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 joints = JointSet::new();

    /*
     * Ground
     */
    let ground_size = 5.0;
    let ground_height = 0.1;

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

    /*
     * Setup groups
     */
    const GREEN_GROUP: InteractionGroups = InteractionGroups::new(0b01, 0b01);
    const BLUE_GROUP: InteractionGroups = InteractionGroups::new(0b10, 0b10);

    /*
     * A green floor that will collide with the GREEN group only.
     */
    let green_floor = ColliderBuilder::cuboid(1.0, 0.1)
        .translation(vector![0.0, 1.0])
        .collision_groups(GREEN_GROUP)
        .build();
    let green_collider_handle =
        colliders.insert_with_parent(green_floor, floor_handle, &mut bodies);

    testbed.set_initial_collider_color(green_collider_handle, [0.0, 1.0, 0.0]);

    /*
     * A blue floor that will collide with the BLUE group only.
     */
    let blue_floor = ColliderBuilder::cuboid(1.0, 0.1)
        .translation(vector![0.0, 2.0])
        .collision_groups(BLUE_GROUP)
        .build();
    let blue_collider_handle = colliders.insert_with_parent(blue_floor, floor_handle, &mut bodies);

    testbed.set_initial_collider_color(blue_collider_handle, [0.0, 0.0, 1.0]);

    /*
     * Create the cubes
     */
    let num = 8;
    let rad = 0.1;

    let shift = rad * 2.0;
    let centerx = shift * (num / 2) as f32;
    let centery = 2.5;

    for j in 0usize..4 {
        for i in 0..num {
            let x = i as f32 * shift - centerx;
            let y = j as f32 * shift + centery;

            // Alternate between the green and blue groups.
            let (group, color) = if i % 2 == 0 {
                (GREEN_GROUP, [0.0, 1.0, 0.0])
            } else {
                (BLUE_GROUP, [0.0, 0.0, 1.0])
            };

            let rigid_body = RigidBodyBuilder::new_dynamic()
                .translation(vector![x, y])
                .build();
            let handle = bodies.insert(rigid_body);
            let collider = ColliderBuilder::cuboid(rad, rad)
                .collision_groups(group)
                .build();
            colliders.insert_with_parent(collider, handle, &mut bodies);

            testbed.set_initial_body_color(handle, color);
        }
    }

    /*
     * Set up the testbed.
     */
    testbed.set_world(bodies, colliders, joints);
    testbed.look_at(point![0.0, 1.0], 100.0);
}