node.module

<?php
// $Id$

/**
 * @file
 * The core that allows content to be submitted to the site.
 */

define('NODE_NEW_LIMIT', time() - 30 * 24 * 60 * 60);

/**
 * Implementation of hook_help().
 */
function node_help($section) {
  switch ($section) {
    case 'admin/help#node':
      $output = t("
      <h3>Nodes</h3>
      <p>The core of the Drupal system is the node. All of the contents of the system are placed in nodes, or extensions of nodes.
      A base node contains:<dl>
      <dt>A Title</dt><dd>Up to 128 characters of text that titles the node.</dd>
      <dt>A Teaser</dt><dd>A small block of text that is meant to get you interested in the rest of node. Drupal will automatically pull a small amount of the body of the node to make the teaser (To configure how long the teaser will be <a href=\"%teaser\">click here</a>). The teaser can be changed if you don't like what Drupal grabs.</dd>
      <dt>The Body</dt><dd>The main text that comprises your content.</dd>
      <dt>A Type</dt><dd>What kind of node is this? Blog, book, forum, comment, unextended, etc.</dd>
      <dt>An Author</dt><dd>The author's name. It will either be \"anonymous\" or a valid user. You <em>cannot</em> set it to an arbitrary value.</dd>
      <dt>Authored on</dt><dd>The date the node was written.</dd>
      <dt>Changed</dt><dd>The last time this node was changed.</dd>
      <dt>Sticky at top of lists</dt><dd>In listings such as the frontpage or a taxonomy overview the teasers of a selected amount of nodes is displayed. If you want to force a node to appear on the top of such a listing, you must set it to 'sticky'. This way it will float to the top of a listing, and it will not be pushed down by newer content.
      <dt>Allow user comments</dt><dd>A node can have comments. These comments can be written by other users (Read-write), or only by admins (Read-only).</dd>
      <dt>Revisions</dt><dd>Drupal has a revision system so that you can \"roll back\" to an older version of a post if the new version is not what you want.</dd>
      <dt>Promote to front page</dt><dd>To get people to look at the new stuff on your site you can choose to move it to the front page. The front page is configured to show the teasers from only a few of the total nodes you have on your site (To configure how many teasers <a href=\"%teaser\">click here</a>).</dd>
      <dt>Published</dt><dd>When using Drupal's moderation system a node remains unpublished -- unavailable to non-moderators -- until it is marked Published.</dd></dl>
      <p>Now that you know what is in a node, here are some of the types of nodes available.</p>", array("%teaser" => url("admin/node/configure/settings")));

      foreach (node_list() as $type => $module) {
        $output .= '<h3>'. t('Node type: %module', array('%module' => node_invoke($type, 'node_name'))). '</h3>';
        $output .= implode("\n", module_invoke_all('help', 'node/add#'. $type));
      }

      return $output;

    case 'admin/modules#description':
      return t('Allows content to be submitted to the site and displayed on pages.');
    case 'admin/node/configure':
    case 'admin/node/configure/settings':
      return t('<p>Settings for the core of Drupal. Almost everything is a node so these settings will affect most of the site.</p>');
    case 'admin/node':
      return t('<p>Below is a list of all of the posts on your site. Other forms of content are listed elsewhere (e.g. <a href="%comments">comments</a>).</p><p>Clicking a title views the post, while clicking an author\'s name views their user information.</p>', array('%comments' => url('admin/comment')));
    case 'admin/node/search':
      return t('<p>Enter a simple pattern to search for a post. This can include the wildcard character *.<br />For example, a search for "br*" might return "bread bakers", "our daily bread" and "brenda".</p>');
  }

  if (arg(0) == 'node' && is_numeric(arg(1)) && arg(2) == 'revisions') {
    return t('The revisions let you track differences between multiple versions of a post.');
  }

  if (arg(0) == 'node' && arg(1) == 'add' && $type = arg(2)) {
    return variable_get($type .'_help', '');
  }
}

/**
 * Implementation of hook_cron().
 */
function node_cron() {
  db_query('DELETE FROM {history} WHERE timestamp < %d', NODE_NEW_LIMIT);
}

