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();

    /*
     * Ground
     */
    let ground_size = 100.0;
    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 num = 100;
    let rad = 0.5;

    let shift = rad * 2.0;
    let centerx = shift * (num as f32) / 2.0;
    let centery = shift / 2.0 + ground_thickness + rad * 1.5;

    for i in 0usize..num {
        for j in i..num {
            let fj = j as f32;
            let fi = i as f32;
            let x = (fi * shift / 2.0) + (fj - fi) * shift - centerx;
            let y = fi * shift + 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);
}
