book.module

<?php
// $Id$

/**
 * @file
 * Allows users to collaboratively author a book.
 */

/**
 * Implementation of hook_node_name().
 */
function book_node_name($node) {
  return t('book page');
}

/**
 * Implementation of hook_perm().
 */
function book_perm() {
  return array('create book pages', 'maintain books', 'edit own book pages');
}

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

  if ($op == 'create') {
    // Only registered users can create book pages.  Given the nature
    // of the book module this is considered to be a good/safe idea.
    return user_access('create book pages');
  }

  if ($op == 'update') {
    // Only registered users can update book pages.  Given the nature
    // of the book module this is considered to be a good/safe idea.
    // One can only update a book page if there are no suggested updates
    // of that page waiting for approval.  That is, only updates that
    // don't overwrite the current or pending information are allowed.

    if ((user_access('maintain books') && !$node->moderate) || ($node->uid == $user->uid && user_access('edit own book pages'))) {
      return TRUE;
    }
    else {
       // do nothing. node-access() will determine further access
    }
  }
}

/**
 * Implementation of hook_link().
 */
function book_link($type, $node = 0, $main = 0) {

  $links = array();

  if ($type == 'node' && isset($node->parent)) {
    if (!$main) {
      if (book_access('create', $node)) {
        $links[] = l(t('add child page'), "node/add/book/parent/$node->nid");
      }
      $links[] = l(t('printer-friendly version'), 'book/print/'. $node->nid, array('title' => t('Show a printer-friendly version of this book page and its sub-pages.')));
    }
  }

  return $links;
}

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

  if ($may_cache) {
    $items[] = array('path' => 'book', 'title' => t('books'),
      'access' => user_access('access content'), 'type' => MENU_NORMAL_ITEM, 'weight' => 5);
    $items[] = array('path' => 'node/add/book', 'title' => t('book page'),
      'access' => user_access('create book pages'));
    $items[] = array('path' => 'admin/node/book', 'title' => t('books'),
      'callback' => 'book_admin',
      'access' => user_access('administer nodes'),
      'weight' => 4);
    $items[] = array('path' => 'admin/node/book/orphan', 'title' => t('orphan pages'),
      'callback' => 'book_admin_orphan',
      'access' => user_access('administer nodes'),
      'weight' => 8);
    $items[] = array('path' => 'book', 'title' => t('books'),
      'callback' => 'book_render',
      'access' => user_access('access content'),
      'type' => MENU_SUGGESTED_ITEM);
    $items[] = array('path' => 'book/print', 'title' => t('printer-friendly version'),
      'callback' => 'book_print',
      'access' => user_access('access content'),
      'type' => MENU_CALLBACK);
  }
  else {
    // To avoid SQL overhead, check whether we are on a node page and whether the
    // user is allowed to maintain books.
    if (arg(0) == 'node' && is_numeric(arg(1)) && user_access('maintain books')) {
      // Only add the outline-tab for non-book pages:
      $result = db_query(db_rewrite_sql("SELECT n.nid FROM {node} n WHERE n.nid = %d AND n.type != 'book'"), arg(1));
      if (db_num_rows($result) > 0) {
        $items[] = array('path' => 'node/'. arg(1) .'/outline', 'title' => t('outline'),
          'callback' => 'book_outline', 'access' => user_access('maintain books'),
          'type' => MENU_LOCAL_TASK, 'weight' => 2);
      }
    }

    // We don't want to cache these menu items because they could change whenever
    // a book page or outline node is edited.
    if (arg(0) == 'admin' && arg(1) == 'node' && arg(2) == 'book') {
      $result = db_query(db_rewrite_sql('SELECT n.nid, n.title FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = 0 ORDER BY b.weight, n.title'));
      while ($book = db_fetch_object($result)) {
        $items[] = array('path' => 'admin/node/book/'. $book->nid, 'title' => t('"%title" book', array('%title' => $book->title)));
      }
    }
  }

  return $items;
}

/**
 * Implementation of hook_block().
 *
 * Displays the book table of contents in a block when the current page is a
 * single-node view of a book node.
 */
function book_block($op = 'list', $delta = 0) {
  $block = array();
  if ($op == 'list') {
    $block[0]['info'] = t('Book navigation');
    return $block;
  }
  else if ($op == 'view') {
    // Only display this block when the user is browsing a book:
    if (arg(0) == 'node' && is_numeric(arg(1))) {
      $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, b.parent FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.nid = %d'), arg(1));
      if (db_num_rows($result) > 0) {
        $node = db_fetch_object($result);

