add_filter('woocommerce_checkout_fields', 'custom_override_checkout_fields');
function custom_override_checkout_fields($fields)
{
    echo '<style> #billing_rzn_social.hidden { display:none; }</style>';
    echo '<style> #billing_giro.hidden { display:none; }</style>';
     $fields['billing']['billing_documento'] = array(
        'type'        => 'select',
        'label'       => __('Tipo Documento', 'woocommerce'),
		'options'     => array(39=>39, 33=>33),
        'required'    => true,
        'class'       => array('form-row-wide'),
        'clear'       => true,
     );
     $fields['billing']['billing_rut'] = array(
        'label'       => __('RUT', 'woocommerce'),
        'required'    => true,
        'class'       => array('form-row-wide'),
        'clear'       => true,
     );
     $fields['billing']['billing_rzn_social'] = array(
        'label'       => __('Razón social <abbr class="required" title="obligatorio">*</abbr>', 'woocommerce'),
        'required'    => false,
        'class'       => array('form-row-wide','billing_rzn_social_label'),
        'clear'       => true,
     );
     $fields['billing']['billing_giro'] = array(
        'label'       => __('Giro <abbr class="required" title="obligatorio">*</abbr>', 'woocommerce'),
        'required'    => false,
        'class'       => array('form-row-wide','billing_giro_label'),
        'clear'       => true,
     );
     return $fields;

}

add_action( 'woocommerce_after_checkout_form', 'fontcl_conditionally_hide_show_new_field', 9999 );
function fontcl_conditionally_hide_show_new_field() {
    wc_enqueue_js( "
        jQuery('#customer_details').on('change', function() {
$('#billing_documento option:eq(0)').text('Boleta electrónica');
$('#billing_documento option:eq(1)').text('Factura electrónica');
        var values = $('#billing_documento :selected').val();
        if ( values === '39' ){

$('#billing_rzn_social').prop('required', false);
            $('#billing_rzn_social').fadeOut();
            $('#billing_rzn_social input').val(' ');
            $('.billing_rzn_social_label').hide();

            $('#billing_giro').prop('required', false);
            $('#billing_giro').fadeOut();
            $('#billing_giro input').val(' ');
            $('.billing_giro_label').hide();

        }else{

$('#billing_rzn_social').prop('required', true);
            $('#billing_rzn_social').fadeIn();
            $('.billing_rzn_social_label').show();

            $('#billing_giro').prop('required', true);
            $('#billing_giro').fadeIn();
            $('.billing_giro_label').show();

            }
        }).change();
    ");
}

add_filter( 'woocommerce_form_field' , 'fontcl_remove_checkout_optional_text', 10, 4 );
    function fontcl_remove_checkout_optional_text( $field, $key, $args, $value ) {
        if( is_checkout() && ! is_wc_endpoint_url() ) {
            $optional = '&nbsp;<span class="optional">(' . esc_html__( 'optional', 'woocommerce' ) . ')</span>';
            $field = str_replace( $optional, '', $field );
        }
    return $field;
}

add_action('woocommerce_after_checkout_validation', 'fontcl_custom_validation_billing_city', 10, 2);
function fontcl_custom_validation_billing_city($fields, $error)
{
    if('IN' != $fields['billing'] && empty($fields['billing_rzn_social']) && $fields['billing_documento'] == '33' ) {
        $error->add('validation', '<strong>Razón social</strong> es un campo requerido.');
    }
    if('IN' != $fields['billing'] && empty($fields['billing_giro']) && $fields['billing_documento'] == '33' ) {
        $error->add('validation', '<strong>Giro</strong> es un campo requerido.');
    }
}

add_action('woocommerce_admin_order_data_after_shipping_address', 'my_custom_checkout_field_display_admin_order_meta', 10, 1);
function my_custom_checkout_field_display_admin_order_meta($order)
{
    $documentos = [33=>'Factura electrónica', 39=>'Boleta electrónica'];
    echo '<h3>Datos DTE</h3>';
    echo '<p><strong>'.__('Tipo Documento').':</strong><br/>'.$documentos[get_post_meta($order->get_id(), '_billing_documento', true)].'</p>';
    echo '<p><strong>'.__('RUT').':</strong><br/>'.get_post_meta($order->get_id(), '_billing_rut', true).'</p>';
	  echo '<p><strong>'.__('Razón social').':</strong><br/>'.get_post_meta($order->get_id(), '_billing_rzn_social', true).'</p>';
    echo '<p><strong>'.__('Giro').':</strong><br/>'.get_post_meta($order->get_id(), '_billing_giro', true).'</p>';
}