<?php
// $Id: comment_subject.module,v 1.3.2.6 2008-11-06 08:49:37 ahoeben Exp $

/**
 * Implementation of hook_form_alter().
 */
function comment_subject_form_alter($form_id, &$form) {
  if ($form_id == 'comment_form' && $form['subject']['#default_value']=='') {
    switch (arg(0)) {
      case 'node':
        $node = node_load(array('nid' => arg(1)));
        $subject = $node->title;
        break;
      case 'comment':
        if (arg(1)=='reply') {
          if (is_numeric(arg(3))) {
            $comment = _comment_load(arg(3));
            $subject = $comment->subject;
          } else {
            $node = node_load(arg(2));
            $subject = $node->title;
          }
        } else if (arg(1)=='edit' && is_numeric(arg(2))) {
          $comment = _comment_load(arg(2));
          $subject = $comment->subject;
        }
        break;
    }
    if (!preg_match('/^' . preg_quote(t('Re:')) . '/i', $subject)) {
      $subject = t('Re:') . ' ' . $subject;
    }
    // comment subjects can not be longer than 64 characters
    $subject = truncate_utf8($subject, 60, TRUE, TRUE);

    if (variable_get('comment_subject_field', 1) == 1) {
      $form['subject']['#default_value'] = $subject;
    } else {
      // comment subject disabled in comment settings
      $form['subject'] = array('#type' => 'hidden', '#default_value' => $subject);
    }
  }
}

?>