        $path = book_location($node);
        $path[] = $node;

        $expand = array();
        foreach ($path as $key => $node) {
          $expand[] = $node->nid;
        }

        $block['subject'] = check_plain($path[0]->title);
        $block['content'] = book_tree($expand[0], 5, $expand);
      }
    }

    return $block;
  }
}

/**
 * Implementation of hook_load().
 */
function book_load($node) {
  global $user;

  $book = db_fetch_object(db_query('SELECT parent, weight, log FROM {book} WHERE nid = %d', $node->nid));

  if (arg(2) == 'edit' && !user_access('administer nodes')) {
    // If a user is about to update a book page, we overload some
    // fields to reflect the changes.
    if ($user->uid) {
      $book->uid = $user->uid;
      $book->name = $user->name;
    }
    else {
      $book->uid = 0;
      $book->name = '';
    }
  }

  return $book;
}

/**
 * Implementation of hook_insert().
 */
function book_insert($node) {
  db_query("INSERT INTO {book} (nid, parent, weight, log) VALUES (%d, %d, %d, '%s')", $node->nid, $node->parent, $node->weight, $node->log);
}

/**
 * Implementation of hook_update().
 */
function book_update($node) {
  db_query("UPDATE {book} SET parent = %d, weight = %d, log = '%s' WHERE nid = %d", $node->parent, $node->weight, $node->log, $node->nid);
}

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

/**
 * Implementation of hook_validate().
 */
function book_validate(&$node) {
  // Set default values for non-administrators.
  if (!user_access('administer nodes')) {
    $node->weight = 0;
    $node->revision = 1;
  }
}

/**
 * Implementation of hook_form().
 */
function book_form(&$node) {
  global $user;

  $op = $_POST['op'];

  $output = form_select(t('Parent'), 'parent', ($node->parent ? $node->parent : arg(4)), book_toc($node->nid), t('The parent that this page belongs in. Note that pages whose parent is &lt;top-level&gt; are regarded as independent, top-level books.'));

  if (function_exists('taxonomy_node_form')) {
    $output .= implode('', taxonomy_node_form('book', $node));
  }

  $output .= form_textarea(t('Body'), 'body', $node->body, 60, 20, '', NULL, TRUE);
  $output .= filter_form('format', $node->format);
  $output .= form_textarea(t('Log message'), 'log', $node->log, 60, 5, t('An explanation of the additions or updates being made to help other authors understand your motivations.'));

  if (user_access('administer nodes')) {
    $output .= form_weight(t('Weight'), 'weight', $node->weight, 15, t('Pages at a given level are ordered first by weight and then by title.'));
  }
  else {
    // If a regular user updates a book page, we create a new revision
    // authored by that user:
    $output .= form_hidden('revision', 1);
  }

  return $output;
}

/**
 * Implementation of function book_outline()
 * Handles all book outline operations.
 */
function book_outline() {

  $op = $_POST['op'];
  $edit = $_POST['edit'];
  $node = node_load(array('nid' => arg(1)));

  if ($node->nid) {
    switch ($op) {
      case t('Add to book outline'):
        db_query('INSERT INTO {book} (nid, parent, weight) VALUES (%d, %d, %d)', $node->nid, $edit['parent'], $edit['weight']);
        drupal_set_message(t('Added the post to the book.'));
        drupal_goto("node/$node->nid");
        break;

      case t('Update book outline'):
        db_query('UPDATE {book} SET parent = %d, weight = %d WHERE nid = %d', $edit['parent'], $edit['weight'], $node->nid);
        drupal_set_message(t('Updated the book outline.'));
        drupal_goto("node/$node->nid");
        break;

      case t('Remove from book outline'):
        db_query('DELETE FROM {book} WHERE nid = %d', $node->nid);
        drupal_set_message(t('Removed the post from the book.'));
        drupal_goto("node/$node->nid");
        break;

      default:
        $page = db_fetch_object(db_query('SELECT * FROM {book} WHERE nid = %d', $node->nid));

