forum.module

<?php
// $Id$

/**
 * @file
 * Provides discussion forums.
 */

/**
 * Implement hook_help().
 */
function forum_help($path, $arg) {
  switch ($path) {
    case 'admin/help#forum':
      $output = '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The Forum module lets you create threaded discussion forums with functionality similar to other message board systems. Forums are useful because they allow community members to discuss topics with one another while ensuring those conversations are archived for later reference. Forums behave by posting topics and threads in nested hierarchies, which allow many discussions to be categorized in various ways. The <a href="@create-topic">forum topic</a> link on the <a href="@content-add">Add new content</a> page creates the first post of a new threaded discussion, or thread. For more information, see the online handbook entry for <a href="@forum">Forum module</a>.', array('@create-topic' => url('node/add/forum'), '@content-add' => url('node/add'), '@forum' => 'http://drupal.org/handbook/modules/forum/')) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<dl>';
      $output .= '<dt>' . t('Navigation') . '</dt>';
      $output .= '<dd>' . t('Enabling the Forum module provides a default <em>Forums</em> menu item in the navigation menu that links to the <a href="@forums">main forums page</a>.', array('@forums' => url('forum'))) . '</dd>';
      $output .= '<dt>' . t('Moving forum topics') . '</dt>';
      $output .= '<dd>' . t('A forum topic (and all of its comments) may be moved between forums by selecting a different forum while editing a forum topic. When moving a forum topic between forums, the <em>Leave shadow copy</em> option creates a link in the original forum pointing to the new location.') . '</dd>';
      $output .= '<dt>' . t('Locking and disabling comments') . '</dt>';
      $output .= '<dd>' . t('Selecting <em>Closed</em> under <em>Comment settings</em> while editing a forum topic will lock (prevent new comments on) the thread. Selecting <em>Disabled</em> under <em>Comment settings</em> while editing a forum topic will hide all existing comments on the thread, and prevent new ones.') . '</dd>';
      $output .= '</dl>';
      return $output;
    case 'admin/structure/forum':
      return '<p>' . t('Forums contain forum topics. Use containers to group related forums.') . '</p>';
    case 'admin/structure/forum/add/container':
      return '<p>' . t('Use containers to group related forums.') . '</p>';
    case 'admin/structure/forum/add/forum':
      return '<p>' . t('A forum holds related forum topics.') . '</p>';
    case 'admin/structure/forum/settings':
      return '<p>' . t('Adjust the display of your forum topics. Organize the forums on the <a href="@forum-structure">forum structure page</a>.', array('@forum-structure' => url('admin/structure/forum'))) . '</p>';
  }
}

/**
 * Implement hook_theme().
 */
function forum_theme() {
  return array(
    'forums' => array(
      'template' => 'forums',
      'variables' => array('forums' => NULL, 'topics' => NULL, 'parents' => NULL, 'tid' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
    ),
    'forum_list' => array(
      'template' => 'forum-list',
      'variables' => array('forums' => NULL, 'parents' => NULL, 'tid' => NULL),
    ),
    'forum_topic_list' => array(
      'template' => 'forum-topic-list',
      'variables' => array('tid' => NULL, 'topics' => NULL, 'sortby' => NULL, 'forum_per_page' => NULL),
    ),
    'forum_icon' => array(
      'template' => 'forum-icon',
      'variables' => array('new_posts' => NULL, 'num_posts' => 0, 'comment_mode' => 0, 'sticky' => 0),
    ),
    'forum_submitted' => array(
      'template' => 'forum-submitted',
      'variables' => array('topic' => NULL),
    ),
    'forum_form' => array(
      'render element' => 'form',
      'file' => 'forum.admin.inc',
    ),
  );
}

