modules/node/node.module

<?php
// $Id: node.module,v 1.1161 2009/11/03 06:47:22 webchick Exp $

/**
 * @file
 * The core that allows content to be submitted to the site. Modules and
 * scripts may programmatically submit nodes using the usual form API pattern.
 */

/**
 * Node is not published.
 */
define('NODE_NOT_PUBLISHED', 0);

/**
 * Node is published.
 */
define('NODE_PUBLISHED', 1);

/**
 * Node is not promoted to front page.
 */
define('NODE_NOT_PROMOTED', 0);

/**
 * Node is promoted to front page.
 */
define('NODE_PROMOTED', 1);

/**
 * Node is not sticky at top of the page.
 */
define('NODE_NOT_STICKY', 0);

/**
 * Node is sticky at top of the page.
 */
define('NODE_STICKY', 1);

/**
 * Nodes changed before this time are always marked as read.
 *
 * Nodes changed after this time may be marked new, updated, or read, depending
 * on their state for the current user. Defaults to 30 days ago.
 */
define('NODE_NEW_LIMIT', REQUEST_TIME - 30 * 24 * 60 * 60);

/**
 * Modules should return this value from hook_node_access() to allow access to a node.
 */
define('NODE_ACCESS_ALLOW', 'allow');

/**
 * Modules should return this value from hook_node_access() to deny access to a node.
 */
define('NODE_ACCESS_DENY', 'deny');

/**
 * Modules should return this value from hook_node_access() to not affect node access.
 */
define('NODE_ACCESS_IGNORE', NULL);

/**
 * Implement hook_help().
 */
function node_help($path, $arg) {
  // Remind site administrators about the {node_access} table being flagged
  // for rebuild. We don't need to issue the message on the confirm form, or
  // while the rebuild is being processed.
  if ($path != 'admin/reports/status/rebuild' && $path != 'batch' && strpos($path, '#') === FALSE
      && user_access('access administration pages') && node_access_needs_rebuild()) {
    if ($path == 'admin/reports/status') {
      $message = t('The content access permissions need to be rebuilt.');
    }
    else {
      $message = t('The content access permissions need to be rebuilt. Please visit <a href="@node_access_rebuild">this page</a>.', array('@node_access_rebuild' => url('admin/reports/status/rebuild')));
    }
    drupal_set_message($message, 'error');
  }

  switch ($path) {
    case 'admin/help#node':
      $output = '<p>' . t('The node module manages content on your site, and stores all posts (regardless of type) as a "node" . In addition to basic publishing settings, including whether the post has been published, promoted to the site front page, or should remain present (or sticky) at the top of lists, the node module also records basic information about the author of a post. Optional revision control over edits is available. For additional functionality, the node module is often extended by other modules.') . '</p>';
      $output .= '<p>' . t('Though each post on your site is a node, each post is also of a particular <a href="@content-type">content type</a>. <a href="@content-type">Content types</a> are used to define the characteristics of a post, including the title and description of the fields displayed on its add and edit pages. Each content type may have different default settings for <em>Publishing options</em> and other workflow controls. By default, the two content types in a standard Drupal installation are <em>Page</em> and <em>Story</em>. Use the <a href="@content-type">content types page</a> to add new or edit existing content types. Additional content types also become available as you enable additional core, contributed and custom modules.', array('@content-type' => url('admin/structure/types'))) . '</p>';
      $output .= '<p>' . t('The administrative <a href="@content">content page</a> allows you to review and manage your site content. The node module makes a number of permissions available for each content type, which may be set by role on the <a href="@permissions">permissions page</a>.', array('@content' => url('admin/content'), '@permissions' => url('admin/config/people/permissions'))) . '</p>';
      $output .= '<p>' . t('For more information, see the online handbook entry for <a href="@node">Node module</a>.', array('@node' => 'http://drupal.org/handbook/modules/node/')) . '</p>';
      return $output;

    case 'admin/content':
      return ' '; // Return a non-null value so that the 'more help' link is shown.

