book.module

<?php
// $Id$

function book_node($field) {
  global $user;

  $info["name"] = t("book page");
  $info["description"] = t("A book is a collaborative writing effort: users can collaborate writing the pages of the book, positioning the pages in the right order, and reviewing or modifying pages previously written.  So when you have some information to share or when you read a page of the book and you didn't like it, or if you think a certain page could have been written better, you can do something about it.");

  return $info[$field];
}

function book_access($op, $node) {
  global $user;

  if ($op == "view") {
    /*
    ** Everyone can access all published book pages whether these pages
    ** are still waiting for approval or not.  We might not always want
    ** to display pages that are waiting for approval, but we take care
    ** of that problem in the book_view() function.
    */

    return $node->status;
  }

  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->uid;
  }

  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 upate a book page if there are no suggested updates
    ** of that page waiting for approval, when it is not a PHP-page and
    ** as long as the "create new revision"-bit is set.  That is, only
    ** updates that don't overwrite the current or pending information
    ** are allowed.
    */

    return $user->uid && !$node->moderate && !$node->format && $node->revision;
  }
}

function book_save($op, $node) {
  global $user;

  if ($op == "approve") {
    return array("status" => 1);
  }

  if ($op == "create") {
    if (user_access("administer nodes")) {
      return array("format", "parent", "weight");
    }
    else {
      return array("format", "moderate" => 1, "parent", "promote" => 0, "status" => 1, "weight");
    }
  }

  if ($op == "decline") {
    return array("status" => 0);
  }

  if ($op == "update") {
    if (user_access("administer nodes")) {
      /*
      ** If a node administrator updates a book page, we don't create a
      ** new revision unless we are explicitly instructed to.
      */

      return array("format", "parent", "weight");
    }
    else {
      /*
      ** If a regular user updates a book page, we always create a new
      ** revision.  All new revisions have to be approved (moderation)
      ** and are not promoted by default.  See also: book_load().
      */

      return array("created" => time(), "format", "moderate" => 1, "parent", "promote" => 0, "score" => 0, "status" => 1, "users" => "", "revisions", "votes" => 0, "weight");
    }
  }

}

function book_link($type, $node = 0, $main = 0) {
  if ($type == "page" && user_access("access content")) {
    $links[] = "<a href=\"module.php?mod=book\" title=\"". t("Read and contribute to the collaborative books.") ."\">". t("collaborative book") ."</a>";
  }

  if ($type == "menu.create" && user_access("post content")) {
    $links[] = "<a href=\"module.php?mod=node&op=add&type=book\" title=\"". t("Add a new book page.") ."\">". t("create book page") ."</a>";
  }

  if ($type == "admin" && user_access("administer nodes")) {
    $links[] = "<a href=\"admin.php?mod=book\">". t("collaborative book") ."</a>";
  }

  if ($type == "node" && $node->type == "book" && book_access("update", $node)) {
    $links[] = "<a href=\"module.php?mod=node&op=edit&id=$node->nid\" title=\"". t("Suggest an update for this book page.") ."\">". t("edit this page") ."</a>";
  }

  return $links ? $links : array();
}

function book_load($node) {
  global $user, $REQUEST_URI;

  $book = db_fetch_object(db_query("SELECT format, parent, weight FROM book WHERE nid = '$node->nid'"));

  if (strstr($REQUEST_URI, "module.php?mod=node&op=edit")) {

    /*
    ** If a user is about to update a book page, we overload some
    ** fields to reflect the changes.  We use the $REQUEST_URI to
    ** dectect this as we don't want to interfer with updating a
    ** book page through the admin pages.  See also: book_save().
    */

    if ($user->uid) {
      $book->uid = $user->uid;
      $book->name = $user->name;
    }
    else {
      $book->uid = 0;
      $book->name = "";
    }
  }

  /*
  ** We set the revision field to indicate that we have to create
  ** a new revision when updating this book page.  We enable this
  ** always such that the "edit this page"-links appear.
  */

