use rapier_testbed3d::TestbedViewer;
use rapier3d::na::ComplexField;
use rapier3d::prelude::*;

pub async fn run(viewer: &mut TestbedViewer) -> anyhow::Result<()> {
    /*
     * World
     */
    let mut world = PhysicsWorld::new();

    /*
     * Ground
     */
    let ground_size = Vector::new(100.0, 1.0, 100.0);
    let nsubdivs = 20;

    let heights = Array2::from_fn(nsubdivs + 1, nsubdivs + 1, |i, j| {
        if i == 0 || i == nsubdivs || j == 0 || j == nsubdivs {
            10.0
        } else {
            let x = i as f32 * ground_size.x / (nsubdivs as f32);
            let z = j as f32 * ground_size.z / (nsubdivs as f32);

            // NOTE: make sure we use the sin/cos from simba to ensure
            // cross-platform determinism of the example when the
            // enhanced_determinism feature is enabled.
            ComplexField::sin(x) + ComplexField::cos(z)
        }
    });

    let rigid_body = RigidBodyBuilder::fixed();
    let collider = ColliderBuilder::heightfield(heights, ground_size);
    let (_handle, _) = world.insert(rigid_body, collider);

    /*
     * Create the cubes
     */
    let num = 8;
    let rad = 1.0;

    let shift = rad * 2.0 + rad;
    let centerx = shift * (num / 2) as f32;
    let centery = shift / 2.0;
    let centerz = shift * (num / 2) as f32;

    for j in 0usize..20 {
        for i in 0..num {
            for k in 0usize..num {
                let x = i as f32 * shift - centerx;
                let y = j as f32 * shift + centery + 3.0;
                let z = k as f32 * shift - centerz;

                // Build the rigid body.
                let rigid_body = RigidBodyBuilder::dynamic().translation(Vector::new(x, y, z));

                let collider = match j % 6 {
                    0 => ColliderBuilder::cuboid(rad, rad, rad),
                    1 => ColliderBuilder::ball(rad),
                    // Rounded cylinders are much more efficient that cylinder, even if the
                    // rounding margin is small.
                    2 => ColliderBuilder::round_cylinder(rad, rad, rad / 10.0),
                    3 => ColliderBuilder::cone(rad, rad),
                    4 => ColliderBuilder::capsule_y(rad, rad),
                    _ => {
                        let shapes = vec![
                            (
                                Pose::IDENTITY,
                                SharedShape::cuboid(rad, rad / 2.0, rad / 2.0),
                            ),
                            (
                                Pose::from_translation(Vector::new(rad, 0.0, 0.0)),
                                SharedShape::cuboid(rad / 2.0, rad, rad / 2.0),
                            ),
                            (
                                Pose::from_translation(Vector::new(-rad, 0.0, 0.0)),
                                SharedShape::cuboid(rad / 2.0, rad, rad / 2.0),
                            ),
                        ];

                        ColliderBuilder::compound(shapes)
                    }
                };

                let (_handle, _) = world.insert(rigid_body, collider);
            }
        }
    }

    /*
     * Set up the testbed.
     */
    viewer.set_world(&mut world);
    viewer.look_at(Vec3::new(100.0, 100.0, 100.0), Vec3::ZERO);

    while viewer.render_frame(&mut world).await {
        if viewer.simulating() {
            world.step();
        }
    }
    Ok(())
}
