node.module

<?php
// $Id$

function node_help($section = "admin/help#node") {
  global $mod;
  $output = "";

  switch ($section) {

    case 'admin/help#node':
      $output .= "<h3>Nodes</h3>";
      $output .= "<p>The core of the Drupal system is the node. All of the contents of the system are placed in nodes, or extensions of nodes.";
      $output .= "A base node contains:<dl>";
      $output .= "<dt>A Title</dt><dd>Up to 128 characters of text that titles the node.</dd>";
      $output .= "<dt>A Teaser</dt><dd>A small block of text that is meant to get you interested in the rest of node. Drupal will automatically pull a small amount of the body of the node to make the teaser (To configure how long the teaser will be <a href=\"%teaser\">click here</a>). The teaser can be changed if you don't like what Drupal grabs.</dd>";
      $output .= "<dt>The Body</dt><dd>The main text that comprises your content.</dd>";
      $output .= "<dt>A Type</dt><dd>What kind of node is this? Blog, book, forum, comment, unextended, etc.</dd>";
      $output .= "<dt>An Author</dt><dd>The author's name. It will either be \"anonymous\" or a valid user. You <i>cannot</i> set it to an arbitrary value.</dd>";
      $output .= "<dt>Authored on</dt><dd>The date the node was written.</dd>";
      $output .= "<dt>Changed</dt><dd>The last time this node was changed.</dd>";
      $output .= "<dt>Static on front page</dt><dd>The front page is configured to show the teasers from only a few of the total nodes you have on your site (To configure how many teasers <a href=\"%teaser\">click here</a>), but if you think a node is important enough that you want it to stay on the front page enable this.</dd>";
      $output .= "<dt>Allow user comments</dt><dd>A node can have comments. These comments can be written by other users (Read-write), or only by admins (Read-only).</dd>";
      $output .= "<dt>Attributes</dt><dd>A way to sort nodes.</dd>";
      $output .= "<dt>Revisions</dt><dd>Drupal has a revision system so that you can \"roll back\" to an older version of a post if the new version is not what you want.</dd>";
      $output .= "<dt>Promote to front page</dt><dd>To get people to look at the new stuff on your site you can choose to move it to the front page.</dd>";
      $output .= "<dt>In moderation queue</dt><dd>Drupal has a moderation system. If it is active, a node is in one of three states: approved and published, approved and unpublished, and awaiting approval. If you are moderating a node it should be in the moderation queue.</dd>";
      $output .= "<dt>Votes</dt><dd>If you are moderating a node this counts how many votes the node has gotten. Once a node gets a certain number of vote it will either be approved or dropped.";
      $output .= "<dt>Score</dt><dd>The score of the node is gotten by the votes it is given.</dd>";
      $output .= "<dt>Users</dt><dd>The list of users who have voted on a moderated node.</dd>";
      $output .= "<dt>Published</dt><dd>When using Drupal's moderation system a node remains unpublished -- unavaliable to non-moderators -- until it is marked Published.</dd></dl>";
      $output .= "<p>Now that you know what is in a node, here are some of the types of nodes available.</p>";

      $output = t($output, array("%teaser" => url("admin/system/modules/node")));

      if ($mod == "admin") {
        foreach (module_list() as $name) {
          if (module_hook($name, "node") && $name != "node") {
            $output .= "<h3>". t("Node type: %module", array("%module" => module_invoke($name, "node", "name"))) ."</h3>";
            $output .= module_invoke($name, "node", "description");
          }
        }
      }
      break;

    case 'admin/system/modules#description':
      $output = t("The core that allows content to be submitted to the site.");
      break;
    case 'admin/system/modules/node':
      $output = t("Settings for the core of Drupal. Almost everything is a node so these settings will affect most of the site.");
      break;
    case 'admin/node':
      $output = t("Below is a list of all of the nodes in your site. Other forms of content are listed elsewhere (e.g. <a href=\"%comments\">comments</a>).<br />Clicking a title views that node, while clicking an author's name edits their user information.<br />Other node-related tasks are available from the menu on the left.", array("%comments" => url("admin/comment")));
      break;
    case 'admin/node/search':
      $output = t("Enter a simple pattern to search for a post. This can include the wildcard character *.<br />For example, a search for \"br*\" might return \"bread bakers\", \"our daily bread\" and \"brenda\".");
      break;
    case 'admin/node/settings':
      $output = t("This page lets you set the defaults used during creation of nodes for all the different node types.<br /><strong>comment:</strong> Read/write setting for comments.<br /><strong>publish:</strong> Is this node publicly viewable, has it been published?<br /><strong>promote:</strong> Is this node to be promoted to the front page?<br /><strong>moderate:</strong> Does this node need approval before it can be viewed?<br /><strong>static:</strong> Is this node always visible on the front page?<br /><strong>revision:</strong> Will this node go into the revision system allowing multiple versions to be saved?");
      break;