/**
 * Gather a listing of links to nodes.
 *
 * @param $result
 *   A DB result object from a query to fetch node objects.  If your query joins the <code>node_comment_statistics</code> table so that the <code>comment_count</code> field is available, a title attribute will be added to show the number of comments.
 * @param $title
 *   A heading for the resulting list.
 *
 * @return
 *   An HTML list suitable as content for a block.
 */
function node_title_list($result, $title = NULL) {
  while ($node = db_fetch_object($result)) {
    $items[] = l($node->title, 'node/'. $node->nid, $node->comment_count ? array('title' => format_plural($node->comment_count, '1 comment', '%count comments')) : '');
  }

  return theme('node_list', $items, $title);
}

/**
 * Format a listing of links to nodes.
 */
function theme_node_list($items, $title = NULL) {
  return theme('item_list', $items, $title);
}

/**
 * Update the 'last viewed' timestamp of the specified node for current user.
 */
function node_tag_new($nid) {
  global $user;

  if ($user->uid) {
    if (node_last_viewed($nid)) {
      db_query('UPDATE {history} SET timestamp = %d WHERE uid = %d AND nid = %d', time(), $user->uid, $nid);
    }
    else {
      @db_query('INSERT INTO {history} (uid, nid, timestamp) VALUES (%d, %d, %d)', $user->uid, $nid, time());
    }
  }
}

/**
 * Retrieves the timestamp at which the current user last viewed the
 * specified node.
 */
function node_last_viewed($nid) {
  global $user;
  static $history;

  if (!isset($history[$nid])) {
    $history[$nid] = db_fetch_object(db_query("SELECT timestamp FROM {history} WHERE uid = '$user->uid' AND nid = %d", $nid));
  }

  return ($history[$nid]->timestamp ? $history[$nid]->timestamp : 0);
}

/**
 * Decide on the type of marker to be displayed for a given node.
 *
 * @param $nid
 *   Node ID whose history supplies the "last viewed" timestamp.
 * @param $timestamp
 *   Time which is compared against node's "last viewed" timestamp.
 * @return
 *   One of the MARK constants.
 */
function node_mark($nid, $timestamp) {
  global $user;
  static $cache;

  if (!$user->uid) {
    return MARK_READ;
  }
  if (!isset($cache[$nid])) {
    $cache[$nid] = node_last_viewed($nid);
  }
  if ($cache[$nid] == 0 && $timestamp > NODE_NEW_LIMIT) {
    return MARK_NEW;
  }
  elseif ($timestamp > $cache[$nid] && $timestamp > NODE_NEW_LIMIT) {
    return MARK_UPDATED;
  }
  return MARK_READ;
}

/**
 * Automatically generate a teaser for a node body in a given format.
 */
function node_teaser($body, $format = NULL) {

  $size = variable_get('teaser_length', 600);

  // find where the delimiter is in the body
  $delimiter = strpos($body, '<!--break-->');

  // If the size is zero, and there is no delimiter, the entire body is the teaser.
  if ($size == 0 && $delimiter == 0) {
    return $body;
  }

  // We check for the presence of the PHP evaluator filter in the current
  // format. If the body contains PHP code, we do not split it up to prevent
  // parse errors.
  if (isset($format)) {
    $filters = filter_list_format($format);
    if (isset($filters['filter/1']) && strpos($body, '<?') !== false) {
      return $body;
    }
  }

  // If a valid delimiter has been specified, use it to chop of the teaser.
  if ($delimiter > 0) {
    return substr($body, 0, $delimiter);
  }

  // If we have a short body, the entire body is the teaser.
  if (strlen($body) < $size) {
    return $body;
  }

  // In some cases, no delimiter has been specified (e.g. when posting using
  // the Blogger API). In this case, we try to split at paragraph boundaries.
  // When even the first paragraph is too long, we try to split at the end of
  // the next sentence.
  $breakpoints = array('</p>' => 4, '<br />' => 0, '<br>' => 0, "\n" => 0, '. ' => 1, '! ' => 1, '? ' => 1, '。' => 1, '؟ ' => 1);
  foreach ($breakpoints as $point => $charnum) {
    if ($length = strpos($body, $point, $size)) {
      return substr($body, 0, $length + $charnum);
    }
  }