  $book->revision = 1;

  return $book;
}

function book_insert($node) {
  if (!user_access("administer nodes")) {
    $node->format = 0;
    $node->weight = 0;
  }

  db_query("INSERT INTO book (nid, format, parent, weight) VALUES ('$node->nid', '$node->format', '$node->parent', '$node->weight')");
}

function book_update($node) {
  if (!user_access("administer nodes")) {
    $node->format = 0;
    $node->weight = 0;
  }

  db_query("UPDATE book SET format = '$node->format', parent = '$node->parent', weight = '$node->weight' WHERE nid = '$node->nid'");
}

function book_delete(&$node) {
  db_query("DELETE FROM book WHERE nid = '$node->nid'");
}

function book_form(&$node, &$help, &$error) {
  global $user, $op;

  $output .= form_select(t("Parent"), "parent", $node->parent, book_toc(), t("The parent subject or category the page belongs in."));

  if ($node->format) {
    if ($op != t("Preview")) {
      $node->body = addslashes($node->body);
    }
  }
  else {
    if ($node->teaser) {
      $output .= form_textarea(t("Teaser"), "teaser", $node->teaser, 60, 5, $error["teaser"]);
    }
  }

  $output .= form_textarea(t("Body"), "body", $node->body, 60, 20, t("Allowed HTML tags") .": ". htmlspecialchars(variable_get("allowed_html", "")));
  $output .= form_textarea(t("Log message"), "history", $node->history, 60, 5, t("An explanation of the additions or updates being made to help the group understand your motivations."));

  if (user_access("administer nodes")) {
    $output .= form_select(t("Weight"), "weight", $node->weight, array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30), t("The heavier pages will sink and the lighter pages will be positioned nearer the top."));
    $output .= form_select("Type", "format", $node->format, array(0 => "HTML / text", 1 => "PHP"));
  }
  else {

    /*
    ** Carry out some explanation or submission guidelines:
    */

    $help = book_node("description");

    /*
    ** If a regular user updates a book page, we create a new revision
    ** authored by that user:
    */

    $output .= form_hidden("revision", 1);
  }

  return $output;
}

function book_node_link($node = 0) {
  global $user, $op, $edit;

  if ($node->type != "book") {

    if ($edit["nid"]) {
      $node = node_load(array("nid" => $edit["nid"]));
    }

    if ($op == t("Add to book outline")) {
      db_query("INSERT INTO book (nid, parent, weight) VALUES ('$node->nid', '". check_query($edit["parent"]) ."', '". check_query($edit["weight"]) ."')");
      $output .= status(t("added the node to the book."));
    }

    if ($op == t("Update book outline")) {
      db_query("UPDATE book SET parent = '". check_query($edit["parent"]) ."', weight = '". check_query($edit["weight"]) ."' WHERE nid = '$node->nid'");
      $output .= status(t("updated the book outline."));
    }

    if ($op == t("Remove from book outline")) {
      db_query("DELETE FROM book WHERE nid = '$node->nid'");
      $output .= status(t("removed the node form the book."));
    }

    $output .= "<h3>". t("Edit book outline") ."</h3>";

    if ($edit["nid"]) {
      $page = db_fetch_object(db_query("SELECT * FROM book WHERE nid = '$node->nid'"));

      $output .= form_select(t("Parent"), "parent", $page->parent, book_toc(), t("The parent subject or category the page belongs in."));
      $output .= form_select(t("Weight"), "weight", $page->weight, array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30), t("The heavier pages will sink and the lighter pages will be positioned nearer the top."));

      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"));
      }

    }
    else {
      $output .= form_submit(t("Edit book outline"));
    }

    $output .= form_hidden("nid", $node->nid);

    return form($output, "post", "admin.php?mod=book&op=outline");
  }
}

/*
** 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 = 1;

    foreach ($conditions as $key => $value) {
      if ($node->$key != $value) {
        $status = 0;
      }
    }

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

/*
** Return the path (call stack) to a certain book page.
*/

function book_location($node, $nodes = array()) {
  $parent = db_fetch_object(db_query("SELECT n.nid, n.title, b.parent FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.nid = '$node->parent'"));
  if ($parent->title) {
    $nodes = book_location($parent, $nodes);
    array_push($nodes, $parent);
  }
  return $nodes;
}

function book_body($node) {
  global $theme, $op;

  if ($node->format == 1) {
    /*
    ** Make sure only authorized users can preview PHP pages.
    */

    if ($op == t("Preview")) {
      if (user_access("administer nodes")) {
        $node->body = stripslashes($node->body);  // see also book_form()
      }
      else {
        return;
      }
    }

    ob_start();
    eval($node->body);
    $output = ob_get_contents();
    ob_end_clean();
  }
  else {
    $output = check_output(filter($node->body), 1);
  }

  return $output;
}

function book_view($node, $main = 0) {
  global $theme, $mod;

