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('Forums and containers are used to organize the threaded discussions.  Forums may be nested in each other.  A container is used to group like forums together with out allowing topics to be created in the container.  Containers can be nested just like forums.  To delete a forum or container choose the appropriate "edit" operation.');
    case 'admin/forum/add/container':
      return t('When creating a contianer you are creating a group to contain multiple forums.  Users are not able to create topic inside container.  You can nest containers inside forums or other containers.');
    case 'admin/forum/add/forum':
      return t('When creating a forum you are creating an area for user to create similar topics for discussion. Forums may be nested underneath other forums or in containers.');
    case 'admin/modules#description':
      return t('Enable threaded discussions about general topics.');
    case 'node/add#forum':
      return t('A forum is a threaded discussion, enabling users to communicate about a particular topic.');
  }
}

/**
 * Implementation of hook_node_name().
 */
function forum_node_name($node) {
  return t('forum topic');
}

/**
 * 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');
}

/**
 * Admiinstration 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']) {
        $output = _forum_confirm_del($edit['tid']);
        break;
      }
      else {
        $edit['name'] = 0;
      }
    case t('Submit'):
      $edit = taxonomy_save_term($edit);
      if (arg(3) == 'container') {
        $containers = variable_get('forum_containers', array());
        $containers[] = $edit['tid'];
        variable_set('forum_containers', $containers);
       }
      drupal_goto('admin/forum');
    default:
      $output = forum_overview();
  }

  print theme('page', $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);
    }
  }
}

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

   $form .= form_hidden('confirm', 1);
   $form .= form_hidden('tid', $tid);
   $form .= form_submit(t('Delete'));
   $form .= form_submit(t('Cancel'));

   return form(form_item(t('Delete "%name"', array('%name' => $term->name)), $form, t('Deleteing a forum or container will delete all sub-forums as well.  Are you sure you want to delete?')));
}

/**
 * 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 = form_textfield(t('Container name'), 'name', $edit['name'], 50, 64, t('The container name is used on the forum listing page to identify a group of forums.'), NULL, TRUE);
  $form .= form_textarea(t('Description'), 'description', $edit['description'], 60, 5, t('The description can provide additional information about the forum grouping.'));

  $form .= _forum_parent_select($edit['tid'], t('Parent'), 'parent][');
  $form .= form_weight(t('Weight'), 'weight', $edit['weight'], 10, t('In listings, the heavier terms (with a larger weight) will sink and the lighter terms will be positioned nearer the top.'));

  $form .= form_hidden('vid', _forum_get_vid());
  $form .= form_submit(t('Submit'));
  if ($edit['tid']) {
    $form .= form_submit(t('Delete'));
    $form .= form_hidden('tid', $edit['tid']);
  }

  return form($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 = form_textfield(t('Forum name'), 'name', $edit['name'], 50, 64, t('The name is used to identify the forum.'), NULL, TRUE);
  $form .= form_textarea(t('Description'), 'description', $edit['description'], 60, 5, t('The description can be used to provide more information about the forum, or further details about the topic.'));

  $form .= _forum_parent_select($edit['tid'], t('Parent'), 'parent][');
  $form .= form_weight(t('Weight'), 'weight', $edit['weight'], 10, t('In listings, the heavier (with a higher weight value) terms will sink and the lighter terms will be positioned nearer the top.'));

  $form .= form_hidden('vid', _forum_get_vid());
  $form .= form_submit(t('Submit'));
  if ($edit['tid']) {
    $form .= form_submit(t('Delete'));
    $form .= form_hidden('tid', $edit['tid']);
  }

  return form($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 $name Name to use in the forum
 */
function _forum_parent_select($tid, $title, $name) {

  $parents = taxonomy_get_parents($tid);
  $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 (!$parents) {
    $parents = 0;
  }

  return form_select($title, $name, $parents, $options, NULL, 0, FALSE, TRUE);
}

/**
 * Returns an overview list of existing forums and contianers
 */
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) .' '. $term->name, l(t('edit container'), "admin/forum/edit/container/$term->tid"));
      }
      else {
        $rows[] = array(_forum_depth($term->depth) .' '. $term->name, l(t('edit forum'), "admin/forum/edit/forum/$term->tid"));
       }