  // If all else fails, we simply truncate the string.
  return truncate_utf8($body, $size);
}

/**
 * Determine the module that defines the node type of the given node.
 *
 * @param &$node
 *   Either a node object, a node array, or a string containing the node type.
 * @return
 *   A string containing the name of the defining module.
 */
function node_get_module_name($node) {
  if (is_array($node)) {
    $type = $node['type'];
  }
  else if (is_object($node)) {
    $type = $node->type;
  }
  else if (is_string($node)) {
    $type = $node;
  }

  $modules = node_list();

  return $modules[$type];
}

/**
 * Get a list of all the defined node types.
 *
 * @return
 *   An associate array of consisting of (node type, module name) pairs for all node types.
 */
function node_list() {
  static $types = array();

  if (empty($types)) {
    foreach (module_list() as $module) {
      if (module_hook($module, 'node_name')) {
        $module_types = module_invoke($module, 'node_types');
        if (is_array($module_types)) {
          foreach ($module_types as $type) {
            $types[$type] = $module;
          }
        }
        else {
          $types[$module] = $module;
        }
      }
    }
  }
  return $types;
}

/**
 * Determine whether a node hook exists.
 *
 * @param &$node
 *   Either a node object, node array, or a string containing the node type.
 * @param $hook
 *   A string containing the name of the hook.
 * @return
 *   TRUE iff the $hook exists in the node type of $node.
 */
function node_hook(&$node, $hook) {
  $function = node_get_module_name($node) ."_$hook";

  return function_exists($function);
}

/**
 * Invoke a node hook.
 *
 * @param &$node
 *   Either a node object, node array, or a string containing the node type.
 * @param $hook
 *   A string containing the name of the hook.
 * @param $a2, $a3, $a4
 *   Arguments to pass on to the hook, after the $node argument.
 * @return
 *   The returned value of the invoked hook.
 */
function node_invoke(&$node, $hook, $a2 = NULL, $a3 = NULL, $a4 = NULL) {
  $function = node_get_module_name($node) ."_$hook";

  if (function_exists($function)) {
    return ($function($node, $a2, $a3, $a4));
  }
}

/**
 * Invoke a hook_nodeapi() operation in all modules.
 *
 * @param &$node
 *   A node object.
 * @param $op
 *   A string containing the name of the nodeapi operation.
 * @param $a3, $a4
 *   Arguments to pass on to the hook, after the $node and $op arguments.
 * @return
 *   The returned value of the invoked hooks.
 */
function node_invoke_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  $return = array();
  foreach (module_list() as $name) {
    $function = $name .'_nodeapi';
    if (function_exists($function)) {
      $result = $function($node, $op, $a3, $a4);
      if (is_array($result)) {
        $return = array_merge($return, $result);
      }
      else if (isset($result)) {
        $return[] = $result;
      }
    }
  }
  return $return;
}

/**
 * Load a node object from the database.
 *
 * @param $param
 *   Either the nid of the node or an array of conditions to match against in the database query
 * @param $revision
 *   Which numbered revision to load. Defaults to the current version.
 * @param $reset
 *   Whether to reset the internal node_load cache.
 *
 * @return
 *   A fully-populated node object.
 */
function node_load($param = array(), $revision = NULL, $reset = NULL) {
  static $nodes = array();

  if ($reset) {
    $nodes = array();
  }

  if (is_numeric($param)) {
    $cachable = $revision == NULL;
    if ($cachable && $nodes[$param]) {
      return $nodes[$param];
    }
    $cond = 'n.nid = '. $param;
  }
  else {
    // Turn the conditions into a query.
    foreach ($param as $key => $value) {
      $cond[] = 'n.'. db_escape_string($key) ." = '". db_escape_string($value) ."'";
    }
    $cond = implode(' AND ', $cond);
  }