  /*
  ** 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 ($node->moderate && $mod != "queue") {
    $revision = book_revision_load($node, array("moderate" => 0, "status" => 1));

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

  /*
  ** Extract the page body.  If body is dynamic (using PHP code), the body
  ** will be generated.
  */

  $node->body = book_body($node);

  /*
  ** Display the node.  If not displayed on the main page, we render
  ** the node as a page in the book with extra links to the previous
  ** and the next page.
  */

  if ($main) {
    $theme->node($node, $main);
  }
  else {
    /*
    ** Construct the "next" and "previous" links:
    */

    if ($node->nid && $node->parent) {
      $next = db_fetch_object(db_query("SELECT n.nid, n.title FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = 1 AND b.parent = '$node->parent' AND (b.weight > '$node->weight' OR (b.weight = '$node->weight' AND n.title > '". check_query($node->title) ."')) AND (n.moderate = 0 OR n.revisions != '') ORDER BY b.weight ASC, n.title ASC"));
      $prev = db_fetch_object(db_query("SELECT n.nid, n.title FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = 1 AND b.parent = '$node->parent' AND (b.weight < '$node->weight' OR (b.weight = '$node->weight' AND n.title < '". check_query($node->title) ."')) AND (n.moderate = 0 OR n.revisions != '') ORDER BY b.weight DESC, n.title DESC"));
    }

    $output .= "<table border=\"0\" cellpadding=\"1\" cellspacing=\"1\" width=\"100%\">";

    if ($node->title) {
      foreach (book_location($node) as $level) {
        $location .= "$indent <a href=\"node.php?id=$level->nid\">$level->title</a><br />";
        $indent .= "-";
      }

      $output .= " <tr><td colspan=\"3\">$location</td></tr>";
      $output .= " <tr><td colspan=\"3\"><hr /></td></tr>";
      $output .= " <tr><td colspan=\"3\"><b><big>". check_output($node->title) ."</big></b>". ($node->body ? "<br /><small><i>". sprintf(t("Last updated by %s on %s"), format_name($node), format_date($node->created)) ."</i></small> " : "") ."</td></tr>";
    }

    if ($node->body) {
      $output .= " <tr><td colspan=\"3\"><br />$node->body</td></tr>";
    }

    if ($node->nid) {
      $output .= " <tr><td colspan=\"3\"><br />". book_tree($node->nid) ."</td></tr>";
    }

    $output .= " <tr><td colspan=\"3\"><hr /></td></tr>";
    $output .= " <tr><td align=\"left\" width=\"33%\">". ($prev ? "<a href=\"node.php?id=$prev->nid\" title=\"". t("View the previous page in this book.") ."\">". t("previous") ."</a>" : t("previous")) ."</td><td align=\"center\" width=\"34%\"><a href=\"module.php?mod=book\" title=\"". t("View this book's table of contents.") ."\">index</a></td><td align=\"right\" width=\"33%\">". ($next ? "<a href=\"node.php?id=$next->nid\" title=\"". t("View the next page in this book.") ."\">". t("next") ."</a>" : t("next")) ."</td></tr>";
    $output .= " <tr><td align=\"left\" width=\"33%\">". ($prev ? "<small>". check_output($prev->title) ."</small>" : "&nbsp;") ."</td><td align=\"center\" width=\"34%\">". ($node->parent ? "<a href=\"node.php?id=$node->parent\" title=\"". t("View this page's parent section.") ."\">". t("up") ."</a>" : t("up")) ."</td><td align=\"right\" width=\"33%\">". ($next ? "<small>". check_output($next->title) ."</small>" : "&nbsp;") ."</td></tr>";
    $output .= " <tr><td colspan=\"3\"><hr /></td></tr>";
    $output .= " <tr><td colspan=\"3\" align=\"right\"><div style=\"margin: 10 10 10 10;\">". $theme->links(link_node($node, $main)) ."</div></td></tr>";
    $output .= "</table>";