    }

    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) {
      $vocabulary = taxonomy_save_vocabulary(array('name' => 'Forums', 'multiple' => '0', 'required' => '1', 'hierarchy' => '1', 'relations' => '0', 'module' => 'forum', 'nodes' => array('forum')));
      $vid = $vocabulary['vid'];
    }
    variable_set('forum_nav_vocabulary', $vid);
  }

  return $vid;
}

/**
 * Implementation of hook_settings
 */
function forum_settings() {
  $output .= form_textfield(t('Forum icon path'), 'forum_icon_path', variable_get('forum_icon_path', ''), 30, 255, 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));
  $output .= form_select(t('Hot topic threshold'), 'forum_hot_topic', variable_get('forum_hot_topic', 15), $number, t('The number of posts a topic must have to be considered hot.'));
  $number = drupal_map_assoc(array(10, 25, 50, 75, 100));
  $output .= form_select(t('Topics per page'), 'forum_per_page', variable_get('forum_per_page', 25), $number, 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'));
  $output .= form_radios(t('Default order'), 'forum_order', variable_get('forum_order', '1'), $forder, t('The default display order for topics.'));

  return $output;
}

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

  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('Forum topics');
      return $blocks;

    case 'configure':
      $output = form_select(t('Number of topics in block'), 'forum_block_num', variable_get('forum_block_num', '5'), drupal_map_assoc(array(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)));
      return $output;

    case 'save':
      variable_set('forum_block_num', $edit['forum_block_num']);
      break;

    case 'view':
      if (user_access('access content')) {
        $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";
        $sql = node_rewrite_sql($sql);
        $content  = node_title_list(db_query_range($sql, 0, variable_get('forum_block_num', '5')), t('Active forum topics:'));

        $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";
        $sql = node_rewrite_sql($sql);
        $content .= node_title_list(db_query_range($sql, 0, variable_get('forum_block_num', '5')), t('New forum topics:'));

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

        $block['subject'] = t('Forum topics');
        $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));
    $sql = node_rewrite_sql($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' => $prev->title));
    }

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

  }

  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 : '';

  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' => "<em>$term->name</em>")));
        }
        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) {
  db_query('UPDATE {forum} SET tid = %d WHERE nid = %d', $node->tid, $node->nid);
}

/**
 * Implementation of hook_form().
 */
function forum_form(&$node) {
  if (!$node->nid) {
    // new topic
    $node->taxonomy[] = arg(3);
  }
  else {
    $node->taxonomy = array($node->tid);
  }

  $output = implode('', taxonomy_node_form('forum', $node));

  if ($node->nid) {
    // if editing, give option to leave shadows
    $shadow = (count(taxonomy_node_get_terms($node->nid)) > 1);
    $output .= form_checkbox(t('Leave shadow copy'), 'shadow', 1, $shadow, t('If you move this topic, you can leave a link in the old forum to the new forum.'));
  }

  $output .= form_textarea(t('Body'), 'body', $node->body, 60, 20, '');
  $output .= filter_form('format', $node->format);

  return $output;
}

/**
 * Implementation of hook_insert().
 */
function forum_insert($node) {
  db_query('INSERT INTO {forum} (nid, tid) VALUES (%d, %d)', $node->nid, $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() - $topic->timestamp), '%author' => format_name($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";
    $sql = node_rewrite_sql($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 /*! USE INDEX (node_comment_timestamp) */, {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";
    $sql = node_rewrite_sql($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'";
  $sql = node_rewrite_sql($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";
  $sql = node_rewrite_sql($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 = node_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.nid = f.nid");
  $sql .= tablesort_sql($forum_topic_list_header, 'n.sticky DESC,');

  $sql_count = node_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";
  $sql = node_rewrite_sql($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')) {
    $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);
    }

    print theme('page', theme('forum_display', $forums, $topics, $parents, $tid, $sortby, $forum_per_page));
  }
  else {
    drupal_set_title(t('Warning'));
    print theme('page', forum_help('admin/settings/forum'));
  }
}

/**
 * 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

  $vocabulary = taxonomy_get_vocabulary(variable_get('forum_nav_vocabulary', ''));
  drupal_set_title($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);
      }
    }
  }
  $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) {
      $output .= '<li>'. t('You are not allowed to post a new forum topic.') .'</li>';
    }
    else {
      $output .= '<li>'. t('<a href="%login">Login</a> to post a new forum topic.', array('%login' => url('user/login'))) .'</li>';
    }
    $output .= '</ul>';

