drupal/modules/forum/forum.module

<?php
// $Id$

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

/**
 * Implement hook_help().
 */
function forum_help($path, $arg) {
  switch ($path) {
    case 'admin/help#forum':
      $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. The <a href="@create-topic">forum topic</a> menu item (under <em>Add new content</em> on the Navigation menu) creates the initial post of a new threaded discussion, or thread.', array('@create-topic' => url('node/add/forum'))) . '</p>';
      $output .= '<p>' . t('A threaded discussion occurs as people leave comments on a forum topic (or on other comments within that topic). A forum topic is contained within a forum, which may hold many similar or related forum topics. Forums are (optionally) nested within a container, which may hold many similar or related forums. Both containers and forums may be nested within other containers and forums, and provide structure for your message board. By carefully planning this structure, you make it easier for users to find and comment on a specific forum topic.') . '</p>';
      $output .= '<p>' . t('When administering a forum, note that:') . '</p>';
      $output .= '<ul><li>' . t('a forum topic (and all of its comments) may be moved between forums by selecting a different forum while editing a forum topic.') . '</li>';
      $output .= '<li>' . t('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.') . '</li>';
      $output .= '<li>' . t('selecting <em>Closed</em> under <em>Comment settings</em> while editing a forum topic will lock (prevent new comments) on the thread.') . '</li>';
      $output .= '<li>' . t('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.') . '</li></ul>';
      $output .= '<p>' . t('For more information, see the online handbook entry for <a href="@forum">Forum module</a>.', array('@forum' => 'http://drupal.org/handbook/modules/forum/')) . '</p>';
      return $output;
    case 'admin/structure/forum':
      return '<p>' . t('This page displays a list of existing forums and containers. Containers (optionally) hold forums, and forums hold forum topics (a forum topic is the initial post to a threaded discussion). To provide structure, both containers and forums may be placed inside other containers and forums.') . '</p>';
    case 'admin/structure/forum/add/container':
      return '<p>' . t('By grouping related or similar forums, containers help organize forums. For example, a container named "Food" may hold two forums named "Fruit" and "Vegetables", respectively.') . '</p>';
    case 'admin/structure/forum/add/forum':
      return '<p>' . t('A forum holds related or similar forum topics (a forum topic is the initial post to a threaded discussion). For example, a forum named "Fruit" may contain forum topics titled "Apples" and "Bananas", respectively.') . '</p>';
    case 'admin/structure/forum/settings':
      return '<p>' . t('These settings allow you to adjust the display of your forum topics. The content types available for use within a forum may be selected by editing the <em>Content types</em> on the <a href="@forum-vocabulary">forum vocabulary page</a>.', array('@forum-vocabulary' => url('admin/structure/taxonomy/edit/vocabulary/' . variable_get('forum_nav_vocabulary', 0)))) . '</p>';
  }
}

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

/**
 * 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 forums and their hierarchy and change forum 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/%taxonomy_term'] = array(
    'page callback' => 'forum_form_main',
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
    '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('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]['value'] =  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 $tid) {
        $term = taxonomy_term_load($tid['value']);
        $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 container for forums. Please 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]['value'];
      $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('value' => $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> is the initial post to 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'),
      'description' => t('Manage forums and configure forum administration settings.'),
    ),
  );
  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);
  }
}

/**
 * Implement 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_attach_pre_insert().
 */
function forum_field_attach_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 $delta) {
        $query->values(array(
          'nid' => $object->nid,
          'title' => $object->title,
          'tid' => $delta['value'],
          'sticky' => $object->sticky,
          'created' => $object->created,
          'comment_count' => 0,
          'last_comment_timestamp' => $object->created,
        ));
      }
    }
    $query->execute();
  }
}

/**
 * Implement hook_field_attach_pre_update().
 */
function forum_field_attach_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 $delta) {
          $query->values(array(
            'nid' => $object->nid,
            'title' => $object->title,
            'tid' => $delta['value'],
            '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', url('forum'), t('Read the latest forum topics.')));
  }
  return $elements;
}

