use bevy::prelude::*;
use bevy::input::mouse::MouseMotion;
use bevy::window::PrimaryWindow;
use bevy::core_pipeline::bloom::{BloomCompositeMode, BloomSettings};
use bevy::core_pipeline::tonemapping::Tonemapping;
use bevy::pbr::CascadeShadowConfigBuilder;
use bevy::transform::TransformSystem;
use bevy::math::{DVec3, DQuat};
use bevy_xpbd_3d::prelude::*;
use std::f32::consts::PI;
use crate::{actor, audio, hud, settings};

pub struct CameraPlugin;

impl Plugin for CameraPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, setup_camera);
        app.add_systems(Update, handle_input);
        app.add_systems(Update, manage_player_actor.after(handle_input));
        app.add_systems(PostUpdate, sync_camera_to_player
            .after(PhysicsSet::Sync)
            .after(apply_input_to_player)
            .before(TransformSystem::TransformPropagate));
        app.add_systems(Update, update_fov);
        app.add_systems(PostUpdate, apply_input_to_player
            .after(PhysicsSet::Sync)
            .before(TransformSystem::TransformPropagate));
    }
}

pub fn setup_camera(
    mut commands: Commands,
) {
    // Add player
    commands.spawn((
        Camera3dBundle {
            camera: Camera {
                hdr: true, // HDR is required for bloom
                clear_color: ClearColorConfig::Custom(Color::BLACK),
                ..default()
            },
            tonemapping: Tonemapping::TonyMcMapface,
            transform: Transform::from_xyz(0.0, 0.0, 8.0).looking_at(Vec3::ZERO, Vec3::Y),
            ..default()
        },
        BloomSettings {
            composite_mode: BloomCompositeMode::EnergyConserving,
            ..default()
        },
    ));

    // Add Light from the Sun
    commands.spawn(DirectionalLightBundle {
        directional_light: DirectionalLight {
            illuminance: 1000.0,
            shadows_enabled: false,
            ..default()
        },
        transform: Transform::from_rotation(Quat::from_rotation_y(PI/2.0)),
        cascade_shadow_config: CascadeShadowConfigBuilder {
            first_cascade_far_bound: 7.0,
            maximum_distance: 25.0,
            ..default()
        }
        .into(),
        ..default()
    });
}

pub fn sync_camera_to_player(
    settings: Res<settings::Settings>,
    mut q_camera: Query<&mut Transform, (With<Camera>, Without<actor::PlayerCamera>)>,
    q_playercam: Query<(&actor::Actor, &Transform), (With<actor::PlayerCamera>, Without<Camera>)>,
) {
    if q_camera.is_empty() || q_playercam.is_empty() {
        return;
    }
    let mut camera_transform = q_camera.get_single_mut().unwrap();
    let (actor, player_transform) = q_playercam.get_single().unwrap();

    // Rotation
    camera_transform.rotation = player_transform.rotation * Quat::from_array([0.0, -1.0, 0.0, 0.0]);

    // Translation
    if settings.third_person {
        camera_transform.translation = player_transform.translation + camera_transform.rotation * (actor.camdistance * Vec3::new(0.0, 0.2, 1.0));
    }
    else {
        camera_transform.translation = player_transform.translation;
    }
}

pub fn update_fov(
    q_player: Query<&actor::LifeForm, With<actor::Player>>,
    mouse_input: Res<ButtonInput<MouseButton>>,
    mut settings: ResMut<settings::Settings>,
    mut q_camera: Query<&mut Projection, With<Camera>>,
) {
    if let (Ok(lifeform), Ok(mut projection)) = (q_player.get_single(), q_camera.get_single_mut())
    {
        let fov: f32;
        if settings.hud_active && mouse_input.pressed(settings.key_zoom) {
            fov = settings.zoom_fov_radians;
            if !settings.is_zooming {
                settings.is_zooming = true;
            }
        } else {
            fov = (lifeform.adrenaline.powf(3.0) * 25.0 + 45.0).to_radians();
            if settings.is_zooming {
                settings.is_zooming = false;
            }
        };
        *projection = Projection::Perspective(PerspectiveProjection { fov: fov, ..default() });
    }
}

