use bevy::prelude::*;
use bevy_xpbd_3d::prelude::*;
use bevy::scene::SceneInstance;
use bevy::math::DVec3;
use crate::{actor, audio, camera, chat, commands, effects, hud, nature, var, world};

pub const ENGINE_SPEED_FACTOR: f32 = 30.0;
const MAX_TRANSMISSION_DISTANCE: f32 = 60.0;
const MAX_INTERACT_DISTANCE: f32 = 30.0;

pub struct ActorPlugin;
impl Plugin for ActorPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(PreUpdate, (
            handle_player_death,
        ));
        app.add_systems(FixedUpdate, (
            update_physics_lifeforms,
            handle_wants_maxrotation,
            handle_wants_maxvelocity,
            handle_gforce,
        ));
        app.add_systems(Update, (
            handle_input,
            handle_collisions,
            handle_damage,
        ));
        app.add_systems(PostUpdate, (
            handle_vehicle_enter_exit,
        ));
        app.add_event::<VehicleEnterExitEvent>();
        app.add_event::<PlayerDiesEvent>();
    }
}

#[derive(Copy, Clone)]
pub enum DamageType {
    Unknown,
    Mental,
    Trauma,
    Asphyxiation,
    //Poison,
    //Radiation,
    //Freeze,
    //Burn,
}

#[derive(Event)] pub struct PlayerDiesEvent(pub DamageType);

#[derive(Event)]
pub struct VehicleEnterExitEvent {
    vehicle: Entity,
    driver: Entity,
    is_entering: bool,
    is_player: bool
}

#[derive(Component)]
pub struct Actor {
    pub id: String,
    pub name: Option<String>,
    pub camdistance: f32,
}
impl Default for Actor {
    fn default() -> Self {
        Self {
            id: "".to_string(),
            name: None,
            camdistance: 15.0,
        }
    }
}

#[derive(Component)]
pub struct HitPoints {
    pub current: f32,
    pub max: f32,
    pub damage: f32,
    pub damagetype: DamageType,
}
impl Default for HitPoints {
    fn default() -> Self {
        Self {
            current: 100.0,
            max: 100.0,
            damage: 0.0,
            damagetype: DamageType::Unknown,
        }
    }
}

#[derive(Component)]
pub struct ExperiencesGForce {
    pub gforce: f32,
    pub damage_threshold: f32,
    pub visual_effect_threshold: f32,
    pub visual_effect: f32,
    pub last_linear_velocity: DVec3,
    pub ignore_gforce_seconds: f32,
}
impl Default for ExperiencesGForce { fn default() -> Self { Self {
    gforce: 0.0,
    damage_threshold: 100.0,
    visual_effect_threshold: 20.0,
    visual_effect: 0.0,
    last_linear_velocity: DVec3::splat(0.0),
    ignore_gforce_seconds: 0.0,
}}}

#[derive(Component)] pub struct Player; // Attached to the suit of the player
#[derive(Component)] pub struct PlayerDrivesThis; // Attached to the entered vehicle
#[derive(Component)] pub struct PlayerCamera; // Attached to the actor to use as point of view
#[derive(Component)] pub struct ActorEnteringVehicle;
#[derive(Component)] pub struct ActorVehicleBeingEntered;
#[derive(Component)] pub struct WantsMaxRotation(pub f64);
#[derive(Component)] pub struct WantsMaxVelocity(pub f64);

#[derive(Component)]
pub struct LifeForm {
    pub is_alive: bool,
    pub adrenaline: f32,
    pub adrenaline_baseline: f32,
    pub adrenaline_jolt: f32,
}
impl Default for LifeForm { fn default() -> Self { Self {
    is_alive: true,
    adrenaline: 0.3,
    adrenaline_baseline: 0.3,
    adrenaline_jolt: 0.0,
}}}

#[derive(Component)]
pub struct Vehicle {
    stored_drivers_collider: Option<Collider>,
}
impl Default for Vehicle { fn default() -> Self { Self {
    stored_drivers_collider: None,
}}}

#[derive(Copy, Clone, PartialEq)]
pub enum EngineType {
    Monopropellant,
    Rocket,
    Ion,
}

#[derive(Component)]
pub struct Engine {
    pub thrust_forward: f32,
    pub thrust_back: f32,
    pub thrust_sideways: f32,
    pub reaction_wheels: f32,
    pub engine_type: EngineType,
    pub warmup_seconds: f32,
    pub current_warmup: f32,
}
impl Default for Engine {
    fn default() -> Self {
        Self {
            thrust_forward: 1.0,
            thrust_back: 1.0,
            thrust_sideways: 1.0,
            reaction_wheels: 1.0,
            engine_type: EngineType::Monopropellant,
            warmup_seconds: 1.5,
            current_warmup: 0.0,
        }
    }
}

