use crate::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 std::f32::consts::PI;

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

const CUBEMAP_PATH: &str = "textures/stars_cubemap.png";

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 skybox
    let skybox_handle = asset_server.load(CUBEMAP_PATH);
    commands.spawn((
        Camera3dBundle {
            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: 150.0,
        },
    ));
    commands.insert_resource(Cubemap {
        is_loaded: false,
        image_handle: skybox_handle,
    });

    // Add spheres
    let sphere_radius = 50.0;
    let sphere_handle = meshes.add(Sphere::new(sphere_radius));
    let white_handle = materials.add(StandardMaterial {
        base_color: Color::GRAY,
        perceptual_roughness: 1.0,
        ..default()
    });
    commands.spawn(PbrBundle {
        mesh: sphere_handle.clone(),
        material: white_handle.clone(),
        transform: Transform::from_xyz(
            0.0,
            0.0,
            -2000.0,
        ),
        ..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 / 5.0,
        )),
        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(CUBEMAP_PATH);
    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;
    }
}