/**
 * Implement hook_menu().
 */
function forum_menu() {
  $items['forum'] = array(
    'title' => 'Forums',
    'page callback' => 'forum_page',
    'access arguments' => array('access content'),
    'file' => 'forum.pages.inc',
  );
  $items['admin/structure/forum'] = array(
    'title' => 'Forums',
    'description' => 'Control forum hierarchy settings.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('forum_overview'),
    'access arguments' => array('administer forums'),
    'file' => 'forum.admin.inc',
  );
  $items['admin/structure/forum/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/structure/forum/add/container'] = array(
    'title' => 'Add container',
    'page callback' => 'forum_form_main',
    'page arguments' => array('container'),
    'access arguments' => array('administer forums'),
    'type' => MENU_LOCAL_ACTION,
    'parent' => 'admin/structure/forum',
    'file' => 'forum.admin.inc',
  );
  $items['admin/structure/forum/add/forum'] = array(
    'title' => 'Add forum',
    'page callback' => 'forum_form_main',
    'page arguments' => array('forum'),
    'access arguments' => array('administer forums'),
    'type' => MENU_LOCAL_ACTION,
    'parent' => 'admin/structure/forum',
    'file' => 'forum.admin.inc',
  );
  $items['admin/structure/forum/settings'] = array(
    'title' => 'Settings',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('forum_admin_settings'),
    'access arguments' => array('administer forums'),
    'weight' => 5,
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/structure/forum',
    'file' => 'forum.admin.inc',
  );
  $items['admin/structure/forum/edit/container/%taxonomy_term'] = array(
    'title' => 'Edit container',
    'page callback' => 'forum_form_main',
    'page arguments' => array('container', 5),
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
    'file' => 'forum.admin.inc',
  );
  $items['admin/structure/forum/edit/forum/%taxonomy_term'] = array(
    'title' => 'Edit forum',
    'page callback' => 'forum_form_main',
    'page arguments' => array('forum', 5),
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
    'file' => 'forum.admin.inc',
  );
  return $items;
}


/**
 * Implement hook_init().
 */
function forum_init() {
  drupal_add_css(drupal_get_path('module', 'forum') . '/forum.css');
}

/**
 * Check whether a content type can be used in a forum.
 *
 * @param $node
 *   A node object.
 *
 * @return
 *   Boolean indicating if the node can be assigned to a forum.
 */
function _forum_node_check_node_type($node) {
  // Fetch information about the forum field.
  $field = field_info_instance('node', 'taxonomy_forums', $node->type);

  return is_array($field);
}

/**
 * Implement hook_node_view().
 */
function forum_node_view($node, $build_mode) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node)) {
    if ((bool)menu_get_object()) {
      // Breadcrumb navigation
      $breadcrumb[] = l(t('Home'), NULL);
      $breadcrumb[] = l($vocabulary->name, 'forum');
      if ($parents = taxonomy_get_parents_all($node->forum_tid)) {
        $parents = array_reverse($parents);
        foreach ($parents as $parent) {
          $breadcrumb[] = l($parent->name, 'forum/' . $parent->tid);
        }
      }
      drupal_set_breadcrumb($breadcrumb);

    }
  }
}

/**
 * Implement hook_node_prepare().
 */
function forum_node_prepare($node) {
  if (_forum_node_check_node_type($node)) {
    if (empty($node->nid)) {
      // New topic
      $node->taxonomy_forums[0]['tid'] =  arg(3);
    }
  }
}

/**
 * Implement hook_node_validate().
 *
 * Check in particular that only a "leaf" term in the associated taxonomy.
 */
function forum_node_validate($node, $form) {
  if (_forum_node_check_node_type($node)) {
    $langcode = $form['taxonomy_forums']['#language'];
    // vocabulary is selected, not a "container" term.
    if (!empty($node->taxonomy_forums[$langcode])) {
      // Extract the node's proper topic ID.
      $containers = variable_get('forum_containers', array());
      foreach ($node->taxonomy_forums[$langcode] as $item) {
        $term = taxonomy_term_load($item['tid']);
        $used = db_query_range('SELECT 1 FROM {taxonomy_term_data} WHERE tid = :tid AND vid = :vid',0 , 1, array(
          ':tid' => $term->tid,
          ':vid' => $term->vid,
        ))->fetchField();
        if ($used && in_array($term->tid, $containers)) {
          form_set_error('taxonomy_forums', t('The item %forum is only a forum container. Select one of the forums below it.', array('%forum' => $term->name)));
        }
      }
    }
  }
}