    case 'admin/structure/types/add':
      return '<p>' . t('Individual content types can have different fields, behaviors, and permissions assigned to them.') . '</p>';

    case 'admin/structure/types/manage/' . $arg[3] . '/fields':
      return '<p>' . t('This form lets you add, edit, and arrange fields within the %type content type.', array('%type' => node_type_get_name($arg[3]))) . '</p>';

    case 'admin/structure/types/manage/' . $arg[3] . '/display':
      return '<p>' . t('This form lets you configure how fields and labels are displayed when %type content is viewed in teaser and full-page mode.', array('%type' => node_type_get_name($arg[3]))) . '</p>';

    case 'admin/structure/types/manage/' . $arg[3] . '/display/' . $arg[5]:
      return '<p>' . t('This form lets you configure how fields should be displayed when rendered %type content in the following contexts.', array('%type' => node_type_get_name($arg[3]))) . '</p>';

    case 'node/%/revisions':
      return '<p>' . t('The revisions let you track differences between multiple versions of a post.') . '</p>';

    case 'node/%/edit':
      $node = node_load($arg[1]);
      $type = node_type_get_type($node);
      return (!empty($type->help) ? '<p>' . filter_xss_admin($type->help) . '</p>' : '');
  }

  if ($arg[0] == 'node' && $arg[1] == 'add' && $arg[2]) {
    $type = node_type_get_type(str_replace('-', '_', $arg[2]));
    return (!empty($type->help) ? '<p>' . filter_xss_admin($type->help) . '</p>' : '');
  }
}

/**
 * Implement hook_theme().
 */
function node_theme() {
  return array(
    'node' => array(
      'render element' => 'elements',
      'template' => 'node',
    ),
    'node_list' => array(
      'variables' => array('items' => NULL, 'title' => NULL),
    ),
    'node_search_admin' => array(
      'render element' => 'form',
    ),
    'node_filter_form' => array(
      'render element' => 'form',
      'file' => 'node.admin.inc',
    ),
    'node_filters' => array(
      'render element' => 'form',
      'file' => 'node.admin.inc',
    ),
    'node_add_list' => array(
      'variables' => array('content' => NULL),
      'file' => 'node.pages.inc',
    ),
    'node_form' => array(
      'render element' => 'form',
      'file' => 'node.pages.inc',
    ),
    'node_preview' => array(
      'variables' => array('node' => NULL),
      'file' => 'node.pages.inc',
    ),
    'node_log_message' => array(
      'variables' => array('log' => NULL),
    ),
    'node_admin_overview' => array(
      'variables' => array('name' => NULL, 'type' => NULL),
    ),
  );
}

/**
 * Implement hook_cron().
 */
function node_cron() {
  db_delete('history')
    ->condition('timestamp', NODE_NEW_LIMIT, '<')
    ->execute();
}

/**
 * Implement hook_entity_info().
 */
function node_entity_info() {
  $return = array(
    'node' => array(
      'label' => t('Node'),
      'controller class' => 'NodeController',
      'base table' => 'node',
      'revision table' => 'node_revision',
      'fieldable' => TRUE,
      'object keys' => array(
        'id' => 'nid',
        'revision' => 'vid',
        'bundle' => 'type',
      ),
      'bundle keys' => array(
        'bundle' => 'type',
      ),
      // Node.module handles its own caching.
      // 'cacheable' => FALSE,
      'bundles' => array(),
    ),
  );
  // Bundles must provide a human readable name so we can create help and error
  // messages, and the path to attach Field admin pages to.
  foreach (node_type_get_names() as $type => $name) {
    $return['node']['bundles'][$type] = array(
      'label' => $name,
      'admin' => array(
        'path' => 'admin/structure/types/manage/%node_type',
        'real path' => 'admin/structure/types/manage/' . str_replace('_', '-', $type),
        'bundle argument' => 4,
        'access arguments' => array('administer content types'),
      ),
    );
  }
  return $return;
}


/**
 * Implement hook_field_build_modes().
 */
function node_field_build_modes($obj_type) {
  $modes = array();
  if ($obj_type == 'node') {
    $modes = array(
      'teaser' => t('Teaser'),
      'full' => t('Full node'),
      'rss' => t('RSS'),
    );
    // Search integration is provided by node.module, so search-related
    // build-modes for nodes are defined here and not in search.module.
    if (module_exists('search')) {
      $modes += array(
        'search_index' => t('Search Index'),
        'search_result' => t('Search Result'),
      );
    }
  }
  return $modes;
}

/**
 * Gather a listing of links to nodes.
 *
 * @param $result
 *   A DB result object from a query to fetch node entities. 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 $title
 *   A heading for the resulting list.
 *
 * @return
 *   An HTML list suitable as content for a block, or FALSE if no result can
 *   fetch from DB result object.
 */
function node_title_list($result, $title = NULL) {
  $items = array();
  $num_rows = FALSE;
  foreach ($result as $node) {
    $items[] = l($node->title, 'node/' . $node->nid, !empty($node->comment_count) ? array('attributes' => array('title' => format_plural($node->comment_count, '1 comment', '@count comments'))) : array());
    $num_rows = TRUE;
  }

  return $num_rows ? theme('node_list', array('items' => $items, 'title' => $title)) : FALSE;
}

