// Bevy basically forces "complex types" with Querys
#![allow(clippy::type_complexity)]

use games::physics2d::*;
use games::*;

fn main() {
    App::new()
        .add_plugins((
            BaseGamePlugin {
                name: "flappy bird (with rewind)".into(),
                game_type: GameType::Two,
            },
            Physics2dPlugin,
        ))
        .insert_resource(Gravity(Vec2::NEG_Y * 9.8 * 100.0))
        .init_resource::<Score>()
        .init_resource::<RewindFrames>()
        .init_resource::<Flaps>()
        .init_resource::<Deaths>()
        .init_state::<PlayerState>()
        .add_systems(
            Startup,
            (
                init_bird,
                init_obstacles,
                init_ui,
                tweak_camera.after(create_camera_2d),
            ),
        )
        .add_systems(OnEnter(PlayerState::Alive), alive_bird)
        .add_systems(OnEnter(PlayerState::Pause), pause_bird)
        .add_systems(OnEnter(PlayerState::Stasis), pause_bird)
        .add_systems(OnEnter(PlayerState::Rewind), pause_bird)
        .add_systems(
            Update,
            (
                // Systems to run when player state changes
                (
                    // Print out when this state changes for debugging purposes
                    debug_state_changes::<PlayerState>,
                    // Toggle (UI) elements when the player dies/alives
                    toggle_state_visibility::<PlayerState>,
                )
                    .run_if(state_changed::<PlayerState>),
                // Detect if the bird is "dead" by checking if it is visible
                // from the point of view of the camera
                detect_dead.run_if(in_state(PlayerState::Alive)),
                // Toggle rewinding state when "R" is pressed/released
                toggle_rewind.run_if(
                    input_just_pressed(KeyCode::KeyR).or(input_just_released(KeyCode::KeyR)),
                ),
                // Systems to run in the "play" state
                (
                    // Only flap when we press the space key
                    flap_kb.run_if(input_just_pressed(KeyCode::Space)),
                    // Rewinding systems
                    record.run_if(any_component_changed::<Transform>),
                )
                    .run_if(in_state(PlayerState::Alive)),
                // Rewinding systems
                rewind.run_if(in_state(PlayerState::Rewind)),
                // Camera follows when bird moves regardless of player state
                camera_follow_bird.run_if(any_component_changed::<Transform>),
                // Pause when the player presses Escape
                pause_game.run_if(input_just_pressed(KeyCode::Escape)),
                // Transition out of the pause screen if the player presses space
                un_pause_game
                    .run_if(input_just_pressed(KeyCode::Space))
                    .run_if(in_state(PlayerState::Pause)),
                // Stats that get synced to the UI
                (
                    sync_resource_to_ui::<Score>.run_if(resource_changed::<Score>),
                    sync_resource_to_ui::<Flaps>.run_if(resource_changed::<Flaps>),
                    sync_resource_to_ui::<Deaths>.run_if(resource_changed::<Deaths>),
                    sync_resource_to_ui::<RewindFrames>.run_if(resource_changed::<RewindFrames>),
                ),
                scoring.run_if(on_event::<CollisionEnded>),
            ),
        )
        .add_observer(flap)
        .run();
}

fn tweak_camera(camera: Single<&mut Camera>) {
    info!("Tweaking camera");
    let mut c = camera.into_inner();
    c.clear_color = ClearColorConfig::Custom(WHITE.into());
}

#[derive(Component)]
struct Bird;

#[derive(States, Clone, Eq, PartialEq, Debug, Hash, Default, Component)]
enum PlayerState {
    Alive,
    Rewind,
    Stasis,
    #[default]
    Pause,
}

// A tape tracking the bird's state every frame
#[derive(Component, Default)]
struct Tape {
    translations: Vec<Vec3>,
    rotations: Vec<Quat>,
    linear_velocities: Vec<LinearVelocity>,
    angular_velocities: Vec<AngularVelocity>,
}

fn init_bird(
    mut commands: Commands,
    server: Res<AssetServer>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
) {
    let material = MeshMaterial2d(materials.add(ColorMaterial {
        texture: Some(server.load("kenny.nl/1-bit-platformer-pack/tile_0380.png")),
        color: ORANGE.into(),
        alpha_mode: AlphaMode2d::Blend,
        ..default()
    }));

    let mesh = Mesh2d(meshes.add(Rectangle::new(1.0, 1.0)));

    let name = Name::new("bird");

    let t = Transform::from_xyz(0.0, 0.0, 0.0).with_scale(Vec3::splat(100.0));

    let physics = (
        RigidBody::Static,
        Collider::circle(0.5),
        Mass(10.0),
        ExternalImpulse::default().with_persistence(false),
    );

    let tape = Tape::default();

    commands.spawn((
        name,
        mesh,
        material,
        physics,
        t,
        Bird,
        tape,
        CollisionEventsEnabled,
    ));
}