pub fn handle_input(
    keyboard_input: Res<ButtonInput<KeyCode>>,
    mut settings: ResMut<settings::Settings>,
) {
    if keyboard_input.just_pressed(settings.key_camera) {
        settings.third_person ^= true;
    }
}

fn manage_player_actor(
    settings: Res<settings::Settings>,
    mut q_playercam: Query<&mut Visibility, With<actor::PlayerCamera>>,
    mut q_hiddenplayer: Query<(&mut Visibility, &mut Position, &mut Rotation, &mut LinearVelocity, &mut AngularVelocity), (With<actor::Player>, Without<actor::PlayerCamera>)>,
    q_ride: Query<(&Transform, &Position, &Rotation, &LinearVelocity, &AngularVelocity), (With<actor::PlayerDrivesThis>, Without<actor::Player>)>,
) {
    for mut vis in &mut q_playercam {
        if settings.third_person {
            *vis = Visibility::Inherited;
        }
        else {
            *vis = Visibility::Hidden;
        }
    }
    for (mut vis, mut pos, mut rot, mut v, mut angv) in &mut q_hiddenplayer {
        // If we are riding a vehicle, place the player at the position where
        // it would be after exiting the vehicle.
        // I would rather place it in the center of the vehicle, but at the time
        // of writing, I couldn't set the position/rotation of the player *during*
        // exiting the vehicle, so I'm doing it here instead, as a workaround.
        *vis = Visibility::Hidden;
        if let Ok((ride_trans, ride_pos, ride_rot, ride_v, ride_angv)) = q_ride.get_single() {
            pos.0 = ride_pos.0 + DVec3::from(ride_trans.rotation * Vec3::new(0.0, 0.0, ride_trans.scale.z * 2.0));
            rot.0 = ride_rot.0 * DQuat::from_array([-1.0, 0.0, 0.0, 0.0]);
            *v = ride_v.clone();
            *angv = ride_angv.clone();
        }
    }
}

#[allow(clippy::too_many_arguments)]
pub fn apply_input_to_player(
    time: Res<Time>,
    settings: Res<settings::Settings>,
    mut windows: Query<&mut Window, With<PrimaryWindow>>,
    mut mouse_events: EventReader<MouseMotion>,
    key_input: Res<ButtonInput<KeyCode>>,
    thruster_sound_controller: Query<&AudioSink, With<audio::ComponentThrusterSound>>,
    rocket_sound_controller: Query<&AudioSink, With<audio::ComponentRocketSound>>,
    ion_sound_controller: Query<&AudioSink, With<audio::ComponentIonSound>>,
    electricmotor_sound_controller: Query<&AudioSink, With<audio::ComponentElectricMotorSound>>,
    q_target: Query<&LinearVelocity, (With<hud::IsTargeted>, Without<actor::PlayerCamera>)>,
    mut q_playercam: Query<(
            &Transform,
            &mut actor::Engine,
            &mut AngularVelocity,
            &mut LinearVelocity,
            &mut ExternalTorque,
        ), (With<actor::PlayerCamera>, Without<Camera>)>,
) {
    let dt = time.delta_seconds();
    let mut play_thruster_sound = false;
    let mut axis_input: DVec3 = DVec3::ZERO;

    let window_result = windows.get_single_mut();
    let mut focused = true;
    if window_result.is_ok() {
        focused = window_result.unwrap().focused;
    }

    let target_v: DVec3 = if let Ok(target) = q_target.get_single() {
        target.0
    } else {
        DVec3::splat(0.0)
    };

    if let Ok((player_transform, mut engine, mut angularvelocity, mut v, mut torque)) = q_playercam.get_single_mut() {
        // Handle key input
        if focused {
            if key_input.pressed(settings.key_forward) {
                axis_input.z += 1.2;
            }
            if key_input.pressed(settings.key_back) {
                axis_input.z -= 1.2;
            }
            if key_input.pressed(settings.key_right) {
                axis_input.x -= 1.2;
            }
            if key_input.pressed(settings.key_left) {
                axis_input.x += 1.2;
            }
            if key_input.pressed(settings.key_up) {
                axis_input.y += 1.2;
            }
            if key_input.pressed(settings.key_down) {
                axis_input.y -= 1.2;
            }
            if key_input.pressed(settings.key_stop) {
                let stop_direction = (target_v - v.0).normalize();
                if stop_direction.length_squared() > 0.3 {
                    axis_input += 1.0 * DVec3::from(player_transform.rotation.inverse() * stop_direction.as_vec3());
                }
            }
        }
        // In typical games we would normalize the input vector so that diagonal movement is as
        // fast as forward or sideways movement.  But here, we merely clamp each direction to an
        // absolute maximum of 1, since every thruster can be used separately. If the forward
        // thrusters and the leftward thrusters are active at the same time, then of course the
        // total diagonal acceleration is faster than the forward acceleration alone.
        axis_input = axis_input.clamp(DVec3::splat(-1.0), DVec3::splat(1.0));