  // Retrieve the node.
  $node = db_fetch_object(db_query(db_rewrite_sql('SELECT n.*, u.uid, u.name, u.picture, u.data FROM {node} n INNER JOIN {users} u ON u.uid = n.uid WHERE '. $cond)));
  $node = drupal_unpack($node);

  // Unserialize the revisions and user data fields.
  if ($node->revisions) {
    $node->revisions = unserialize($node->revisions);
  }

  // Call the node specific callback (if any) and piggy-back the
  // results to the node or overwrite some values.
  if ($extra = node_invoke($node, 'load')) {
    foreach ($extra as $key => $value) {
      $node->$key = $value;
    }
  }

  if ($extra = node_invoke_nodeapi($node, 'load')) {
    foreach ($extra as $key => $value) {
      $node->$key = $value;
    }
  }

  // Return the desired revision.
  if (!is_null($revision) && is_array($node->revisions[$revision])) {
   $node = $node->revisions[$revision]['node'];
  }

  if ($cachable) {
    $nodes[$param] = $node;
  }

  return $node;
}

/**
 * Save a node object into the database.
 */
function node_save($node) {
  // Fetch fields to save to node table:
  $fields = node_invoke_nodeapi($node, 'fields');

  // Serialize the revisions field:
  if ($node->revisions) {
    $node->revisions = serialize($node->revisions);
  }

  // Apply filters to some default node fields:
  if (empty($node->nid)) {
    // Insert a new node.

    // Set some required fields:
    if (!$node->created) {
      $node->created = time();
    }
    if (!$node->changed) {
      $node->changed = time();
    }
    $node->nid = db_next_id('{node}_nid');

    // Prepare the query:
    foreach ($node as $key => $value) {
      if (in_array((string) $key, $fields)) {
        $k[] = db_escape_string($key);
        $v[] = $value;
        $s[] = "'%s'";
      }
    }

    // Insert the node into the database:
    db_query("INSERT INTO {node} (". implode(", ", $k) .") VALUES(". implode(", ", $s) .")", $v);

    // Call the node specific callback (if any):
    node_invoke($node, 'insert');
    node_invoke_nodeapi($node, 'insert');
  }
  else {
    // Update an existing node.

    // Set some required fields:
    $node->changed = time();

    // Prepare the query:
    foreach ($node as $key => $value) {
      if (in_array($key, $fields)) {
        $q[] = db_escape_string($key) ." = '%s'";
        $v[] = $value;
      }
    }

    // Update the node in the database:
    db_query("UPDATE {node} SET ". implode(', ', $q) ." WHERE nid = '$node->nid'", $v);

    // Call the node specific callback (if any):
    node_invoke($node, 'update');
    node_invoke_nodeapi($node, 'update');
  }

  // Clear the cache so an anonymous poster can see the node being added or updated.
  cache_clear_all();

  // Return the node ID:
  return $node->nid;
}

/**
 * Generate a display of the given node.
 *
 * @param $node
 *   A node array or node object.
 * @param $teaser
 *   Whether to display only the teaser for the node.
 * @param $page
 *   Whether the node is being displayed by itself as a page.
 * @param $links
 *   Whether or not to display node links. Links are omitted for node previews.
 *
 * @return
 *   An HTML representation of the themed node.
 */
function node_view($node, $teaser = FALSE, $page = FALSE, $links = TRUE) {
  $node = array2object($node);

  // Remove the delimiter (if any) that separates the teaser from the body.
  // TODO: this strips legitimate uses of '<!--break-->' also.
  $node->body = str_replace('<!--break-->', '', $node->body);

