use crate::{actor, camera};
use bevy::prelude::*;
use bevy::core_pipeline::Skybox;
use bevy::asset::LoadState;
use bevy::render::render_resource::{TextureViewDescriptor, TextureViewDimension};
use bevy::pbr::CascadeShadowConfigBuilder;
use bevy::core_pipeline::bloom::{BloomCompositeMode, BloomSettings};
use std::f32::consts::PI;

const ASTEROID_SIZE: f32 = 100.0;
const MOON_SIZE: f32 = 50.0;
const MARS_SIZE: f32 = 10.0;
const SUN_SIZE: f32 = 5000.0;
const ASTRONAUT_SIZE: f32 = 5.0;

const SUN_BRIGHTNESS: f32 = 1e5;
const SKYBOX_BRIGHTNESS: f32 = 300.0;

const ASSET_CUBEMAP: &str = "textures/stars_cubemap.png";
const ASSET_ASTRONAUT: &str = "tmp/alien.glb#Scene0";

pub struct WorldPlugin;
impl Plugin for WorldPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, setup);
        app.add_systems(Update, asset_loaded.after(load_cubemap_asset));
    }
}

#[derive(Resource)]
pub struct Cubemap {
    is_loaded: bool,
    image_handle: Handle<Image>,
}

pub fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    mut ambient_light: ResMut<AmbientLight>,
    asset_server: Res<AssetServer>,
) {
    // Add player
    commands.spawn((
        actor::Player,
        actor::Actor::default(),
        actor::LifeForm::default(),
        actor::Suit {
            oxygen: actor::OXY_M,
            ..default()
        }
    ));

    // Add skybox
    let skybox_handle = asset_server.load(ASSET_CUBEMAP);
    commands.spawn((
        Camera3dBundle {
            camera: Camera {
                hdr: true, // HDR is required for bloom
                ..default()
            },
            transform: Transform::from_xyz(0.0, 0.0, 8.0).looking_at(Vec3::ZERO, Vec3::Y),
            ..default()
        },
        camera::CameraController::default(),
        Skybox {
            image: skybox_handle.clone(),
            brightness: SKYBOX_BRIGHTNESS,
        },
        BloomSettings {
            composite_mode: BloomCompositeMode::EnergyConserving,
            ..default()
        },
    ));
    commands.insert_resource(Cubemap {
        is_loaded: false,
        image_handle: skybox_handle,
    });

    // Add some hand-placed asteroids
    let sphere_handle = meshes.add(Sphere::new(1.0));
    let gray_handle = materials.add(StandardMaterial {
        base_color: Color::GRAY,
        perceptual_roughness: 1.0,
        ..default()
    });
    let brown_handle = materials.add(StandardMaterial {
        base_color: Color::Rgba { alpha: 1.0, red: 0.8, green: 0.5, blue: 0.1 },
        perceptual_roughness: 1.0,
        ..default()
    });
    commands.spawn((
        actor::Actor::default(),
        PbrBundle {
            mesh: sphere_handle.clone(),
            material: gray_handle.clone(),
            transform: Transform::from_xyz(
                0.0,
                0.0,
                -500.0,
            ).with_scale(Vec3::splat(MOON_SIZE)),
            ..default()
        },
    ));
    commands.spawn((
        actor::Actor::default(),
        PbrBundle {
            mesh: sphere_handle.clone(),
            material: brown_handle.clone(),
            transform: Transform::from_xyz(
                300.0,
                40.0,
                250.0,
            ).with_scale(Vec3::splat(MARS_SIZE)),
            ..default()
        },
    ));

    // Generate a bunch of asteriods
    let asteroid_color_handle = materials.add(StandardMaterial {
        base_color: Color::rgb(0.25, 0.2, 0.2),
        perceptual_roughness: 1.0,
        ..default()
    });
    for i in -12..12 {
        for j in -13..13 {
            for k in -14..14 {
                let offset = 500.0;
                let dist = 18000.0;
                let wobble = dist/2.0;
                let (i, j, k) = (i as f32, j as f32, k as f32);
                commands.spawn((
                    actor::Actor::default(),
                    PbrBundle {
                        mesh: sphere_handle.clone(),
                        material: asteroid_color_handle.clone(),
                        transform: Transform::from_xyz(
                            offset + dist * i + wobble * (j+k/PI).sin() * (k+j/PI).cos(),
                            offset + dist * j + wobble * (k+i/PI).sin() * (i+k/PI).cos(),
                            offset + dist * k + wobble * (i+j/PI).sin() * (j+i/PI).cos(),
                        ).with_scale(Vec3::splat(ASTEROID_SIZE)),
                        ..default()
                    }
                ));
            }
        }
    }

    // Add THE SUN
    let hydrogenfusion_handle = materials.add(StandardMaterial {
        emissive: Color::rgb_linear(SUN_BRIGHTNESS, 0.9 * SUN_BRIGHTNESS, SUN_BRIGHTNESS),
        ..default()
    });
    commands.spawn(PbrBundle {
        mesh: sphere_handle.clone(),
        material: hydrogenfusion_handle.clone(),
        transform: Transform::from_xyz(
            0.0,
            30000.0,
            -500000.0,
        ).with_scale(Vec3::splat(SUN_SIZE)),
        ..default()
    });

    // Add alien
    commands.spawn(SceneBundle {
            transform: Transform {
                translation: Vec3::new(
                    0.0,
                    0.0,
                    100.0,
                ),
                rotation: Quat::from_rotation_y(-PI / 3.),
                scale: Vec3::splat(ASTRONAUT_SIZE),
            },
            scene: asset_server.load(ASSET_ASTRONAUT),
            ..default()
        });

    // Space is DARK
    ambient_light.brightness = 0.0;

    // Add Light
    commands.spawn(DirectionalLightBundle {
        directional_light: DirectionalLight {
            illuminance: 1000.0,
            shadows_enabled: false,
            ..default()
        },
        transform: Transform::from_rotation(Quat::from_euler(
            EulerRot::ZYX,
            0.0,
            PI / 1.0,
            -PI / 7.0,
        )),
        cascade_shadow_config: CascadeShadowConfigBuilder {
            first_cascade_far_bound: 7.0,
            maximum_distance: 25.0,
            ..default()
        }
        .into(),
        ..default()
    });
}

pub fn load_cubemap_asset(
    mut cubemap: ResMut<Cubemap>,
    asset_server: Res<AssetServer>,
) {
    cubemap.image_handle = asset_server.load(ASSET_CUBEMAP);
    cubemap.is_loaded = false;
}

pub fn asset_loaded(
    asset_server: Res<AssetServer>,
    mut images: ResMut<Assets<Image>>,
    mut cubemap: ResMut<Cubemap>,
    mut skyboxes: Query<&mut Skybox>,
) {
    if !cubemap.is_loaded && asset_server.load_state(&cubemap.image_handle) == LoadState::Loaded {
        let image = images.get_mut(&cubemap.image_handle).unwrap();
        if image.texture_descriptor.array_layer_count() == 1 {
            image.reinterpret_stacked_2d_as_array(image.height() / image.width());
            image.texture_view_descriptor = Some(TextureViewDescriptor {
                dimension: Some(TextureViewDimension::Cube),
                ..default()
            });
        }

        for mut skybox in &mut skyboxes {
            skybox.image = cubemap.image_handle.clone();
        }

        cubemap.is_loaded = true;
    }
}