        $output  = form_select(t('Parent'), 'parent', $page->parent, book_toc($node->nid), t('The parent page in the book.'));
        $output .= form_weight(t('Weight'), 'weight', $node->weight, 15, t('Pages at a given level are ordered first by weight and then by title.'));

        if ($page->nid) {
          $output .= form_submit(t('Update book outline'));
          $output .= form_submit(t('Remove from book outline'));
        }
        else {
          $output .= form_submit(t('Add to book outline'));
        }

        drupal_set_title(check_plain($node->title));
        return form($output);
    }
  }
}


/**
 * Return the the most recent revision that matches the specified conditions.
 */
function book_revision_load($page, $conditions = array()) {

  $revisions = array_reverse(node_revision_list($page));

  foreach ($revisions as $revision) {

    // Extract the specified revision:
    $node = node_revision_load($page, $revision);

    // Check to see if the conditions are met:
    $status = TRUE;

    foreach ($conditions as $key => $value) {
      if ($node->$key != $value) {
        $status = FALSE;
      }
    }

    if ($status) {
      return $node;
    }
  }
}

/**
 * Return the path (call stack) to a certain book page.
 */
function book_location($node, $nodes = array()) {
  $parent = db_fetch_object(db_query(db_rewrite_sql('SELECT n.nid, n.title, b.parent, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.nid = %d'), $node->parent));
  if ($parent->title) {
    $nodes = book_location($parent, $nodes);
    array_push($nodes, $parent);
  }
  return $nodes;
}

function book_location_down($node, $nodes = array()) {
  $last_direct_child = db_fetch_object(db_query(db_rewrite_sql('SELECT n.nid, n.title, b.parent, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = %d ORDER BY b.weight DESC, n.title DESC'), $node->nid));
  if ($last_direct_child) {
    array_push($nodes, $last_direct_child);
    $nodes = book_location_down($last_direct_child, $nodes);
  }
  return $nodes;
}

/**
 * Fetch the node object of the previous page of the book.
 */
function book_prev($node) {
  // If the parent is zero, we are at the start of a book so there is no previous.
  if ($node->parent == 0) {
    return NULL;
  }

  // Previous on the same level:
  $direct_above = db_fetch_object(db_query(db_rewrite_sql("SELECT n.nid, n.title FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = %d AND n.status = 1 AND n.moderate = 0 AND (b.weight < %d OR (b.weight = %d AND n.title < '%s')) ORDER BY b.weight DESC, n.title DESC"), $node->parent, $node->weight, $node->weight, $node->title));
  if ($direct_above) {
    // Get last leaf of $above.
    $path = book_location_down($direct_above);

    return $path ? (count($path) > 0 ? array_pop($path) : NULL) : $direct_above;
  }
  else {
    // Direct parent:
    $prev = db_fetch_object(db_query(db_rewrite_sql('SELECT n.nid, n.title FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.nid = %d AND n.status = 1 AND n.moderate = 0'), $node->parent));
    return $prev;
  }
}

/**
 * Fetch the node object of the next page of the book.
 */
function book_next($node) {
  // get first direct child
  $child = db_fetch_object(db_query(db_rewrite_sql('SELECT n.nid, n.title, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = %d AND n.status = 1 AND n.moderate = 0 ORDER BY b.weight ASC, n.title ASC'), $node->nid));
  if ($child) {
    return $child;
  }

  // No direct child: get next for this level or any parent in this book.
  array_push($path = book_location($node), $node); // Path to top-level node including this one.

  while (($leaf = array_pop($path)) && count($path)) {
    $next = db_fetch_object(db_query(db_rewrite_sql("SELECT n.nid, n.title, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = %d AND n.status = 1 AND n.moderate = 0 AND (b.weight > %d OR (b.weight = %d AND n.title > '%s')) ORDER BY b.weight ASC, n.title ASC"), $leaf->parent, $leaf->weight, $leaf->weight, $leaf->title));
    if ($next) {
      return $next;
    }
  }
}

function book_content($node, $teaser = FALSE) {
  $op = $_POST['op'];