    $theme->box(t("Handbook"), $output);
  }
}

function book_toc_recurse($nid, $indent, $toc, $children) {

  if ($children[$nid]) {
    foreach ($children[$nid] as $foo => $node) {
      $toc[$node->nid] = "$indent $node->title";
      $toc = book_toc_recurse($node->nid, "$indent--", $toc, $children);
    }
  }

  return $toc;
}

function book_toc($parent = 0, $indent = "", $toc = array()) {

  $result = db_query("SELECT n.nid, n.title, b.parent FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = '1' 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 the user is an administrator, add the root node; only
  ** administrators can start new books.
  */

  if (user_access("administer nodes")) {
    $toc[0] = "<root>";
  }

  /*
  ** Iterate root book nodes:
  */

  $toc = book_toc_recurse($parent, $indent, $toc, $children);

  return $toc;
}


function book_tree_recurse($nid, $depth, $children) {

  if ($depth > 0) {
    if ($children[$nid]) {
      foreach ($children[$nid] as $foo => $node) {
        $output .= "<li><a href=\"node.php?id=$node->nid\">". check_output($node->title) ."</a></li>";

        if ($tree = book_tree_recurse($node->nid, $depth - 1, $children)) {
          $output .= "<ul>$tree</ul>";
        }
      }
    }
  }

  return $output;
}


function book_tree($parent = 0, $depth = 3) {

  $result = db_query("SELECT n.nid, n.title, b.parent FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = '1' 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;
  }

  $output = book_tree_recurse($parent, $depth, $children);
  $output = "<ul>$output</ul>";

  return $output;
}


function book_render() {
  global $theme;

  $result = db_query("SELECT n.nid FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE b.parent = 0 AND n.status = 1 AND (n.moderate = 0 OR n.revisions != '') ORDER BY b.weight");

  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:
      $output .= "<dt><a href=\"node.php?id=$node->nid\">". check_output($node->title) ."</a></dt><dd>". book_body($node) ."<br /><br /></dd>";
    }
  }

  $theme->header();
  $theme->box(t("Handbook"), "<dl>$output</dl>");
  $theme->footer();
}

function book_page() {
  global $op, $id, $theme;

  if (user_access("access content")) {
    switch ($op) {
      case "feed":
        print book_export_html($id, $depth = 1);
        break;
      default:
        book_render();
    }
  }
  else {
    $theme->header();
    $theme->box(t("Access denied"), message_access());
    $theme->footer();
  }
}

function book_export_html($id = "", $depth = 1) {
  $result = db_query("SELECT n.nid FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = 1 AND n.nid = '". check_input($id) ." AND (n.moderate = 0 OR n.revisions != '')'");

  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:
      $output .= "<h$depth>". check_output($node->title) ."</h$depth>";

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

  $output .= book_export_html_recurse($id, $depth);

  return $output;
}

function book_export_html_recurse($parent = "", $depth = 1) {
  $result = db_query("SELECT n.nid FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.status = 1 AND b.parent = '$parent' AND (n.moderate = 0 OR n.revisions != '') ORDER BY b.weight");

  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:
      $output .= "<h$depth>". check_output($node->title) ."</h$depth>";

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

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

  return $output;
}

function book_admin_view_line($node, $depth = 0) {

  /*
  ** Extract the revision number:
  */

  if ($list = node_revision_list($node)) {
    $revision = end($list);
  }
  else {
    $revision = 0;
  }

  /*
  ** Diplay the book page:
  */

  $output .= "<tr>";
  $output .= " <td><div style=\"padding-left: ". (25 * $depth) ."px;\"><a href=\"node.php?id=$node->nid\">". check_output($node->title) ."</a></div></td>";
  $output .= " <td align=\"center\">$revision</td>";
  $output .= " <td><a href=\"admin.php?mod=node&op=edit&id=$node->nid\">". t("edit node") ."</td>";
  //TODO: get this link to work. Must pass $nid along so it is received by book_node_link()  
  //$output .= " <td><a href=\"admin.php?mod=book&nid=$node->nid&op=Edit+book+outline\">". t("edit book outline") ."</td>";
  $output .= " <td><a href=\"admin.php?mod=node&op=delete&id=$node->nid\">". t("delete node") ."</td>";
  $output .= "</tr>";

  return $output;
}

function book_admin_view_book($nid, $depth = 1) {
  $weight = array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30);