/**
 * Implement hook_form().
 */
function forum_form($node, $form_state) {
  $type = node_type_get_type($node);
  $form['title'] = array('#type' => 'textfield', '#title' => check_plain($type->title_label), '#default_value' => !empty($node->title) ? $node->title : '', '#required' => TRUE, '#weight' => -5);

  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_term_path().
 */
function forum_term_path($term) {
  return 'forum/' . $term->tid;
}

/**
 * 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['parents']) {
    $variables['parents'] = array_reverse($variables['parents']);
    foreach ($variables['parents'] as $p) {
      if ($p->tid == $variables['tid']) {
        $title = $p->name;
      }
      else {
        $breadcrumb[] = l($p->name, 'forum/' . $p->tid);
      }
    }
  }
  drupal_set_breadcrumb($breadcrumb);
  drupal_set_title($title);

  if ($variables['forums_defined'] = count($variables['forums']) || count($variables['parents'])) {
    // Format the "post new content" links listing.
    $forum_types = array();

    // Loop through all bundles for forum taxonomy vocabulary field.
    $field = field_info_field('taxonomy_' . $vocabulary->machine_name);
    foreach ($field['bundles'] as $type) {
      // Check if the current user has the 'create' permission for this node type.
      if (node_access('create', $type)) {
        // Fetch the "General" name of the content type;
        // Push the link with title and url to the array.
        $forum_types[$type] = array('title' => t('Post new @node_type', array('@node_type' => node_type_get_name($type))), 'href' => 'node/add/' . str_replace('_', '-', $type) . '/' . $variables['tid']);
      }
    }

    if (empty($forum_types)) {
      // The user is logged-in; but denied access to create any new forum content type.
      if ($user->uid) {
        $forum_types['disallowed'] = array('title' => t('You are not allowed to post new content in the forum.'));
      }
      // The user is not logged-in; and denied access to create any new forum content type.
      else {
        $forum_types['login'] = array('title' => t('<a href="@login">Login</a> to post new content in the forum.', array('@login' => url('user/login', array('query' => drupal_get_destination())))), 'html' => TRUE);
      }
    }
    $variables['links'] = $forum_types;

    if (!empty($variables['forums'])) {
      $variables['forums'] = theme('forum_list', $variables['forums'], $variables['parents'], $variables['tid']);
    }
    else {
      $variables['forums'] = '';
    }

    if ($variables['tid'] && !in_array($variables['tid'], variable_get('forum_containers', array()))) {
      $variables['topics'] = theme('forum_topic_list', $variables['tid'], $variables['topics'], $variables['sortby'], $variables['forum_per_page']);
      drupal_add_feed(url('taxonomy/term/' . $variables['tid'] . '/0/feed'), 'RSS - ' . $title);
    }
    else {
      $variables['topics'] = '';
    }

    // Provide separate template suggestions based on what's being output. Topic id is also accounted for.
    // Check both variables to be safe then the inverse. Forums with topic ID's take precedence.
    if ($variables['forums'] && !$variables['topics']) {
      $variables['template_files'][] = 'forums-containers';
      $variables['template_files'][] = 'forums-' . $variables['tid'];
      $variables['template_files'][] = 'forums-containers-' . $variables['tid'];
    }
    elseif (!$variables['forums'] && $variables['topics']) {
      $variables['template_files'][] = 'forums-topics';
      $variables['template_files'][] = 'forums-' . $variables['tid'];
      $variables['template_files'][] = 'forums-topics-' . $variables['tid'];
    }
    else {
      $variables['template_files'][] = 'forums-' . $variables['tid'];
    }

  }
  else {
    drupal_set_title(t('No forums defined'), PASS_THROUGH);
    $variables['links'] = array();
    $variables['forums'] = '';
    $variables['topics'] = '';
  }
}

