Unpublish a product in #woocommerce when it's sold out

functions.php

<?php

/*
 * Unpublish products after purchase
 */
	add_action( 'woocommerce_thankyou', 'yanco_unpublish_product_if_sold_out', 10, 1 );
	function yanco_unpublish_product_if_sold_out( $order_id ) {
	    $order = new WC_Order( $order_id );

	    $all_products = $order->get_items();

	    foreach ( $all_products as $product ) {

	        $product_object = wc_get_product( $product['product_id'] );

			if( get_post_meta( $product['product_id'], '_manage_stock' ) == 'yes' ) {
				// This will only work if stock management has been enabled
				$product_stock_quantity = $product_object->get_stock_quantity();

		        if( $product_stock_quantity == 0) {
		            wp_update_post(
						array(
			                'ID' => $product['product_id'],
			                'post_status' => 'draft'
		                )
					);
		        }
				else if ( $product_stock_quantity < 1 ) {
					wp_update_post(
						array(
			                'ID' => $product['product_id'],
			                'post_status' => 'draft'
		                )
					);
				}
				elseif ( $product_stock_quantity == null ) {
					wp_update_post(
						array(
			                'ID' => $product['product_id'],
			                'post_status' => 'draft'
		                )
					);
				} else {

				}
			}
	    }
	}