Calculate discount from MSRP price compatibility for WooCommerce MSRP Pricing

Calculate discounts based on MSRP prices.

if (!function_exists('advanced_woo_discount_rules_get_msrp_price')) {
    function advanced_woo_discount_rules_get_msrp_price($product_price, $product, $quantity, $cart_item, $calculate_discount_from) {
		if (is_object($product) && method_exists($product, 'get_id')) {
			$msrp_price = get_post_meta($product->get_id(), '_msrp_price', true);
            if ($msrp_price !== false && $msrp_price !== '') {
                $product_price = $msrp_price;
            }
		}
        return $product_price;
    }

    add_filter('advanced_woo_discount_rules_product_original_price_on_before_calculate_discount', 'advanced_woo_discount_rules_get_msrp_price', 100, 5);
    add_filter('advanced_woo_discount_rules_product_price_on_before_calculate_discount', 'advanced_woo_discount_rules_get_msrp_price', 100, 5);
}