<?php

/**
 * @file
 * Contains code to make it easier to have exportable objects.
 *
 * Documentation for exportable objects is contained in help/export.html
 */

/**
 * A bit flag used to let us know if an object is in the database.
 */
define('EXPORT_IN_DATABASE', 0x01);

/**
 * A bit flag used to let us know if an object is a 'default' in code.
 */
define('EXPORT_IN_CODE', 0x02);

/**
 * @defgroup export_crud CRUD functions for export.
 * @{
 * export.inc supports a small number of CRUD functions that should always
 * work for every exportable object, no matter how complicated. These
 * functions allow complex objects to provide their own callbacks, but
 * in most cases, the default callbacks will be used.
 *
 * Note that defaults are NOT set in the $schema because it is presumed
 * that a module's personalized CRUD functions will already know which
 * $table to use and not want to clutter up the arguments with it.
 */

/**
 * Create a new object for the given $table.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $set_defaults
 *   If TRUE, which is the default, then default values will be retrieved
 *   from schema fields and set on the object.
 *
 * @return
 *   The loaded object.
 */
function ctools_export_crud_new($table, $set_defaults = TRUE) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['create callback']) && function_exists($export['create callback'])) {
    return $export['create callback']($set_defaults);
  }
  else {
    return ctools_export_new_object($table, $set_defaults);
  }
}

/**
 * Load a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $name
 *   The unique ID to load. The field for this ID will be specified by
 *   the export key, which normally defaults to 'name'.
 *
 * @return
 *   The loaded object.
 */
function ctools_export_crud_load($table, $name) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['load callback']) && function_exists($export['load callback'])) {
    return $export['load callback']($name);
  }
  else {
    $result = ctools_export_load_object($table, 'names', array($name));
    if (isset($result[$name])) {
      return $result[$name];
    }
  }
}

/**
 * Load multiple exportable objects.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $names
 *   An array of unique IDs to load. The field for these IDs will be specified
 *   by the export key, which normally defaults to 'name'.
 *
 * @return
 *   An array of the loaded objects.
 */
function ctools_export_crud_load_multiple($table, array $names) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  $results = array();
  if (!empty($export['load multiple callback']) && function_exists($export['load multiple callback'])) {
    $results = $export['load multiple callback']($names);
  }
  else {
    $results = ctools_export_load_object($table, 'names', $names);
  }

  // Ensure no empty results are returned.
  return array_filter($results);
}

/**
 * Load all exportable objects of a given type.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $reset
 *   If TRUE, the static cache of all objects will be flushed prior to
 *   loading all. This can be important on listing pages where items
 *   might have changed on the page load.
 * @return
 *   An array of all loaded objects, keyed by the unique IDs of the export key.
 */
function ctools_export_crud_load_all($table, $reset = FALSE) {
  $schema = ctools_export_get_schema($table);
  if (empty($schema['export'])) {
    return array();
  }

  $export = $schema['export'];

  if ($reset) {
    ctools_export_load_object_reset($table);
  }

  if (!empty($export['load all callback']) && function_exists($export['load all callback'])) {
    return $export['load all callback']($reset);
  }
  else {
    return ctools_export_load_object($table, 'all');
  }
}

/**
 * Save a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to save.
 *
 * @return
 *   Failure to write a record will return FALSE. Otherwise SAVED_NEW or
 *   SAVED_UPDATED is returned depending on the operation performed. The
 *   $object parameter contains values for any serial fields defined by the $table
 */
function ctools_export_crud_save($table, &$object) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['save callback']) && function_exists($export['save callback'])) {
    return $export['save callback']($object);
  }
  else {
    // Objects should have a serial primary key. If not, simply fail to write.
    if (empty($export['primary key'])) {
      return FALSE;
    }

    $key = $export['primary key'];
    if ($object->export_type & EXPORT_IN_DATABASE) {
      // Existing record.
      $update = array($key);
    }
    else {
      // New record.
      $update = array();
      $object->export_type = EXPORT_IN_DATABASE;
    }
    return drupal_write_record($table, $object, $update);
  }
}

/**
 * Delete a single exportable object.
 *
 * This only deletes from the database, which means that if an item is in
 * code, then this is actually a revert.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to delete, or the export key.
 */
function ctools_export_crud_delete($table, $object) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['delete callback']) && function_exists($export['delete callback'])) {
    return $export['delete callback']($object);
  }
  else {
    // If we were sent an object, get the export key from it. Otherwise
    // assume we were sent the export key.
    $value = is_object($object) ? $object->{$export['key']} : $object;
    db_delete($table)
      ->condition($export['key'], $value)
      ->execute();
  }
}

