forum.module

<?php
// $Id$

/**
 * @file
 * Enable threaded discussions about general topics.
 */

/**
 * Implementation of hook_help().
 */
function forum_help($section) {
  switch ($section) {
    case 'admin/forum':
      return t('<p>This is a list of existing containers and forums that you can edit. Containers hold forums and, in turn, forums hold threaded discussions. Both containers and forums can be placed inside other containers and forums. By planning the structure of your containers and forums well, you make it easier for users to find a topic area of interest to them.</p>');
    case 'admin/forum/add/container':
      return t('<p>Containers help you organize your forums. The job of a container is to hold, or contain, other forums that are related. For example, a container named "Food" might hold two forums named "Fruit" and "Vegetables".</p>');
    case 'admin/forum/add/forum':
      return t('<p>A forum holds discussion topics that are related. For example, a forum named "Fruit" might contain topics titled "Apples" and "Bananas".</p>');
    case 'admin/modules#description':
      return t('Enables threaded discussions about general topics.');
    case 'admin/forum/configure':
      return t('This is where you can configure system-wide options for how your forums act and display.');
    case 'node/add#forum':
      return t('Create a new topic for discussion in the forums.');
  }
}

/**
 * Implementation of hook_node_info().
 */
function forum_node_info() {
  return array('forum' => array('name' => t('forum topic'), 'base' => 'forum'));
}

/**
 * Implementation of hook_access().
 */
function forum_access($op, $node) {
  global $user;

  if ($op == 'create') {
    return user_access('create forum topics');
  }

  if ($op == 'update' || $op == 'delete') {
    if (user_access('edit own forum topics') && ($user->uid == $node->uid)) {
      return TRUE;
    }
  }
}

/**
 * Implementation of hook_perm().
 */
function forum_perm() {
  return array('create forum topics', 'edit own forum topics', 'administer forums');
}

/**
 * Administration page which allows maintaining forums
 */
function forum_admin() {
  $op = $_POST['op'];
  $edit = $_POST['edit'];

  if (empty($op)) {
    $op = arg(2);
  }

  switch ($op) {
    case 'add':
      if (arg(3) == 'forum') {
        $output = forum_form_forum();
      }
      else if (arg(3) == 'container') {
        $output = forum_form_container();
      }
      break;
    case 'edit':
      if (arg(3) == 'forum') {
        $output = forum_form_forum(object2array(taxonomy_get_term(arg(4))));
      }
      else if (arg(3) == 'container') {
         $output = forum_form_container(object2array(taxonomy_get_term(arg(4))));
      }
      break;
    case t('Delete'):
      if (!$edit['confirm']) {
        $output = _forum_confirm_delete($edit['tid']);
        break;
      }
      else {
        $name = $edit['name'];
        $edit['name'] = 0;
      }
    case t('Submit'):
      $status = taxonomy_save_term($edit);
      if (arg(3) == 'container') {
        switch ($status) {
          case SAVED_NEW:
            $containers = variable_get('forum_containers', array());
            $containers[] = $edit['tid'];
            variable_set('forum_containers', $containers);
            drupal_set_message(t('Created new forum container %term.', array('%term' => theme('placeholder', $edit['name']))));
            break;
          case SAVED_UPDATED:
            drupal_set_message(t('The forum container %term has been updated.', array('%term' => theme('placeholder', $edit['name']))));
            break;
          case SAVED_DELETED:
            drupal_set_message(t('The forum container %term has been deleted.', array('%term' => theme('placeholder', $name))));
            break;
        }
      }
      else {
        switch ($status) {
          case SAVED_NEW:
            drupal_set_message(t('Created new forum %term.', array('%term' => theme('placeholder', $edit['name']))));
            break;
          case SAVED_UPDATED:
            drupal_set_message(t('The forum %term has been updated.', array('%term' => theme('placeholder', $edit['name']))));
            break;
          case SAVED_DELETED:
            drupal_set_message(t('The forum %term has been deleted.', array('%term' => theme('placeholder', $name))));
            break;
        }
      }
      drupal_goto('admin/forum');
    default:
      $output = forum_overview();
  }

  return $output;
}

/**
 * Implementation of hook_taxonomy().
 */
function forum_taxonomy($op, $type, $object) {
  if ($op == 'delete' && $type == 'term' && $object->vid == _forum_get_vid())  {
    $results = db_query('SELECT f.nid FROM {forum} f WHERE f.tid = %d', $object->tid);
    while ($node = db_fetch_object($results)) {
      $edit['nid'] = $node->nid;
      $edit['confirm'] = TRUE;
      node_delete($edit);
    }
  }
  elseif ($op == 'delete' && $type == 'vocabulary' && $object->vid == _forum_get_vid())  {
    variable_del('forum_nav_vocabulary');
  }
}

