use rapier3d::prelude::*;
use rapier_testbed3d::Testbed;

pub fn init_world(testbed: &mut Testbed) {
    /*
     * World
     */
    let mut bodies = RigidBodySet::new();
    let mut colliders = ColliderSet::new();
    let joints = JointSet::new();

    /*
     * Ground.
     */
    let ground_size = 10.0;
    let ground_height = 0.1;

    let rigid_body = RigidBodyBuilder::new_static()
        .translation(vector![0.0, -ground_height, 0.0])
        .build();
    let handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(ground_size, ground_height, ground_size).build();
    colliders.insert_with_parent(collider, handle, &mut bodies);

    /*
     * Create the boxes
     */
    let num = 6;
    let rad = 0.2;

    let shift = rad * 2.0;
    let centerx = shift * num as f32 / 2.0;
    let centery = shift / 2.0 + 3.04;
    let centerz = shift * num as f32 / 2.0;

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

                // Build the rigid body.
                let rigid_body = RigidBodyBuilder::new_dynamic()
                    .translation(vector![x, y, z])
                    .build();
                let handle = bodies.insert(rigid_body);
                let collider = ColliderBuilder::cuboid(rad, rad, rad).build();
                colliders.insert_with_parent(collider, handle, &mut bodies);
            }
        }
    }

    /*
     * Setup a velocity-based kinematic rigid body.
     */
    let platform_body = RigidBodyBuilder::new_kinematic_velocity_based()
        .translation(vector![0.0, 1.5 + 0.8, -10.0 * rad])
        .build();
    let velocity_based_platform_handle = bodies.insert(platform_body);
    let collider = ColliderBuilder::cuboid(rad * 10.0, rad, rad * 10.0).build();
    colliders.insert_with_parent(collider, velocity_based_platform_handle, &mut bodies);

    /*
     * Setup a position-based kinematic rigid body.
     */
    let platform_body = RigidBodyBuilder::new_kinematic_position_based()
        .translation(vector![0.0, 2.0 + 1.5 + 0.8, -10.0 * rad])
        .build();
    let position_based_platform_handle = bodies.insert(platform_body);
    let collider = ColliderBuilder::cuboid(rad * 10.0, rad, rad * 10.0).build();
    colliders.insert_with_parent(collider, position_based_platform_handle, &mut bodies);

    /*
     * Setup a callback to control the platform.
     */
    let mut count = 0;
    testbed.add_callback(move |_, physics, _, run_state| {
        count += 1;
        if count % 100 > 50 {
            return;
        }

        let velocity = vector![
            0.0,
            (run_state.time * 5.0).sin(),
            run_state.time.sin() * 5.0
        ];

        // Update the velocity-based kinematic body by setting its velocity.
        if let Some(platform) = physics.bodies.get_mut(velocity_based_platform_handle) {
            platform.set_linvel(velocity, true);
        }

        // Update the position-based kinematic body by setting its next position.
        if let Some(platform) = physics.bodies.get_mut(position_based_platform_handle) {
            let mut next_tra = *platform.translation();
            next_tra += velocity * physics.integration_parameters.dt;
            platform.set_next_kinematic_translation(next_tra);
        }
    });

    /*
     * Run the simulation.
     */
    testbed.set_world(bodies, colliders, joints);
    testbed.look_at(point![-10.0, 5.0, -10.0], Point::origin());
}