/**
 * Get the exported code of a single exportable object.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to delete, or the export key.
 * @param $indent
 *   Any indentation to apply to the code, in case this object is embedded
 *   into another, for example.
 *
 * @return
 *   A string containing the executable export of the object.
 */
function ctools_export_crud_export($table, $object, $indent = '') {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['export callback']) && function_exists($export['export callback'])) {
    return $export['export callback']($object, $indent);
  }
  else {
    return ctools_export_object($table, $object, $indent);
  }
}

/**
 * Turn exported code into an object.
 *
 * Note: If the code is poorly formed, this could crash and there is no
 * way to prevent this.
 *
 * @param $table
 *   The name of the table to use to retrieve $schema values. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $code
 *   The code to eval to create the object.
 *
 * @return
 *   An object created from the export. This object will NOT have been saved
 *   to the database. In the case of failure, a string containing all errors
 *   that the system was able to determine.
 */
function ctools_export_crud_import($table, $code) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['import callback']) && function_exists($export['import callback'])) {
    return $export['import callback']($code);
  }
  else {
    ob_start();
    eval($code);
    ob_end_clean();

    if (empty(${$export['identifier']})) {
      $errors = ob_get_contents();
      if (empty($errors)) {
        $errors = t('No item found.');
      }
      return $errors;
    }

    $item = ${$export['identifier']};

    // Set these defaults just the same way that ctools_export_new_object sets
    // them.
    $item->export_type = NULL;
    $item->{$export['export type string']} = t('Local');

    return $item;
  }
}

/**
 * Change the status of a certain object.
 *
 * @param $table
 *   The name of the table to use to enable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to enable, or the machine readable name.
 * @param $status
 *   The status, in this case, is whether or not it is 'disabled'.
 */
function ctools_export_crud_set_status($table, $object, $status) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!empty($export['status callback']) && function_exists($export['status callback'])) {
    $export['status callback']($object, $status);
  }
  else {
    if (is_object($object)) {
      ctools_export_set_object_status($object, $status);
    }
    else {
      ctools_export_set_status($table, $object, $status);
    }
  }

}


/**
 * Enable a certain object.
 *
 * @param $table
 *   The name of the table to use to enable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to enable, or the machine readable name.
 */
function ctools_export_crud_enable($table, $object) {
  return ctools_export_crud_set_status($table, $object, FALSE);
}

/**
 * Disable a certain object.
 *
 * @param $table
 *   The name of the table to use to disable a certain object. This table
 *   must have an 'export' section containing data or this function
 *   will fail.
 * @param $object
 *   The fully populated object to disable, or the machine readable name.
 */
function ctools_export_crud_disable($table, $object) {
  return ctools_export_crud_set_status($table, $object, TRUE);
}

/**
 * @}
 */

/**
 * Load some number of exportable objects.
 *
 * This function will cache the objects, load subsidiary objects if necessary,
 * check default objects in code and properly set them up. It will cache
 * the results so that multiple calls to load the same objects
 * will not cause problems.
 *
 * It attempts to reduce, as much as possible, the number of queries
 * involved.
 *
 * @param $table
 *   The name of the table to be loaded from. Data is expected to be in the
 *   schema to make all this work.
 * @param $type
 *   A string to notify the loader what the argument is
 *   - all: load all items. This is the default. $args is unused.
 *   - names: $args will be an array of specific named objects to load.
 *   - conditions: $args will be a keyed array of conditions. The conditions
 *       must be in the schema for this table or errors will result.
 * @param $args
 *   An array of arguments whose actual use is defined by the $type argument.
 */
function ctools_export_load_object($table, $type = 'all', $args = array()) {
  $cache = &drupal_static(__FUNCTION__);
  $cached_database = &drupal_static('ctools_export_load_object_all');

  $schema = ctools_export_get_schema($table);
  if (empty($schema) || !db_table_exists($table)) {
    return array();
  }

  $export = $schema['export'];

  if (!isset($cache[$table])) {
    $cache[$table] = array();
  }

  // If fetching all and cached all, we've done so and we are finished.
  if ($type == 'all' && !empty($cached_database[$table])) {
    return $cache[$table];
  }

  $return = array();

