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

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

    /*
     * Ground
     */
    let ground_size = 100.1;
    let ground_height = 0.1;

    let rigid_body = RigidBodyBuilder::fixed().translation(Vec3::new(0.0, -ground_height, 0.0));
    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_size);
    world.insert(rigid_body, collider);

    /*
     * Create the cubes
     */
    let num = 4;
    let numj = 20;
    let rad = 1.0;

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

    let mut offset = -(num as f32) * (rad * 2.0 + rad) * 0.5;

    for j in 0usize..numj {
        for i in 0..num {
            for k in 0usize..num {
                let x = i as f32 * shiftx - centerx + offset;
                let y = j as f32 * shifty + centery + 3.0;
                let z = k as f32 * shiftz - centerz + offset;

                // Build the rigid body.
                let rigid_body = RigidBodyBuilder::dynamic()
                    .translation(Vec3::new(x, y, z))
                    .linvel(Vec3::new(0.0, -1000.0, 0.0))
                    .ccd_enabled(true);

                let collider = match j % 5 {
                    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),
                    _ => ColliderBuilder::capsule_y(rad, rad),
                };

                world.insert(rigid_body, collider);
            }
        }

        offset -= 0.05 * rad * (num as f32 - 1.0);
    }

    /*
     * 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(())
}
