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/build/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. To rearrange forums and containers, grab a drag-and-drop handle under the <em>Name</em> column and drag the forum or container to a new location in the list. (Grab a handle by clicking and holding the mouse while hovering over a handle icon.) Remember that your changes will not be saved until you click the <em>Save</em> button at the bottom of the page.') . '</p>';
    case 'admin/build/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/build/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/build/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/content/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_topic_navigation' => array(
      'template' => 'forum-topic-navigation',
      'arguments' => array('node' => NULL),
    ),
    'forum_submitted' => array(
      'template' => 'forum-submitted',
      'arguments' => array('topic' => NULL),
    ),
  );
}

/**
 * Fetch a forum term.
 *
 * @param $tid
 *   The ID of the term which should be loaded.
 *
 * @return
 *   An associative array containing the term data or FALSE if the term cannot be loaded, or is not part of the forum vocabulary.
 */
function forum_term_load($tid) {
  return db_select('taxonomy_term_data', 't')
    ->fields('t', array('tid', 'vid', 'name', 'description', 'weight'))
    ->condition('tid', $tid)
    ->condition('vid', variable_get('forum_nav_vocabulary', 0))
    ->addTag('term_access')
    ->execute()
    ->fetchAssoc();
}

/**
 * Implement hook_menu().
 */
function forum_menu() {
  $items['forum'] = array(
    'title' => 'Forums',
    'page callback' => 'forum_page',
    'access arguments' => array('access content'),
  );
  $items['admin/build/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'),
  );
  $items['admin/build/forum/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/build/forum/add/container'] = array(
    'title' => 'Add container',
    'page callback' => 'forum_form_main',
    'page arguments' => array('container'),
    'access arguments' => array('administer forums'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/build/forum',
  );
  $items['admin/build/forum/add/forum'] = array(
    'title' => 'Add forum',
    'page callback' => 'forum_form_main',
    'page arguments' => array('forum'),
    'access arguments' => array('administer forums'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/build/forum',
  );
  $items['admin/build/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/build/forum',
  );
  $items['admin/build/forum/edit/%forum_term'] = array(
    'page callback' => 'forum_form_main',
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/build/forum/edit/container/%forum_term'] = array(
    'title' => 'Edit container',
    'page callback' => 'forum_form_main',
    'page arguments' => array('container', 5),
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/build/forum/edit/forum/%forum_term'] = array(
    'title' => 'Edit forum',
    'page callback' => 'forum_form_main',
    'page arguments' => array('forum', 5),
    'access arguments' => array('administer forums'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}


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

/**
 * _forum_node_check_node_type
 *
 * @param mixed $node
 * @param mixed $vocabulary
 * @access protected
 * @return bool
 */
function _forum_node_check_node_type($node, $vocabulary) {
  // We are going to return if $node->type is not one of the node
  // types assigned to the forum vocabulary. If forum_nav_vocabulary
  // is undefined or the vocabulary does not exist, it clearly cannot
  // be assigned to $node->type, so return to avoid E_ALL warnings.
  if (empty($vocabulary)) {
    return FALSE;
  }

  // Operate only on node types assigned for the forum vocabulary.
  if (!in_array($node->type, $vocabulary->nodes)) {
    return FALSE;
  }

  return TRUE;
}

/**
 * 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, $vocabulary)) {
    if ((bool)menu_get_object() && taxonomy_node_get_terms_by_vocabulary($node, $vid) && $tree = taxonomy_get_tree($vid)) {
      // Get the forum terms from the (cached) tree
      foreach ($tree as $term) {
        $forum_terms[] = $term->tid;
      }
      foreach ($node->taxonomy as $term_id => $term) {
        if (in_array($term_id, $forum_terms)) {
          $node->tid = $term_id;
        }
      }
      // Breadcrumb navigation
      $breadcrumb[] = l(t('Home'), NULL);
      $breadcrumb[] = l($vocabulary->name, 'forum');
      if ($parents = taxonomy_get_parents_all($node->tid)) {
        $parents = array_reverse($parents);
        foreach ($parents as $p) {
          $breadcrumb[] = l($p->name, 'forum/' . $p->tid);
        }
      }
      drupal_set_breadcrumb($breadcrumb);

      if ($build_mode == 'full') {
        $node->content['forum_navigation'] = array(
          '#markup' => theme('forum_topic_navigation', $node),
          '#weight' => 100,
        );
      }
    }
  }
}