/**
 * Returns a confirmation page for deleting a forum taxonomy term
 *
 * @param $tid ID of the term to be deleted
 */
function _forum_confirm_delete($tid) {
  $term = taxonomy_get_term($tid);

  $form['tid'] = array(type => 'hidden', value => $tid);

  return confirm_form('forum_confirm_delete', $form, t('Are you sure you want to delete the forum %name?', array('%name' => theme('placeholder', $term->name))),
                  'admin/forums', t('Deleting a forum or container will delete all sub-forums as well. This action cannot be undone.'), t('Delete'), t('Cancel'));
}

/**
 * Returns a form for adding a container to the forum vocabulary
 *
 * @param $edit Associative array containing a container term to be added or edited.
 */
function forum_form_container($edit = array()) {
  $form['name'] = array(title => t('Container name'), type => 'textfield', default_value => $edit['name'], size => 60, maxlength =>  64, description => t('The container name is used to identify related forums.'), required => TRUE);
  $form['description'] = array(type => 'textarea', title => t('Description'), default_value => $edit['description'], cols => 60, rows => 5, description => ('The container description can give users more information about the forums it contains.'));
  $form['parent'][tree] = TRUE;
  $form['parent'][0] = _forum_parent_select($edit['tid'], t('Parent'), 'container');
  $form['weight'] = array(type => 'weight', title => t('Weight'), default_value => $edit['weight'], delta => 10, description => t('When listing containers, those with with light (small) weights get listed before containers with heavier (larger) weights. Containers with equal weights are sorted alphabetically.'));

  $form['vid'] = array(type => 'hidden', value => _forum_get_vid());
  $form['submit'] = array(type => 'submit', value => t('Submit'));
  if ($edit['tid']) {
    $form['delete'] = array(type => 'submit', value => t('Delete'));
    $form['tid'] = array(type => 'hidden', value => $edit['tid']);
  }

  return drupal_get_form('forum_form_container', $form);
}

/**
 * Returns a form for adding a forum to the forum vocabulary
 *
 * @param $edit Associative array containing a forum term to be added or edited.
 */
function forum_form_forum($edit = array()) {
  $form['name'] = array(type => 'textfield', title => t('Forum name'), default_value => $edit['name'], size => 60, maxlength =>  64, description => t('The forum name is used to identify related discussions.'), required => TRUE);
  $form['description'] = array(type => 'textarea', title => t('Description'), default_value => $edit['description'], cols => 60, rows => 5, description => ('The forum description can give users more information about the discussion topics it contains.'));
  $form['parent'][tree] = TRUE;
  $form['parent'][0] = _forum_parent_select($edit['tid'], t('Parent'), 'forum');
  $form['weight'] = array(type => 'weight', title => t('Weight'), default_value => $edit['weight'], delta => 10, description => t('When listing forums, those with with light (small) weights get listed before containers with heavier (larger) weights. Forums with equal weights are sorted alphabetically.'));

  $form['vid'] = array(type => 'hidden', value => _forum_get_vid());
  $form['submit' ] = array(type => 'submit', value => t('Submit'));
  if ($edit['tid']) {
    $form['delete'] = array(type => 'submit', value => t('Delete'));
    $form['tid'] = array(type => 'hidden', value => $edit['tid']);
  }

  return drupal_get_form('forum_form_forum', $form);
}

/**
 * Returns a select box for available parent terms
 *
 * @param $tid ID of the term which is being added or edited
 * @param $title Title to display the select box with
 * @param $child_type Whether the child is forum or container
 */
function _forum_parent_select($tid, $title, $child_type) {

  $parents = taxonomy_get_parents($tid);
  if ($parents) {
    $parent = array_shift($parents);
    $parent = $parent->tid;
  }
  else {
    $parent = 0;
  }