        // Apply movement update
        let forward_factor = engine.current_warmup * (if axis_input.z > 0.0 {
            engine.thrust_forward
        } else {
            engine.thrust_back
        });
        let right_factor = engine.thrust_sideways * engine.current_warmup;
        let up_factor = engine.thrust_sideways * engine.current_warmup;
        let factor = DVec3::new(right_factor as f64, up_factor as f64, forward_factor as f64);

        if axis_input.length_squared() > 0.003 {
            let acceleration_global: DVec3 = DVec3::from(player_transform.rotation * (axis_input * factor).as_vec3());
            let mut acceleration_total: DVec3 = (actor::ENGINE_SPEED_FACTOR * dt) as f64 * acceleration_global;
            let threshold = 1e-5;
            if key_input.pressed(settings.key_stop) {
                // Decelerate (or match velocity to target_v)
                let dv = v.0 - target_v;
                for i in 0..3 {
                    if dv[i].abs() < threshold {
                        v[i] = target_v[i];
                    }
                    else if dv[i].signum() != (dv[i] + acceleration_total[i]).signum() {
                        // Almost stopped, but we overshot v=0
                        v[i] = target_v[i];
                        acceleration_total[i] = 0.0;
                    }
                }
            }
            v.0 += acceleration_total;
            engine.current_warmup = (engine.current_warmup + dt / engine.warmup_seconds).clamp(0.0, 1.0);
            play_thruster_sound = true;
        }
        else {
            engine.current_warmup = (engine.current_warmup - dt / engine.warmup_seconds).clamp(0.0, 1.0);
        }

        // Handle mouse input and mouse-like key bindings
        let mut play_reactionwheel_sound = false;
        let mut mouse_delta = Vec2::ZERO;
        let mut pitch_yaw_rot = Vec3::ZERO;
        let sensitivity_factor = if settings.is_zooming { settings.zoom_sensitivity_factor } else { 1.0 };
        let mouseless_sensitivity = 40.0 * sensitivity_factor;
        if key_input.pressed(settings.key_mouseup) {
            pitch_yaw_rot[0] -= mouseless_sensitivity;
        }
        if key_input.pressed(settings.key_mousedown) {
            pitch_yaw_rot[0] += mouseless_sensitivity;
        }
        if key_input.pressed(settings.key_mouseleft) {
            pitch_yaw_rot[1] += mouseless_sensitivity; }
        if key_input.pressed(settings.key_mouseright) {
            pitch_yaw_rot[1] -= mouseless_sensitivity;
        }
        if key_input.pressed(settings.key_rotateleft) {
            pitch_yaw_rot[2] -= mouseless_sensitivity;
        }
        if key_input.pressed(settings.key_rotateright) {
            pitch_yaw_rot[2] += mouseless_sensitivity;
        }
        for mouse_event in mouse_events.read() {
            mouse_delta += mouse_event.delta;
        }
        if mouse_delta != Vec2::ZERO {
            if key_input.pressed(settings.key_rotate) {
                pitch_yaw_rot[2] += mouse_delta.x;
            } else {
                pitch_yaw_rot[0] += mouse_delta.y;
                pitch_yaw_rot[1] -= mouse_delta.x;
            }
        }

        let angular_slowdown: f64 = (2.0 - engine.reaction_wheels.powf(0.01).clamp(1.001, 1.1)) as f64;
        if pitch_yaw_rot.length_squared() > 1.0e-18 {
            play_reactionwheel_sound = true;
            pitch_yaw_rot *= settings.mouse_sensitivity * sensitivity_factor * engine.reaction_wheels;
            torque.apply_torque(DVec3::from(
                    player_transform.rotation * Vec3::new(
                        pitch_yaw_rot[0] * 2.0,
                        pitch_yaw_rot[1],
                        pitch_yaw_rot[2])));
            angularvelocity.0 *= angular_slowdown.clamp(0.97, 1.0) as f64;
        }
        else {
            if angularvelocity.length_squared() > 1.0e-18 {
                angularvelocity.0 *= angular_slowdown;
            }
            else {
                angularvelocity.0 = DVec3::splat(0.0);
            }
        }