  $result = db_query("SELECT n.nid FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE b.parent = '$nid' ORDER BY b.weight, n.title");

  while ($node = db_fetch_object($result)) {
    $node = node_load(array("nid" => $node->nid));
    $output .= book_admin_view_line($node, $depth);
    $output .= book_admin_view_book($node->nid, $depth + 1);
  }

  return $output;
}

function book_admin_view($nid, $depth = 0) {

  $node = node_load(array("nid" => $nid));

  $output .= "<h3>". check_output($node->title) ."</h3>";
  $output .= "<table border=\"1\" cellpadding=\"2\" cellspacing=\"2\">";
  //TODO: change colspan below to 3 after adding new link in book_admin_view_line()   
  $output .= " <tr><th>title</th><th>rev</th><th colspan=\"2\">operations</th></tr>";
  $output .= book_admin_view_line($node);
  $output .= book_admin_view_book($nid);
  $output .= "</table>";

  return $output;
}

function book_admin_orphan() {

  $result = db_query("SELECT n.nid, n.title, b.parent FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE n.type = 'book'");

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

  $output .= "<table border=\"1\" cellpadding=\"2\" cellspacing=\"2\">";
  $output .= " <tr><th>title</th><th colspan=\"2\">operations</th></tr>";
  foreach ($pages as $nid => $node) {
    if ($node->parent && empty($pages[$node->parent])) {
      $output .= "<tr><td><a href=\"node.php?id=$node->nid\">". check_output($node->title) ."</a></td><td><a href=\"admin.php?mod=node&op=edit&id=$node->nid\">". t("edit page") ."</td><td><a href=\"admin.php?mod=node&op=delete&id=$node->nid\">". t("delete page") ."</td>";
    }
  }
  $output .= "</table>";

  return $output;
}

function book_admin_links() {
  $result = db_query("SELECT n.nid, n.title FROM node n LEFT JOIN book b ON n.nid = b.nid WHERE b.parent = 0 ORDER BY b.weight, n.title");

  while ($book = db_fetch_object($result)) {
    $links[] = "<a href=\"admin.php?mod=book&op=view&id=$book->nid\">". t("book") .": <i>". check_output($book->title) ."</i></a>";
  }
  $links[] = "<a href=\"admin.php?mod=book&op=orphan\">". t("orphan pages") ."</a>";
  $links[] = "<a href=\"module.php?mod=book&op=feed\" title=\"" . t("display all books in a single HTML page") . ".\">" . t("export to HTML") . "</a>";
  $links[] = "<a href=\"admin.php?mod=book&op=help\">" . t("help") . "</a>";
  return $links;
}

function book_admin() {
  global $id, $op;

  if (user_access("administer nodes")) {

    /*
    ** Compile a list of the administrative links:
    */

    $links = book_admin_links();
    
    print "<small>". implode(" &middot; ", $links) ."</small><hr />";

    switch ($op) {
      case t("Edit book outline"):
      case t("Add to book outline"):
      case t("Remove from book outline"):
      case t("Update book outline"):
        print book_node_link();
        break;
      case "orphan":
        print book_admin_orphan();
        break;
      case "view":
        print book_admin_view($id);
        break;
      case "help":
        book_help();
        break;
      default:
    }
  }
}

function book_help() {
  ?>
  
<p>The Collaborative Book is a magnificient mechanism for organizing content authored by many users.
You may use it to organize a Manual (e.g. <a href="http://www.drupal.org">Drupal Handbook</a>),
to <a href="#faq">maintain an FAQ</a>, or to manage any outline-like content. Books can have
Chapters, Sections, etc. In fact, books can have an arbitrarily deep nesting strucuture.</p>

<p>Under the covers, a Book is only an organization of nodes. These nodes are often of type <i>book page</i>,
but can be of any content type. Every node in the book has a <i>Parent</i>. The Parent is the node
which "contains" the child node. This is how book.module establishes its hierarchy. On any given level
in the hierarchy, a book can contain many nodes. Book uses the Weight field to order these sibling nodes.</p>