/**
 * Format a listing of links to nodes.
 *
 * @ingroup themeable
 */
function theme_node_list($variables) {
  return theme('item_list', $variables);
}

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

  if ($user->uid) {
    db_merge('history')
      ->key(array(
        'uid' => $user->uid,
        'nid' => $nid,
      ))
      ->fields(array('timestamp' => REQUEST_TIME))
      ->execute();
  }
}

/**
 * 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_query("SELECT timestamp FROM {history} WHERE uid = :uid AND nid = :nid", array(':uid' => $user->uid, ':nid' => $nid))->fetchObject();
  }

  return (isset($history[$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;
}

/**
 * Extract the type name.
 *
 * @param $node
 *   Either a string or object, containing the node type information.
 *
 * @return
 *   Node type of the passed in data.
 */
function _node_extract_type($node) {
  return is_object($node) ? $node->type : $node;
}

/**
 * Returns a list of all the available node types.
 *
 * @return
 *   An array of node types, keyed by the type.
 * @see node_type_get_type()
 */
function node_type_get_types() {
  return _node_types_build()->types;
}

/**
 * Returns the node type of the passed node or node type string.
 *
 *@param $node
 *   A node object or string that indicates the node type to return.
 * @return
 *   A single node type, as an object or FALSE if the node type is not found.
 *   The node type is an array with following content:
 *
 *   @code
 *   array(
 *     'type' => 'Machine readable type name',
 *     'name' => 'Name of the node type',
 *     'base' => 'Indicates to which module this node type belongs',
 *     'description' => 'Description of the node type',
 *     // ...
 *   )
 *   @endcode
 */
function node_type_get_type($node) {
  $type = _node_extract_type($node);
  $types = _node_types_build()->types;
  return isset($types[$type]) ? $types[$type] : FALSE;
}

/**
 * Returns the node type base of the passed node or node type string.
 *
 * The base indicates which module implement this node type and is used to
 * execute node type specific hooks.
 *
 * @see node_invoke()
 *
 * @param $node
 *   A node object or string that indicates the node type to return.
 * @return
 *   The node type base or FALSE if the node type is not found.
 */
function node_type_get_base($node) {
  $type = _node_extract_type($node);
  $types = _node_types_build()->types;
  return isset($types[$type]) && isset($types[$type]->base) ? $types[$type]->base : FALSE;
}

/**
 * Returns a list of available node names.
 *
 * @return
 *   An array of node type names, keyed by the type.
 */
function node_type_get_names() {
  return _node_types_build()->names;
}

/**
 * Returns the node type name of the passed node or node type string.
 *
 * @param $node
 *   A node object or string that indicates the node type to return.
 *
 * @return
 *   The node type name or FALSE if the node type is not found.
 */
function node_type_get_name($node) {
  $type = _node_extract_type($node);
  $types = _node_types_build()->names;
  return isset($types[$type]) ? $types[$type] : FALSE;
}

/**
 * Resets the database cache of node types.
 *
 * All new or non-modified module-defined node types are saved to the database.
 */
function node_types_rebuild() {
  // Reset and load updated node types.
  drupal_static_reset('_node_types_build');
  foreach (node_type_get_types() as $type => $info) {
    if (!empty($info->is_new)) {
      node_type_save($info);
    }
    if (!empty($info->disabled)) {
      node_type_delete($info->type);
    }
  }
}

/**
 * Menu argument loader; Load a node type by string.
 *
 * @param $name
 *   The machine-readable name of a node type to load; having '_' replaced with
 *   '-'.
 *
 * @return
 *   A node type object or FALSE if $name does not exist.
 */
function node_type_load($name) {
  return node_type_get_type(strtr($name, array('-' => '_')));
}

/**
 * Saves a node type to the database.
 *
 * @param $info
 *   The node type to save, as an object.
 *
 * @return
 *   Status flag indicating outcome of the operation.
 */
function node_type_save($info) {
  $is_existing = FALSE;
  $existing_type = !empty($info->old_type) ? $info->old_type : $info->type;
  $is_existing = (bool) db_query_range('SELECT 1 FROM {node_type} WHERE type = :type', 0, 1, array(':type' => $existing_type))->fetchField();
  $type = node_type_set_defaults($info);