  }

  return $output;
}

function node_help_page() {
  print theme("page", node_help());
}


/*
** Accepts a DB result object which can be used to fetch node objects.
** Returns an HTML list suitable as content for a block.
*/
function node_title_list($result, $title = NULL) {
  while ($node = db_fetch_object($result)) {
    $number = module_invoke("comment", "num_all", $node->nid);
    $items[] = l($node->title, "node/view/$node->nid", array("title" => format_plural($number, "%count comment", "%count comments")));
  }

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

function theme_node_list($items, $title = NULL) {
  return theme("item_list", $items, $title);
}

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

  if ($user->uid) {
    $result = db_query("SELECT timestamp FROM {history} WHERE uid = %d AND nid = %d", $user->uid, $nid);
    if (db_fetch_object($result)) {
      db_query("UPDATE {history} SET timestamp = %d WHERE uid = %d AND nid = %d", time(), $user->uid, $nid);
    }
    else {
      db_query("INSERT INTO {history} (uid, nid, timestamp) VALUES (%d, %d, %d)", $user->uid, $nid, time());
    }
  }
}

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

  $history = db_fetch_object(db_query("SELECT timestamp FROM {history} WHERE uid = '$user->uid' AND nid = %d", $nid));
  return ($history->timestamp ? $history->timestamp : 0);
}

/**
 * Determines whether the supplied timestamp is newer than the user's last view
 * of a given node
 *
 * @param $nid node-id twhose history supplies the 'last viewed' timestamp
 * @param $timestamp time which is compared against node's 'last veiwed'
 *   timestamp
 */
function node_is_new($nid, $timestamp) {
  global $user;
  static $cache;

  if (!isset($cache[$nid])) {
    if ($user->uid) {
      $history = db_fetch_object(db_query("SELECT timestamp FROM {history} WHERE uid = %d AND nid = %d", $user->uid, $nid));
      $cache[$nid] = $history->timestamp ? $history->timestamp : 0;
    }
    else {
      $cache[$nid] = time();
    }
  }

  if ($timestamp > $cache[$nid]) {
    return 1;
  }
  else {
    return 0;
  }
}

function node_teaser($body) {

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

  /*
  ** If the size is zero, teasers are disabled so we
  ** return the entire body.
  */

  if ($size == 0) {
    return $body;
  }

  /*
  ** If a valid delimiter has been specified, use it to
  ** chop of the teaser.  The delimiter can be outside
  ** the allowed range but no more than a factor two.
  */

  $delimiter = strpos($body, "<!--break-->");
  if ($delimiter > 0) {
    return substr($body, 0, $delimiter);
  }

  /*
  ** If we have a short body, return the entire body:
  */

  if (strlen($body) < $size) {
    return $body;
  }

  /*
  ** In some cases no delimiter has been specified (eg.
  ** when posting using the Blogger API) in which case
  ** we try to split at paragraph boundaries.
  */

  if ($length = strpos($body, "</p>", $size)) {
    return substr($body, 0, $length + 4);
  }

  if ($length = strpos($body, "<br />", $size)) {
    return substr($body, 0, $length);
  }

  if ($length = strpos($body, "<br>", $size)) {
    return substr($body, 0, $length);
  }

  if ($length = strpos($body, "\n", $size)) {
    return substr($body, 0, $length);
  }

  /*
  ** When even the first paragraph is too long, try to
  ** split at the end of the next sentence.
  */

  if ($length = strpos($body, ". ", $size)) {
    return substr($body, 0, $length + 1);
  }

  if ($length = strpos($body, "! ", $size)) {
    return substr($body, 0, $length + 1);
  }

  if ($length = strpos($body, "? ", $size)) {
    return substr($body, 0, $length + 1);
  }