/**
 * Implement hook_node_presave().
 *
 * Assign forum taxonomy when adding a topic from within a forum.
 */
function forum_node_presave($node) {
  if (_forum_node_check_node_type($node)) {
    // Make sure all fields are set properly:
    $node->icon = !empty($node->icon) ? $node->icon : '';
    $langcode = array_shift(array_keys($node->taxonomy_forums));
    if (!empty($node->taxonomy_forums[$langcode])) {
      $node->forum_tid = $node->taxonomy_forums[$langcode][0]['tid'];
      $old_tid = db_query_range("SELECT f.tid FROM {forum} f INNER JOIN {node} n ON f.vid = n.vid WHERE n.nid = :nid ORDER BY f.vid DESC", 0, 1, array(':nid' => $node->nid))->fetchField();
      if ($old_tid && isset($node->forum_tid) && ($node->forum_tid != $old_tid) && !empty($node->shadow)) {
        // A shadow copy needs to be created. Retain new term and add old term.
        $node->taxonomy_forums[$langcode][] = array('tid' => $old_tid);
      }
    }
  }
}

/**
 * Implement hook_node_update().
 */
function forum_node_update($node) {
  if (_forum_node_check_node_type($node)) {
    if (empty($node->revision) && db_query('SELECT tid FROM {forum} WHERE nid=:nid', array(':nid' => $node->nid))->fetchField()) {
      if (!empty($node->forum_tid)) {
        db_update('forum')
          ->fields(array('tid' => $node->forum_tid))
          ->condition('vid', $node->vid)
          ->execute();
      }
      // The node is removed from the forum.
      else {
        db_delete('forum')
          ->condition('nid', $node->nid)
          ->execute();
      }
    }
    else {
      if (!empty($node->forum_tid)) {
        db_insert('forum')
          ->fields(array(
            'tid' => $node->forum_tid,
            'vid' => $node->vid,
            'nid' => $node->nid,
          ))
          ->execute();
      }
    }
    // If the node has a shadow forum topic, update the record for this
    // revision.
    if ($node->shadow) {
      db_delete('forum')
        ->condition('nid', $node->nid)
        ->condition('vid', $node->vid)
        ->execute();
      db_insert('forum')
        ->fields(array(
          'nid' => $node->nid,
          'vid' => $node->vid,
          'tid' => $node->forum_tid,
        ))
        ->execute();
     }
  }
}

/**
 * Implement hook_node_insert().
 */
function forum_node_insert($node) {
  if (_forum_node_check_node_type($node)) {
    if (!empty($node->forum_tid)) {
      $nid = db_insert('forum')
        ->fields(array(
          'tid' => $node->forum_tid,
          'vid' => $node->vid,
          'nid' => $node->nid,
        ))
        ->execute();
    }
  }
}

/**
 * Implement hook_node_delete().
 */
function forum_node_delete($node) {
  if (_forum_node_check_node_type($node)) {
    db_delete('forum')
      ->condition('nid', $node->nid)
      ->execute();
    db_delete('forum_index')
      ->condition('nid', $node->nid)
      ->execute();
  }
}

/**
 * Implement hook_node_load().
 */
function forum_node_load($nodes) {
  $node_vids = array();
  foreach ($nodes as $node) {
    if (_forum_node_check_node_type($node)) {
      $node_vids[] = $node->vid;
    }
  }
  if (!empty($node_vids)) {
    $query = db_select('forum', 'f');
    $query
      ->fields('f', array('nid', 'tid'))
      ->condition('f.vid', $node_vids);
    $result = $query->execute();
    foreach ($result as $record) {
      $nodes[$record->nid]->forum_tid = $record->tid;
    }
  }
}

/**
 * Implement hook_node_info().
 */
function forum_node_info() {
  return array(
    'forum' => array(
      'name' => t('Forum topic'),
      'base' => 'forum',
      'description' => t('A <em>forum topic</em> starts a new discussion thread within a forum.'),
      'title_label' => t('Subject'),
    )
  );
}