  // Always display the most recently approved revision of a node
  // (if any) unless we have to display this page in the context of
  // the moderation queue.
  if ($op != t('Preview') && $node->moderate && arg(0) != 'queue') {
    $revision = book_revision_load($node, array('moderate' => 0, 'status' => 1));

    if ($revision) {
      $node = $revision;
    }
  }

  // Extract the page body.
  $node = node_prepare($node, $teaser);

  return $node;
}

/**
 * Implementation of hook_view().
 *
 * If not displayed on the main page, we render the node as a page in the
 * book with extra links to the previous and next pages.
 */
function book_view(&$node, $teaser = FALSE, $page = FALSE) {
  $node = book_content($node, $teaser);

  if (!$teaser && $node->moderate) {
    $node->body .= '<div class="log"><div class="title">'. t('Log') .':</div>'. $node->log .'</div>';
  }
}

/**
 * Implementation of hook_nodeapi().
 *
 * Appends book navigation to all nodes in the book.
 */
function book_nodeapi(&$node, $op, $teaser, $page) {
  switch ($op) {
    case 'view':
      if (!$teaser) {
        $book = db_fetch_array(db_query('SELECT * FROM {book} WHERE nid = %d', $node->nid));
        if ($book) {
          if ($node->moderate && user_access('administer nodes')) {
            drupal_set_message(t("This update/post awaits moderation and won't be accessible until approved."));
          }

          foreach ($book as $key => $value) {
            $node->$key = $value;
          }
          $node = theme('book_navigation', $node);
          if ($page) {
            menu_set_location($node->breadcrumb);
          }
        }
      }
      break;
  }
}

/**
 * Prepares both the custom breadcrumb trail and the forward/backward
 * navigation for a node presented as a book page.
 *
 * @ingroup themeable
 */
function theme_book_navigation($node) {
  $path = book_location($node);

  // Construct the breadcrumb:

  $node->breadcrumb = array(); // Overwrite the trail with a book trail.
  foreach ($path as $level) {
    $node->breadcrumb[] = array('path' => 'node/'. $level->nid, 'title' =>  $level->title);
  }
  $node->breadcrumb[] = array('path' => 'node/'. $node->nid);

  if ($node->nid) {
    $output .= '<div class="book">';

    if ($tree = book_tree($node->nid)) {
      $output .= '<div class="tree">'. $tree .'</div>';
    }

    if ($prev = book_prev($node)) {
      $links .= '<div class="prev">';
      $links .= l(t('previous'), 'node/'. $prev->nid, array('title' => t('View the previous page.')));
      $links .= '</div>';
      $titles .= '<div class="prev">'. check_plain($prev->title) .'</div>';
    }
    else {
      $links .= '<div class="prev">&nbsp;</div>'; // Make an empty div to fill the space.
    }
    if ($next = book_next($node)) {
      $links .= '<div class="next">';
      $links .= l(t('next'), 'node/'. $next->nid, array('title' => t('View the next page.')));
      $links .= '</div>';
      $titles .= '<div class="next">'. check_plain($next->title) .'</div>';
    }
    else {
      $links .= '<div class="next">&nbsp;</div>'; // Make an empty div to fill the space.
    }
    if ($node->parent) {
      $links .= '<div class="up">';
      $links .= l(t('up'), 'node/'. $node->parent, array('title' => t('View this page\'s parent section.')));
      $links .= '</div>';
    }

    $output .= '<div class="nav">';
    $output .= ' <div class="links">'. $links .'</div>';
    $output .= ' <div class="titles">'. $titles .'</div>';
    $output .= '</div>';
    $output .= '</div>';
  }

  $node->body = $node->body.$output;

  return $node;
}

function book_toc_recurse($nid, $indent, $toc, $children, $exclude) {
  if ($children[$nid]) {
    foreach ($children[$nid] as $foo => $node) {
      if (!$exclude || $exclude != $node->nid) {
        $toc[$node->nid] = $indent .' '. $node->title;
        $toc = book_toc_recurse($node->nid, $indent .'--', $toc, $children, $exclude);
      }
    }
  }

  return $toc;
}

function book_toc($exclude = 0) {
  $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, b.parent, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.status = 1 ORDER BY b.weight, n.title'));

  while ($node = db_fetch_object($result)) {
    if (!$children[$node->parent]) {
      $children[$node->parent] = array();
    }
    array_push($children[$node->parent], $node);
  }

  $toc = array();

  // If the user is an administrator, add the top-level book page;
  // only administrators can start new books.
  if (user_access('administer nodes')) {
    $toc[0] = '<'. t('top-level') .'>';
  }