  /*
  ** Nevermind, we split it the hard way ...
  */

  return substr($body, 0, $size);
}

function node_invoke(&$node, $hook, $a2 = NULL, $a3 = NULL, $a4 = NULL) {
  if (is_array($node)) {
    $function = $node["type"] ."_$hook";
  }
  else if (is_object($node)) {
    $function = $node->type ."_$hook";
  }
  else if (is_string($node)) {
    $function = $node ."_$hook";
  }

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

function node_invoke_nodeapi(&$node, $op, $arg = 0) {
  $return = array();
  foreach (module_list() as $name) {
    $function = $name ."_nodeapi";
    if (function_exists($function)) {
      $result = $function($node, $op, $arg);
      if (isset($result)) {
        $return = array_merge($return, $result);
      }
    }
  }
  return $return;
}

function node_load($conditions, $revision = -1) {

  /*
  ** Turn the conditions into a query:
  */

  foreach ($conditions as $key => $value) {
    $cond[] = "n.". check_query($key) ." = '". check_query($value) ."'";
  }

  /*
  ** Retrieve the node:
  */

  $node = db_fetch_object(db_query("SELECT n.*, u.uid, u.name FROM {node} n INNER JOIN {users} u ON u.uid = n.uid WHERE ". implode(" AND ", $cond)));

  /*
  ** Unserialize the revisions field:
  */

  if ($node->revisions) {
    $node->revisions = unserialize($node->revisions);
  }

  /*
  ** Call the node specific callback (if any) and piggy-back the
  ** results to the node or overwrite some values:
  */

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

  /*
  ** Return the desired revision
  */
  if ($revision != -1 && isset($node->revisions[$revision])) {
    $node = $node->revisions[$revision]["node"];
  }

  return $node;
}

function node_save($node) {

  /*
  ** Fetch fields to save to node table:
  */
  $fields = node_invoke_nodeapi($node, "fields");

  /*
  ** Serialize the revisions field:
  */

  if ($node->revisions) {
    $node->revisions = serialize($node->revisions);
  }

  /*
  ** Apply filters to some default node fields:
  */

  if (empty($node->nid)) {

    /*
    ** Insert a new node:
    */

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

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

    $keysfmt = implode(", ", $s);
    // need to quote the placeholders for the values
    $valsfmt = "'". implode("', '", $s) ."'";

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

    // Call the node specific callback (if any):
    node_invoke($node, "insert");
    node_invoke_nodeapi($node, "insert");
  }
  else {

    /*
    ** Update an existing node:
    */

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

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

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

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

  /*
  ** Clear the cache so an anonymous poster can see the node being
  ** added or updated.
  */

  cache_clear_all();

  /*
  ** Return the node ID:
  */

  return $node->nid;

}

function node_view($node, $main = 0, $page = 0) {

  $node = array2object($node);

  /*
  ** Remove the delimiter (if any) that seperates the teaser from the
  ** body. TODO: this strips legitimate uses of '<!--break-->' also.
  */

  $node->body = str_replace("<!--break-->", "", $node->body);

  /*
  ** The "view" hook can be implemented to overwrite the default function
  ** to display nodes.
  */

  if (module_hook($node->type, "view")) {
    return node_invoke($node, "view", $main, $page);
  }
  else {

    /*
    ** Default behavior:
    */

    return theme("node", node_prepare($node, $main), $main, $page);
  }
}

function node_prepare($node, $main = 0) {
  if ($main == 0) {
    $node->body = check_output($node->body);
  }
  else {
    $node->teaser = check_output($node->teaser);
  }
  return $node;
}

function node_show($node, $cid) {

  if (node_access("view", $node)) {

    $output = node_view($node, 0, 1);

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

    /*
    ** Update the history table, stating that this user viewed this node.
    */

    node_tag_new($node->nid);

    return $output;
  }
  else {
    drupal_set_message(message_access());
  }
}

function node_access($op, $node = 0) {

  if (user_access("administer nodes")) {
    return 1;
  }

  /*
  ** Convert the node to an object if necessary:
  */

  $node = array2object($node);