  $children = taxonomy_get_tree(_forum_get_vid, $tid);

  // A term can't be the child of itself, nor of its children.
  foreach ($children as $child) {
    $exclude[] = $child->tid;
  }
  $exclude[] = $tid;

  $tree = taxonomy_get_tree(_forum_get_vid());
  $options[0] = '<'. t('root') .'>';
  if ($tree) {
    foreach ($tree as $term) {
      if (!in_array($term->tid, $exclude)) {
        $options[$term->tid] = _forum_depth($term->depth).$term->name;
      }
    }
  }
  if ($child_type == 'container') {
    $description = t('Containers are usually placed at the top (root) level of your forum but you can also place a container inside a parent container or forum.');
  }
  else if ($child_type == 'forum') {
    $description = t('You may place your forum inside a parent container or forum, or at the top (root) level of your forum.');
  }

  return array(type => 'select', title => $title, default_value => $parent, options => $options, description => $description, required => TRUE);
}

/**
 * Returns an overview list of existing forums and containers
 */
function forum_overview() {
  $header = array(t('Name'), t('Operations'));

  $tree = taxonomy_get_tree(_forum_get_vid());
  if ($tree) {
    foreach ($tree as $term) {
      if (in_array($term->tid, variable_get('forum_containers', array()))) {
        $rows[] = array(_forum_depth($term->depth) .' '. check_plain($term->name), l(t('edit container'), "admin/forum/edit/container/$term->tid"));
      }
      else {
        $rows[] = array(_forum_depth($term->depth) .' '. check_plain($term->name), l(t('edit forum'), "admin/forum/edit/forum/$term->tid"));
       }

    }
  }
  else {
    $rows[] = array(array('data' => '<em>' . t('There are no existing containers or forums. You may add some on the <a href="%container">add container</a> or <a href="%forum">add forum</a> pages.', array('%container' => url('admin/forum/add/container'), '%forum' => url('admin/forum/add/forum'))) . '</em>', 'colspan' => 2));
  }
  return theme('table', $header, $rows);
}

/**
 * Helper function used to generate indentation for forum list
 *
 * @param $depth Depth of the indentation
 * @param $graphic HTML text to be repeated for each stage of depth
 */
function _forum_depth($depth, $graphic = '--') {
  for ($n = 0; $n < $depth; $n++) {
    $result .= $graphic;
  }
  return $result;
}

/**
 * Returns the vocabulary id for forum navigation.
 */
function _forum_get_vid() {
  $vid = variable_get('forum_nav_vocabulary', '');
  if (empty($vid)) {
    // Check to see if a forum vocabulary exists
    $vid = db_result(db_query("SELECT vid FROM {vocabulary} WHERE module = '%s'", 'forum'));
    if (!$vid) {
      $edit = array('name' => 'Forums', 'multiple' => 0, 'required' => 1, 'hierarchy' => 1, 'relations' => 0, 'module' => 'forum', 'nodes' => array('forum'));
      taxonomy_save_vocabulary($edit);
      $vid = $edit['vid'];
    }
    variable_set('forum_nav_vocabulary', $vid);
  }

  return $vid;
}

/**
 * Implementation of hook_settings
 */
function forum_admin_configure() {

  $form = array();
  $form['forum_icon_path'] = array(type => 'textfield', title => t('Forum icon path'), default_value => variable_get('forum_icon_path', ''), size => 30, maxlength =>  255, description => t('The path to the forum icons.  Leave blank to disable icons. Don\'t add a trailing slash.  Default icons are available in the "misc" directory. You may use images of whatever size you wish, but it is recommended to use 15x15 or 16x16. '));
  $number = drupal_map_assoc(array(5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 80, 100, 10000));
  $form['forum_hot_topic'] = array(type => 'select', title => t('Hot topic threshold'), default_value => variable_get('forum_hot_topic', 15), options => $number, description => t('The number of posts a topic must have to be considered hot.'));
  $number = drupal_map_assoc(array(10, 25, 50, 75, 100));
  $form['forum_per_page'] = array(type => 'select', title => t('Topics per page'), default_value => variable_get('forum_per_page', 25), options => $number, description => t('The default number of topics displayed per page; links to browse older messages are automatically being displayed.'));
  $forder = array(1 => t('Date - newest first'), 2 => t('Date - oldest first'), 3 => t('Posts - most active first'), 4=> t('Posts - least active first'));
  $form['forum_order'] = array(type => 'radios', title => t('Default order'), default_value => variable_get('forum_order', '1'), options => $forder, description => t('The default display order for topics.'));