/**
 * Implement hook_permission().
 */
function forum_permission() {
  $perms = array(
    'administer forums' => array(
      'title' => t('Administer forums'),
    ),
  );
  return $perms;
}

/**
 * Implement hook_taxonomy().
 */
function forum_taxonomy_term_delete($tid) {
  // For containers, remove the tid from the forum_containers variable.
  $containers = variable_get('forum_containers', array());
  $key = array_search($tid, $containers);
  if ($key !== FALSE) {
    unset($containers[$key]);
  }
  variable_set('forum_containers', $containers);
}

/**
 * Implement hook_comment_publish().
 *
 * This actually handles the insert and update of published nodes since
 * comment_save() calls hook_comment_publish() for all published comments.
 */
function forum_comment_publish($comment) {
  _forum_update_forum_index($comment->nid);
}

/**
 * Implement forum_comment_update().
 *
 * Comment module doesn't call hook_comment_unpublish() when saving individual
 * comments so we need to check for those here.
 */
function forum_comment_update($comment) {
  // comment_save() calls hook_comment_publish() for all published comments
  // so we to handle all other values here.
  if (!$comment->status) {
    _forum_update_forum_index($comment->nid);
  }
}

/**
 * Implements forum_comment_unpublish().
 */
function forum_comment_unpublish($comment) {
  _forum_update_forum_index($comment->nid);
}

/**
 * Implement forum_comment_delete().
 */
function forum_comment_delete($comment) {
  _forum_update_forum_index($comment->nid);
}

/**
 * Implement hook_field_storage_pre_insert().
 */
function forum_field_storage_pre_insert($obj_type, $object, &$skip_fields) {
  if ($obj_type == 'node' && $object->status && _forum_node_check_node_type($object)) {
    $query = db_insert('forum_index')->fields(array('nid', 'title', 'tid', 'sticky', 'created', 'comment_count', 'last_comment_timestamp'));
    foreach ($object->taxonomy_forums as $language) {
      foreach ($language as $item) {
        $query->values(array(
          'nid' => $object->nid,
          'title' => $object->title[FIELD_LANGUAGE_NONE][0]['value'],
          'tid' => $item['tid'],
          'sticky' => $object->sticky,
          'created' => $object->created,
          'comment_count' => 0,
          'last_comment_timestamp' => $object->created,
        ));
      }
    }
    $query->execute();
  }
}

/**
 * Implement hook_field_storage_pre_update().
 */
function forum_field_storage_pre_update($obj_type, $object, &$skip_fields) {
  $first_call = &drupal_static(__FUNCTION__, array());

  if ($obj_type == 'node' && $object->status && _forum_node_check_node_type($object)) {
    // We don't maintain data for old revisions, so clear all previous values
    // from the table. Since this hook runs once per field, per object, make
    // sure we only wipe values once.
    if (!isset($first_call[$object->nid])) {
      $first_call[$object->nid] = FALSE;
      db_delete('forum_index')->condition('nid', $object->nid)->execute();
    }
    // Only save data to the table if the node is published.
    if ($object->status) {
      $query = db_insert('forum_index')->fields(array('nid', 'title', 'tid', 'sticky', 'created', 'comment_count', 'last_comment_timestamp'));
      foreach ($object->taxonomy_forums as $language) {
        foreach ($language as $item) {
          $query->values(array(
            'nid' => $object->nid,
            'title' => $object->title[FIELD_LANGUAGE_NONE][0]['value'],
            'tid' => $item['tid'],
            'sticky' => $object->sticky,
            'created' => $object->created,
            'comment_count' => 0,
            'last_comment_timestamp' => $object->created,
          ));
        }
      }
      $query->execute();
      // The logic for determining last_comment_count is fairly complex, so
      // call _forum_update_forum_index() too.
      _forum_update_forum_index($object->nid);
    }
  }
}