#[derive(Component)]
pub struct Suit {
    pub oxygen: f32,
    pub power: f32,
    pub oxygen_max: f32,
    pub power_max: f32,
    pub integrity: f32, // [0.0 - 1.0]
}
impl Default for Suit { fn default() -> Self { SUIT_SIMPLE } }

const SUIT_SIMPLE: Suit = Suit {
    power: 1e5,
    power_max: 1e5,
    oxygen: nature::OXY_D,
    oxygen_max: nature::OXY_D,
    integrity: 1.0,
};

pub fn update_physics_lifeforms(
    time: Res<Time>,
    mut query: Query<(&mut LifeForm, &mut HitPoints, &mut Suit, &LinearVelocity)>,
) {
    let d = time.delta_seconds();
    for (mut lifeform, mut hp, mut suit, velocity) in query.iter_mut() {
        if lifeform.adrenaline_jolt.abs() > 1e-3 {
            lifeform.adrenaline_jolt *= 0.99;
        }
        else {
            lifeform.adrenaline_jolt = 0.0
        }
        let speed = velocity.length();
        if speed > 1000.0 {
            lifeform.adrenaline += 0.001;
        }
        lifeform.adrenaline = (lifeform.adrenaline - 0.0001 + lifeform.adrenaline_jolt * 0.01).clamp(0.0, 1.0);

        let mut oxygen_drain = nature::OXY_S;
        let integr_threshold = 0.5;
        if suit.integrity < integr_threshold {
            // The oxygen drain from suit integrity scales with (2 - 2x)^4,
            // which is a function with ~16 at x=0 and 0 at x=1.
            // Furthermore, x is divided by the integrity threshold (e.g. 0.5)
            // to squeeze the function horizontally, and change the range for
            // the x parameter from [0-1] to [0-integritythreshold]
            //
            // 16 |.
            //    |.
            //    |'.
            //    | '.
            //    |   '..
            //    |______''....
            //    x=0         x=1
            let drain_scaling = (2.0 - 2.0 * suit.integrity / integr_threshold).powf(4.0);
            oxygen_drain += suit.oxygen * 0.01 * drain_scaling;
        }
        suit.oxygen = (suit.oxygen - oxygen_drain*d).clamp(0.0, suit.oxygen_max);
        if suit.oxygen <= 0.0 {
            hp.damage += 1.0 * d;
            hp.damagetype = DamageType::Asphyxiation;
        }
    }
}

pub fn handle_input(
    mut commands: Commands,
    keyboard_input: Res<ButtonInput<KeyCode>>,
    mut settings: ResMut<var::Settings>,
    q_talker: Query<(&chat::Talker, &Transform), (Without<actor::Player>, Without<Camera>)>,
    player: Query<Entity, With<actor::Player>>,
    q_camera: Query<&Transform, With<Camera>>,
    q_vehicles: Query<(Entity, &Transform), (With<actor::Vehicle>, Without<actor::Player>, Without<Camera>)>,
    mut ew_conv: EventWriter<chat::StartConversationEvent>,
    mut ew_vehicle: EventWriter<VehicleEnterExitEvent>,
    mut ew_playerdies: EventWriter<PlayerDiesEvent>,
    q_player_drives: Query<Entity, With<PlayerDrivesThis>>,
) {
    if q_camera.is_empty() || player.is_empty() {
        return;
    }
    let camtrans = q_camera.get_single().unwrap();
    let player_entity = player.get_single().unwrap();

    if keyboard_input.just_pressed(settings.key_interact) {
        // Talking to people
        let objects: Vec<(chat::Talker, &Transform)> = q_talker
            .iter()
            .map(|(talker, transform)| (talker.clone(), transform))
            .collect();
        // TODO: replace Transform.translation with Position
        if let (Some(talker), dist) = camera::find_closest_target::<chat::Talker>(objects, camtrans) {
            if dist <= MAX_TRANSMISSION_DISTANCE {
                ew_conv.send(chat::StartConversationEvent{talker: talker.clone()});
            }
        }
        // Entering Vehicles
        if q_player_drives.is_empty() {
            let objects: Vec<(Entity, &Transform)> = q_vehicles
                .iter()
                .collect();
            if let (Some(entity), dist) = camera::find_closest_target::<Entity>(objects, camtrans) {
                if dist <= MAX_INTERACT_DISTANCE {
                    commands.entity(entity).insert(ActorVehicleBeingEntered);
                    commands.entity(player_entity).insert(ActorEnteringVehicle);
                    ew_vehicle.send(VehicleEnterExitEvent{
                        vehicle: entity,
                        driver: player_entity,
                        is_entering: q_player_drives.is_empty(),
                        is_player: true,
                    });
                }
            }
        }
    }
    else if keyboard_input.just_pressed(settings.key_vehicle) {
        // Exiting Vehicles
        for vehicle_entity in &q_player_drives {
            commands.entity(vehicle_entity).insert(ActorVehicleBeingEntered);
            commands.entity(player_entity).insert(ActorEnteringVehicle);
            ew_vehicle.send(VehicleEnterExitEvent{
                vehicle: vehicle_entity,
                driver: player_entity,
                is_entering: false,
                is_player: true,
            });
            break;
        }
    }
    else if keyboard_input.just_pressed(settings.key_restart) {
        settings.god_mode = false;
        ew_playerdies.send(PlayerDiesEvent(DamageType::Mental));
    }
}

