EU VAT Assistant - Validate VAT number and update order data

/**
 * Aelia EU VAT Assistant for WooCommerce - Validate VAT number and store VAT information against
 * an existing order.
 *
 * HOW TO USE THIS CODE
 * This code shows how to use the EU VAT Assistant to call the VIES service to validate a EU VAT number
 * and how to store or update the VAT information collected during that process. You can wrap this code
 * in a plugin, and wrap it into a function, then call it on Ajax events such as "wp_ajax_woocommerce_calc_line_taxes"
 * or "wp_ajax_collect_order_vat_info".
 * Note: when linking the execution of the code to the Ajax event, you should use a high priority (e.g. 1), so that
 * your custom code runs before the "standard" one. This is important because, normally, Ajax handler terminate the
 * script after running, and that would prevent your code from being executed.
 *
 * @see WC_AJAX::calc_line_taxes()
 * @see Aelia\WC\EU_VAT_Assistant\WC_Aelia_EU_VAT_Assistant::wp_ajax_collect_order_vat_info()
 *
 * IMPORTANT
 * This code will not remove VAT from an existing order that had taxes added to it, nor will it refund
 * VAT that has already been paid. If a customer placed an order and paid VAT, e.g. because they forgot,
 * to enter their VAT number, or because their number, you will have to refund such VAT manually. We recommend
 * to consult your tax advisor to discuss the best way to handle this process, in compliance with your local
 * tax laws.
 *
 * DISCLAIMER
 * THE USE OF THIS CODE IS AT YOUR OWN RISK. You remain fully liable for compliance with tax laws.
 * This code is offered free of charge and there is no warranty for it, to the extent permitted by applicable law.
 * Except when otherwise stated in writing the copyright holders and/or other parties provide the program "as is"
 * without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of
 * merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the program
 * is with you. Should the program prove defective, you assume the cost of all necessary servicing, repair or correction.
 *
 * The code is provided as an example and it's not covered by our support service. We won't be able to offer free support
 * in relation to it. Should you need a consultation, or assistance to customise this code, you can contact us to avail
 * of our paid consultation services: https://aelia.co/hire_us
 */

// Replace "123" with the ID of an actual order
$order = new  Aelia\WC\EU_VAT_Assistant\Order(123);

// Call the VAT validation function. This call assumes that the order
// already has a VAT number stored in its "vat_number" meta
$raw_vies_response = apply_filters('wc_aelia_eu_vat_assistant_validate_vat_number', null, $order->get_billing_country(),    $order->get_meta('vat_number'), true);

if(!empty($raw_vies_response)) {
    // Extract the VAT validation
    $vat_number_validated = $raw_vies_response['euva_validation_result'];
    $order->update_meta_data('_vat_number_validated', $vat_number_validated);

    // Store the VIES response against the order
    $order->update_meta_data('vies_response', $raw_vies_response);

    if(is_array($raw_vies_response) && isset($raw_vies_response['raw_response']) && is_array($raw_vies_response['raw_response'])) {
        // Change all the keys in the response to lower-case. This is to avoid issues with keys being
        // returned like "requestIdentifier", "RequestIdentifier", "requestidentifier" by different versions
        // of the VIES service
        $raw_vies_response['raw_response'] = array_change_key_case($raw_vies_response['raw_response'], CASE_LOWER);
    }

    // Store the consultation number, if present
    if(!empty($raw_vies_response['raw_response']['requestidentifier'])) {
        $order->update_meta_data('vies_consultation_number', $raw_vies_response['raw_response']['requestidentifier']);
    }
    else {
        $order->update_meta_data('vies_consultation_number', __('Not returned', 'text-domain'));
    }
    $order->save_meta_data();

    // Generate and store details about order VAT
    $order->update_vat_data();
    // Save EU VAT compliance evidence
    $order->store_vat_evidence();
}