/**
 * Implement hook_node_prepare().
 */
function forum_node_prepare($node) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    if (empty($node->nid)) {
      // New topic
      $node->taxonomy[arg(3)] = (object) array(
        'vid' => $vid,
        '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) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    // vocabulary is selected, not a "container" term.
    if ($node->taxonomy) {
      // Extract the node's proper topic ID.
      $vocabulary = $vid;
      $containers = variable_get('forum_containers', array());
      foreach ($node->taxonomy as $term) {
        $used = db_query_range('SELECT 1 FROM {taxonomy_term_data} WHERE tid = :tid AND vid = :vid', array(
          ':tid' => $term,
          ':vid' => $vocabulary,
        ), 0, 1)->fetchField();
        if ($used && in_array($term, $containers)) {
          $term = taxonomy_term_load($term);
          form_set_error('taxonomy', 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) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    // Make sure all fields are set properly:
    $node->icon = !empty($node->icon) ? $node->icon : '';

    if ($node->taxonomy && $tree = taxonomy_get_tree($vid)) {
      // Get the forum terms from the (cached) tree if we have a taxonomy.
      foreach ($tree as $term) {
        $forum_terms[] = $term->tid;
      }
      foreach ($node->taxonomy as $term_id) {
        if (in_array($term_id, $forum_terms)) {
          $node->tid = $term_id;
        }
      }
      $old_tid = db_query_range("SELECT t.tid FROM {taxonomy_term_node} t INNER JOIN {node} n ON t.vid = n.vid WHERE n.nid = :nid ORDER BY t.vid DESC", array(':nid' => $node->nid), 0, 1)->fetchField();
      if ($old_tid && isset($node->tid) && ($node->tid != $old_tid) && !empty($node->shadow)) {
        // A shadow copy needs to be created. Retain new term and add old term.
        $node->taxonomy[] = $old_tid;
      }
    }
  }
}

/**
 * Implement hook_node_update().
 */
function forum_node_update($node) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    if (empty($node->revision) && db_query('SELECT tid FROM {forum} WHERE nid=:nid', array(':nid' => $node->nid))->fetchField()) {
      if (!empty($node->tid)) {
        db_update('forum')
          ->fields(array('tid' => $node->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->tid)) {
        db_insert('forum')
          ->fields(array(
            'tid' => $node->tid,
            'vid' => $node->vid,
            'nid' => $node->nid,
          ))
          ->execute();
      }
    }
  }
}

/**
 * Implement hook_node_insert().
 */
function forum_node_insert($node) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    if (!empty($node->tid)) {
      $nid = db_insert('forum')
        ->fields(array(
          'tid' => $node->tid,
          'vid' => $node->vid,
          'nid' => $node->nid,
        ))
        ->execute();
    }
  }
}

/**
 * Implement hook_node_delete().
 */
function forum_node_delete($node) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabulary = taxonomy_vocabulary_load($vid);
  if (_forum_node_check_node_type($node, $vocabulary)) {
    db_delete('forum')
      ->condition('nid', $node->nid)
      ->execute();
  }
}

/**
 * Implement hook_node_load().
 */
function forum_node_load($nodes, $types) {
  $vid = variable_get('forum_nav_vocabulary', 0);
  // If no forum vocabulary is set up, return.
  if ($vid == '') {
    return;
  }
  $vocabulary = taxonomy_vocabulary_load($vid);

  $node_vids = array();
  foreach ($nodes as $node) {
    if (isset($vocabulary->nodes[$node->type])) {
      $node_vids[] = $node->vid;
    }
  }
  if (!empty($node_vids)) {
    $result = db_query('SELECT nid, tid FROM {forum} WHERE vid IN(:node_vids)', array(':node_vids' => $node_vids));
    foreach ($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_access().
 */
function forum_access($op, $node, $account) {
  switch ($op) {
    case 'create':
      return user_access('create forum content', $account);
    case 'update':
      return user_access('edit any forum content', $account) || (user_access('edit own forum content', $account) && ($account->uid == $node->uid));
    case 'delete':
      return user_access('delete any forum content', $account) || (user_access('delete own forum content', $account) && ($account->uid == $node->uid));
  }
}

/**
 * Implement hook_perm().
 */
function forum_perm() {
  $perms = array(
    'administer forums' => array(
      'title' => t('Administer forums'),
      'description' => t('Manage forums and configure forum administration settings.'),
    ),
  );
  $perms += node_list_permissions('forum');
  return $perms;
}

/**
 * Implement hook_taxonomy().
 */
function forum_taxonomy($op, $type, $term = NULL) {
  if ($op == 'delete' && $term['vid'] == variable_get('forum_nav_vocabulary', 0)) {
    switch ($type) {
      case 'term':
        $result = db_query('SELECT tn.nid FROM {taxonomy_term_node} tn WHERE tn.tid = :tid', array(':tid' => $term['tid']));
        foreach ($result as $node) {
          // node_delete will also remove any association with non-forum vocabularies.
          node_delete($node->nid);
        }

        // For containers, remove the tid from the forum_containers variable.
        $containers = variable_get('forum_containers', array());
        $key = array_search($term['tid'], $containers);
        if ($key !== FALSE) {
          unset($containers[$key]);
        }
        variable_set('forum_containers', $containers);
        break;
      case 'vocabulary':
        variable_del('forum_nav_vocabulary');
    }
  }
}

