.translation;
		particle_effect.color = color.0;
	}
}

fn win_setup(
	mut commands: Commands,
	mut meshes: ResMut<Assets<Mesh>>,
	mut materials: ResMut<Assets<ColorMaterial>>,
	asset_server: Res<AssetServer>,
) {
	let font = asset_server.get_handle("UacariLegacy-Thin.ttf");
	commands
		.spawn_bundle(ColorMesh2dBundle {
			mesh: meshes
				.add(Mesh::from(Quad {
					size: Vec2 { x: 512., y: 64. },
					flip: false,
				}))
				.into(),
			material: materials.add(ColorMaterial::from(Color::rgba(0., 0., 0., 0.9))),
			transform: Transform::from_xyz(0., 0., 3.),
			..default()
		})
		.insert(Level)
		.insert(WinText);
	commands
		.spawn_bundle(Text2dBundle {
			text: Text::from_section(
				"Press ENTER to level up",
				TextStyle {
					font,
					font_size: 36.0,
					color: Color::WHITE,
				},
			)
			.with_alignment(TextAlignment::CENTER),
			transform: Transform::from_xyz(0., 0., 4.),
			..Default::default()
		})
		.insert(Level)
		.insert(WinText);
}

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;
		let mut target_translation = character_transform.translation;
		// prevent camera from going too low
		target_translation.y = target_translation.y.max(half_height - MARGIN);

		camera_transform.translation = camera_transform
			.translation
			.lerp(target_translation, time.delta_seconds() * FOLLOW_SPEED);

		// always make sure that camera is away from the object in order to render them
		camera_transform.translation.z = 999.0;
	}
}

fn move_win_text_system(
	camera_query: Query<&Transform, With<Camera>>,
	mut win_text_query: Query<&mut Transform, (With<WinText>, Without<Camera>)>,
) {
	let camera_pos = camera_query.single();
	for mut pos in win_text_query.iter_mut() {
		pos.translation.x = camera_pos.translation.x;
		pos.translation.y = camera_pos.translation.y;
	}
}

fn level_keyboard_system(
	mut commands: Commands,
	mut current_level: ResMut<CurrentLevel>,
	mut level_startup_event: EventWriter<LevelStartupEvent>,
	mut camera_query: Query<&mut Transform, With<Camera>>,
	keyboard_input: Res<Input<KeyCode>>,
	mut character_list: ResMut<CharacterList>,
	level_query: Query<Entity, With<Level>>,
	mut app_state: ResMut<State<AppState>>,
) {
	if app_state.current() == &AppState::Win && keyboard_input.just_pressed(KeyCode::Return) {
		current_level.0 = Some(LevelId(
			current_level.0.map_or(0, |level_id| level_id.0 + 1),
		));
		app_state.replace(AppState::Game).unwrap();
	}

	if keyboard_input.just_pressed(KeyCode::R) {
		character_list.0.clear();
		for entity in level_query.iter() {
			commands.entity(entity).despawn_recursive();
		}
		if app_state.replace(AppState::Game).is_err() {
			crate::levels::setup_level(&mut level_startup_event, &mut camera_query);
		}
	}
}