use bevy::{
    diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
    ecs::prelude::*,
    math::{Mat4, Quat, Vec3},
    pbr2::{
        AmbientLight, DirectionalLight, DirectionalLightBundle, PbrBundle, PointLight,
        PointLightBundle, StandardMaterial,
    },
    prelude::{App, Assets, BuildChildren, Transform},
    render2::{
        camera::{OrthographicProjection, PerspectiveCameraBundle},
        color::Color,
        mesh::{shape, Mesh},
    },
    PipelinedDefaultPlugins,
};

fn main() {
    App::new()
        .add_plugins(PipelinedDefaultPlugins)
        .add_plugin(FrameTimeDiagnosticsPlugin::default())
        .add_plugin(LogDiagnosticsPlugin::default())
        .add_startup_system(setup)
        .run();
}

/// set up a simple 3D scene
fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    let box_size = 2.0;
    let box_thickness = 0.15;
    let box_offset = (box_size + box_thickness) / 2.0;

    // left - red
    let mut transform = Transform::from_xyz(-box_offset, box_offset, 0.0);
    transform.rotate(Quat::from_rotation_z(std::f32::consts::FRAC_PI_2));
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Box::new(
            box_size,
            box_thickness,
            box_size,
        ))),
        transform,
        material: materials.add(StandardMaterial {
            base_color: Color::rgb(0.63, 0.065, 0.05),
            ..Default::default()
        }),
        ..Default::default()
    });
    // right - green
    let mut transform = Transform::from_xyz(box_offset, box_offset, 0.0);
    transform.rotate(Quat::from_rotation_z(std::f32::consts::FRAC_PI_2));
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Box::new(
            box_size,
            box_thickness,
            box_size,
        ))),
        transform,
        material: materials.add(StandardMaterial {
            base_color: Color::rgb(0.14, 0.45, 0.091),
            ..Default::default()
        }),
        ..Default::default()
    });
    // bottom - white
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Box::new(
            box_size + 2.0 * box_thickness,
            box_thickness,
            box_size,
        ))),
        material: materials.add(StandardMaterial {
            base_color: Color::rgb(0.725, 0.71, 0.68),
            ..Default::default()
        }),
        ..Default::default()
    });
    // top - white
    let transform = Transform::from_xyz(0.0, 2.0 * box_offset, 0.0);
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Box::new(
            box_size + 2.0 * box_thickness,
            box_thickness,
            box_size,
        ))),
        transform,
        material: materials.add(StandardMaterial {
            base_color: Color::rgb(0.725, 0.71, 0.68),
            ..Default::default()
        }),
        ..Default::default()
    });
    // back - white
    let mut transform = Transform::from_xyz(0.0, box_offset, -box_offset);
    transform.rotate(Quat::from_rotation_x(std::f32::consts::FRAC_PI_2));
    commands.spawn_bundle(PbrBundle {
        mesh: meshes.add(Mesh::from(shape::Box::new(
            box_size + 2.0 * box_thickness,
            box_thickness,
            box_size + 2.0 * box_thickness,
        ))),
        transform,
        material: materials.add(StandardMaterial {
            base_color: Color::rgb(0.725, 0.71, 0.68),
            ..Default::default()
        }),
        ..Default::default()
    });

    // ambient light
    commands.insert_resource(AmbientLight {
        color: Color::WHITE,
        brightness: 0.02,
    });
    // top light
    commands
        .spawn_bundle(PbrBundle {
            mesh: meshes.add(Mesh::from(shape::Plane { size: 0.4 })),
            transform: Transform::from_matrix(Mat4::from_scale_rotation_translation(
                Vec3::ONE,
                Quat::from_rotation_x(std::f32::consts::PI),
                Vec3::new(0.0, box_size + 0.5 * box_thickness, 0.0),
            )),
            material: materials.add(StandardMaterial {
                base_color: Color::WHITE,
                emissive: Color::WHITE * 100.0,
                ..Default::default()
            }),
            ..Default::default()
        })
        .with_children(|builder| {
            builder.spawn_bundle(PointLightBundle {
                point_light: PointLight {
                    color: Color::WHITE,
                    intensity: 25.0,
                    ..Default::default()
                },
                transform: Transform::from_translation((box_thickness + 0.05) * Vec3::Y),
                ..Default::default()
            });
        });
    // directional light
    const HALF_SIZE: f32 = 10.0;
    commands.spawn_bundle(DirectionalLightBundle {
        directional_light: DirectionalLight {
            illuminance: 10000.0,
            shadow_projection: OrthographicProjection {
                left: -HALF_SIZE,
                right: HALF_SIZE,
                bottom: -HALF_SIZE,
                top: HALF_SIZE,
                near: -10.0 * HALF_SIZE,
                far: 10.0 * HALF_SIZE,
                ..Default::default()
            },
            ..Default::default()
        },
        transform: Transform::from_rotation(Quat::from_rotation_x(-std::f32::consts::PI / 2.0)),
        ..Default::default()
    });

    // camera
    commands.spawn_bundle(PerspectiveCameraBundle {
        transform: Transform::from_xyz(0.0, box_offset, 4.0)
            .looking_at(Vec3::new(0.0, box_offset, 0.0), Vec3::Y),
        ..Default::default()
    });
}