<p>Book pages are a special, powerful node type. These nodes are specifically designed to be included in a book.
Their special power comes from the bilility to embed PHP within the body of the page. This capability is only offerred
to Administrators, since malicious users could abuse this power. In addiiton, book pages contain a 'Log Message'
field which helps your users understand the motivation behind an edit of a book page. Each edited version of a book
page is usually stored as a new revision of a node. This capability makes it easy to revert to an old version of a page,
should that become desirable.</p>

<p>Like other node types, Book submissions and edits may be subject to moderation, depending on your configuration.
Similarly, Books use <a href="/admin.php?mod=user&op=permission">permissions</a> to determine who may
read and write to them. Only Administrators are allowed to create new books, which are really just nodes whose
Parent is <i>&lt;root&gt;</i>. To include an existing node in your book, click on the Administer link in that node.
At the bottom of this Admin page, click on the <i>Edit Book Outline</i> button. This enables you to place the node
wherever you'd like within the book hierarchy. To add a new node into your book, use the <i>create book page</i> link.</p>

<p>Administrators may review the hierarchy of their books by clicking on the <a href="/admin.php?mod=book">Collaborative Book link</a>
in the Admin center. There, nodes may be edited, reorganized, removed from book, and deleted. This behavior may change in the future. When a Parent node is deleted, he may leave behind child nodes.
These nodes are now <i>orphans</i>. Administrators should periodically <a href="/admin.php?mod=book&op=orphan">
review their books for orphans</a> and reaffiliate those pages as desired. Finally, administrators may also
<a href="/admin.php?mod=book&op=feed">export their books</a> to a single, flat HTML page which is suitable for printing.</p>

<a name="faq"></a><h3>Maintain an FAQ with <i>Collaborative Book</i></h3>

<p>The Collaborative Book (i.e. <code>book.module</code>) in Drupal is a
terrific way to easily manage an FAQ (Frequently Asked Questions) section of
your web site. The main benefit for an administrator is that you don't have
to write all the questions/answers by yourself. Let the community do it for
you!</p>

<p>In order to setup the FAQ, you have to create a new <i>Book</i> which will
hold all your content. To do so, click on <i>Create Book Page</i> in your
user box. Give it a thoughtful Title, and Body. A title like "Estonia
Travel - FAQ" is nice. You may always edit these fields later. You will
probably want to designate <i><root></i> as the Parent of this page. Leave
the <i>Log Message</i> and <i>Type</i> fields blank for now. After you've
submitted this book page, you are ready to begin filling up your book with
Questions that are Frequently Asked.</p>

<p>Whenever you come across a post which you want to include in your FAQ,
click on the <i>administer</i> link. Then click on the <i>Edit book
outline</i> button at the bottom of the page. Then place the relevant post
wherever is most appropriate in your book by selecting a <i>Parent</i>. Books
are quite flexible. They can have sections like <i>Flying to Estonia</i>,
<i>Eating in Estonia</i> and so on. As you get more experienced with the
<i>Collaborative Book</i>, you can reorganize posts in your book so that it
stays organized.</p>

<p>Notes:</p>
<ul>
<li>any comments attached to those relevant posts which you designate as book
pages will also be transported into your book. This is a great feature, since
much wisdom is shared via comments. And remember that all future comments and
edits will automatically be reflected in your book.</li>
<li>You may wish to edit the title and teaser of posts when adding them to
your FAQ. This is done on the same page as the <i>Edit book outline</i>
button. Clear titles help users navigate quickly to the information that they
seek.
</li>
<li>Book pages may come from any content type (blog, story, page, etc.). If
you are creating a post solely for inclusion in your book, then use the
<i>Create book page</i> link.</li>
<li>If you don't see the <i>administer</i> link, then you probably have
insufficient <a
href="/admin.php?mod=user&op=permission">permissions</a>.</li>
<li>If you want to get really fancy, note that Books are one of the few
content types which allow raw PHP in their <i>body</i>. So you've got lots of
geeky possibilities there.</li>
</ul>

  <?php
  
}  
?>