  $fields = array(
    'type' => (string) $type->type,
    'name' => (string) $type->name,
    'base' => (string) $type->base,
    'has_title' => (int) $type->has_title,
    'title_label' => (string) $type->title_label,
    'has_body' => (int) $type->has_body,
    'body_label' => (string) $type->body_label,
    'description' => (string) $type->description,
    'help' => (string) $type->help,
    'custom' => (int) $type->custom,
    'modified' => (int) $type->modified,
    'locked' => (int) $type->locked,
  );

  if ($is_existing) {
    db_update('node_type')
      ->fields($fields)
      ->condition('type', $existing_type)
      ->execute();

    if (!empty($type->old_type) && $type->old_type != $type->type) {
      field_attach_rename_bundle('node', $type->old_type, $type->type);
    }
    node_configure_fields($type);
    module_invoke_all('node_type_update', $type);
    $status = SAVED_UPDATED;
  }
  else {
    $fields['orig_type'] = (string) $type->orig_type;
    db_insert('node_type')
      ->fields($fields)
      ->execute();

    field_attach_create_bundle('node', $type->type);
    node_configure_fields($type);
    module_invoke_all('node_type_insert', $type);
    $status = SAVED_NEW;
  }

  // Clear the node type cache.
  drupal_static_reset('_node_types_build');

  return $status;
}

/**
 * Manage the field(s) for a node type.
 *
 * Currently, the node module manages a single Field API field,
 * 'body'.  If $type->has_body is true, this function ensures the
 * 'body' field exists and creates an instance of it for the bundle
 * $type->type (e.g. 'page', 'story', ...).  If $type->has_body is
 * false, this function removes the instance (if it exists) for the
 * 'body' field on $type->type.
 */
function node_configure_fields($type) {
   // Add or remove the body field, as needed.
  $field = field_info_field('body');
  $instance = field_info_instance('node', 'body', $type->type);
  if ($type->has_body) {
    if (empty($field)) {
      $field = array(
        'field_name' => 'body',
        'type' => 'text_with_summary',
        'translatable' => TRUE,
      );
      $field = field_create_field($field);
    }
    if (empty($instance)) {
      $instance = array(
        'field_name' => 'body',
        'object_type' => 'node',
        'bundle' => $type->type,
        'label' => $type->body_label,
        'widget_type' => 'text_textarea_with_summary',
        'settings' => array('display_summary' => TRUE),

        // Define default formatters for the teaser and full view.
        'display' => array(
          'full' => array(
            'label' => 'hidden',
            'type' => 'text_default',
          ),
          'teaser' => array(
            'label' => 'hidden',
            'type' => 'text_summary_or_trimmed',
          ),
        ),
      );
      field_create_instance($instance);
    }
    else {
      $instance['label'] = $type->body_label;
      $instance['settings']['display_summary'] = TRUE;
      field_update_instance($instance);
    }
  }
  elseif (!empty($instance)) {
    field_delete_instance($instance);
  }

  if ($type->has_title) {
    // Add the title field if not present.
    $field = field_info_field('title');
    $instance = field_info_instance('node', 'title', $type->type);

    if (empty($field)) {
      $field = array(
        'field_name' => 'title',
        'type' => 'text',
      );
      $field = field_create_field($field);
    }
    if (empty($instance)) {
      $weight = -5;
      $instance = array(
        'field_name' => 'title',
        'object_type' => 'node',
        'bundle' => $type->type,
        'label' => $type->title_label,
        'widget_type' => 'text',
        'widget' => array(
          'weight' => $weight,
        ),
        'required' => TRUE,
        'locked' => TRUE,
        'display' => array(
          'full' => array(
            'label' => 'hidden',
            'type' => 'text_default',
            'weight' => $weight,
          ),
          'teaser' => array(
            'label' => 'hidden',
            'type' => 'text_default',
            'weight' => $weight,
          ),
        ),
      );
      field_create_instance($instance);
    }
    else {
      $instance['label'] = $type->title_label;
      field_update_instance($instance);
    }
  }
}

/**
 * Deletes a node type from the database.
 *
 * @param $type
 *   The machine-readable name of the node type to be deleted.
 */
function node_type_delete($type) {
  $info = node_type_get_type($type);
  db_delete('node_type')
    ->condition('type', $type)
    ->execute();
  module_invoke_all('node_type_delete', $info);