/**
 * Implement hook_form_alter().
 */
function forum_form_alter(&$form, $form_state, $form_id) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  if (isset($form['vid']) && $form['vid']['#value'] == $vid) {
    // Hide critical options from forum vocabulary.
    if ($form_id == 'taxonomy_form_vocabulary') {
      $form['help_forum_vocab'] = array(
        '#markup' => t('This is the designated forum vocabulary. Some of the normal vocabulary options have been removed.'),
        '#weight' => -1,
      );
      $form['hierarchy'] = array('#type' => 'value', '#value' => 1);
      $form['delete']['#access'] = FALSE;
    }
    // Hide multiple parents select from forum terms.
    elseif ($form_id == 'taxonomy_form_term') {
      $form['advanced']['parent']['#access'] = FALSE;
    }
  }
  if ($form_id == 'forum_node_form') {
    $langcode = $form['taxonomy_forums']['#language'];
    // Make the vocabulary required for 'real' forum-nodes.
    $form['taxonomy_forums'][$langcode]['#required'] = TRUE;
    $form['taxonomy_forums'][$langcode]['#multiple'] = FALSE;
  }
}

/**
 * Implement hook_block_info().
 */
function forum_block_info() {
  $blocks['active'] = array(
    'info' => t('Active forum topics'),
    'cache' => DRUPAL_CACHE_CUSTOM,
  );
  $blocks['new'] = array(
    'info' => t('New forum topics'),
    'cache' => DRUPAL_CACHE_CUSTOM,
  );
  return $blocks;
}

/**
 * Implement hook_block_configure().
 */
function forum_block_configure($delta = '') {
  $form['forum_block_num_' . $delta] = array('#type' => 'select', '#title' => t('Number of topics'), '#default_value' => variable_get('forum_block_num_' . $delta, '5'), '#options' => drupal_map_assoc(array(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)));
  return $form;
}

/**
 * Implement hook_block_save().
 */
function forum_block_save($delta = '', $edit = array()) {
  variable_set('forum_block_num_' . $delta, $edit['forum_block_num_' . $delta]);
}

/**
 * Implement hook_block_view().
 *
 * Generates a block containing the currently active forum topics and the
 * most recently added forum topics.
 */
function forum_block_view($delta = '') {
  $query = db_select('forum_index', 'f')
    ->fields('f')
    ->addTag('node_access');
  switch ($delta) {
    case 'active':
      $title = t('Active forum topics');
      $query
        ->orderBy('f.last_comment_timestamp', 'DESC')
        ->range(0, variable_get('forum_block_num_active', '5'));
      break;

    case 'new':
      $title = t('New forum topics');
      $query
        ->orderBy('f.created', 'DESC')
        ->range(0, variable_get('forum_block_num_new', '5'));
      break;
  }

  $cache_keys = array_merge(array('forum', $delta), drupal_render_cid_parts());
  // Cache based on the altered query. Enables us to cache with node access enabled.
  $query->preExecute();
  $cache_keys[] = md5(serialize(array((string) $query, $query->getArguments())));

  $block['subject'] = $title;
  $block['content'] = array(
     '#access' => user_access('access content'),
     '#pre_render' => array('forum_block_view_pre_render'),
     '#cache' => array(
        'keys' => $cache_keys,
        'expire' => CACHE_TEMPORARY,
     ),
     '#query' => $query,
  );
  return $block;
}

/**
* A #pre_render callback. Lists nodes based on the element's #query property.
*
* @see forum_block_view().
*
* @return
*   A renderable array.
*/
function forum_block_view_pre_render($elements) {
  $result = $elements['#query']->execute();
  if ($node_title_list = node_title_list($result)) {
    $elements['forum_list'] = array('#markup' => $node_title_list);
    $elements['forum_more'] = array('#markup' => theme('more_link', array('url' => url('forum'), 'title' => t('Read the latest forum topics.'))));
  }
  return $elements;
}

/**
 * Implement hook_form().
 */
function forum_form($node, $form_state) {
  $type = node_type_get_type($node);

  if (!empty($node->nid)) {
    $forum_terms = $node->taxonomy_forums;
    // If editing, give option to leave shadows
    $shadow = (count($forum_terms) > 1);
    $form['shadow'] = array('#type' => 'checkbox', '#title' => t('Leave shadow copy'), '#default_value' => $shadow, '#description' => t('If you move this topic, you can leave a link in the old forum to the new forum.'));
    $form['forum_tid'] = array('#type' => 'value', '#value' => $node->forum_tid);
  }