  /*
  ** Construct a function:
  */

  if ($node->type) {
    $type = $node->type;
  }
  else {
    $type = $node;
  }

  // Can't use node_invoke:
  // the access hook takes the $op parameter before the $node parameter.
  return module_invoke($type, "access", $op, $node);
}

function node_perm() {
  return array("administer nodes", "access content");
}

function node_search($keys) {

  // Return the results of performing a search using the indexed search
  // for this particular type of node.
  //
  // Pass an array to the "do_search" function which dictates what it
  // will search through, and what it will search for
  //
  // "keys"'s value is the keywords entered by the user
  //
  // "type"'s value is used to identify the node type in the search
  // index.
  //
  // "select"'s value is used to relate the data from the specific nodes
  // table to the data that the search_index table has in it, and the the
  // do_search functino will rank it.
  //
  // The select must always provide the following fields - lno, title,
  // created, uid, name, count
  //
  $find = do_search(array("keys" => $keys, "type" => "node", "select" => "select s.lno as lno, n.title as title, n.created as created, u.uid as uid, u.name as name, s.count as count FROM {search_index} s, {node} n INNER JOIN {users} u ON n.uid = u.uid WHERE s.lno = n.nid AND s.type = 'node' AND s.word like '%' AND n.status = 1"));

  return $find;
}

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

  return $output;
}

function node_comment_mode($nid) {
  static $comment_mode;
  if (!isset($comment_mode[$nid])) {
    $comment_mode[$nid] = db_result(db_query("SELECT comment FROM {node} WHERE nid = %d", $nid));
  }
  return $comment_mode[$nid];
}

function node_link($type, $node = 0, $main = 0) {

  $links = array();

  if ($type == "node") {
    if ($node->links) {
      $links = $node->links;
    }

    if ($main == 1 && $node->teaser && strlen($node->teaser) != strlen($node->body)) {
      $links[] = l(t("read more"), "node/view/$node->nid", array("title" => t("Read the rest of this posting."), "class" => "read-more"));
    }

    if (user_access("administer nodes")) {
      $links[] = l(t("administer"), "admin/node/edit/$node->nid", array("title" => t("Administer this node.")));
    }

    if (user_access("administer nodes") && $node->revisions) {
      $links[] = l(t("revisions"), "node/revisions/$node->nid", array("title" => t("Administer revisions.")));
    }
  }

  if ($type == "system") {
    menu("node/add", t("create content"), 'node_page', 1, MENU_HIDE_NOCHILD);

    if (user_access("administer nodes")) {
      menu("admin/node", t("content"), "node_admin");
      menu("admin/node/search", t("search"), "node_admin", 8);
      menu("admin/node/help", t("help"), "node_help_page", 9);
      menu("admin/node/edit", t("edit post"), "node_admin", 0, MENU_HIDE);
      menu("admin/node/settings", t("settings"), "node_admin", 8);
    }

    if (user_access("access content")) {
      menu("node", t("content"), "node_page", 0, MENU_HIDE);
    }
  }

  return $links;
}

function node_admin_edit($node) {

  if (is_numeric($node)) {
    $node = node_load(array("nid" => $node));
  }

  $output .= node_form($node);

  /*
  ** Display the node form extensions:
  */
  $output .= implode("\n", module_invoke_all("node_link", $node));

  return $output;

}

function node_admin_nodes() {
  $filters = array(
    array(t("View posts that are new or updated"), "ORDER BY n.changed DESC"),
    array(t("View posts that need approval"), "WHERE n.status = 0 OR n.moderate = 1 ORDER BY n.changed DESC"),
    array(t("View posts that are promoted"), "WHERE n.status = 1 AND n.promote = 1 ORDER BY n.changed DESC"),
    array(t("View posts that are not promoted"), "WHERE n.status = 1 AND n.promote = 0 ORDER BY n.changed DESC"),
    array(t("View posts that are static"), "WHERE n.status = 1 AND n.static = 1 ORDER BY n.changed DESC"),
    array(t("View posts that are unpublished"), "WHERE n.status = 0 AND n.moderate = 0 ORDER BY n.changed DESC")
   );

