woo-custom-price-with-order-update

/**
 * Adjust Woo Price in Points
 * If an order item has the product attribute "size"
 * and the size is "large", deduct the extra cost the variation
 * enforces when paying with points.
 * @version 1.1
 */
function mycredpro_adjust_point_cost_woo( $cost, $order, $is_cart, $this ) {

	if ( $is_cart ) return $cost;

	$items = $order->get_items();

	$amount_to_deduct = 0;
	$product_factory  = new WC_Product_Factory();
	foreach ( $items as $item_id => $item ) {

		if ( ! isset( $item['pa_size'] ) ) continue;

		$sizes_that_cost_extra = array( 'L', 'XL', 'XXL' );

		if ( in_array( $item['pa_size'], $sizes_that_cost_extra ) ) {

			$product          = $product_factory->get_product( $item['product_id'] );
			$amount_to_deduct = $amount_to_deduct + ( $item['qty'] * 2 );

			$order->update_product( $item_id, $product, array(
				'qty'    => $item['qty'],
				'totals' => array(
					'subtotal' => ( $product->get_price() - 2 )
				)
			) );

		}

	}

	if ( $amount_to_deduct > 0 ) {

		$order->calculate_totals();

		$cost = $cost - $amount_to_deduct;

	}

	return $cost;

}
add_filter( 'mycred_woo_order_cost', 'mycredpro_adjust_point_cost_woo', 10, 4 );