pub fn handle_vehicle_enter_exit(
    mut commands: Commands,
    mut er_vehicle: EventReader<VehicleEnterExitEvent>,
    mut q_drivers: Query<(Entity, &mut Visibility, Option<&Collider>), (Without<ActorVehicleBeingEntered>, With<ActorEnteringVehicle>)>,
    mut q_vehicles: Query<(Entity, &mut Vehicle, &mut Visibility), (With<ActorVehicleBeingEntered>, Without<ActorEnteringVehicle>)>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
) {
    for event in er_vehicle.read() {
        for (driver, mut driver_vis, driver_collider) in q_drivers.iter_mut() {
            if driver == event.driver {
                for (vehicle, mut vehicle_component, mut vehicle_vis) in q_vehicles.iter_mut() {
                    if !event.is_player {
                        continue;
                    }
                    if vehicle == event.vehicle {
                        if event.is_entering {
                            // Entering Vehicle
                            if let Some(collider) = driver_collider {
                                vehicle_component.stored_drivers_collider = Some(collider.clone());
                            }
                            commands.entity(driver).remove::<RigidBody>();
                            *driver_vis = Visibility::Hidden; //seems to have no effect...
                            ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::EnterVehicle));
                            commands.entity(driver).remove::<PlayerCamera>();
                            commands.entity(driver).remove::<Collider>();
                            commands.entity(vehicle).insert(PlayerCamera);
                            commands.entity(vehicle).insert(PlayerDrivesThis);
                        }
                        else {
                            // Exiting Vehicle
                            if let Some(collider) = &vehicle_component.stored_drivers_collider {
                                commands.entity(driver).insert(collider.clone());
                            }
                            commands.entity(driver).insert(RigidBody::Dynamic);
                            ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::Switch));
                            commands.entity(vehicle).remove::<PlayerCamera>();
                            commands.entity(driver).insert(PlayerCamera);
                            commands.entity(vehicle).remove::<PlayerDrivesThis>();
                            *vehicle_vis = Visibility::Visible;
                        }
                    }
                }
            }
        }
    }
}

fn handle_collisions(
    mut collision_event_reader: EventReader<CollisionStarted>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    q_player: Query<(Entity, Option<&Player>), With<PlayerCamera>>,
    mut q_player_lifeform: Query<(&mut LifeForm, &mut Suit), With<Player>>,
) {
    if let (Ok((player, player_maybe)), Ok((mut lifeform, mut suit))) = (q_player.get_single(), q_player_lifeform.get_single_mut()) {
        for CollisionStarted(entity1, entity2) in collision_event_reader.read() {
            if *entity1 == player || *entity2 == player {
                ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::Crash));
                lifeform.adrenaline_jolt += 0.1;

                if player_maybe.is_some() {
                    suit.integrity -= 0.03;
                }
            }
        }
    }
}

fn handle_wants_maxrotation(
    //time: Res<Time>,
    mut query: Query<(&mut AngularVelocity, &Engine, &WantsMaxRotation)>,
) {
    let epsilon = 0.0001;
    //let d = time.delta_seconds();
    for (mut v_ang, engine, maxrot) in &mut query {
        let total = v_ang.0.length();
        if total <= maxrot.0 + epsilon {
            if total > maxrot.0 {
                v_ang.0 = DVec3::splat(0.0);
            }
        }
        else {
            let angular_slowdown: f64 = (2.0 - engine.reaction_wheels.powf(0.01).clamp(1.001, 1.1)) as f64;
            v_ang.0 *= angular_slowdown;
        }
    }
}

fn handle_wants_maxvelocity(
    time: Res<Time>,
    mut query: Query<(&mut LinearVelocity, &Engine, &WantsMaxVelocity)>,
) {
    let dt = time.delta_seconds();
    let epsilon = 0.0001;
    for (mut v, engine, maxv) in &mut query {
        let total = v.0.length();
        if total <= maxv.0 + epsilon {
            if total > maxv.0 {
                v.0 = DVec3::splat(0.0);
            }
            // already not moving
            continue;
        }