  $operations = array(
    array(t("Approve the selected posts"), "UPDATE {node} SET status = 1, moderate = 0 WHERE nid = %d"),
    array(t("Promote the selected posts"), "UPDATE {node} SET status = 1, promote = 1 WHERE nid = %d"),
    array(t("Make the selected posts static"), "UPDATE {node} SET status = 1, static = 1 WHERE nid = %d"),
    array(t("Demote the selected posts"), "UPDATE {node} SET promote = 0 WHERE nid = %d"),
    array(t("Unpublish the selected posts"), "UPDATE {node} SET status = 0 WHERE nid = %d")
  );

  /*
  ** Handle operations:
  */

  if (empty($_SESSION["node_overview_filter"])) {
    $_SESSION["node_overview_filter"] = 0;
  }

  if (isset($_POST["edit"]["filter"])) {
    $_SESSION["node_overview_filter"] = $_POST["edit"]["filter"];
  }

  if (isset($_POST["edit"]["operation"])) {
    $operation = $operations[$_POST["edit"]["operation"]][1];
    foreach ($_POST["edit"]["status"] as $nid => $value) {
      if ($value) {
        db_query($operation, $nid);
      }
    }

    drupal_set_message(t("the update has been performed."));
  }

  $filter = $_SESSION["node_overview_filter"];

  /*
  ** Render filter form:
  */

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

  $form  = form_select(NULL, "filter", $filter, $options);
  $form .= form_submit(t("Go"));

  $output .= "<h3>". t("Filter options") ."</h3>";
  $output .= "<div class=\"container-inline\">$form</div>";

  /*
  ** Render operations form:
  */

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

  $form = form_select(NULL, "operation", 0, $options);
  $form .= form_submit(t("Go"));

  $output .= "<h3>". t("Update options") ."</h3>";
  $output .= "<div class=\"container-inline\">$form</div>";

  /*
  ** Overview table:
  */

  $result = pager_query("SELECT n.*, u.name, u.uid FROM {node} n INNER JOIN {users} u ON n.uid = u.uid ". $filters[$filter][1], 50);
  $header = array(NULL, t("title"), t("type"), t("author"), t("status"), array("data" => t("operations"), "colspan" => 2));

  while ($node = db_fetch_object($result)) {
    $rows[] = array(form_checkbox(NULL, "status][$node->nid", 1, 0), l($node->title, "node/view/$node->nid") ." ". (node_is_new($node->nid, $node->changed) ? theme_mark() : ""), module_invoke($node->type, "node", "name"), format_name($node), ($node->status ? t("published") : t("not published")), l(t("edit node"), "admin/node/edit/$node->nid"), l(t("delete node"), "admin/node/delete/$node->nid"));
  }

  if ($pager = theme("pager", NULL, 50, 0)) {
    $rows[] = array(array("data" => $pager, "colspan" => 7));
  }

  $output .= "<h3>". $filters[$filter][0] ."</h3>";
  $output .= theme("table", $header, $rows);
  return form($output);
}

function node_admin_settings($edit) {
  $op = $_POST["op"];

  if ($op == t("Save configuration")) {
    /*
    ** Save the configuration options:
    */

    foreach ($edit as $name => $value) {
      variable_set($name, $value);
    }
    drupal_set_message(t("the content settings have been saved."));
  }

  if ($op == t("Reset to defaults")) {
    /*
    ** Reset the configuration options to their default value:
    */

    foreach ($edit as $name => $value) {
      variable_del($name);
    }
    drupal_set_message(t("the content settings have been reset to their default values."));
  }

  $header = array_merge(array(t("type")), array_keys(node_invoke_nodeapi($node, "settings")));
  foreach (module_list() as $name) {
    if (module_hook($name, "node")) {
      $node->type = $name;
      $cols = array();
      foreach (node_invoke_nodeapi($node, "settings") as $setting) {
        $cols[] = array("data" => $setting, "align" => "center", "width" => 55);
      }
      $rows[] = array_merge(array(module_invoke($name, "node", "name")), $cols);
    }
  }

  $output .= theme("table", $header, $rows);

  /* This is an idea for the future.
  foreach (module_list() as $name) {
    if (module_hook($name, "node")) {
      $node->type = $name;

      // Create theme("table", ) data:
      $header = array_keys(node_invoke_nodeapi($node, "settings"));
      $cols = array();
      foreach (node_invoke_nodeapi($node, "settings") as $setting) {
        $cols[] = array("data" => $setting, "align" => "center", "width" => 75);
      }