  // Don't load anything we've already cached.
  if ($type == 'names' && !empty($args)) {
    foreach ($args as $id => $name) {
      if (isset($cache[$table][$name])) {
        $return[$name] = $cache[$table][$name];
        unset($args[$id]);
      }
    }

    // If nothing left to load, return the result.
    if (empty($args)) {
      return $return;
    }
  }

  // Build the query
  $query = db_select($table, 't__0')->fields('t__0');
  $alias_count = 1;
  if (!empty($schema['join'])) {
    foreach ($schema['join'] as $join_key => $join) {
      if ($join_schema = drupal_get_schema($join['table'])) {
        $query->join($join['table'], 't__' . $alias_count, 't__0.' . $join['left_key'] . ' = ' . 't__' . $alias_count . '.' . $join['right_key']);
        $query->fields('t__' . $alias_count);
        $alias_count++;

        // Allow joining tables to alter the query through a callback.
        if (isset($join['callback']) && function_exists($join['callback'])) {
          $join['callback']($query, $schema, $join_schema);
        }
      }
    }
  }

  $conditions = array();
  $query_args = array();

  // If they passed in names, add them to the query.
  if ($type == 'names') {
    $query->condition($export['key'], $args, 'IN');
  }
  else if ($type == 'conditions') {
    foreach ($args as $key => $value) {
      if (isset($schema['fields'][$key])) {
        $query->condition($key, $value);
      }
    }
  }

  $result = $query->execute();

  $status = variable_get($export['status'], array());
  // Unpack the results of the query onto objects and cache them.
  foreach ($result as $data) {
    if (isset($schema['export']['object factory']) && function_exists($schema['export']['object factory'])) {
      $object = $schema['export']['object factory']($schema, $data);
    }
    else {
      $object = _ctools_export_unpack_object($schema, $data, $export['object']);
    }
    $object->table = $table;
    $object->{$export['export type string']} = t('Normal');
    $object->export_type = EXPORT_IN_DATABASE;
    // Determine if default object is enabled or disabled.
    if (isset($status[$object->{$export['key']}])) {
      $object->disabled = $status[$object->{$export['key']}];
    }

    $cache[$table][$object->{$export['key']}] = $object;
    if ($type == 'conditions') {
      $return[$object->{$export['key']}] = $object;
    }
  }

  // Load subrecords.
  if (isset($export['subrecords callback']) && function_exists($export['subrecords callback'])) {
    $export['subrecords callback']($cache[$table]);
  }

  if ($type == 'names' && !empty($args) && !empty($export['cache defaults'])) {
    $defaults = _ctools_export_get_some_defaults($table, $export, $args);
  }
  else {
    $defaults = _ctools_export_get_defaults($table, $export);
  }

  if ($defaults) {
    foreach ($defaults as $object) {
      if ($type == 'conditions') {
        // if this does not match all of our conditions, skip it.
        foreach ($args as $key => $value) {
          if (!isset($object->$key)) {
            continue 2;
          }
          if (is_array($value)) {
            if (!in_array($object->$key, $value)) {
              continue 2;
            }
          }
          else if ($object->$key != $value) {
            continue 2;
          }
        }
      }
      else if ($type == 'names') {
        if (!in_array($object->{$export['key']}, $args)) {
          continue;
        }
      }

      // Determine if default object is enabled or disabled.
      if (isset($status[$object->{$export['key']}])) {
        $object->disabled = $status[$object->{$export['key']}];
      }

      if (!empty($cache[$table][$object->{$export['key']}])) {
        $cache[$table][$object->{$export['key']}]->{$export['export type string']} = t('Overridden');
        $cache[$table][$object->{$export['key']}]->export_type |= EXPORT_IN_CODE;
        $cache[$table][$object->{$export['key']}]->export_module = isset($object->export_module) ? $object->export_module : NULL;
        if ($type == 'conditions') {
          $return[$object->{$export['key']}] = $cache[$table][$object->{$export['key']}];
        }
      }
      else {
        $object->{$export['export type string']} = t('Default');
        $object->export_type = EXPORT_IN_CODE;
        $object->in_code_only = TRUE;
        $object->table = $table;

        $cache[$table][$object->{$export['key']}] = $object;
        if ($type == 'conditions') {
          $return[$object->{$export['key']}] = $object;
        }
      }
    }
  }