/**
 * 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['content_types']['nodes']['#required'] = TRUE;
      $form['hierarchy'] = array('#type' => 'value', '#value' => 1);
      $form['settings']['required'] = array('#type' => 'value', '#value' => FALSE);
      $form['settings']['relations'] = array('#type' => 'value', '#value' => FALSE);
      $form['settings']['tags'] = array('#type' => 'value', '#value' => FALSE);
      $form['settings']['multiple'] = array('#type' => 'value', '#value' => FALSE);
      unset($form['delete']);
    }
    // Hide multiple parents select from forum terms.
    elseif ($form_id == 'taxonomy_form_term') {
      $form['advanced']['parent']['#access'] = FALSE;
    }
  }
  if ($form_id == 'forum_node_form') {
    // Make the vocabulary required for 'real' forum-nodes.
    $vid = variable_get('forum_nav_vocabulary', 0);
    $form['taxonomy'][$vid]['#required'] = TRUE;
    $form['taxonomy'][$vid]['#options'][''] = t('- Please choose -');
  }
}

/**
 * Implement hook_block_list().
 */
function forum_block_list() {
  $blocks['active']['info'] = t('Active forum topics');
  $blocks['new']['info'] = t('New forum topics');
  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 = '') {
  if (user_access('access content')) {
    $query = db_select('node', 'n');
    $query->join('taxonomy_term_node', 'tn', 'tn.vid = n.vid');
    $query->join('taxonomy_term_data', 'td', 'td.tid = tn.tid');
    $query->join('node_comment_statistics', 'ncs', 'n.nid = ncs.nid');
    $query
      ->fields('n', array('nid', 'title'))
      ->fields('ncs', array('comment_count', 'last_comment_timestamp'))
      ->condition('n.status', 1)
      ->condition('td.vid', variable_get('forum_nav_vocabulary', 0))
      ->addTag('node_access');
    switch ($delta) {
      case 'active':
        $title = t('Active forum topics');
        $query
          ->orderBy('ncs.last_comment_timestamp', 'DESC')
          ->range(0, variable_get('forum_block_num_active', '5'));
        break;

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

    $result = $query->execute();
    $content = node_title_list($result);
    if (!empty($content)) {
      $block['subject'] = $title;
      $block['content'] = $content . theme('more_link', url('forum'), t('Read the latest forum topics.'));
      return $block;
    }
  }
}

/**
 * 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)) {
    $vid = variable_get('forum_nav_vocabulary', 0);
    $forum_terms = taxonomy_node_get_terms_by_vocabulary($node, $vid);
    // 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['#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('taxonomy_term_node', 'r', 'n.vid = r.vid');
    $query->addExpression('COUNT(n.nid)', 'topic_count');
    $query->addExpression('SUM(ncs.comment_count)', 'comment_count');
    $counts = $query
      ->fields('r', 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('taxonomy_term_node', 'tn', 'n.vid = tn.vid AND tn.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->timestamp = $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('taxonomy_term_node', 'tn', 'n.vid = tn.vid AND tn.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' => 'n.title'),
    array('data' => t('Replies'), 'field' => 'ncs.comment_count'),
    array('data' => t('Created'), 'field' => 'n.created'),
    array('data' => t('Last reply'), 'field' => 'ncs.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('node_comment_statistics', 'ncs')->extend('PagerDefault')->extend('TableSort');
  $query->join('node', 'n', 'n.nid = ncs.nid');
  $query->join('users', 'cu', 'ncs.last_comment_uid = cu.uid');
  $query->join('taxonomy_term_node', 'r', 'n.vid = r.vid AND r.tid = :tid', array(':tid' => $tid));
  $query->join('users', 'u', 'n.uid = u.uid');
  $query->join('forum', 'f', 'n.vid = f.vid');
  $query->addExpression('IF(ncs.last_comment_uid != 0, cu.name, ncs.last_comment_name)', 'last_comment_name');
  $query->addField('n', 'created', 'timestamp');
  $query->addField('n', 'comment', 'comment_mode');
  $query->addField('ncs', 'comment_count', 'num_comments');
  $query->addField('f', 'tid', 'forum_tid');
  $query
    ->addTag('node_access')
    ->fields('n', array('nid', 'title', 'type', 'sticky'))
    ->fields('r', array('tid'))
    ->fields('u', array('name', 'uid'))
    ->fields('ncs', array('last_comment_timestamp', 'last_comment_uid'))
    ->condition('n.status', 1)
    ->orderBy('n.sticky', 'DESC')
    ->orderByHeader($forum_topic_list_header)
    ->orderBy('n.created', 'DESC')
    ->limit($forum_per_page);

  $count_query = db_select('node', 'n');
  $count_query->join('taxonomy_term_node', 'r', 'n.vid = r.vid AND r.tid = :tid', array(':tid' => $tid));
  $count_query->addExpression('COUNT(*)');
  $count_query
    ->condition('n.status', 1)
    ->addTag('node_access');

  $query->setCountQuery($count_query);
  $result = $query->execute();
  $topics = array();
  foreach ($result as $topic) {
    if ($user->uid) {
      // folder is new if topic is new or there are new comments since last visit
      if ($topic->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->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->num_comments > 0) {
      $last_reply = new stdClass();
      $last_reply->timestamp = $topic->last_comment_timestamp;
      $last_reply->name = $topic->last_comment_name;
      $last_reply->uid = $topic->last_comment_uid;
      $topic->last_reply = $last_reply;
    }