      $output .= "<h2>". module_invoke($name, "node", "name") ."</h2>";
      $output .= theme("table", $header, array($cols));
      $output .= "<br /><br />";
    }
  }
  */

  $output .= form_submit(t("Save configuration"));
  $output .= form_submit(t("Reset to defaults"));

  return form($output);

}

function node_revision_overview($nid) {

  if (user_access("administer nodes")) {
    $node = node_load(array("nid" => $nid));

    if ($node->revisions) {
      $header = array(t("older revisions"), array("colspan" => "3", "data" => t("operations")));

      foreach ($node->revisions as $key => $revision) {
        $rows[] = array(t("revision #%r revised by %u on %d", array("%r" => $key, "%u" => format_name(user_load(array("uid" => $revision["uid"]))), "%d" => format_date($revision["timestamp"], "small"))) . ($revision["history"] ? "<br /><small>". $revision["history"] ."</small>" : ""), l(t("view"), "node/view/$node->nid", array(), "revision=$key"), l(t("rollback"), "node/rollback-revision/$node->nid/$key"), l(t("delete"), "node/delete-revision/$node->nid/$key"));
      }
      $output .= theme("table", $header, $rows);
    }
  }

  return $output;
}


/*
** Return the revision with the specified revision number.
*/

function node_revision_load($node, $revision) {
  return $node->revisions[$revision]["node"];
}

/*
** Create and return a new revision of the given node.
*/

function node_revision_create($node) {
  global $user;

  /*
  ** 'revision' is the name of the field used to indicicate that we
  ** have to create a new revision of a node.
  */

  if ($node->nid && $node->revision) {
    $prev = node_load(array("nid" => $node->nid));
    $node->revisions = $prev->revisions;
    unset($prev->revisions);
    $node->revisions[] = array("uid" => $user->uid, "timestamp" => time(), "node" => $prev, "history" => $node->history);
  }

  return $node;
}

/*
** Roll-back to the revision with the specified revision number.
*/

function node_revision_rollback($nid, $revision) {
  global $user;

  if (user_access("administer nodes")) {
    $node = node_load(array("nid" => $nid));

    /*
    ** Extract the specified revision:
    */

    $rev = $node->revisions[$revision]["node"];

    /*
    ** Inherit all the past revisions:
    */

    $rev->revisions = $node->revisions;

    /*
    ** Save the original/current node:
    */

    $rev->revisions[] = array("uid" => $user->uid, "timestamp" => time(), "node" => $node);

    /*
    ** Remove the specified revision:
    */

    unset($rev->revisions[$revision]);

    /*
    ** Save the node:
    */

    foreach ($node as $key => $value) {
      $filter[] = $key;
    }

    node_save($rev, $filter);

    drupal_set_message(t("rollbacked to revision #%revision of '%title'", array("%revision" => $revision, "%title" => $node->title)));
  }
}

/*
** Delete the revision with specified revision number.
*/

function node_revision_delete($nid, $revision) {

  if (user_access("administer nodes")) {
    $node = node_load(array("nid" => $nid));

    unset($node->revisions[$revision]);

    node_save($node, array("nid", "revisions"));

    drupal_set_message(t("deleted revision #%revision of '%title'", array("%revision" => $revision, "%title" => $node->title)));
  }
}

/*
** Return a list of all the existing revision numbers.
*/

function node_revision_list($node) {
  if (is_array($node->revisions)) {
    return array_keys($node->revisions);
  }
  else {
    return array();
  }
}

function node_admin() {
  $op = $_POST["op"];
  $edit = $_POST["edit"];

  if (user_access("administer nodes")) {

    if (empty($op)) {
      $op = arg(2);
    }

    /*
    ** Compile a list of the administrative links:
    */
    switch ($op) {
      case "search":
        $output = search_type("node", url("admin/node/search"), $_POST["keys"]);
        break;
      case "edit":
        $output = node_admin_edit(arg(3));
        break;
      case "delete":
        $output = node_delete(array("nid" => arg(3)));
        break;
      case t("Preview"):
        $edit = node_validate($edit, $error);
        $output = node_preview($edit, $error);
        break;
      case t("Submit"):
        $output = node_submit($edit);
        break;
      case t("Delete"):
        $output = node_delete($edit);
        break;