  // Clear the node type cache.
  drupal_static_reset('_node_types_build');
}

/**
 * Updates all nodes of one type to be of another type.
 *
 * @param $old_type
 *   The current node type of the nodes.
 * @param $type
 *   The new node type of the nodes.
 *
 * @return
 *   The number of nodes whose node type field was modified.
 */
function node_type_update_nodes($old_type, $type) {
  return db_update('node')
    ->fields(array('type' => $type))
    ->condition('type', $old_type)
    ->execute();
}

/**
 * Builds and returns the list of available node types.
 *
 * The list of types is built by querying hook_node_info() in all modules, and
 * by comparing this information with the node types in the {node_type} table.
 *
 */
function _node_types_build() {
  $_node_types = &drupal_static(__FUNCTION__);
  if (is_object($_node_types)) {
    return $_node_types;
  }
  $_node_types = (object)array('types' => array(), 'names' => array());

  $info_array = module_invoke_all('node_info');
  foreach ($info_array as $type => $info) {
    $info['type'] = $type;
    $_node_types->types[$type] = node_type_set_defaults($info);
    $_node_types->names[$type] = $info['name'];
  }
  $type_result = db_select('node_type', 'nt')
    ->addTag('translatable')
    ->addTag('node_type_access')
    ->fields('nt')
    ->orderBy('nt.type', 'ASC')
    ->execute();
  foreach ($type_result as $type_object) {
    // Check for node types from disabled modules and mark their types for removal.
    // Types defined by the node module in the database (rather than by a separate
    // module using hook_node_info) have a base value of 'node_content'. The isset()
    // check prevents errors on old (pre-Drupal 7) databases.
    if (isset($type_object->base) && $type_object->base != 'node_content' && empty($info_array[$type_object->type])) {
      $type_object->disabled = TRUE;
    }
    if (!isset($_node_types->types[$type_object->type]) || $type_object->modified) {
      $_node_types->types[$type_object->type] = $type_object;
      $_node_types->names[$type_object->type] = $type_object->name;

      if ($type_object->type != $type_object->orig_type) {
        unset($_node_types->types[$type_object->orig_type]);
        unset($_node_types->names[$type_object->orig_type]);
      }
    }
  }

  asort($_node_types->names);

  return $_node_types;
}

/**
 * Set the default values for a node type.
 *
 * The defaults are for a type defined through hook_node_info().
 * When populating a custom node type $info should have the 'custom'
 * key set to 1.
 *
 * @param $info
 *   An object or array containing values to override the defaults.
 *
 * @return
 *  A node type object.
 */
function node_type_set_defaults($info = array()) {
  static $type;

  if (!isset($type)) {
    $type = new stdClass();
    $type->type = '';
    $type->name = '';
    $type->base = '';
    $type->description = '';
    $type->help = '';
    $type->has_title = 1;
    $type->has_body = 1;
    $type->title_label = t('Title');
    $type->body_label = t('Body');
    $type->custom = 0;
    $type->modified = 0;
    $type->locked = 1;
    $type->is_new = 1;
  }

  $new_type = clone $type;
  $info = (array) $info;
  foreach ($info as $key => $data) {
    $new_type->$key = $data;
  }
  // If the type has no title or body, set an empty label.
  if (!$new_type->has_title) {
    $new_type->title_label = '';
  }
  if (!$new_type->has_body) {
    $new_type->body_label = '';
  }
  $new_type->orig_type = isset($info['type']) ? $info['type'] : '';

  return $new_type;
}

/**
 * Implements hook_rdf_mapping().
 */
function node_rdf_mapping() {
  return array(
    array(
      'type' => 'node',
      'bundle' => RDF_DEFAULT_BUNDLE,
      'mapping' => array(
        'rdftype' => array('sioc:Item', 'foaf:Document'),
        'title' => array(
          'predicates' => array('dc:title'),
        ),
        'created' => array(
          'predicates' => array('dc:date', 'dc:created'),
          'datatype' => 'xsd:dateTime',
          'callback' => 'date_iso8601',
        ),
        'changed' => array(
          'predicates' => array('dc:modified'),
        ),
        'body' => array(
          'predicates' => array('content:encoded'),
        ),
        'uid' => array(
          'predicates' => array('sioc:has_creator'),
        ),
        'name' => array(
          'predicates' => array('foaf:name'),
        ),
      ),
    ),
  );
}

/**
 * Determine whether a node hook exists.
 *
 * @param $node
 *   A node object or a string containing the node type.
 * @param $hook
 *   A string containing the name of the hook.
 * @return
 *   TRUE if the $hook exists in the node type of $node.
 */
function node_hook($node, $hook) {
  $base = node_type_get_base($node);
  return module_hook($base, $hook);
}