  // The 'view' hook can be implemented to overwrite the default function
  // to display nodes.
  if (node_hook($node, 'view')) {
    node_invoke($node, 'view', $teaser, $page);
  }
  else {
    $node = node_prepare($node, $teaser);
  }
  // Allow modules to change $node->body before viewing.
  node_invoke_nodeapi($node, 'view', $teaser, $page);
  if ($links) {
    $node->links = module_invoke_all('link', 'node', $node, !$page);
  }
  // unset unused $node part so that a bad theme can not open a security hole
  if ($teaser) {
    unset($node->body);
  }
  else {
    unset($node->teaser);
  }

  return theme('node', $node, $teaser, $page);
}

/**
 * Apply filters to a node in preparation for theming.
 */
function node_prepare($node, $teaser = FALSE) {
  $node->readmore = (strlen($node->teaser) < strlen($node->body));
  if ($teaser == FALSE) {
    $node->body = check_output($node->body, $node->format, FALSE);
  }
  else {
    $node->teaser = check_output($node->teaser, $node->format, FALSE);
  }
  return $node;
}

/**
 * Generate a page displaying a single node, along with its comments.
 */
function node_show($node, $cid) {
  $output = node_view($node, FALSE, TRUE);

  if (function_exists('comment_render') && $node->comment) {
    $output .= comment_render($node, $cid);
  }

  // Update the history table, stating that this user viewed this node.
  node_tag_new($node->nid);

  return $output;
}

/**
 * Implementation of hook_perm().
 */
function node_perm() {
  return array('administer nodes', 'access content');
}

/**
 * Implementation of hook_search().
 */
function node_search($op = 'search', $keys = null) {
  switch ($op) {
    case 'name':
      return t('content');
    case 'reset':
      variable_del('node_cron_last');
      return;
    case 'status':
      $last = variable_get('node_cron_last', 0);
      $total = db_result(db_query('SELECT COUNT(*) FROM {node} WHERE status = 1 AND moderate = 0'));
      $remaining = db_result(db_query('SELECT COUNT(*) FROM {node} n LEFT JOIN {node_comment_statistics} c ON n.nid = c.nid WHERE n.status = 1 AND n.moderate = 0 AND (n.created > %d OR n.changed > %d OR c.last_comment_timestamp > %d)', $last, $last, $last));
      return array('remaining' => $remaining, 'total' => $total);
    case 'search':
      list($join, $where) = _db_rewrite_sql();
      $find = do_search($keys, 'node', 'INNER JOIN {node} n ON n.nid = i.sid '. $join .' INNER JOIN {users} u ON n.uid = u.uid', 'n.status = 1'. (empty($where) ? '' : ' AND '. $where));
      $results = array();
      foreach ($find as $item) {
        $node = node_load($item);
        $extra = node_invoke_nodeapi($node, 'search result');
        $results[] = array('link' => url('node/'. $item),
                           'type' => node_invoke($node, 'node_name'),
                           'title' => $node->title,
                           'user' => format_name($node),
                           'date' => $node->changed,
                           'extra' => $extra,
                           'snippet' => search_excerpt($keys, check_output($node->body, $node->format, FALSE)));
      }
      return $results;
  }
}

/**
 * Menu callback; presents general node configuration options.
 */
function node_configure() {
  if ($_POST) {
    system_settings_save();
  }

  $output .= form_select(t('Number of posts on main page'), 'default_nodes_main', variable_get('default_nodes_main', 10), drupal_map_assoc(array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30)), t('The default maximum number of posts to display per page on overview pages such as the main page.'));
  $output .= form_select(t('Length of trimmed posts'), 'teaser_length', variable_get('teaser_length', 600), array(0 => t('Unlimited'), 200 => t('200 characters'), 400 => t('400 characters'), 600 => t('600 characters'), 800 => t('800 characters'), 1000 => t('1000 characters'), 1200 => t('1200 characters'), 1400 => t('1400 characters'), 1600 => t('1600 characters'), 1800 => t('1800 characters'), 2000 => t('2000 characters')), t("The maximum number of characters used in the trimmed version of a post.  Drupal will use this setting to determine at which offset long posts should be trimmed.  The trimmed version of a post is typically used as a teaser when displaying the post on the main page, in XML feeds, etc.  To disable teasers, set to 'Unlimited'. Note that this setting will only affect new or updated content and will not affect existing teasers."));
  $output .= form_radios(t('Preview post'), 'node_preview', variable_get('node_preview', 0), array(t('Optional'), t('Required')), t('Must users preview posts before submitting?'));

  return system_settings_form($output);
}

/**
 * Retrieve the comment mode for the given node ID (none, read, or read/write).
 */
function node_comment_mode($nid) {
  static $comment_mode;
  if (!isset($comment_mode[$nid])) {
    $comment_mode[$nid] = db_result(db_query('SELECT comment FROM {node} WHERE nid = %d', $nid));
  }
  return $comment_mode[$nid];
}