/**
 * Process variables to format a forum listing.
 *
 * $variables contains the following information:
 * - $forums
 * - $parents
 * - $tid
 *
 * @see forum-list.tpl.php
 * @see theme_forum_list()
 */
function template_preprocess_forum_list(&$variables) {
  global $user;
  $row = 0;
  // Sanitize each forum so that the template can safely print the data.
  foreach ($variables['forums'] as $id => $forum) {
    $variables['forums'][$id]->description = !empty($forum->description) ? filter_xss_admin($forum->description) : '';
    $variables['forums'][$id]->link = url("forum/$forum->tid");
    $variables['forums'][$id]->name = check_plain($forum->name);
    $variables['forums'][$id]->is_container = !empty($forum->container);
    $variables['forums'][$id]->zebra = $row % 2 == 0 ? 'odd' : 'even';
    $row++;

    $variables['forums'][$id]->new_text = '';
    $variables['forums'][$id]->new_url = '';
    $variables['forums'][$id]->new_topics = 0;
    $variables['forums'][$id]->old_topics = $forum->num_topics;
    if ($user->uid) {
      $variables['forums'][$id]->new_topics = _forum_topics_unread($forum->tid, $user->uid);
      if ($variables['forums'][$id]->new_topics) {
        $variables['forums'][$id]->new_text = format_plural($variables['forums'][$id]->new_topics, '1 new', '@count new');
        $variables['forums'][$id]->new_url = url("forum/$forum->tid", array('fragment' => 'new'));
      }
      $variables['forums'][$id]->old_topics = $forum->num_topics - $variables['forums'][$id]->new_topics;
    }
    $variables['forums'][$id]->last_reply = theme('forum_submitted', $forum->last_post);
  }
  // Give meaning to $tid for themers. $tid actually stands for term id.
  $variables['forum_id'] = $variables['tid'];
  unset($variables['tid']);
}

/**
 * Preprocess variables to format the topic listing.
 *
 * $variables contains the following data:
 * - $tid
 * - $topics
 * - $sortby
 * - $forum_per_page
 *
 * @see forum-topic-list.tpl.php
 * @see theme_forum_topic_list()
 */
function template_preprocess_forum_topic_list(&$variables) {
  global $forum_topic_list_header;

  // Create the tablesorting header.
  $ts = tablesort_init($forum_topic_list_header);
  $header = '';
  foreach ($forum_topic_list_header as $cell) {
    $cell = tablesort_header($cell, $forum_topic_list_header, $ts);
    $header .= _theme_table_cell($cell, TRUE);
  }
  $variables['header'] = $header;

  if (!empty($variables['topics'])) {
    $row = 0;
    foreach ($variables['topics'] as $id => $topic) {
      $variables['topics'][$id]->icon = theme('forum_icon', $topic->new, $topic->comment_count, $topic->comment_mode, $topic->sticky);
      $variables['topics'][$id]->zebra = $row % 2 == 0 ? 'odd' : 'even';
      $row++;

      // We keep the actual tid in forum table, if it's different from the
      // current tid then it means the topic appears in two forums, one of
      // them is a shadow copy.
      if ($variables['tid'] != $topic->forum_tid) {
        $variables['topics'][$id]->moved = TRUE;
        $variables['topics'][$id]->title = check_plain($topic->title);
        $variables['topics'][$id]->message = l(t('This topic has been moved'), "forum/$topic->forum_tid");
      }
      else {
        $variables['topics'][$id]->moved = FALSE;
        $variables['topics'][$id]->title = l($topic->title, "node/$topic->nid");
        $variables['topics'][$id]->message = '';
      }
      $topic->uid = $topic->last_comment_uid ? $topic->last_comment_uid : $topic->uid;
      $variables['topics'][$id]->created = theme('forum_submitted', $topic);
      $variables['topics'][$id]->last_reply = theme('forum_submitted', isset($topic->last_reply) ? $topic->last_reply : NULL);

      $variables['topics'][$id]->new_text = '';
      $variables['topics'][$id]->new_url = '';
      if ($topic->new_replies) {
        $variables['topics'][$id]->new_text = format_plural($topic->new_replies, '1 new', '@count new');
        $variables['topics'][$id]->new_url = url("node/$topic->nid", array('query' => comment_new_page_count($topic->num_comments, $topic->new_replies, $topic), 'fragment' => 'new'));
      }

