Hidden author module

<?php
/**
 * @file
 * Shows you the option to publish a node as anonymous depending on permissions.
 */

/**
 * Implements hook_form_BASE_FORM_ID_alter().
 */
function hidden_author_form_node_form_alter(&$form, $form_state) {
  // Get weight.
  $weight = variable_get('hidden_author_node_weight', -4);
  // Get content types enabled that were saved in hidden_author settings.
  $content_types = variable_get('hidden_author_content_types', array('article' => 'article'));

  if (isset($content_types[$form['#node']->type])) {
    if (user_access('post anonymous nodes')) {
      $form['anonymous'] = array(
        '#type' => 'checkbox',
        '#title' => t('Post anonymously'),
        '#weight' => $weight,
        '#default_value' => hidden_author_get_author_id('node', $form['#node']) ? TRUE : FALSE,
      );
    }
  }
}

/**
 * Implements hook_node_insert().
 */
function hidden_author_node_insert($node) {
  // Checks if anonymous is enabled.
  if ($node->anonymous) {
    db_insert('hidden_author')
      ->fields(array(
        'entity_type' => 'node',
        'bundle' => $node->type,
        'entity_id' => $node->nid,
        'revision_id' => $node->vid,
        'uid' => $node->hidden_author,
      ))
      ->execute();
  }
}

/**
 * Implements hook_node_update().
 */
function hidden_author_node_update($node) {
  // Checks if anonymous is enabled.
  if (!$node->anonymous) {
    hidden_author_node_delete($node);
  }
  elseif (!hidden_author_get_author_id('node', $node)) {
    hidden_author_node_insert($node);
  }
}

/**
 * Implements hook_node_presave().
 */
function hidden_author_node_presave($node) {
  // Checks if anonymous is enabled.
  $is_hidden = hidden_author_get_author_id('node', $node);
  if (!$is_hidden && $node->anonymous) {
  $node->hidden_author = $node->uid;
  $node->uid = 0;
  $node->name = t('Anonymous');
  }
  elseif ($is_hidden) {
  if ($node->anonymous) {
    $node->hidden_author = $is_hidden['uid'];
    }
  else {
    $author = user_load($is_hidden['uid']);
      $node->uid = $author->uid;
      $node->name = $author->name;
    }
  }
}

/**
 * Implements hook_node_delete().
 */
function hidden_author_node_delete($node) {
  // Deletes a single row in hidden_author table.
  db_delete('hidden_author')
    ->condition('entity_type', 'node', '=')
    ->condition('bundle', $node->type, '=')
    ->condition('entity_id', $node->nid, '=')
    ->condition('revision_id', $node->vid, '=')
    ->execute();
}

/**
 * Get the author uid and entity id for given entity.
 */
function hidden_author_get_author_id($entity_type, $object) {
  if ($entity_type == 'node' && empty($object->nid)) {
    return;
  }

  // Build query.
  $res = db_select('hidden_author', 'e')
    ->fields('e', array('entity_id', 'uid'))
    ->condition('entity_type', $entity_type, '=')
  ;

  if ($entity_type == 'node') {
    $res
      ->condition('bundle', $object->type, '=')
      ->condition('entity_id', $object->nid, '=')
      ->condition('revision_id', $object->vid, '=');
  }

  $db_result = $res
    ->execute()
    ->fetchAssoc();

  return $db_result;
}

/**
 * Implements hook_menu().
 */
function hidden_author_menu() {
  $items['admin/config/content/hidden_author-rules'] = array(
    'title' => 'hidden author settings',
    'description' => 'This page provides hidden author settings.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('hidden_author_list_content_type'),
    'access callback' => 'user_access',
    'access arguments' => array('administer hidden_author'),
    'file' => 'hidden_author.admin.inc',
    'type' => MENU_NORMAL_ITEM,
  );
  return $items;
}

/**
 * Implements hook_help().
 */
function hidden_author_help($path, $arg) {
  switch ($path) {
    case 'admin/config/content/hidden_author-rules':
      return t('this is some help text for Hidden Author module');
    case 'admin/help#hidden_author';
      return _hidden_author_help();
  }
}

/**
 * Callback function for hidden_author_help().
 */
function _hidden_author_help() {
  $file = drupal_get_path('module', 'hidden_author') . '/README.txt';
  if (file_exists($file)) {
    return _filter_autop(check_plain(file_get_contents($file)));
  }
}

/**
 * Implements hook_permission().
 */
function hidden_author_permission() {
  return array(
    'administer hidden author' => array(
      'title' => t('Administer Hidden Author'),
      'description' => t('Allows you to configure Hidden Author settings.'),
    ),
    'post anonymous nodes' => array(
      'title' => t('Post anonymous nodes'),
      'description' => t('Allows you to post anonymous nodes.'),
    ),
    'view hidden author' => array(
      'title' => t('View Hidden Author'),
      'description' => t('Allows you to view Hidden Author.'),
    ),
  );
}