  // If fetching all, we've done so and we are finished.
  if ($type == 'all') {
    $cached_database[$table] = TRUE;
    return $cache[$table];
  }

  if ($type == 'names') {
    foreach ($args as $name) {
      if (isset($cache[$table][$name])) {
        $return[$name] = $cache[$table][$name];
      }
    }
  }

  // For conditions,
  return $return;
}

/**
 * Reset all static caches in ctools_export_load_object() or static caches for
 * a given table in ctools_export_load_object().
 *
 * @param $table
 *   String that is the name of a table. If not defined, all static caches in
 *   ctools_export_load_object() will be reset.
 */
function ctools_export_load_object_reset($table = NULL) {
  // Reset plugin cache to make sure new include files are picked up.
  ctools_include('plugins');
  ctools_get_plugins_reset();
  if (empty($table)) {
    drupal_static_reset('ctools_export_load_object');
    drupal_static_reset('ctools_export_load_object_all');
    drupal_static_reset('_ctools_export_get_defaults');
  }
  else {
    $cache = &drupal_static('ctools_export_load_object');
    $cached_database = &drupal_static('ctools_export_load_object_all');
    $cached_defaults = &drupal_static('_ctools_export_get_defaults');
    unset($cache[$table]);
    unset($cached_database[$table]);
    unset($cached_defaults[$table]);
  }
}

/**
 * Get the default version of an object, if it exists.
 *
 * This function doesn't care if an object is in the database or not and
 * does not check. This means that export_type could appear to be incorrect,
 * because a version could exist in the database. However, it's not
 * incorrect for this function as it is *only* used for the default
 * in code version.
 */
function ctools_get_default_object($table, $name) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  if (!$export['default hook']) {
    return;
  }

  // Try to load individually from cache if this cache is enabled.
  if (!empty($export['cache defaults'])) {
    $defaults = _ctools_export_get_some_defaults($table, $export, array($name));
  }
  else {
    $defaults = _ctools_export_get_defaults($table, $export);
  }

  $status = variable_get($export['status'], array());

  if (!isset($defaults[$name])) {
    return;
  }

  $object = $defaults[$name];

  // Determine if default object is enabled or disabled.
  if (isset($status[$object->{$export['key']}])) {
    $object->disabled = $status[$object->{$export['key']}];
  }

  $object->{$export['export type string']} = t('Default');
  $object->export_type = EXPORT_IN_CODE;
  $object->in_code_only = TRUE;

  return $object;
}

/**
 * Call the hook to get all default objects of the given type from the
 * export. If configured properly, this could include loading up an API
 * to get default objects.
 */
function _ctools_export_get_defaults($table, $export) {
  $cache = &drupal_static(__FUNCTION__, array());

  // If defaults may be cached, first see if we can load from cache.
  if (!isset($cache[$table]) && !empty($export['cache defaults'])) {
    $cache[$table] = _ctools_export_get_defaults_from_cache($table, $export);
  }

  if (!isset($cache[$table])) {
    // If we're caching, attempt to get a lock. We will wait a short time
    // on the lock, but not too long, because it's better to just rebuild
    // and throw away results than wait too long on a lock.
    if (!empty($export['cache defaults'])) {
      for ($counter = 0; !($lock = lock_acquire('ctools_export:' . $table)) && $counter > 5; $counter++) {
        lock_wait('ctools_export:' . $table, 1);
        ++$counter;
      }
    }

    $cache[$table] = array();

    if ($export['default hook']) {
      if (!empty($export['api'])) {
        ctools_include('plugins');
        $info = ctools_plugin_api_include($export['api']['owner'], $export['api']['api'],
          $export['api']['minimum_version'], $export['api']['current_version']);
        $modules = array_keys($info);
      }
      else {
        $modules = module_implements($export['default hook']);
      }

      foreach ($modules as $module) {
        $function = $module . '_' . $export['default hook'];
        if (function_exists($function)) {
          foreach ((array) $function($export) as $name => $object) {
            // Record the module that provides this exportable.
            $object->export_module = $module;

            if (empty($export['api'])) {
              $cache[$table][$name] = $object;
            }
            else {
              // If version checking is enabled, ensure that the object can be used.
              if (isset($object->api_version) &&
                version_compare($object->api_version, $export['api']['minimum_version']) >= 0 &&
                version_compare($object->api_version, $export['api']['current_version']) <= 0) {
                $cache[$table][$name] = $object;
              }
            }
          }
        }
      }

      drupal_alter($export['default hook'], $cache[$table]);