  return system_settings_form('forum_admin_configure', $form);
}

/**
 * Implementation of hook_load().
 */
function forum_load($node) {
  $forum = db_fetch_object(db_query('SELECT * FROM {forum} WHERE vid = %d', $node->vid));

  return $forum;
}

/**
 * Implementation of hook_block().
 *
 * Generates a block containing the currently active forum topics and the
 * most recently added forum topics.
 */
function forum_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    case 'list':
      $blocks[0]['info'] = t('Active forum topics');
      $blocks[1]['info'] = t('New forum topics');
      return $blocks;

    case 'configure':
      $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;

    case 'save':
      variable_set('forum_block_num_'. $delta, $edit['forum_block_num_'. $delta]);
      break;

    case 'view':
      if (user_access('access content')) {
        switch ($delta) {
          case 0:
            $title = t('Active forum topics');
            $sql = db_rewrite_sql("SELECT n.nid, n.title, l.last_comment_timestamp, l.comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid WHERE n.status = 1 AND n.type = 'forum' ORDER BY l.last_comment_timestamp DESC");
            $result = db_query_range($sql, 0, variable_get('forum_block_num_0', '5'));
            if (db_num_rows($result)) {
              $content = node_title_list($result);
            }
            break;

          case 1:
            $title = t('New forum topics');
            $sql = db_rewrite_sql("SELECT n.nid, n.title, l.comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid WHERE n.type = 'forum' AND n.status = 1 ORDER BY n.nid DESC");
            $result = db_query_range($sql, 0, variable_get('forum_block_num_1', '5'));
            if (db_num_rows($result)) {
              $content = node_title_list($result);
            }
            break;
        }

        if ($content) {
          $content .= '<div class="more-link">'. l(t('more'), 'forum', array('title' => t('Read the latest forum topics.'))) .'</div>';
        }

        $block['subject'] = $title;
        $block['content'] = $content;

        return $block;
      }
  }
}

/**
 * Implementation of hook_link().
 */
function forum_link($type, $node = 0, $main = 0) {
  global $user;

  $links = array();

  if (!$main && $type == 'node' && $node->type == 'forum') {
    // get previous and next topic

    $sql = "SELECT n.nid, n.title, n.sticky, l.comment_count, l.last_comment_timestamp FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid INNER JOIN {term_node} r ON n.nid = r.nid AND r.tid = %d WHERE n.status = 1 AND n.type = 'forum' ORDER BY n.sticky DESC, ". _forum_get_topic_order_sql(variable_get('forum_order', 1));
    $sql = db_rewrite_sql($sql);
    $result = db_query($sql, $node->tid);

    while ($topic = db_fetch_object($result)) {
      if ($stop == 1) {
        $next = new StdClass();
        $next->nid = $topic->nid;
        $next->title = $topic->title;
        break;
      }
      if ($topic->nid == $node->nid) {
        $stop = 1;
      }
      else {
        $prev = new StdClass();
        $prev->nid = $topic->nid;
        $prev->title = $topic->title;
      }
    }

    if ($prev) {
      $links[] = l(t('previous forum topic'), "node/$prev->nid", array('title' => check_plain($prev->title)));
    }

    if ($next) {
      $links[] = l(t('next forum topic'), "node/$next->nid", array('title' => check_plain($next->title)));
    }
  }

  return $links;
}

/**
 * Implementation of hook_menu().
 */
function forum_menu($may_cache) {
  $items = array();

  if ($may_cache) {
    $items[] = array('path' => 'node/add/forum', 'title' => t('forum topic'),
      'access' => user_access('create forum topics'));

    $items[] = array('path' => 'forum', 'title' => t('forums'),
      'callback' => 'forum_page',
      'access' => user_access('access content'),
      'type' => MENU_SUGGESTED_ITEM);

    $items[] = array('path' => 'admin/forum', 'title' => t('forums'),
      'callback' => 'forum_admin',
      'access' => user_access('administer forums'),
      'type' => MENU_NORMAL_ITEM);