    }
  }
  else {
    // Make this safe for the template
    $variables['topics'] = array();
  }
  // Give meaning to $tid for themers. $tid actually stands for term id.
  $variables['topic_id'] = $variables['tid'];
  unset($variables['tid']);

  $variables['pager'] = theme('pager', NULL);
}

/**
 * Process variables to format the icon for each individual topic.
 *
 * $variables contains the following data:
 * - $new_posts
 * - $num_posts = 0
 * - $comment_mode = 0
 * - $sticky = 0
 *
 * @see forum-icon.tpl.php
 * @see theme_forum_icon()
 */
function template_preprocess_forum_icon(&$variables) {
  $variables['hot_threshold'] = variable_get('forum_hot_topic', 15);
  if ($variables['num_posts'] > $variables['hot_threshold']) {
    $variables['icon'] = $variables['new_posts'] ? 'hot-new' : 'hot';
  }
  else {
    $variables['icon'] = $variables['new_posts'] ? 'new' : 'default';
  }

  if ($variables['comment_mode'] == COMMENT_NODE_CLOSED || $variables['comment_mode'] == COMMENT_NODE_HIDDEN) {
    $variables['icon'] = 'closed';
  }

  if ($variables['sticky'] == 1) {
    $variables['icon'] = 'sticky';
  }
}

/**
 * Process variables to format submission info for display in the forum list and topic list.
 *
 * $variables will contain: $topic
 *
 * @see forum-submitted.tpl.php
 * @see theme_forum_submitted()
 */
function template_preprocess_forum_submitted(&$variables) {
  $variables['author'] = isset($variables['topic']->uid) ? theme('username', $variables['topic']) : '';
  $variables['time'] = isset($variables['topic']->created) ? format_interval(REQUEST_TIME - $variables['topic']->created) : '';
}

function _forum_user_last_visit($nid) {
  global $user;
  $history = &drupal_static(__FUNCTION__, array());

  if (empty($history)) {
    $result = db_query('SELECT nid, timestamp FROM {history} WHERE uid = :uid', array(':uid' => $user->uid));
    foreach ($result as $t) {
      $history[$t->nid] = $t->timestamp > NODE_NEW_LIMIT ? $t->timestamp : NODE_NEW_LIMIT;
    }
  }
  return isset($history[$nid]) ? $history[$nid] : NODE_NEW_LIMIT;
}

function _forum_get_topic_order($sortby) {
  switch ($sortby) {
    case 1:
      return array('field' => 'ncs.last_comment_timestamp', 'sort' => 'desc');
      break;
    case 2:
      return array('field' => 'ncs.last_comment_timestamp', 'sort' => 'asc');
      break;
    case 3:
      return array('field' => 'ncs.comment_count', 'sort' => 'desc');
      break;
    case 4:
      return array('field' => 'ncs.comment_count', 'sort' => 'asc');
      break;
  }
}

/**
 * Updates the taxonomy index for a given node.
 *
 * @param $nid
 *   The ID of the node to update.
 */
function _forum_update_forum_index($nid) {
  $count = db_query('SELECT COUNT(cid) FROM {comment} WHERE nid = :nid AND status = :status', array(
    ':nid' => $nid,
    ':status' => COMMENT_PUBLISHED,
  ))->fetchField();

  if ($count > 0) {
    // Comments exist.
    $last_reply = db_query_range('SELECT cid, name, timestamp, uid FROM {comment} WHERE nid = :nid AND status = :status ORDER BY cid DESC', array(
      ':nid' => $nid,
      ':status' => COMMENT_PUBLISHED,
    ), 0, 1)->fetchObject();
    db_update('forum_index')
      ->fields( array(
        'comment_count' => $count,
        'last_comment_timestamp' => $last_reply->timestamp,
      ))
      ->condition('nid', $nid)
      ->execute();
  }
  else {
    // Comments do not exist.
    $node = db_query('SELECT uid, created FROM {node} WHERE nid = :nid', array(':nid' => $nid))->fetchObject();
    db_update('forum_index')
      ->fields( array(
        'comment_count' => 0,
        'last_comment_timestamp' => $node->created,
      ))
      ->condition('nid', $nid)
      ->execute();
  }
}