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<?php

/**

 * @file

 * An API module providing by-user access control lists.

 *

 * This module handles ACLs on behalf of other modules. The two main reasons

 * to do this are so that modules using ACLs can share them with each

 * other without having to actually know much about them, and so that

 * ACLs can easily co-exist with the existing node_access system.

 */

/**

 * Create a new ACL.

 *

 * The client module will have to keep track of the ACL. For that it can

 * assign either a $name or a $number to this ACL.

 *

 * @param $module

 *   The name of the client module.

 * @param $name

 *   An arbitrary name for this ACL, freely defined by the client module.

 * @param $number

 *   An arbitrary number for this ACL, freely defined by the client module.

 * @return

 *   The ID of the newly created ACL.

 */

function acl_create_acl($module, $name = NULL, $number = NULL) {

  $acl = array(

    'module' => $module,

    'name' => $name,

    'number' => $number

  );

  drupal_write_record('acl', $acl);

  return $acl['acl_id'];

}

/**

 * Create a new ACL (obsolete).

 *

 * @see acl_create_acl()

 */

function acl_create_new_acl($module, $name = NULL, $number = NULL) {

  return acl_create_acl($module, $name, $number);

}

/**

 * Delete an existing ACL.

 */

function acl_delete_acl($acl_id) {

  db_delete('acl')

    ->condition('acl_id', $acl_id)

    ->execute();

  db_delete('acl_user')

    ->condition('acl_id', $acl_id)

    ->execute();

  db_delete('acl_node')

    ->condition('acl_id', $acl_id)

    ->execute();

}

/**

 * Add the specified UID to an ACL.

 */

function acl_add_user($acl_id, $uid) {

  $test_uid = db_query("SELECT uid FROM {acl_user} WHERE acl_id = :acl_id AND uid = :uid", array(

    'acl_id' => $acl_id,

    'uid' => $uid,

  ))->fetchField();

  if (!$test_uid) {

    db_insert('acl_user')

    ->fields(array(

      'acl_id' => $acl_id,

      'uid' => $uid,

    ))

    ->execute();

  }

}

/**

 * Remove the specified UID from an ACL.

 */

function acl_remove_user($acl_id, $uid) {

  db_delete('acl_user')

    ->condition('acl_id', $acl_id)

    ->condition('uid', $uid)

    ->execute();

}

/**

 * Provide a form to edit the ACL that can be embedded in other forms.

 * Pass $new_acl=TRUE if you have no ACL yet, but do supply a string

 * like 'my_module_new_acl' as $acl_id anyway.

 */

function acl_edit_form(&$form_state, $acl_id, $label = NULL, $new_acl = FALSE) {

  $form_state['build_info']['files'][] = _acl_module_load_include('admin.inc');

  return _acl_edit_form($acl_id, $label, $new_acl);

}

/**

 * Provide access control to all nodes selected by a subquery, based upon an ACL id.

 */

function acl_add_nodes($subselect, $acl_id, $view, $update, $delete, $priority = 0) {

  db_delete('acl_node')

    ->condition('acl_id', $acl_id)

    ->condition('nid', $subselect, 'IN')

    ->execute();

  $subselect->addExpression($acl_id, 'acl_id');

  $subselect->addExpression((int) $view, 'grant_view');

  $subselect->addExpression((int) $update, 'grant_update');

  $subselect->addExpression((int) $delete, 'grant_delete');

  $subselect->addExpression($priority, 'priority');

  db_insert('acl_node')

    ->from($subselect)

    ->execute();

}

/**

 * Provide access control to a node based upon an ACL id.

 */

function acl_node_add_acl($nid, $acl_id, $view, $update, $delete, $priority = 0) {

  acl_node_add_acl_record(array(

    'acl_id'       => $acl_id,

    'nid'          => $nid,

    'grant_view'   => (int) $view,

    'grant_update' => (int) $update,

    'grant_delete' => (int) $delete,

    'priority'     => $priority,

  ));

}

/**

 * Provide access control to a node based upon an ACL id.

