WCSSM: Force the native sale-price overwrite

functions.php

// Force the native sale-price overwrite
add_filter( 'get_post_metadata', 'wcssm_markus_filter_sale_price_meta', 11, 4 );
function wcssm_markus_filter_sale_price_meta( $value, $object_id, $meta_key, $single ) {

	if ( $meta_key === '_sale_price' ) {

		remove_filter( 'get_post_metadata', 'wcssm_markus_filter_sale_price_meta', 11, 4 );

		if ( $sale = WCSSM::get_applicable_sale( $object_id ) ) {
			$value = $sale['price'];
		}

		add_filter( 'get_post_metadata', 'wcssm_markus_filter_sale_price_meta', 11, 4 );

	}

	return $value;

}