Example: Reward buyer with 1 point for each product in an order, once the order is marked as completed. Requires WooCommerce 3.0+

reward-completed-woo-orders

/**
 * Reward Completed Orders
 * Will give a user 1 point for each product in an order.
 * @version 1.0.1
 */
function mycred_pro_reward_completed_orders( $order_id ) {

	if ( ! function_exists( 'mycred' ) ) return;

	$order   = wc_get_order( $order_id );
	$user_id = $order->get_user_id();
	$point_type_key = 'something';

	$mycred  = mycred( $point_type_key );

	if ( ! $mycred->exclude_user( $user_id ) ) {

		foreach ( $order->get_items() as $item ) {

			$mycred->add_creds(
				'book_return',
				$user_id,
				1,
				'Returned book',
				$item['product_id'],
				array( 'ref_type' => 'post' ),
				$point_type_key
			);

		}

	}

}
add_action( 'woocommerce_order_status_completed', 'mycred_pro_reward_completed_orders' );