 */

function acl_node_add_acl_record(array $record) {

  db_delete('acl_node')

    ->condition('acl_id', $record['acl_id'])

    ->condition('nid', $record['nid'])

    ->execute();

  db_insert('acl_node')

    ->fields($record)

    ->execute();

}

/**

 * Remove an ACL completely from a node.

 */

function acl_node_remove_acl($nid, $acl_id) {

  db_delete('acl_node')

    ->condition('acl_id', $acl_id)

    ->condition('nid', $nid)

    ->execute();

}

/**

 * Clear all of a module's ACLs from a node.

 */

function acl_node_clear_acls($nid, $module) {

  $select = db_select('acl', 'a')

    ->fields('a', array('acl_id'))

    ->condition('a.module', $module);

  db_delete('acl_node')

    ->condition('nid', $nid)

    ->condition('acl_id', $select, 'IN')

    ->execute();

}

/**

 * Get the id of an ACL by name (+ optionally number).

 */

function acl_get_id_by_name($module, $name, $number = NULL) {

  $query = db_select('acl', 'a')

    ->fields('a', array('acl_id'))

    ->condition('a.module', $module)

    ->condition('a.name', $name);

  if (isset($number)) {

    $query->condition('a.number', $number);

  }

  return $query->execute()->fetchField();

}

/**

 * Get the id of an ACL by number.

 */

function acl_get_id_by_number($module, $number) {

  $query = db_select('acl', 'a')

    ->fields('a', array('acl_id'))

    ->condition('a.module', $module)

    ->condition('a.number', $number);

  return $query->execute()->fetchField();

}

/**

 * Determine whether an ACL has some assigned users.

 */

function acl_has_users($acl_id) {

  return db_query("SELECT COUNT(uid) FROM {acl_user} WHERE acl_id = :acl_id", array(

    'acl_id' => $acl_id,

  ))->fetchField();

}

/**

 * Determine whether an ACL has a specific assigned user.

 */

function acl_has_user($acl_id, $uid) {

  return db_query("SELECT COUNT(uid) FROM {acl_user} WHERE acl_id = :acl_id AND uid = :uid", array(

    'acl_id' => $acl_id,

    'uid' => $uid,

  ))->fetchField();

}

/**

 * Get an array of acl_ids held by a user.

 */

function acl_get_ids_by_user($module, $uid, $name = NULL, $number = NULL) {

  $query = db_select('acl', 'a');

  $query->join('acl_user', 'au', 'a.acl_id = au.acl_id');

  $query

    ->fields('a', array('acl_id'))

    ->condition('a.module', $module)

    ->condition('au.uid', $uid);

  if (isset($name)) {

    $query->condition('a.name', $name);

  }

  if (isset($number)) {

    $query->condition('a.number', $number);

  }

  $acl_ids = $query->execute()->fetchCol();

  return $acl_ids;

}

/**

 * Get the uids of an ACL.

 */

function acl_get_uids($acl_id) {

  $uids = db_query("SELECT uid FROM {acl_user} WHERE acl_id = :acl_id", array(

    'acl_id' => $acl_id,

  ))->fetchCol();

  return $uids;

}

/**

 * Implements hook_node_access_records().

 */

function acl_node_access_records($node) {

  if (!$node->nid) {

    return;

  }

  $result = db_query("SELECT n.*, 'acl' AS realm, n.acl_id AS gid, a.module FROM {acl_node} n INNER JOIN {acl} a ON n.acl_id = a.acl_id WHERE nid = :nid", array(

    'nid' => $node->nid,

  ), array('fetch' => PDO::FETCH_ASSOC));

  $grants = array();

  foreach ($result as $grant) {

    if (module_invoke($grant['module'], 'enabled')) {

      if (acl_has_users($grant['gid'])) {

        $grants[] = $grant;

      }

      else {

        //just deny access

        $grants[] = array(

          'realm' => 'acl',

          'gid' => $grant['gid'],

          'grant_view' => 0,

          'grant_update' => 0,

          'grant_delete' => 0,

          'priority' => $grant['priority'],

        );

      }

    }

  }

  return $grants;

}

/**

 * Implements hook_node_grants().

