Bulk Delete Expired Unused WooCommerce Coupons (Batched, Safe)

/**
 * One-time cleanup of expired, never-used WooCommerce coupons.
 *
 * Triggered by visiting:
 *   /wp-admin/?cleancoupons=count    — see how many would be deleted (dry run)
 *   /wp-admin/?cleancoupons=run      — actually delete (in batches of 200)
 *
 * Only deletes coupons that:
 *   - have an expiry date set
 *   - expired more than 14 days ago
 *   - have never been used (usage_count is 0 or missing)
 */
add_action('admin_init', 'carticy_clean_expired_coupons');
function carticy_clean_expired_coupons()
{
    if (!isset($_GET['cleancoupons']) || !current_user_can('manage_options')) {
        return;
    }

    @set_time_limit(300);
    wp_raise_memory_limit('admin');

    global $wpdb;

    $action     = sanitize_text_field(wp_unslash($_GET['cleancoupons']));
    $batch_size = 200;
    $stale_days = 14;
    $cutoff     = strtotime('-' . $stale_days . ' days');

    // Use a subquery so we never have a bare `lt` operator in our main SQL
    $candidate_sql = $wpdb->prepare(
        "SELECT p.ID
         FROM {$wpdb->posts} p
         INNER JOIN {$wpdb->postmeta} pm_exp
             ON p.ID = pm_exp.post_id AND pm_exp.meta_key = 'date_expires'
         LEFT JOIN {$wpdb->postmeta} pm_use
             ON p.ID = pm_use.post_id AND pm_use.meta_key = 'usage_count'
         WHERE p.post_type = 'shop_coupon'
         AND p.post_status = 'publish'
         AND pm_exp.meta_value != ''
         AND CAST(pm_exp.meta_value AS UNSIGNED) BETWEEN 1 AND %d
         AND (pm_use.meta_value IS NULL OR pm_use.meta_value = '0')
         ORDER BY p.ID ASC
         LIMIT %d",
        $cutoff,
        $batch_size
    );

    if ($action === 'count') {
        $count_sql = str_replace('LIMIT %d', '', $candidate_sql);
        $count_sql = str_replace('SELECT p.ID', 'SELECT COUNT(DISTINCT p.ID)', $count_sql);
        $total     = (int) $wpdb->get_var($count_sql);
        wp_die(sprintf(
            '%d expired unused coupons would be deleted. Visit ?cleancoupons=run to delete the first batch of %d.',
            $total,
            $batch_size
        ));
    }

    if ($action === 'run') {
        $ids = $wpdb->get_col($candidate_sql);
        $deleted = 0;
        foreach ($ids as $id) {
            wp_delete_post((int) $id, true);
            $deleted++;
        }

        $remaining_sql = str_replace('LIMIT %d', '', $candidate_sql);
        $remaining_sql = str_replace('SELECT p.ID', 'SELECT COUNT(DISTINCT p.ID)', $remaining_sql);
        $remaining     = (int) $wpdb->get_var($remaining_sql);

        wp_die(sprintf(
            'Deleted %d coupons in this batch. %d remaining. Refresh ?cleancoupons=run to continue.',
            $deleted,
            $remaining
        ));
    }
}