  $toc = book_toc_recurse(0, '', $toc, $children, $exclude);

  return $toc;
}

function book_tree_recurse($nid, $depth, $children, $unfold = array()) {
  if ($depth > 0) {
    if ($children[$nid]) {
      foreach ($children[$nid] as $foo => $node) {
        if (in_array($node->nid, $unfold)) {
          if ($tree = book_tree_recurse($node->nid, $depth - 1, $children, $unfold)) {
            $output .= '<li class="expanded">';
            $output .= l($node->title, 'node/'. $node->nid);
            $output .= '<ul>'. $tree .'</ul>';
            $output .= '</li>';
          }
          else {
            $output .= '<li class="leaf">'. l($node->title, 'node/'. $node->nid) .'</li>';
          }
        }
        else {
          if ($tree = book_tree_recurse($node->nid, 1, $children)) {
            $output .= '<li class="collapsed">'. l($node->title, 'node/'. $node->nid) .'</li>';
          }
          else {
            $output .= '<li class="leaf">'. l($node->title, 'node/'. $node->nid) .'</li>';
          }
        }
      }
    }
  }

  return $output;
}

function book_tree($parent = 0, $depth = 3, $unfold = array()) {
  $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, b.parent, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.status = 1 AND n.moderate = 0 ORDER BY b.weight, n.title'));

  while ($node = db_fetch_object($result)) {
    $list = $children[$node->parent] ? $children[$node->parent] : array();
    array_push($list, $node);
    $children[$node->parent] = $list;
  }

  if ($tree = book_tree_recurse($parent, $depth, $children, $unfold)) {
    return '<div class="menu"><ul>'. $tree .'</ul></div>';
  }
}

/**
 * Menu callback; prints a listing of all books.
 */
function book_render() {
  $result = db_query(db_rewrite_sql('SELECT n.nid FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = 0 AND n.status = 1 AND n.moderate = 0 ORDER BY b.weight, n.title'));

  while ($page = db_fetch_object($result)) {
    // Load the node:
    $node = node_load(array('nid' => $page->nid));

    if ($node) {
      // Take the most recent approved revision, extract the page and check output:
      $node = book_content($node, TRUE);
      // Output the content:
      $output .= '<div class="book">';
      $output .= '<div class="title">'. l($node->title, 'node/'. $node->nid) .'</div>';
      $output .= '<div class="body">'. $node->teaser .'</div>';
      $output .= '</div>';
    }
  }

  drupal_set_title(t('Books'));
  return $output;
}

/**
 * Menu callback; generates printer-friendly book page with all descendants.
 */
function book_print($nid = 0, $depth = 1) {
  global $base_url;
  $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.status = 1 AND n.nid = %d AND n.moderate = 0 ORDER BY b.weight, n.title'), $nid);

  while ($page = db_fetch_object($result)) {
    // load the node:
    $node = node_load(array('nid' => $page->nid));

    if ($node) {
      // output the content:
      if (node_hook($node, 'content')) {
        $node = node_invoke($node, 'content');
      }
      // Allow modules to change $node->body before viewing.
      node_invoke_nodeapi($node, 'view', $node->body, false);

      $output .= '<h1 id="'. $node->nid .'" name="'. $node->nid .'" class="book-h'. $depth .'">'. check_plain($node->title) .'</h1>';

      if ($node->body) {
        $output .= $node->body;
      }
    }
  }

  $output .= book_print_recurse($nid, $depth);

  $html = '<html><head><title>'. check_plain($node->title) .'</title>';
  $html .= '<base href="'. $base_url .'/" />';
  $html .= "<style type=\"text/css\">\n@import url(misc/print.css);\n</style>";
  $html .= '</head><body>'. $output .'</body></html>';

  print $html;
}

function book_print_recurse($parent = '', $depth = 1) {
  $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, b.weight FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE n.status = 1 AND b.parent = %d AND n.moderate = 0 ORDER BY b.weight, n.title'), $parent);

  while ($page = db_fetch_object($result)) {
    // Load the node:
    $node = node_load(array('nid' => $page->nid));