#[derive(Component, Clone)]
struct Ground;

#[derive(Component, Clone)]
struct Pipe;

#[derive(Component, Clone)]
struct Hitbox;

fn init_obstacles(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
    server: Res<AssetServer>,
) {
    let ground = {
        let material = MeshMaterial2d(materials.add(ColorMaterial {
            texture: Some(server.load("kenny.nl/1-bit-platformer-pack/tile_0088.png")),
            color: BLACK.into(),
            ..default()
        }));

        let mesh = Mesh2d(meshes.add(Rectangle::new(1.0, 1.0)));

        let name = Name::new("ground");

        let physics = (RigidBody::Static, Collider::rectangle(1.0, 1.0));

        (name, mesh, material, physics, Ground)
    };
    let pipe = {
        let material = MeshMaterial2d(materials.add(ColorMaterial {
            texture: Some(server.load("kenny.nl/1-bit-platformer-pack/tile_0247.png")),
            color: GREEN.into(),
            ..default()
        }));

        let mesh = Mesh2d(meshes.add(Rectangle::new(1.0, 1.0)));
        let physics = (RigidBody::Static, Collider::rectangle(1.0, 1.0));
        let name = Name::new("pipe");

        (
            name.clone(),
            mesh.clone(),
            material.clone(),
            physics.clone(),
            Pipe,
        )
    };
    let hitbox = {
        let physics = (
            RigidBody::Static,
            Collider::rectangle(1.0, 10.0),
            Sensor,
            CollisionEventsEnabled,
        );
        let name = Name::new("hitbox");

        (name.clone(), physics.clone(), Hitbox)
    };

    // TODO: Instead of spawning infinite floor/pipes, we should instead spawn enough for 1-3 a few
    // screens and then "move" them around.
    // This is considerably more complexity so can be implemented later, but would keep memory
    // overhead fairly static.
    (1..10).for_each(|i| {
        // TODO: Jitter up/down/close/far of pipes for challenge
        let above =
            Transform::from_xyz(300.0 * i as f32, 300.0, -1.0).with_scale(Vec3::splat(100.0));
        commands.spawn((pipe.clone(), above));

        let below =
            Transform::from_xyz(300.0 * i as f32, -200.0, -1.0).with_scale(Vec3::splat(100.0));
        commands.spawn((pipe.clone(), below));

        let hitbox_pos =
            Transform::from_xyz(300.0 * i as f32, 0.0, 10.0).with_scale(Vec3::splat(100.0));
        commands.spawn((hitbox_pos, hitbox.clone()));

        let floor1 =
            Transform::from_xyz(300.0 * i as f32 - 100.0, -300.0, 1.0).with_scale(Vec3::splat(100.0));
        commands.spawn((ground.clone(), floor1));

        let floor2 =
            Transform::from_xyz(300.0 * i as f32, -300.0, 1.0).with_scale(Vec3::splat(100.0));
        commands.spawn((ground.clone(), floor2));

        let floor3 =
            Transform::from_xyz(300.0 * i as f32 + 100.0, -300.0, 1.0).with_scale(Vec3::splat(100.0));
        commands.spawn((ground.clone(), floor3));
    });
}

fn init_ui(mut commands: Commands) {
    commands.spawn((
        Node {
            align_self: AlignSelf::Center,
            justify_self: JustifySelf::Center,
            flex_direction: FlexDirection::Column,
            ..default()
        },
        PlayerState::Stasis,
        children![
            (
                Text::new("You Died"),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
            (
                SyncResource::<Score>::default(),
                Text::default(),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
            (
                SyncResource::<Flaps>::default(),
                Text::default(),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
            (
                SyncResource::<RewindFrames>::default(),
                Text::default(),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
            (
                SyncResource::<Deaths>::default(),
                Text::default(),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
            (
                Text::new("Press R to Rewind"),
                TextLayout::new_with_justify(JustifyText::Center)
            ),
        ],
    ));

    fn start_game(_trigger: Trigger<Pointer<Click>>, mut next: ResMut<NextState<PlayerState>>) {
        next.set(PlayerState::Alive);
    }