/**
 * Invoke a node hook.
 *
 * @param $node
 *   A node object 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, $a4 = NULL) {
  if (node_hook($node, $hook)) {
    $base = node_type_get_base($node);
    $function = $base . '_' . $hook;
    return ($function($node, $a2, $a3, $a4));
  }
}

/**
 * Load node entities from the database.
 *
 * This function should be used whenever you need to load more than one node
 * from the database. Nodes are loaded into memory and will not require
 * database access if loaded again during the same page request.
 *
 * @see entity_load()
 *
 * @param $nids
 *   An array of node IDs.
 * @param $conditions
 *   An array of conditions on the {node} table in the form 'field' => $value.
 * @param $reset
 *   Whether to reset the internal node_load cache.
 *
 * @return
 *   An array of node objects indexed by nid.
 */
function node_load_multiple($nids = array(), $conditions = array(), $reset = FALSE) {
  return entity_load('node', $nids, $conditions, $reset);
}

/**
 * Load a node object from the database.
 *
 * @param $nid
 *   The node ID.
 * @param $vid
 *   The revision ID.
 * @param $reset
 *   Whether to reset the node_load_multiple cache.
 *
 * @return
 *   A fully-populated node object.
 */
function node_load($nid = NULL, $vid = NULL, $reset = FALSE) {
  $nids = (isset($nid) ? array($nid) : array());
  $conditions = (isset($vid) ? array('vid' => $vid) : array());
  $node = node_load_multiple($nids, $conditions, $reset);
  return $node ? reset($node) : FALSE;
}

/**
 * Perform validation checks on the given node.
 */
function node_validate(stdClass $node, $form = array()) {
  $type = node_type_get_type($node);

  if (isset($node->nid) && (node_last_changed($node->nid) > $node->changed)) {
    form_set_error('changed', t('The content on this page has either been modified by another user, or you have already submitted modifications using this form. As a result, your changes cannot be saved.'));
  }

  if (user_access('administer nodes')) {
    // Validate the "authored by" field.
    if (!empty($node->name) && !($account = user_load_by_name($node->name))) {
      // The use of empty() is mandatory in the context of usernames
      // as the empty string denotes the anonymous user. In case we
      // are dealing with an anonymous user we set the user ID to 0.
      form_set_error('name', t('The username %name does not exist.', array('%name' => $node->name)));
    }

    // Validate the "authored on" field.
    if (!empty($node->date) && strtotime($node->date) === FALSE) {
      form_set_error('date', t('You have to specify a valid date.'));
    }
  }

  // Do node-type-specific validation checks.
  node_invoke($node, 'validate', $form);
  module_invoke_all('node_validate', $node, $form);
}

/**
 * Prepare node for save and allow modules to make changes.
 */
function node_submit($node) {
  global $user;

  if (user_access('administer nodes')) {
    // Populate the "authored by" field.
    if ($account = user_load_by_name($node->name)) {
      $node->uid = $account->uid;
    }
    else {
      $node->uid = 0;
    }
  }
  $node->created = !empty($node->date) ? strtotime($node->date) : REQUEST_TIME;
  $node->validated = TRUE;

  return $node;
}

/**
 * Save changes to a node or add a new node.
 *
 * @param $node
 *   The $node object to be saved. If $node->nid is
 *   omitted (or $node->is_new is TRUE), a new node will be added.
 */
function node_save(stdClass $node) {
  field_attach_presave('node', $node);
  // Let modules modify the node before it is saved to the database.
  module_invoke_all('node_presave', $node);
  global $user;

  if (!isset($node->is_new)) {
    $node->is_new = empty($node->nid);
  }

  // Apply filters to some default node fields:
  if ($node->is_new) {
    // Insert a new node.
    $node->is_new = TRUE;

    // When inserting a node, $node->log must be set because
    // {node_revision}.log does not (and cannot) have a default
    // value. If the user does not have permission to create
    // revisions, however, the form will not contain an element for
    // log so $node->log will be unset at this point.
    if (!isset($node->log)) {
      $node->log = '';
    }
  }
  elseif (!empty($node->revision)) {
    $node->old_vid = $node->vid;
    unset($node->vid);
  }
  else {
    // When updating a node, avoid clobbering an existing log entry with an empty one.
    if (empty($node->log)) {
      unset($node->log);
    }
  }

  // Set some required fields:
  if (empty($node->created)) {
    $node->created = REQUEST_TIME;
  }
  // The changed timestamp is always updated for bookkeeping purposes (revisions, searching, ...)
  $node->changed = REQUEST_TIME;