 */

function acl_node_grants($account, $op) {

  $acl_ids = db_query("SELECT acl_id FROM {acl_user} WHERE uid = :uid", array(

    'uid' => $account->uid,

  ))->fetchCol();

  return (!empty($acl_ids) ? array('acl' => $acl_ids) : NULL);

}

/**

 * Implements hook_node_delete().

 */

function acl_node_delete($node) {

  db_delete('acl_node')

    ->condition('nid', $node->nid)

    ->execute();

}

/**

 * Implements hook_user_cancel().

 */

function acl_user_cancel($edit, $account, $method) {

  db_delete('acl_user')

    ->condition('uid', $account->uid)

    ->execute();

}

/**

 * Helper function to load include files.

 */

function _acl_module_load_include($type) {

  static $loaded = array();

  if (!isset($loaded[$type])) {

    $path = module_load_include($type, 'acl');

    $loaded[$type] = drupal_get_path('module', 'acl') . "/acl.$type";

  }

  return $loaded[$type];

}

/**

 * Implements hook_node_access_explain().

 */

function acl_node_access_explain($row) {

  static $interpretations = array();

  if ($row->realm == 'acl') {

    if (!isset($interpretations[$row->gid])) {

      $acl = db_query("SELECT * FROM {acl} WHERE acl_id = :acl_id", array(

        'acl_id' => $row->gid,

      ))->fetchObject();

      $acl->tag = '?';

      if (!isset($acl->name)) {

        $acl->tag = $acl->number;

      }

      elseif (!isset($acl->number)) {

        $acl->tag = $acl->name;

      }

      else {

        $acl->tag = $acl->name . '-' . $acl->number;

      }

      $result = db_query("SELECT u.name FROM {acl_user} au, {users} u WHERE au.acl_id = :acl_id AND au.uid = u.uid", array(

        'acl_id' => $row->gid,

      ));

      foreach ($result as $user) {

        $users[] = $user->name;

      }

      if (isset($users)) {

        $users = implode(', ', $users);

        $interpretations[$row->gid] = _acl_get_explanation("$acl->module/$acl->tag: $users", $acl->acl_id, $acl->module, $acl->name, $acl->number, $users);

      }

      elseif ($row->gid == 0) {

        $result = db_query("SELECT an.acl_id, a.module, a.name FROM {acl_node} an JOIN {acl} a ON an.acl_id = a.acl_id LEFT JOIN {acl_user} au ON a.acl_id = au.acl_id WHERE an.nid = :nid AND au.uid IS NULL", array(

          'nid' => $row->nid,

        ));

        foreach ($result as $acl) {

          $rows[] = _acl_get_explanation("$acl->acl_id: $acl->module/$acl->tag", $acl->acl_id, $acl->module, $acl->name, $acl->number);

        }

        if (!empty($rows)) {

          return implode('<br />', $rows);

        }

        return 'No access via ACL.';

      }

      else {

        $interpretations[$row->gid] = _acl_get_explanation("$acl->module/$acl->tag: no users!", $acl->acl_id, $acl->module, $acl->name, $acl->number);

      }

    }

    return $interpretations[$row->gid];

  }

}

/**

 * Helper function to ask the client for its interpretation of the given

 * grant record.

 */

function _acl_get_explanation($text, $acl_id, $module, $name, $number, $users = NULL) {

  $hook = $module .'_acl_explain';

  if (function_exists($hook)) {

    return '<span title="'. $hook($acl_id, $name, $number, $users) .'">'. $text .'</span>';

  }

  return $text;

}