/**
  * custom_columns function.
  *
  * @access public
  * @param mixed $column
  * @return void
  */
 public function custom_columns($column)
 {
     global $post, $download_monitor;
     $download = new DLM_Download($post->ID);
     $file = $download->get_file_version();
     switch ($column) {
         case "thumb":
             echo $download->get_the_image();
             break;
         case "download_id":
             echo $post->ID;
             break;
         case "download_cat":
             if (!($terms = get_the_term_list($post->ID, 'dlm_download_category', '', ', ', ''))) {
                 echo '<span class="na">&ndash;</span>';
             } else {
                 echo $terms;
             }
             break;
         case "download_tag":
             if (!($terms = get_the_term_list($post->ID, 'dlm_download_tag', '', ', ', ''))) {
                 echo '<span class="na">&ndash;</span>';
             } else {
                 echo $terms;
             }
             break;
         case "featured":
             if ($download->is_featured()) {
                 echo '<span class="yes">' . __('Yes', 'download-monitor') . '</span>';
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
         case "members_only":
             if ($download->is_members_only()) {
                 echo '<span class="yes">' . __('Yes', 'download-monitor') . '</span>';
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
         case "redirect_only":
             if ($download->redirect_only()) {
                 echo '<span class="yes">' . __('Yes', 'download-monitor') . '</span>';
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
         case "file":
             if ($file) {
                 echo '<a href="' . $download->get_the_download_link() . '"><code>' . $file->filename;
                 if ($size = $download->get_the_filesize()) {
                     echo ' &ndash; ' . $size;
                 }
                 echo '</code></a>';
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
         case "version":
             if ($file && $file->version) {
                 echo $file->version;
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
         case "download_count":
             echo number_format($download->get_the_download_count(), 0, '.', ',');
             break;
         case "featured":
             if ($download->is_featured()) {
                 echo '<img src="' . $download_monitor->plugin_url() . '/assets/images/on.png" alt="yes" />';
             } else {
                 echo '<span class="na">&ndash;</span>';
             }
             break;
     }
 }