    $output .= theme('forum_list', $forums, $parents, $tid);

    if ($tid && !in_array($tid, variable_get('forum_containers', array()))) {
      $output .= theme('forum_topic_list', $tid, $topics, $sortby, $forum_per_page);
    }
    $output .= '</div>';
  }
  else {
    drupal_set_title(t('No forums defined'));
    $output = '';
  }

  return $output;
}

/**
 * Format the forum listing.
 *
 * @ingroup themeable
 */
function theme_forum_list($forums, $parents, $tid) {
  global $user;

  if ($forums) {

    $header = array(t('Forum'), t('Topics'), t('Posts'), t('Last post'));

    foreach ($forums as $forum) {
      if ($forum->container) {
        $description  = '<div style="margin-left: '. ($forum->depth * 30) ."px;\">\n";
        $description .= ' <div class="name">'. l($forum->name, "forum/$forum->tid") ."</div>\n";

        if ($forum->description) {
          $description .= " <div class=\"description\">$forum->description</div>\n";
        }
        $description .= "</div>\n";

        $rows[] = array(array('data' => $description, 'class' => 'container', 'colspan' => '4'));
      }
      else {
        $forum->old_topics = _forum_topics_read($forum->tid, $user->uid);
        if ($user->uid) {
          $new_topics = $forum->num_topics - $forum->old_topics;
        }
        else {
          $new_topics = 0;
        }

        $description  = '<div style="margin-left: '. ($forum->depth * 30) ."px;\">\n";
        $description .= ' <div class="name">'. l($forum->name, "forum/$forum->tid") ."</div>\n";

        if ($forum->description) {
          $description .= " <div class=\"description\">$forum->description</div>\n";
        }
        $description .= "</div>\n";

        $rows[] = array(
          array('data' => $description, 'class' => 'forum'),
          array('data' => $forum->num_topics . ($new_topics ? '<br />'. l(t('%a new', array('%a' => $new_topics)), "forum/$forum->tid", NULL, NULL, 'new') : ''), 'class' => 'topics'),
          array('data' => $forum->num_posts, 'class' => 'posts'),
          array('data' => _forum_format($forum->last_post), 'class' => 'last-reply'));
      }
    }

    return theme('table', $header, $rows);

  }

}

/**
 * Format the topic listing.
 *
 * @ingroup themeable
 */
function theme_forum_topic_list($tid, $topics, $sortby, $forum_per_page) {
  global $forum_topic_list_header;

  if ($topics) {

    foreach ($topics as $topic) {
      // folder is new if topic is new or there are new comments since last visit
      if ($topic->tid != $tid) {
        $rows[] = array(
          array('data' => _forum_icon($topic->new, $topic->num_comments, $topic->comment_mode, $topic->sticky), 'class' => 'icon'),
          array('data' => $topic->title, 'class' => 'title'),
          array('data' => l(t('This topic has been moved'), "forum/$topic->tid"), 'colspan' => '3')
        );
      }
      else {
        $rows[] = array(
          array('data' => _forum_icon($topic->new, $topic->num_comments, $topic->comment_mode, $topic->sticky), 'class' => 'icon'),
          array('data' => l($topic->title, "node/$topic->nid"), 'class' => 'topic'),
          array('data' => $topic->num_comments . ($topic->new_replies ? '<br />'. l(t('%a new', array('%a' => $topic->new_replies)), "node/$topic->nid", NULL, NULL, 'new') : ''), 'class' => 'replies'),
          array('data' => _forum_format($topic), 'class' => 'created'),
          array('data' => _forum_format($topic->last_reply), 'class' => 'last-reply')
        );
      }
    }

    if ($pager = theme('pager', NULL, $forum_per_page, 0, tablesort_pager())) {
      $rows[] = array(array('data' => $pager, 'colspan' => '5', 'class' => 'pager'));
    }
  }

  $output .= theme('table', $forum_topic_list_header, $rows);

  return $output;
}

function _forum_icon($new_posts, $num_posts = 0, $comment_mode = 0, $sticky = 0) {

  $base_path = variable_get('forum_icon_path', '');
  if ($base_path) {
    if ($num_posts > variable_get('forum_hot_topic', 15)) {
      $icon = $new_posts ? 'hot-new' : 'hot';
    }
    else {
      $icon = $new_posts ? 'new' : 'default';
    }

    if ($comment_mode == 1) {
      $icon = 'closed';
    }

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

    // default
    $file = "misc/forum-$icon.png";

    $output = theme('image', $file);
  }
  else {
    $output = '&nbsp;';
  }

  if ($new_posts) {
    $output = "<a name=\"new\">$output</a>";
  }

  return $output;
}

function _forum_user_last_visit($nid) {
  global $user;
  static $history = array();

  if (empty($history)) {
    $result = db_query('SELECT nid, timestamp FROM {history} WHERE uid = %d', $user->uid);
    while ($t = db_fetch_object($result)) {