    $items[] = array('path' => 'admin/forum/list', 'title' => t('list'),
      'access' => user_access('administer forums'),
      'type' => MENU_DEFAULT_LOCAL_TASK, 'weight' => -10);
    $items[] = array('path' => 'admin/forum/add/container', 'title' => t('add container'),
      'access' => user_access('administer forums'),
      'type' => MENU_LOCAL_TASK);
    $items[] = array('path' => 'admin/forum/add/forum', 'title' => t('add forum'),
      'access' => user_access('administer forums'),
      'type' => MENU_LOCAL_TASK);
    $items[] = array('path' => 'admin/forum/configure', 'title' => t('configure'),
      'callback' => 'forum_admin_configure',
      'access' => user_access('administer forums'),
      'type' => MENU_LOCAL_TASK);

    $items[] = array('path' => 'admin/forum/edit/container', 'title' => t('edit container'),
      'access' => user_access('administer forums'),
      'type' => MENU_CALLBACK);
    $items[] = array('path' => 'admin/forum/edit/forum', 'title' => t('edit forum'),
      'access' => user_access('administer forums'),
      'type' => MENU_CALLBACK);
  }

  return $items;
}

/**
 * Implementation of hook_view().
 */
function forum_view(&$node, $teaser = FALSE, $page = FALSE) {

  if ($page) {
    $vocabulary = taxonomy_get_vocabulary(variable_get('forum_nav_vocabulary', ''));
    // Breadcrumb navigation
    $breadcrumb = array();
    $breadcrumb[] = array('path' => 'forum', 'title' => $vocabulary->name);
    if ($parents = taxonomy_get_parents_all($node->tid)) {
      $parents = array_reverse($parents);
      foreach ($parents as $p) {
        $breadcrumb[] = array('path' => 'forum/'. $p->tid, 'title' => $p->name);
      }
    }
    $breadcrumb[] = array('path' => 'node/'. $node->nid);
    menu_set_location($breadcrumb);
  }

  $node = node_prepare($node, $teaser);
}

/**
 * Implementation of hook_validate().
 *
 * Check in particular that only a "leaf" term in the associated taxonomy
 * vocabulary is selected, not a "container" term.
 */
function forum_validate(&$node) {
  // Make sure all fields are set properly:
  $node->icon = $node->icon ? $node->icon : '';

  node_validate_title($node,t('You have to specify a subject.'));

  if ($node->taxonomy) {
    // Extract the node's proper topic ID.
    $vocabulary = variable_get('forum_nav_vocabulary', '');
    $containers = variable_get('forum_containers', array());
    foreach ($node->taxonomy as $term) {
      if (db_result(db_query('SELECT COUNT(*) FROM {term_data} WHERE tid = %d AND vid = %d', $term, $vocabulary))) {
        if (in_array($term, $containers)) {
          $term = taxonomy_get_term($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' => theme('placeholder', $term->name))));
        }
        else {
          $node->tid = $term;
        }
      }
    }
    if ($node->tid && $node->shadow) {
      $terms = array_keys(taxonomy_node_get_terms($node->nid));
      if (!in_array($node->tid, $terms)) {
        $terms[] = $node->tid;
      }
      $node->taxonomy = $terms;
    }
  }
}

/**
 * Implementation of hook_update().
 */
function forum_update($node) {
  if ($node->is_new || $node->revision) {
    db_query("INSERT INTO {forum} (nid, vid, tid) VALUES (%d, %d, %d)", $node->nid, $node->vid, $node->tid);
  }
  else {
    db_query('UPDATE {forum} SET tid = %d WHERE vid = %d', $node->tid, $node->vid);
  }
}

/**
 * Implementation of hook_form().
 */
function forum_form(&$node) {
  $form['title'] = array(type => 'textfield', title => t('Subject'), default_value => $node->title, size => 60, maxlength => 128, required => TRUE);

  if (!$node->nid) {
    // new topic
    $node->taxonomy[] = arg(3);
  }
  else {
    $node->taxonomy = array($node->tid);
  }

  if (function_exists('taxonomy_node_form')) {
    $form['taxonomy'] = taxonomy_node_form('forum', $node);
  }

  if ($node->nid) {
    // if editing, give option to leave shadows
    $shadow = (count(taxonomy_node_get_terms($node->nid)) > 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['body'] = array(type => 'textarea', title => t('Body'), default_value => $node->body, required => TRUE
  );
  $form = array_merge($form, filter_form($node->format));

  return $form;
}

/**
 * Implementation of hook_insert().
 */
function forum_insert($node) {
  db_query('INSERT INTO {forum} (nid, vid, tid) VALUES (%d, %d, %d)', $node->nid, $node->vid, $node->tid);
}