        // Play sound effects
        if let Ok(sink) = electricmotor_sound_controller.get_single() {
            let volume = sink.volume();
            let speed = sink.speed();
            let action = pitch_yaw_rot.length_squared().powf(0.2) * 0.0005;
            if play_reactionwheel_sound && !settings.mute_sfx {
                sink.set_volume((volume + action).clamp(0.0, 1.0));
                sink.set_speed((speed + action * 0.2).clamp(0.2, 0.5));
                sink.play()
            } else {
                if volume <= 0.01 {
                    sink.pause()
                } else {
                    sink.set_volume((volume - 0.01).clamp(0.0, 1.0));
                    sink.set_speed((speed - 0.03).clamp(0.2, 0.5));
                }
            }
        }
        if let Ok(sink) = thruster_sound_controller.get_single() {
            if play_thruster_sound && !settings.mute_sfx && engine.engine_type == actor::EngineType::Monopropellant {
                sink.play()
            } else {
                sink.pause()
            }
        }
        if let Ok(sink) = rocket_sound_controller.get_single() {
            if play_thruster_sound && !settings.mute_sfx && engine.engine_type == actor::EngineType::Rocket {
                sink.play()
            } else {
                sink.pause()
            }
        }
        if let Ok(sink) = ion_sound_controller.get_single() {
            if play_thruster_sound && !settings.mute_sfx && engine.engine_type == actor::EngineType::Ion {
                sink.play()
            } else {
                sink.pause()
            }
        }
    }
}

// Find the closest world object that the player is looking at
#[inline]
pub fn find_closest_target<TargetSpecifier>(
    objects: Vec<(TargetSpecifier, &Transform)>,
    camera_transform: &Transform,
) -> (Option<TargetSpecifier>, f32)
    where TargetSpecifier: Clone
{
    let mut closest_entity: Option<TargetSpecifier> = None;
    let mut closest_distance: f32 = f32::MAX;
    let target_vector: Vec3 = (camera_transform.rotation * Vec3::new(0.0, 0.0, -1.0))
        .normalize_or_zero();
    for (entity, trans) in objects {
        // Use Transform instead of Position because we're basing this
        // not on the player mesh but on the camera, which doesn't have a position.
        let (angular_diameter, angle, distance) = calc_angular_diameter_known_target_vector(
                trans, camera_transform, &target_vector);
        if angle <= angular_diameter.clamp(0.001, PI) {
            // It's in the field of view!
            //commands.entity(entity).insert(IsTargeted);
            if distance < closest_distance {
                closest_distance = distance;
                closest_entity = Some(entity);
            }
        }
    }
    return (closest_entity, closest_distance);
}

#[inline]
pub fn calc_angular_diameter_known_target_vector(
    target: &Transform,
    camera: &Transform,
    target_vector: &Vec3,
) -> (f32, f32, f32) {
    let pos_vector: Vec3 = (target.translation - camera.translation)
        .normalize_or_zero();
    let cosine_of_angle: f32 = target_vector.dot(pos_vector);
    let angle: f32 = cosine_of_angle.acos();
    let distance: f32 = target.translation.distance(camera.translation);
    let leeway: f32 = 1.3;
    let angular_diameter: f32 = if distance > 0.0 {
        // Angular Diameter
        leeway * (target.scale[0] / distance).asin()
    }
    else {
        0.0
    };
    return (angular_diameter, angle, distance);
}

#[inline]
pub fn calc_angular_diameter(
    target: &Transform,
    camera: &Transform,
) -> (f32, f32, f32) {
    let target_vector: Vec3 = (camera.rotation * Vec3::new(0.0, 0.0, -1.0))
        .normalize_or_zero();
    return calc_angular_diameter_known_target_vector(target, camera, &target_vector);
}