    commands
        .spawn((
            Node {
                align_self: AlignSelf::Center,
                justify_self: JustifySelf::Center,
                flex_direction: FlexDirection::Column,
                ..default()
            },
            Button,
            // TODO: Add Pause (basically Stasis) state
            PlayerState::Pause,
            children![Text::new("Go!"),],
        ))
        .observe(start_game);

    commands
        .spawn(Node {
            align_self: AlignSelf::End,
            justify_self: JustifySelf::Center,
            flex_direction: FlexDirection::Row,
            ..default()
        })
        .with_children(|parent| {
            parent
                .spawn((
                    Node { ..default() },
                    Button,
                    children![Text::new("Rewind!"),],
                ))
                .observe(start_rewind)
                .observe(end_rewind);

            parent
                .spawn((Node { ..default() }, Button, children![Text::new("Flap!"),]))
                .observe(flap_button);
        });

    commands.spawn((
        Node {
            align_self: AlignSelf::Start,
            justify_self: JustifySelf::Center,
            ..default()
        },
        BackgroundColor(WHITE.into()),
        SyncResource::<Score>::default(),
        Text::default(),
        TextLayout::new_with_justify(JustifyText::Center),
    ));
}

fn start_rewind(_trigger: Trigger<Pointer<Pressed>>, mut next: ResMut<NextState<PlayerState>>) {
    next.set(PlayerState::Rewind);
}

fn end_rewind(_trigger: Trigger<Pointer<Released>>, mut next: ResMut<NextState<PlayerState>>) {
    next.set(PlayerState::Alive);
}

fn flap_button(
    trigger: Trigger<Pointer<Pressed>>,
    mut commands: Commands,
    bird: Single<Entity, With<Bird>>,
) {
    let e = *bird;
    info!("Flapping {:?}", e);
    commands.trigger_targets(Flap, e);
}

/// Pause the game when the player presses "Escape"
fn pause_game(mut next: ResMut<NextState<PlayerState>>) {
    next.set(PlayerState::Pause);
}

fn un_pause_game(mut next: ResMut<NextState<PlayerState>>) {
    next.set(PlayerState::Alive);
}

// TODO: Create floor (and ceiling?)
// Q: Move bird + camera or move world around bird & camera?
// TODO: Obstacles
#[derive(Component, Clone, Event)]
struct Flap;

// Observer for flapping
fn flap(
    trigger: Trigger<Flap>,
    mut bird: Query<&mut ExternalImpulse, With<Bird>>,
    mut flaps: ResMut<Flaps>,
) {
    info!("real flap for {:?}", trigger.target());
    // Increment flap stat
    flaps.0 += 1;

    // Flap birds wings
    if let Ok(mut f) = bird.get_mut(trigger.target()) {
        f.apply_impulse(Vec2::Y * 5000.0 + Vec2::X * 1000.0);
    }
}

fn flap_kb(
    #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
    #[cfg(debug_assertions)] keycode: Res<ButtonInput<KeyCode>>,
    birds: Query<Entity, With<Bird>>,
    mut commands: Commands,
) {
    debug_assert!(
        matches!(state.get(), PlayerState::Alive),
        "Only flap when playing"
    );
    debug_assert!(
        keycode.just_pressed(KeyCode::Space),
        "Only flap when space is just pressed"
    );

    birds.iter().for_each(|e| {
        info!("Flapping {:?}", e);
        commands.trigger_targets(Flap, e);
    });
}

fn toggle_rewind(keycode: Res<ButtonInput<KeyCode>>, mut next: ResMut<NextState<PlayerState>>) {
    debug_assert!(
        keycode.just_pressed(KeyCode::KeyR) || keycode.just_released(KeyCode::KeyR),
        "Only toggle rewind when R is pressed"
    );

    if keycode.just_pressed(KeyCode::KeyR) {
        debug!("Toggling rewind ON");
        next.set(PlayerState::Rewind)
    } else {
        debug!("Toggling rewind OFF");
        next.set(PlayerState::Alive)
    }
}

fn record(
    #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
    mut birds: Query<(&Transform, &LinearVelocity, &AngularVelocity, &mut Tape), With<Bird>>,
) {
    debug_assert!(
        matches!(state.get(), PlayerState::Alive),
        "Only record in the alive state"
    );