/**
 * Implementation of hook_link().
 */
function node_link($type, $node = 0, $main = 0) {
  $links = array();

  if ($type == 'node') {
    if (array_key_exists('links', $node)) {
      $links = $node->links;
    }

    if ($main == 1 && $node->teaser && $node->readmore) {
      $links[] = l(t('read more'), "node/$node->nid", array('title' => t('Read the rest of this posting.'), 'class' => 'read-more'));
    }
  }

  return $links;
}

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

  if ($may_cache) {
    $items[] = array('path' => 'admin/node', 'title' => t('content'),
      'callback' => 'node_admin',
      'access' => user_access('administer nodes'));
    $items[] = array('path' => 'admin/node/action', 'title' => t('content'),
      'type' => MENU_CALLBACK);
    $items[] = array('path' => 'admin/node/overview', 'title' => t('list'),
      'type' => MENU_DEFAULT_LOCAL_TASK, 'weight' => -10);
    $items[] = array('path' => 'admin/settings/node', 'title' => t('posts'),
      'callback' => 'node_configure',
      'access' => user_access('administer nodes'));
    $items[] = array('path' => 'admin/settings/content-types', 'title' => t('content types'),
      'callback' => 'node_types_configure',
      'access' => user_access('administer nodes'));
    if (module_exist('search')) {
      $items[] = array('path' => 'admin/node/search', 'title' => t('search'),
        'callback' => 'node_admin',
        'access' => user_access('administer nodes'),
        'type' => MENU_LOCAL_TASK);
    }

    $items[] = array('path' => 'node', 'title' => t('content'),
      'callback' => 'node_page',
      'access' => user_access('access content'),
      'type' => MENU_SUGGESTED_ITEM);
    $items[] = array('path' => 'node/add', 'title' => t('create content'),
      'callback' => 'node_page',
      'access' => user_access('access content'),
      'type' => MENU_ITEM_GROUPING,
      'weight' => 1);
  }
  else {
    if (arg(0) == 'node' && is_numeric(arg(1))) {
      $node = node_load(arg(1));
      if ($node->nid) {
        $items[] = array('path' => 'node/'. arg(1), 'title' => t('view'),
          'callback' => 'node_page',
          'access' => node_access('view', $node),
          'type' => MENU_CALLBACK);
        $items[] = array('path' => 'node/'. arg(1) .'/view', 'title' => t('view'),
            'type' => MENU_DEFAULT_LOCAL_TASK, 'weight' => -10);
        $items[] = array('path' => 'node/'. arg(1) .'/edit', 'title' => t('edit'),
          'callback' => 'node_page',
          'access' => node_access('update', $node),
          'weight' => 1,
          'type' => MENU_LOCAL_TASK);
        $items[] = array('path' => 'node/'. arg(1) .'/delete', 'title' => t('delete'),
          'callback' => 'node_delete_page',
          'access' => node_access('delete', $node),
          'weight' => 1,
          'type' => MENU_CALLBACK);

        if ($node->revisions) {
          $items[] = array('path' => 'node/'. arg(1) .'/revisions', 'title' => t('revisions'),
            'callback' => 'node_page',
            'access' => user_access('administer nodes'),
            'weight' => 2,
            'type' => MENU_LOCAL_TASK);
        }
      }
    }
    else if (arg(0) == 'admin' && arg(1) == 'node' && arg(2) == 'configure' && arg(3) == 'types' && is_string(arg(4))) {
      $items[] = array('path' => 'admin/settings/content-types/'. arg(4),
        'title' => t("'%name' content type", array('%name' => node_invoke(arg(4), 'node_name'))),
        'type' => MENU_CALLBACK);
    }
  }

  return $items;
}

function node_last_changed($nid) {
  $node = db_fetch_object(db_query('SELECT changed FROM {node} WHERE nid = %d', $nid));
  return ($node->changed);
}