        // TODO: respect engine parameters for different thrusts for different directions
        let avg_thrust = (engine.thrust_forward + engine.thrust_back + engine.thrust_sideways) / 3.0;
        let acceleration = (avg_thrust * dt) as f64 * -v.0;
        v.0 += acceleration;
        if v.0.length() + epsilon < acceleration.length() {
            v.0 = DVec3::splat(0.0);
        }
    }
}

fn handle_player_death(
    mut cmd: Commands,
    mut er_playerdies: EventReader<PlayerDiesEvent>,
    q_scenes: Query<(Entity, &SceneInstance), With<world::DespawnOnPlayerDeath>>,
    q_noscenes: Query<Entity, (With<world::DespawnOnPlayerDeath>, Without<SceneInstance>)>,
    ew_spawn: EventWriter<commands::SpawnEvent>,
    mut scene_spawner: ResMut<SceneSpawner>,
    mut ew_sfx: EventWriter<audio::PlaySfxEvent>,
    mut ew_effect: EventWriter<effects::SpawnEffectEvent>,
    mut log: ResMut<hud::Log>,
    mut settings: ResMut<var::Settings>,
) {
    for death in er_playerdies.read() {
        if settings.god_mode {
            return;
        }
        settings.reset_player_settings();
        for entity in &q_noscenes {
            cmd.entity(entity).despawn();
        }
        for (entity, sceneinstance) in &q_scenes {
            cmd.entity(entity).despawn();
            scene_spawner.despawn_instance(**sceneinstance);
        }
        log.clear();
        //cmd.run_system(commands::load_defs); // why is it so complicated to get SystemId?

        match death.0 {
            DamageType::Mental => {
                ew_effect.send(effects::SpawnEffectEvent {
                    class: effects::Effects::FadeIn(Color::BLACK),
                    duration: 4.0,
                });
            }
            DamageType::Asphyxiation => {
                ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::WakeUp));
                ew_effect.send(effects::SpawnEffectEvent {
                    class: effects::Effects::FadeIn(Color::BLACK),
                    duration: 1.0,
                });
            }
            DamageType::Trauma | _ => {
                ew_sfx.send(audio::PlaySfxEvent(audio::Sfx::WakeUp));
                ew_effect.send(effects::SpawnEffectEvent {
                    class: effects::Effects::FadeIn(Color::MAROON),
                    duration: 1.0,
                });
            }
        }

        commands::load_defs(ew_spawn);
        return;
    }
}

fn handle_damage(
    mut ew_playerdies: EventWriter<PlayerDiesEvent>,
    mut q_hp: Query<(&mut HitPoints, Option<&Player>), Changed<HitPoints>>,
    settings: Res<var::Settings>,
) {
    for (mut hp, player_maybe) in &mut q_hp {
        if player_maybe.is_some() {
            if !settings.god_mode {
                hp.current -= hp.damage;
            }
            if hp.current <= 0.0 {
                ew_playerdies.send(PlayerDiesEvent(hp.damagetype));
            }
        }
        else {
            hp.current -= hp.damage;
        }
        hp.damage = 0.0;
    }
}

fn handle_gforce(
    time: Res<Time>,
    mut q_actor: Query<(&LinearVelocity, &mut HitPoints, &mut ExperiencesGForce)>,
) {
    let dt = time.delta_seconds();
    let factor = 1.0 / dt / nature::EARTH_GRAVITY;
    for (v, mut hp, mut gforce) in &mut q_actor {
        gforce.gforce = factor * (v.0 - gforce.last_linear_velocity).length() as f32;
        gforce.last_linear_velocity = v.0;
        if gforce.ignore_gforce_seconds > 0.0 {
            gforce.ignore_gforce_seconds -= dt;
            continue;
        }
        if gforce.gforce > gforce.damage_threshold {
            hp.damage += (gforce.gforce - gforce.damage_threshold).powf(2.0) / 3000.0;
            hp.damagetype = DamageType::Trauma;
        }

        if gforce.visual_effect > 0.0001 {
            gforce.visual_effect *= 0.984;
        }
        else if gforce.visual_effect > 0.0 {
            gforce.visual_effect = 0.0;
        }
        if gforce.gforce > gforce.visual_effect_threshold {
            gforce.visual_effect += (gforce.gforce - gforce.visual_effect_threshold).powf(2.0) / 300000.0
        }
    }
}