/**
 * Implementation of hook_delete().
 */
function forum_delete(&$node) {
  db_query('DELETE FROM {forum} WHERE nid = %d', $node->nid);
}

/**
 * Formats a topic for display
 *
 * @TODO Give a better description. Not sure where this function is used yet.
 */
function _forum_format($topic) {
  if ($topic && $topic->timestamp) {
    return t('%time ago<br />by %author', array('%time' => format_interval(time() - $topic->timestamp), '%author' => theme('username', $topic)));
  }
  else {
    return message_na();
  }
}

/**
 * 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) {

  if (!$tid) {
    $tid = 0;
  }

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

  if (count($_forums)) {

    $counts = array();

    $sql = "SELECT r.tid, COUNT(n.nid) AS topic_count, SUM(l.comment_count) AS comment_count FROM {node} n INNER JOIN {node_comment_statistics} l ON n.nid = l.nid INNER JOIN {term_node} r ON n.nid = r.nid WHERE n.status = 1 AND n.type = 'forum' GROUP BY r.tid";
    $sql = db_rewrite_sql($sql);
    $_counts = db_query($sql, $forum->tid);
    while ($count = db_fetch_object($_counts)) {
      $counts[$count->tid] = $count;
    }
  }

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

    if ($counts[$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;
    }

    // This query does not use full ANSI syntax since MySQL 3.x does not support
    // table1 INNER JOIN table2 INNER JOIN table3 ON table2_criteria ON table3_criteria
    // used to join node_comment_statistics to users.
    $sql = "SELECT n.nid, l.last_comment_timestamp, IF(l.last_comment_uid, cu.name, l.last_comment_name) as last_comment_name, l.last_comment_uid FROM {node} n, {node_comment_statistics} l, {users} cu, {term_node} r WHERE  n.nid = r.nid AND r.tid = %d AND n.status = 1 AND n.type = 'forum' AND l.last_comment_uid = cu.uid AND n.nid = l.nid ORDER BY l.last_comment_timestamp DESC";
    $sql = db_rewrite_sql($sql);
    $topic = db_fetch_object(db_query_range($sql, $forum->tid, 0, 1));

    $last_post = new StdClass();
    $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;
}

function _forum_topics_read($term, $uid) {
  // Calculate the number of topics the user has read. Assume all entries older
  // than NODE_NEW_LIMIT are read, and include the recent posts that user has
  // read.
  $sql = "SELECT COUNT(n.nid) FROM {node} n INNER JOIN {term_node} r ON n.nid = r.nid AND r.tid = %d WHERE n.created <= %d AND n.status = 1 AND n.type = 'forum'";
  $sql = db_rewrite_sql($sql);
  $ancient = db_result(db_query($sql, $term, NODE_NEW_LIMIT));
  $sql = "SELECT COUNT(n.nid) FROM {node} n INNER JOIN {history} h ON n.nid = h.nid AND h.uid = %d INNER JOIN {term_node} r ON n.nid = r.nid AND r.tid = %d WHERE n.status = 1 AND n.type = 'forum' AND n.created > %d";
  $sql = db_rewrite_sql($sql);
  $recent = db_result(db_query($sql, $uid, $term, NODE_NEW_LIMIT));

  return $ancient + $recent;
}

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

  $forum_topic_list_header = array(
    array('data' => '&nbsp;'),
    array('data' => t('Topic'), 'field' => 'n.title'),
    array('data' => t('Replies'), 'field' => 'l.comment_count'),
    array('data' => t('Created'), 'field' => 'n.created'),
    array('data' => t('Last reply'), 'field' => 'l.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'];
    }
  }

  $term = taxonomy_get_term($tid);