    // Take the most recent approved revision:
    if ($node->moderate) {
      $node = book_revision_load($node, array('moderate' => 0, 'status' => 1));
    }

    if ($node) {
      // Output the content:
      if (node_hook($node, 'content')) {
        $node = node_invoke($node, 'content');
      }
      // Allow modules to change $node->body before viewing.
      node_invoke_nodeapi($node, 'view', $node->body, false);

      $output .= '<h1 id="'. $node->nid .'" name="'. $node->nid .'" class="book-h'. $depth .'">'. check_plain($node->title) .'</h1>';

      if ($node->body) {
        $output .= '<ul>'. $node->body .'</ul>';
      }

      $output .= book_print_recurse($node->nid, $depth + 1);
    }
  }

  return $output;
}

function book_admin_view_line($node, $depth = 0) {
  return array('<div style="padding-left: '. (25 * $depth) .'px;">'. form_textfield(NULL, $node->nid .'][title', $node->title, 64, 255) .'</div>', form_weight(NULL, $node->nid .'][weight', $node->weight, 15), l(t('view'), 'node/'. $node->nid), l(t('edit'), 'node/'. $node->nid .'/edit'), l(t('delete'), 'admin/node/delete/'. $node->nid));
}

function book_admin_view_book($nid, $depth = 1) {
  $result = db_query(db_rewrite_sql('SELECT n.nid FROM {node} n INNER JOIN {book} b ON n.nid = b.nid WHERE b.parent = %d ORDER BY b.weight, n.title'), $nid);

  $rows = array();

  while ($node = db_fetch_object($result)) {
    $node = node_load(array('nid' => $node->nid));
    $rows[] = book_admin_view_line($node, $depth);
    $rows = array_merge($rows, book_admin_view_book($node->nid, $depth + 1));
  }

  return $rows;
}

/**
 * Display an administrative view of the hierarchy of a book.
 */
function book_admin_view($nid, $depth = 0) {
  if ($nid) {
    $node = node_load(array('nid' => $nid));

    $output .= '<h3>'. check_plain($node->title) .'</h3>';

    $header = array(t('Title'), t('Weight'), array('data' => t('Operations'), 'colspan' => '3'));
    $rows[] = book_admin_view_line($node);
    $rows = array_merge($rows, book_admin_view_book($nid));

    $output .= theme('table', $header, $rows);
    $output .= form_submit(t('Save book pages'));

    return form($output);
  }
}

function book_admin_save($nid, $edit = array()) {
  if ($nid) {
    $book = node_load(array('nid' => $nid));

    foreach ($edit as $nid => $value) {
      // Check to see whether the title needs updating:
      $title = db_result(db_query('SELECT title FROM {node} WHERE nid = %d', $nid));
      if ($title != $value['title']) {
        db_query("UPDATE {node} SET title = '%s' WHERE nid = %d", $value['title'], $nid);
      }

      // Check to see whether the weight needs updating:
      $weight = db_result(db_query('SELECT weight FROM {book} WHERE nid = %d', $nid));
      if ($weight != $value['weight']) {
        db_query('UPDATE {book} SET weight = %d WHERE nid = %d', $value['weight'], $nid);
      }
    }

    $message = t('Updated book %title.', array('%title' => theme('placeholder', $book->title)));
    watchdog('content', $message);

    return $message;
  }
}

/**
 * Menu callback; displays a listing of all orphaned book pages.
 */
function book_admin_orphan() {
  $result = db_query(db_rewrite_sql('SELECT n.nid, n.title, n.status, b.parent FROM {node} n INNER JOIN {book} b ON n.nid = b.nid'));

  while ($page = db_fetch_object($result)) {
    $pages[$page->nid] = $page;
  }

  if ($pages) {
    $output .= '<h3>'. t('Orphan pages') .'</h3>';
    $header = array(t('Title'), t('Weight'), array('data' => t('Operations'), 'colspan' => '3'));
    foreach ($pages as $nid => $node) {
      if ($node->parent && empty($pages[$node->parent])) {
        $rows[] = book_admin_view_line($node, $depth);
        $rows = array_merge($rows, book_admin_view_book($node->nid, $depth + 1));
      }
    }
    $output .= theme('table', $header, $rows);
  }

  return $output;
}

/**
 * Menu callback; displays the book administration page.
 */
function book_admin($nid = 0) {
  $op = $_POST['op'];
  $edit = $_POST['edit'];

  switch ($op) {
    case t('Save book pages'):