quick generate google_shop_feed.xml on wordpress

google_shop_feed.php

<?php

require_once( dirname( __FILE__ ) . '/wp-load.php' );


$args = array(
    'post_type' => 'product',
    'posts_per_page' => 9999999
);

$query = new \WP_Query($args);

$getCategories = get_categories( array(
    'taxonomy' => 'product_cat',
));

if ( $query->have_posts() ) {

    $loopCount = 0;
    $file = $_SERVER['DOCUMENT_ROOT'] . '/google_shop_feed.xml';

    $optionFirmId = get_option( 'my_option_xml_firmId' );
    $optionRate = get_option( 'kurs' );

    $headerXml = '<?xml version="1.0" encoding="UTF-8"?>
	<rss xmlns:g="http://base.google.com/ns/1.0" version="2.0">
	<channel>
		<title>test</title>
		<link>https://starterkit.com.ua</link>
		<description>Максимальный комфорт вашего жилья благодаря системам умного дома</description>';
    $footerXml = '</rss>';

    $current .= $headerXml;

    while ($query->have_posts()) {
        $query->the_post();

        global $post;
        // global $product;
        // global $woocommerce;

        $custom_text = get_post_custom_values('text_for_xml');
        $custom_vendor = get_post_custom_values('factory_xml');
        $custom_vendor = ($custom_vendor[0]) ? $custom_vendor[0] : 'Ajax';
        $custom_code = get_post_custom_values('code_from_shop');

        $category = get_the_terms( $post->ID, 'product_cat' );
        $price = $product->get_price();	
        $stock = get_post_meta( get_the_ID(), '_stock_status', true);

        $priceArr = explode('-', $price);

        $current .= '<item> 
                        <g:id>'. $product->get_id() .'</g:id>
                        <g:title>'. $product->get_name() .'</g:title>
						<g:description>'. $custom_text[0] .'</g:description>
						<g:link>'. get_the_permalink() .'</g:link>
						<g:image_link>'. get_the_post_thumbnail_url() .'</g:image_link>';
						if( $stock == instock ){
		$current .= '<g:availability>in stock</g:availability>';
						} else {
		$current .= '<g:availability>preorder</g:availability>';
						};						
        $current .= '<g:price>'. round($price, 2) .' UAH</g:price>
						<g:brand>'. $custom_vendor .'</g:brand>'; 
		$sep = ' > ';
		$cat_name = $sep . $category[1]->name;
		
		$current .= '<g:product_type>'. $category[0]->name .' '. $cat_name .'</g:product_type>';	
		$current .= '</item>';

        $loopCount++;
    }

    $current .= '</channel>';
    $current .= $footerXml;
    $res = file_put_contents($file, $current);
    echo 'Post update! Count = ' . $loopCount;
	echo '<br>';
    echo current_time('d/m/Y H:i');
}