  $node->timestamp = REQUEST_TIME;
  $update_node = TRUE;

  // When converting the title property to fields we preserved the {node}.title
  // db column for performance, setting the default language value into this
  // column. After this we restore the field data structure to the previous node
  // title field.
  $title_field = $node->title;
  $langcode = FIELD_LANGUAGE_NONE;
  $node->title = $title_field[$langcode][0]['value'];

  // Generate the node table query and the node_revisions table query.
  if ($node->is_new) {
    drupal_write_record('node', $node);
    _node_save_revision($node, $user->uid);
    $op = 'insert';
  }
  else {
    drupal_write_record('node', $node, 'nid');
    if (!empty($node->revision)) {
      _node_save_revision($node, $user->uid);
    }
    else {
      _node_save_revision($node, $user->uid, 'vid');
      $update_node = FALSE;
    }
    $op = 'update';
  }
  if ($update_node) {
    db_update('node')
      ->fields(array('vid' => $node->vid))
      ->condition('nid', $node->nid)
      ->execute();
  }

  // Restore the title field data structure after db storage.
  $node->title = $title_field;

  // Call the node specific callback (if any). This can be
  // node_invoke($node, 'insert') or
  // node_invoke($node, 'update').
  node_invoke($node, $op);

  // Save fields.
  $function = "field_attach_$op";
  $function('node', $node);

  module_invoke_all('node_' . $op, $node);

  // Update the node access table for this node.
  node_access_acquire_grants($node);

  // Clear internal properties.
  unset($node->is_new);

  // Clear the page and block caches.
  cache_clear_all();

  // Ignore slave server temporarily to give time for the
  // saved node to be propagated to the slave.
  db_ignore_slave();
}

/**
 * Helper function to save a revision with the uid of the current user.
 *
 * Node is taken by reference, because drupal_write_record() updates the
 * $node with the revision id, and we need to pass that back to the caller.
 */
function _node_save_revision(stdClass $node, $uid, $update = NULL) {
  $temp_uid = $node->uid;
  $node->uid = $uid;
  if (isset($update)) {
    drupal_write_record('node_revision', $node, $update);
  }
  else {
    drupal_write_record('node_revision', $node);
  }
  $node->uid = $temp_uid;
}

/**
 * Delete a node.
 *
 * @param $nid
 *   A node ID.
 */
function node_delete($nid) {
  node_delete_multiple(array($nid));
}

/**
 * Delete multiple nodes.
 *
 * @param $nids
 *   An array of node IDs.
 */
function node_delete_multiple($nids) {
  if (!empty($nids)) {
    $nodes = node_load_multiple($nids, array());

    db_delete('node')
      ->condition('nid', $nids, 'IN')
      ->execute();
    db_delete('node_revision')
      ->condition('nid', $nids, 'IN')
      ->execute();
    db_delete('history')
      ->condition('nid', $nids, 'IN')
      ->execute();

    foreach ($nodes as $nid => $node) {
      // Call the node-specific callback (if any):
      node_invoke($node, 'delete');
      module_invoke_all('node_delete', $node);
      field_attach_delete('node', $node);

      // Remove this node from the search index if needed.
      // This code is implemented in node module rather than in search module,
      // because node module is implementing search module's API, not the other
      // way around.
      if (module_exists('search')) {
        search_reindex($nid, 'node');
      }
    }

    // Clear the page and block and node_load_multiple caches.
    cache_clear_all();
    entity_get_controller('node')->resetCache();
  }
}

/**
 * Delete a node revision.
 *
 * @param $revision_id
 *   The revision ID to delete.
 */
function node_revision_delete($revision_id) {
  if ($revision = node_load(NULL, $revision_id)) {
    // Prevent deleting the current revision.
    $node = node_load($revision->nid);
    if ($revision_id == $node->vid) {
      return FALSE;
    }

    db_delete('node_revision')
      ->condition('nid', $revision->nid)
      ->condition('vid', $revision->vid)
      ->execute();
    module_invoke_all('node_revision_delete', $revision);
    field_attach_delete_revision('node', $revision);
    return TRUE;
  }
  return FALSE;
}

/**
 * Generate an array for rendering the given node.
 *
 * @param $node
 *   A node object.
 * @param $build_mode
 *   Build mode, e.g. 'full', 'teaser'...
 *
 * @return
 *   An array as expected by drupal_render().
 */
function node_build($node, $build_mode = 'full') {
  // Populate $node->content with a render() array.
  node_build_content($node, $build_mode);