/**
 * Generate the content administration overview.
 */
function node_admin_nodes() {
  /*
  ** Operations
  */
  $operations = array(
    'approve' =>   array(t('Approve the selected posts'), 'UPDATE {node} SET status = 1, moderate = 0 WHERE nid = %d'),
    'promote' =>   array(t('Promote the selected posts'), 'UPDATE {node} SET status = 1, promote = 1 WHERE nid = %d'),
    'sticky' =>    array(t('Make the selected posts sticky'), 'UPDATE {node} SET status = 1, sticky = 1 WHERE nid = %d'),
    'demote' =>    array(t('Demote the selected posts'), 'UPDATE {node} SET promote = 0 WHERE nid = %d'),
    'unpublish' => array(t('Unpublish the selected posts'), 'UPDATE {node} SET status = 0 WHERE nid = %d'),
    'delete' =>    array(t('Delete the selected posts'), '')
  );

  // Handle operations
  $op = $_POST['op'];

  $edit = $_POST['edit'];
  if (($op == t('Update') || $op == t('Delete all')) && isset($edit['operation']) && isset($edit['nodes'])) {
    $edit['nodes'] = array_diff($edit['nodes'], array(0));
    if (count($edit['nodes']) == 0) {
      form_set_error('', t('Please select some items to perform the update on.'));
    }
    else {
      if ($operations[$edit['operation']][1]) {
        // Flag changes
       $operation = $operations[$edit['operation']][1];
        foreach ($edit['nodes'] as $nid => $value) {
          if ($value) {
            db_query($operation, $nid);
          }
        }
        drupal_set_message(t('The update has been performed.'));
      }
      else if ($edit['operation'] == 'delete') {
        // Mass delete
        if ($edit['confirm']) {
          foreach ($edit['nodes'] as $nid => $value) {
            node_delete(array('nid' => $nid, 'confirm' => 1));
          }
          drupal_set_message(t('The items have been deleted.'));
        }
        else {
          $extra = '<ul>';
          foreach ($edit['nodes'] as $nid => $value) {
            if ($value) {
              $title = db_result(db_query('SELECT title FROM {node} WHERE nid = %d', $nid));
              $extra .= '<li>'. form_hidden('nodes]['. $nid, 1) . check_plain($title) .'</li>';
            }
          }
          $extra .= '</ul>';
          $extra .= form_hidden('operation', 'delete');

          $output = theme('confirm',
                          t('Are you sure you want to delete these items?'),
                          'admin/node',
                          t('This action cannot be undone.'),
                          t('Delete all'),
                          t('Cancel'),
                          $extra);
          return $output;
        }
      }
    }
  }

  /*
  ** Filters
  */
  $node_types = drupal_map_assoc(array_keys(node_list()));
  foreach ($node_types as $k => $v) {
    $node_types[$k] = node_invoke($v, 'node_name');
  }
  // Regular filters
  $filters = array(
    'status'   => array('title' => t('status'),
                        'options' => array('status-1'   => t('published'),     'status-0' => t('not published'),
                                           'moderate-1' => t('in moderation'), 'moderate-0' => t('not in moderation'),
                                           'promote-1'  => t('promoted'),      'promote-0' => t('not promoted'),
                                           'sticky-1'   => t('sticky'),        'sticky-0' => t('not sticky'))),
    'type'     => array('title' => t('type'), 'where' => "n.type = '%s'",
                        'options' => $node_types));
  // Merge all vocabularies into one for retrieving $value below
  if ($taxonomy = module_invoke('taxonomy', 'form_all')) {
    $terms = array();
    foreach ($taxonomy as $key => $value) {
      $terms = $terms + $value;
    }
    $filters['category'] = array('title' => t('category'), 'where' => 'tn.tid = %d',
                                 'options' => $terms, 'join' => 'INNER JOIN {term_node} tn ON n.nid = tn.nid');
  }

