use rapier2d::prelude::*;
use rapier_testbed2d::Testbed;

pub fn init_world(testbed: &mut Testbed) {
    /*
     * World
     */
    let mut bodies = RigidBodySet::new();
    let mut colliders = ColliderSet::new();
    let impulse_joints = ImpulseJointSet::new();
    let multibody_joints = MultibodyJointSet::new();

    let num = 80;
    let rad = 0.5;

    /*
     * Ground
     */
    let ground_size = num as f32 * rad * 10.0;
    let ground_thickness = 1.0;

    let rigid_body = RigidBodyBuilder::fixed();
    let ground_handle = bodies.insert(rigid_body);
    let collider = ColliderBuilder::cuboid(ground_size, ground_thickness);
    colliders.insert_with_parent(collider, ground_handle, &mut bodies);

    /*
     * Create the cubes
     */

    let shiftx_centerx = [
        (rad * 2.0 + 0.0002, -(num as f32) * rad * 2.0 * 1.5),
        (rad * 2.0 + rad, num as f32 * rad * 2.0 * 1.5),
    ];

    for (shiftx, centerx) in shiftx_centerx {
        let shifty = rad * 2.0;
        let centery = shifty / 2.0 + ground_thickness;

        for i in 0..num {
            for j in 0usize..1 + i * 2 {
                let fj = j as f32;
                let fi = i as f32;
                let x = (fj - fi) * shiftx + centerx;
                let y = (num as f32 - fi - 1.0) * shifty + centery;

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

    /*
     * Set up the testbed.
     */
    testbed.set_world(bodies, colliders, impulse_joints, multibody_joints);
    testbed.look_at(point![0.0, 2.5], 5.0);
}