  $build = $node->content;
  // We don't need duplicate rendering info in node->content.
  unset($node->content);

  $build += array(
    '#theme' => 'node',
    '#node' => $node,
    '#build_mode' => $build_mode,
  );
  // Add contextual links for this node.
  $build['#contextual_links']['node'] = menu_contextual_links('node', array($node->nid));

  return $build;
}

/**
 * Builds a structured array representing the node's content.
 *
 * The content built for the node (field values, comments, file attachments or
 * other node components) will vary depending on the $build_mode parameter.
 *
 * Drupal core defines the following build modes for nodes, with the following
 * default use cases:
 *   - full (default): node is being displayed on its own page (node/123)
 *   - teaser: node is being displayed on the default home page listing, on
 *     taxonomy listing pages, or on blog listing pages.
 *   - rss: node displayed in an RSS feed.
 *   If search.module is enabled:
 *   - search_index: node is being indexed for search.
 *   - search_result: node is being displayed as a search result.
 *   If book.module is enabled:
 *   - print: node is being displayed in print-friendly mode.
 * Contributed modules might define additional build modes, or use existing
 * build modes in additional contexts.
 *
 * @param $node
 *   A node object.
 * @param $build_mode
 *   Build mode, e.g. 'full', 'teaser'...
 *
 */
function node_build_content(stdClass $node, $build_mode = 'full') {
  // Remove previously built content, if exists.
  $node->content = array();

  // The 'view' hook can be implemented to overwrite the default function
  // to display nodes.
  if (node_hook($node, 'view')) {
    $node = node_invoke($node, 'view', $build_mode);
  }

  // Build fields content.
  $node->content += field_attach_view('node', $node, $build_mode);

  // Always display a read more link on teasers because we have no way
  // to know when a teaser view is different than a full view.
  $links = array();
  if ($build_mode == 'teaser') {
    $links['node_readmore'] = array(
      'title' => t('Read more'),
      'href' => 'node/' . $node->nid,
      'attributes' => array('rel' => 'tag', 'title' => strip_tags($node->title[FIELD_LANGUAGE_NONE][0]['value']))
    );
  }
  $node->content['links']['node'] = array(
    '#theme' => 'links',
    '#links' => $links,
    '#attributes' => array('class' => array('links', 'inline')),
  );

  // Allow modules to make their own additions to the node.
  module_invoke_all('node_view', $node, $build_mode);

  // Allow modules to modify the structured node.
  drupal_alter('node_build', $node, $build_mode);
}

/**
 * Implement hook_language_negotiation_info().
 */
function node_language_negotiation_info() {
  $providers = array();

  $providers['node-language'] = array(
    'types' => array(LANGUAGE_TYPE_CONTENT),
    'callbacks' => array('language' => 'node_language_provider'),
    'file' => drupal_get_path('module', 'node') . '/node.module',
    'name' => t('Node'),
    'description' => t('The current node language is used.'),
  );

  return $providers;
}

/**
 * Return the language of the current node.
 *
 * @param $languages
 *   An array of valid language objects.
 *
 * @return
 *   A valid language code on succes, FALSE otherwise.
 */
function node_language_provider($languages) {
  require_once DRUPAL_ROOT . '/includes/path.inc';

  $path = isset($_GET['q']) ? $_GET['q'] : '';
  list($language, $path) = language_url_split_prefix($path, $languages);
  $language = $language ? $language : language_default();
  $path = drupal_get_normal_path($path, $language->language);

  // We cannot use args now.
  $path = explode('/', $path);
  // Act only if we are in a node page.
  if (isset($path[0]) && isset($path[1]) && $path[0] == 'node' && $nid = intval($path[1])) {
    // We cannot perform a node load here.
    $result = db_query('SELECT n.language FROM {node} n WHERE n.nid = :nid', array(':nid' => $nid))->fetchAssoc();
    return $result['language'];
  }

  return FALSE;
}

/**
 * Generate an array which displays a node detail page.
 *
 * @param $node
 *   A node object.
 * @param $message
 *   A flag which sets a page title relevant to the revision being viewed.
 * @return
 *   A $page element suitable for use by drupal_page_render().
 */
function node_show(stdClass $node, $message = FALSE) {
  if ($message) {
    drupal_set_title(t('Revision of %title from %date', array('%title' => $node->title[FIELD_LANGUAGE_NONE][0]['value'], '%date' => format_date($node->revision_timestamp))), PASS_THROUGH);
  }

  // Update the history tab