<?php
// $Id$

/**
 * @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.
 */
function acl_create_new_acl($module, $name) {
  $acl = array(
    'module' => $module,
    'name' => $name,
  );
  drupal_write_record('acl', $acl);
  return $acl['acl_id'];
}

/**
 * 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 $acl_id anyway.
 */
function acl_edit_form($acl_id, $label = NULL, $new_acl = FALSE) {
  module_load_include('admin.inc', 'acl');
  return _acl_edit_form($acl_id, $label, $new_acl);
}

/**
 * Provide access control to a node based upon an ACL id.
 */
function acl_node_add_acl($nid, $acl_id, $view, $update, $delete, $priority = 0) {
  db_delete('acl_node')
    ->condition('acl_id', $acl_id)
    ->condition('nid', $nid)
    ->execute();
  db_insert('acl_node')
  ->fields(array(
    'acl_id' => $acl_id,
    'nid' => $nid,
    'grant_view' => (int) $view,
    'grant_update' => (int) $update,
    'grant_delete' => (int) $delete,
    'priority' => $priority,
  ))
  ->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 ACL's from a node.
 */
function acl_node_clear_acls($nid, $module) {
  $result = db_query("SELECT acl_id FROM {acl} WHERE module = :module", array(
    'module' => $module
  ));
  foreach ($result as $acl) {
    $acls[] = $acl->acl_id;
  }
  if ($acls) {
    db_delete('acl_node')
      ->condition('nid', $nid)
      ->condition('acl_id', $acls, 'IN')
      ->execute();
  }
}

/**
 * Gets the id of an acl
 */
function acl_get_id_by_name($module, $name) {
  return db_query("SELECT acl_id FROM {acl} WHERE module = :module AND name = :name", array(
    'module' => $module,
    'name' => $name,
  ))->fetchField();
}

/**
 * Determines if 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();
}

/**
 * Determines if 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();
}

/**
 * Gets the uids of an acl
 */
function acl_get_uids($acl_id) {
  $result = db_query("SELECT uid FROM {acl_user} WHERE acl_id = :acl_id", array(
    'acl_id' => $acl_id,
  ));
  $return = array();
  foreach ($result as $row) {
    $return[$row->uid] = $row->uid;
  }
  return (empty($return) ? NULL : $return);
}

/**
 * Implementation of 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,
  ));
  $grants = array();
  foreach ($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' => 0,
          'grant_view' => 0,
          'grant_update' => 0,
          'grant_delete' => 0,
          'priority' => $grant->priority,
        );
      }
    }
  }
  return $grants;
}

/**
 * Implementation of hook_node_grants().
 */
function acl_node_grants($account, $op) {
  $array = array(
    'acl' => array(),
  );
  $result = db_query("SELECT acl_id FROM {acl_user} WHERE uid = :uid", array(
    'uid' => $account->uid,
  ));
  foreach ($result as $row) {
    $array['acl'][] = $row->acl_id;
  }
  return !empty($array['acl']) ? $array : NULL;
}

/**
 * Implementation of hook_node_delete().
 */
function acl_node_delete($node) {
  db_delete('acl_node')
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Implementation of hook_user_cancel().
 */
function acl_user_cancel($edit, $account, $method) {
  db_delete('acl_user')
    ->condition('uid', $account->uid)
    ->execute();
}

/**
 * Implementation of 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();
      $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)) {
        $interpretations[$row->gid] = $acl->module . '/' . $acl->name . ': ' . implode(', ', $users);
      }
      elseif ($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->acl_id . ':&nbsp;' . $acl->module . '/' . $acl->name;
        }
        if (!empty($rows)) {
          return implode('<br />', $rows);
        }
        return 'No access via ACL.';
      }
      else {
        $interpretations[$row->gid] .= ': no users!';
      }
    }
    return $interpretations[$row->gid];
  }
}