  // Initialize/reset filters
  if (!isset($_SESSION['node_overview_filter']) || !is_array($_SESSION['node_overview_filter']) || $op == t('Reset')) {
    $_SESSION['node_overview_filter'] = array();
  }
  $session = &$_SESSION['node_overview_filter'];
  $filter = $edit['filter'];
  if (($op == t('Filter') || $op == t('Refine')) && isset($filter)) {
    if (isset($filters[$filter]['options'][$edit[$filter]])) {
      $session[] = array($filter, $edit[$filter]);
    }
  }
  if ($op == t('Undo')) {
    array_pop($session);
  }
  if ($op != '') {
    drupal_goto('admin/node');
  }

  /*
  ** Form
  */
  $output .= '<div id="node-admin-filter">';
  // Existing filters
  $form = '<ul>';
  $i = 0;
  foreach ($session as $filter) {
    list($type, $value) = $filter;
    $params = array('%a' => '<strong>'. $filters[$type]['title'] .'</strong>', '%b' => '<strong>'. $filters[$type]['options'][$value] .'</strong>');
    $form .= '<li>'. ($i++ ? t('<em>and</em> where <strong>%a</strong> is <strong>%b</strong>', $params) : t('<strong>%a</strong> is <strong>%b</strong>', $params)) .'</li>';
  }

  // New filter form
  if (isset($filters['category'])) {
    $filters['category']['options'] = $taxonomy;
  }
  $values = '';
  $options = array();
  foreach ($filters as $key => $value) {
    $options[$key] = $value['title'];
    $b .= form_select('', $key, 1, $filters[$key]['options']);
  }

  $buttons = '';
  if (count($options)) {
    $form .= '<li><dl class="multiselect">';
    $a = '';
    foreach ($options as $key => $value) {
      $a .= form_radio($value, 'filter', $key);
    }
    if (!$i) {
      $form .= t('<dd class="a">%a</dd> <dt>is</dt> <dd class="b">%b</dd>', array('%a' => $a, '%b' => $b));
    }
    else {
      $form .= t('<dt><em>and</em> where</dt> <dd class="a">%a</dd> <dt>is</dt> <dd class="b">%b</dd>', array('%a' => $a, '%b' => $b));
    }
    $form .= '</dl>';
    $buttons = form_submit(count($session) ? t('Refine') : t('Filter'));
  }
  if (count($session)) {
    $buttons .= form_submit(t('Undo')) . form_submit(t('Reset'));
  }
  $form .= '<div class="container-inline" id="node-admin-buttons">'. $buttons .'</div>';
  $form .= '</li></ul><br class="clear" />';
  $output .= form_group(t('Show only items where'), $form);

  // Build query
  $where = $args = array();
  $join = '';
  foreach ($session as $filter) {
    list($key, $value) = $filter;
    if ($key == 'status') {
      // Note: no exploit hole as $value has already been checked
      list($key, $value) = explode('-', $value, 2);
      $where[] = 'n.'. $key .' = %d';
    }
    else {
      $where[] = $filters[$key]['where'];
    }
    $args[] = $value;
    $join .= $filters[$key]['join'];
  }
  $where = count($where) ? 'WHERE '. implode(' AND ', $where) : '';
  $result = pager_query('SELECT n.*, u.name, u.uid FROM {node} n '. $join .' INNER JOIN {users} u ON n.uid = u.uid '. $where .' ORDER BY n.changed DESC', 50, 0, NULL, $args);

  // Make sure the update controls are disabled if we don't have any rows to select from.
  $disabled = !db_num_rows($result);

  $options = array();
  foreach ($operations as $key => $value) {
    $options[$key] = $value[0];
  }

  $form = form_select(NULL, 'operation', 'approve', $options, NULL, ($disabled ? 'disabled="disabled"' : ''));
  $form .= form_submit(t('Update'), 'op', ($disabled ? array('disabled' => 'disabled') : array()));