  $sql = db_rewrite_sql("SELECT n.nid, f.tid, n.title, n.sticky, u.name, u.uid, n.created AS timestamp, n.comment AS comment_mode, l.last_comment_timestamp, IF(l.last_comment_uid, cu.name, l.last_comment_name) AS last_comment_name, l.last_comment_uid, l.comment_count AS num_comments FROM {node} n, {node_comment_statistics} l, {users} cu, {term_node} r, {users} u, {forum} f WHERE n.status = 1 AND l.last_comment_uid = cu.uid AND n.nid = l.nid AND n.nid = r.nid AND r.tid = %d AND n.uid = u.uid AND n.vid = f.vid");
  $sql .= tablesort_sql($forum_topic_list_header, 'n.sticky DESC,');
  $sql .= ', n.created DESC';  // Always add a secondary sort order so that the news forum topics are on top.

  $sql_count = db_rewrite_sql("SELECT COUNT(n.nid) FROM {node} n INNER JOIN {term_node} r ON n.nid = r.nid AND r.tid = %d WHERE n.status = 1 AND n.type = 'forum'");

  $result = pager_query($sql, $forum_per_page, 0, $sql_count, $tid);

  while ($topic = db_fetch_object($result)) {
    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;
    }
    $topics[] = $topic;
  }

  return $topics;
}

/**
 * Finds the first unread node for a given forum.
 */
function _forum_new($tid) {
  global $user;

  $sql = "SELECT n.nid FROM {node} n LEFT JOIN {history} h ON n.nid = h.nid AND h.uid = %d INNER JOIN {term_node} r ON n.nid = r.nid AND r.tid = %d WHERE n.status = 1 AND n.type = 'forum' AND h.nid IS NULL AND n.created > %d ORDER BY created";
  $sql = db_rewrite_sql($sql);
  $nid = db_result(db_query_range($sql, $user->uid, $tid, NODE_NEW_LIMIT, 0, 1));

  return $nid ? $nid : 0;
}

/**
 * Menu callback; prints a forum listing.
 */
function forum_page($tid = 0) {
  global $user;

  if (module_exist('taxonomy') && module_exist('comment')) {
    $forum_per_page = variable_get('forum_per_page', 25);
    $sortby = variable_get('forum_order', 1);

    $forums = forum_get_forums($tid);
    $parents = taxonomy_get_parents_all($tid);
    if ($tid && !in_array($tid, variable_get('forum_containers', array()))) {
      $topics = forum_get_topics($tid, $sortby, $forum_per_page);
    }

    return theme('forum_display', $forums, $topics, $parents, $tid, $sortby, $forum_per_page);
  }
  else {
    drupal_set_message(t('The forum module requires both the taxonomy module and the comment module to be enabled and configured.'), 'error');
    return ' ';
  }
}

/**
 * Format the forum body.
 *
 * @ingroup themeable
 */
function theme_forum_display($forums, $topics, $parents, $tid, $sortby, $forum_per_page) {
  global $user;
  // forum list, topics list, topic browser and 'add new topic' link

  $vocabulary = taxonomy_get_vocabulary(variable_get('forum_nav_vocabulary', ''));
  $title = $vocabulary->name;

  // Breadcrumb navigation:
  $breadcrumb = array();
  if ($tid) {
    $breadcrumb[] = array('path' => 'forum', 'title' => $title);
  }

  if ($parents) {
    $parents = array_reverse($parents);
    foreach ($parents as $p) {
      if ($p->tid == $tid) {
        $title = $p->name;
      }
      else {
        $breadcrumb[] = array('path' => 'forum/'. $p->tid, 'title' => $p->name);
      }
    }
  }

  drupal_set_title($title);

  $breadcrumb[] = array('path' => $_GET['q']);
  menu_set_location($breadcrumb);

  if (count($forums) || count($parents)) {
    $output  = '<div id="forum">';
    $output .= '<ul>';

    if (module_exist('tracker')) {
      if ($user->uid) {
        $output .= ' <li>'. l(t('My forum discussions.'), "tracker/$user->uid") .'</li>';
      }

      $output .= ' <li>'. l(t('Active forum discussions.'), 'tracker') .'</li>';
    }

    if (user_access('create forum topics')) {
      $output .= '<li>'. l(t('Post new forum topic.'), "node/add/forum/$tid") .'</li>';
    }
    else if ($user->uid) {