    birds
        .iter_mut()
        .for_each(|(transform, linear_velocity, angular_velocity, mut tape)| {
            tape.translations.push(transform.translation);
            tape.rotations.push(transform.rotation);
            tape.linear_velocities.push(*linear_velocity);
            tape.angular_velocities.push(*angular_velocity);
        });
}

fn rewind(
    #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
    mut birds: Query<
        (
            &mut Transform,
            &mut AngularVelocity,
            &mut LinearVelocity,
            &mut Tape,
        ),
        With<Bird>,
    >,
    mut frames: ResMut<RewindFrames>,
) {
    debug_assert!(
        matches!(state.get(), PlayerState::Rewind),
        "Only rewind in the rewinding state"
    );

    birds.iter_mut().for_each(
        |(mut transform, mut angular_velocity, mut linear_velocity, mut tape)| {
            match (tape.translations.pop(), tape.rotations.pop()) {
                (Some(t), Some(r)) => {
                    transform.translation = t;
                    transform.rotation = r;
                    frames.0 += 1;
                }
                (None, None) => (),
                _ => panic!("Translations and rotations are out of sync!"),
            }
            // TODO: Only need to set {angular|linear}_velocity at end of Rewind
            if let Some(av) = tape.angular_velocities.pop() {
                *angular_velocity = av;
            }
            if let Some(lv) = tape.linear_velocities.pop() {
                *linear_velocity = lv;
            }
        },
    );
}

// PERF: May run more than necessary, should be event-driven on aabb intersection
fn detect_dead(
    #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
    bird: Single<&ColliderAabb, With<Bird>>,
    obstacles: Query<&ColliderAabb, Or<(With<Ground>, With<Pipe>)>>,
    mut next: ResMut<NextState<PlayerState>>,
) {
    debug_assert!(
        matches!(state.get(), PlayerState::Alive),
        "Only check if dead while alive"
    );

    if obstacles.iter().any(|obstacle| bird.intersects(obstacle)) {
        next.set(PlayerState::Stasis);
    }
}

fn alive_bird(
    #[cfg(debug_assertions)] state: Res<State<PlayerState>>,
    mut bird: Single<&mut RigidBody, With<Bird>>,
) {
    debug_assert!(matches!(state.get(), PlayerState::Alive));
    debug!("Setting bird to Dynamic");
    **bird = RigidBody::Dynamic;
}

fn pause_bird(
    state: Res<State<PlayerState>>,
    mut bird: Single<&mut RigidBody, With<Bird>>,
    mut deaths: ResMut<Deaths>,
) {
    debug_assert!(!matches!(state.get(), PlayerState::Alive));

    // Increment death count
    if state.get() == &PlayerState::Stasis { deaths.0 += 1 }

    debug!("Setting bird to Static");
    **bird = RigidBody::Static;
}

fn camera_follow_bird(
    bird: Single<&Transform, (With<Bird>, Changed<Transform>)>,
    mut camera: Single<&mut Transform, (With<Camera>, Without<Bird>)>,
) {
    camera.translation.x = bird.translation.x;
}

/// How many pipes the player has passed
#[derive(Resource, Default)]
struct Score(usize);

impl Display for Score {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        writeln!(f, "Score: {}", self.0)
    }
}

/// Number of frames that were rewound
#[derive(Resource, Default)]
struct RewindFrames(usize);

impl Display for RewindFrames {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        writeln!(f, "Frames Rewound: {}", self.0)
    }
}

// Track number of times player flapped their wings
#[derive(Resource, Default)]
struct Flaps(usize);

impl Display for Flaps {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        writeln!(f, "Flaps: {}", self.0)
    }
}

// Track number of times player died
#[derive(Resource, Default)]
struct Deaths(usize);

impl Display for Deaths {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        writeln!(f, "Deaths: {}", self.0)
    }
}

// TODO: Scoring is bugged, need to make it correct.
fn scoring(
    mut events: EventReader<CollisionEnded>,
    state: Res<State<PlayerState>>,
    bird: Query<Entity, With<Bird>>,
    hitboxes: Query<Entity, With<Hitbox>>,
    mut score: ResMut<Score>,
) {
    events
        .read()
        .filter(|CollisionEnded(a, b)| bird.contains(*a) && hitboxes.contains(*b))
        .for_each(|_| {
            info!("Hit event while {:?}", state.get());
            match state.get() {
                PlayerState::Alive => score.0 = score.0.saturating_add(1),
                PlayerState::Rewind => score.0 = score.0.saturating_sub(1),
                PlayerState::Pause | PlayerState::Stasis => (),
            }
        })
}