  $form['#submit'][] = 'forum_submit';
  // Assign the forum topic submit handler.

  return $form;
}

/**
 * Implement hook_url_outbound_alter().
 */
function forum_url_outbound_alter(&$path, &$options, $original_path) {
  if (preg_match('!^taxonomy/term/(\d+)!', $path, $matches)) {
    $term = taxonomy_term_load($matches[1]);
    if ($term && $term->vocabulary_machine_name == 'forums') {
      $path = 'forum/' . $matches[1];
    }
  }
}

/**
 * Returns a list of all forums for a given taxonomy id
 *
 * Forum objects contain the following fields
 * -num_topics Number of topics in the forum
 * -num_posts Total number of posts in all topics
 * -last_post Most recent post for the forum
 *
 * @param $tid
 *   Taxonomy ID of the vocabulary that holds the forum list.
 * @return
 *   Array of object containing the forum information.
 */
function forum_get_forums($tid = 0) {

  $forums = array();
  $vid = variable_get('forum_nav_vocabulary', 0);
  $_forums = taxonomy_get_tree($vid, $tid);

  if (count($_forums)) {
    $query = db_select('node', 'n');
    $query->join('node_comment_statistics', 'ncs', 'n.nid = ncs.nid');
    $query->join('forum', 'f', 'n.vid = f.vid');
    $query->addExpression('COUNT(n.nid)', 'topic_count');
    $query->addExpression('SUM(ncs.comment_count)', 'comment_count');
    $counts = $query
      ->fields('f', array('tid'))
      ->condition('status', 1)
      ->groupBy('tid')
      ->addTag('node_access')
      ->execute()
      ->fetchAllAssoc('tid');
  }

  foreach ($_forums as $forum) {
    if (in_array($forum->tid, variable_get('forum_containers', array()))) {
      $forum->container = 1;
    }

    if (!empty($counts[$forum->tid])) {
      $forum->num_topics = $counts[$forum->tid]->topic_count;
      $forum->num_posts = $counts[$forum->tid]->topic_count + $counts[$forum->tid]->comment_count;
    }
    else {
      $forum->num_topics = 0;
      $forum->num_posts = 0;
    }

    $query = db_select('node', 'n');
    $query->join('users', 'u1', 'n.uid = u1.uid');
    $query->join('forum', 'f', 'n.vid = f.vid AND f.tid = :tid', array(':tid' => $forum->tid));
    $query->join('node_comment_statistics', 'ncs', 'n.nid = ncs.nid');
    $query->join('users', 'u2', 'ncs.last_comment_uid = u2.uid');
    $query->addExpression('IF (ncs.last_comment_uid != 0, u2.name, ncs.last_comment_name)', 'last_comment_name');

    $topic = $query
      ->fields('ncs', array('last_comment_timestamp', 'last_comment_uid'))
      ->condition('n.status', 1)
      ->orderBy('last_comment_timestamp', 'DESC')
      ->range(0, 1)
      ->addTag('node_access')
      ->execute()
      ->fetchObject();

    $last_post = new stdClass();
    if (!empty($topic->last_comment_timestamp)) {
      $last_post->created = $topic->last_comment_timestamp;
      $last_post->name = $topic->last_comment_name;
      $last_post->uid = $topic->last_comment_uid;
    }
    $forum->last_post = $last_post;

    $forums[$forum->tid] = $forum;
  }

  return $forums;
}

/**
 * Calculate the number of nodes the user has not yet read and are newer
 * than NODE_NEW_LIMIT.
 */
function _forum_topics_unread($term, $uid) {
  $query = db_select('node', 'n');
  $query->join('forum', 'f', 'n.vid = f.vid AND f.tid = :tid', array(':tid' => $term));
  $query->join('history', 'h', 'n.nid = h.nid AND h.uid = :uid', array(':uid' => $uid));
  $query->addExpression('COUNT(n.nid)', 'count');
  return $query
    ->condition('status', 1)
    ->condition('n.created', NODE_NEW_LIMIT, '>')
    ->isNull('h.nid')
    ->addTag('node_access')
    ->execute()
    ->fetchField();
}

function forum_get_topics($tid, $sortby, $forum_per_page) {
  global $user, $forum_topic_list_header;

  $forum_topic_list_header = array(
    NULL,
    array('data' => t('Topic'), 'field' => 'f.title'),
    array('data' => t('Replies'), 'field' => 'f.comment_count'),
    array('data' => t('Last reply'), 'field' => 'f.last_comment_timestamp'),
  );

  $order = _forum_get_topic_order($sortby);
  for ($i = 0; $i < count($forum_topic_list_header); $i++) {
    if ($forum_topic_list_header[$i]['field'] == $order['field']) {
      $forum_topic_list_header[$i]['sort'] = $order['sort'];
    }
  }

  $query = db_select('forum_index', 'f')->extend('PagerDefault')->extend('TableSort');
  $query->fields('f');
  $query
    ->condition('f.tid', $tid)
    ->addTag('node_access')
    ->orderBy('f.sticky', 'DESC')
    ->orderByHeader($forum_topic_list_header)
    ->orderBy('f.last_comment_timestamp', 'DESC')
    ->limit($forum_per_page);

  $count_query = db_select('forum_index', 'f');
  $count_query->condition('f.tid', $tid);
  $count_query->addExpression('COUNT(*)');
  $count_query->addTag('node_access');

  $query->setCountQuery($count_query);
  $result = $query->execute();
  $nids = array();
  foreach ($result as $record) {
    $nids[] = $record->nid;
  }
  if ($nids) {
    $result = db_query("SELECT n.title, n.nid, n.sticky, n.created, n.uid, n.comment AS comment_mode, ncs.*, f.tid AS forum_tid, u.name, IF (ncs.last_comment_uid != 0, u2.name, ncs.last_comment_name) AS last_comment_name FROM {node} n INNER JOIN {node_comment_statistics} ncs ON n.nid = ncs.nid INNER JOIN {forum} f ON n.vid = f.vid INNER JOIN {users} u ON n.uid = u.uid INNER JOIN {users} u2 ON ncs.last_comment_uid = u2.uid WHERE n.nid IN (:nids)", array(':nids' => $nids));
  }
  else {
    $result = array();
  }

  $topics = array();
  foreach ($result as $topic) {
    if ($user->uid) {
      // folder is new if topic is new or there are new comments since last visit
      if ($topic->forum_tid != $tid) {
        $topic->new = 0;
      }
      else {
        $history = _forum_user_last_visit($topic->nid);
        $topic->new_replies = comment_num_new($topic->nid, $history);
        $topic->new = $topic->new_replies || ($topic->last_comment_timestamp > $history);
      }
    }
    else {
      // Do not track "new replies" status for topics if the user is anonymous.
      $topic->new_replies = 0;
      $topic->new = 0;
    }

    if ($topic->comment_count > 0) {
      $last_reply = new stdClass();
      $last_reply->created = $topic->last_comment_timestamp;
      $last_reply->name = $topic->last_comment_name;
      $last_reply->uid = $topic->last_comment_uid;
      $topic->last_reply = $last_reply;
    }
    $topics[] = $topic;
  }

  return $topics;
}

/**
 * Process variables for forums.tpl.php
 *
 * The $variables array contains the following arguments:
 * - $forums
 * - $topics
 * - $parents
 * - $tid
 * - $sortby
 * - $forum_per_page
 *
 * @see forums.tpl.php
 */
function template_preprocess_forums(&$variables) {
  global $user;

  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  $title = !empty($vocabulary->name) ? $vocabulary->name : '';

  // Breadcrumb navigation:
  $breadcrumb[] = l(t('Home'), NULL);
  if ($variables['tid']) {
    $breadcrumb[] = l($vocabulary->name, 'forum');
  }
  if ($variables[