      // If we acquired a lock earlier, cache the results and release the
      // lock.
      if (!empty($lock)) {
        // Cache the index.
        $index = array_keys($cache[$table]);
        cache_set('ctools_export_index:' . $table, $index, $export['default cache bin']);

        // Cache each object.
        foreach ($cache[$table] as $name => $object) {
          cache_set('ctools_export:' . $table . ':' . $name, $object, $export['default cache bin']);
        }
        lock_release('ctools_export:' . $table);
      }
    }
  }

  return $cache[$table];
}

/**
 * Attempt to load default objects from cache.
 *
 * We can be instructed to cache default objects by the schema. If so
 * we cache them as an index which is a list of all default objects, and
 * then each default object is cached individually.
 *
 * @return Either an array of cached objects, or NULL indicating a cache
 *   rebuild is necessary.
 */
function _ctools_export_get_defaults_from_cache($table, $export) {
  $data = cache_get('ctools_export_index:' . $table, $export['default cache bin']);
  if (!$data || !is_array($data->data)) {
    return;
  }

  // This is the perfectly valid case where there are no default objects,
  // and we have cached this state.
  if (empty($data->data)) {
    return array();
  }

  $keys = array();
  foreach ($data->data as $name) {
    $keys[] = 'ctools_export:' . $table . ':' . $name;
  }

  $data = cache_get_multiple($keys, $export['default cache bin']);

  // If any of our indexed keys missed, then we have a fail and we need to
  // rebuild.
  if (!empty($keys)) {
    return;
  }

  // Now, translate the returned cache objects to actual objects.
  $cache = array();
  foreach ($data as $cached_object) {
    $cache[$cached_object->data->{$export['key']}] = $cached_object->data;
  }

  return $cache;
}

/**
 * Get a limited number of default objects.
 *
 * This attempts to load the objects directly from cache. If it cannot,
 * the cache is rebuilt. This does not disturb the general get defaults
 * from cache object.
 *
 * This function should ONLY be called if default caching is enabled.
 * It does not check, it is assumed the caller has already done so.
 */
function _ctools_export_get_some_defaults($table, $export, $names) {
  foreach ($names as $name) {
    $keys[] = 'ctools_export:' . $table . ':' . $name;
  }

  $data = cache_get_multiple($keys, $export['default cache bin']);

  // Cache hits remove the $key from $keys by reference. Cache
  // misses do not. A cache miss indicates we may have to rebuild.
  if (!empty($keys)) {
    return _ctools_export_get_defaults($table, $export);
  }

  // Now, translate the returned cache objects to actual objects.
  $cache = array();
  foreach ($data as $cached_object) {
    $cache[$cached_object->data->{$export['key']}] = $cached_object->data;
  }

  return $cache;
}

/**
 * Unpack data loaded from the database onto an object.
 *
 * @param $schema
 *   The schema from drupal_get_schema().
 * @param $data
 *   The data as loaded from the database.
 * @param $object
 *   If an object, data will be unpacked onto it. If a string
 *   an object of that type will be created.
 */
function _ctools_export_unpack_object($schema, $data, $object = 'stdClass') {
  if (is_string($object)) {
    if (class_exists($object)) {
      $object = new $object;
    }
    else {
      $object = new stdClass;
    }
  }

  // Go through our schema and build correlations.
  foreach ($schema['fields'] as $field => $info) {
    if (isset($data->$field)) {
      $object->$field = empty($info['serialize']) ? $data->$field : unserialize($data->$field);
    }
    else {
      $object->$field = NULL;
    }
  }

  if (isset($schema['join'])) {
    foreach ($schema['join'] as $join_key => $join) {
      $join_schema = ctools_export_get_schema($join['table']);
      if (!empty($join['load'])) {
        foreach ($join['load'] as $field) {
          $info = $join_schema['fields'][$field];
          $object->$field = empty($info['serialize']) ? $data->$field : unserialize($data->$field);
        }
      }
    }
  }

  return $object;
}

/**
 * Unpack data loaded from the database onto an object.
 *
 * @param $table
 *   The name of the table this object represents.
 * @param $data
 *   The data as loaded from the database.
 */
function ctools_export_unpack_object($table, $data) {
  $schema = ctools_export_get_schema($table);
  return _ctools_export_unpack_object($schema, $data, $schema['export']['object']);
}

/**
 * Export a field.
 *
 * This is a replacement for var_export(), allowing us to more nicely
 * format exports. It will recurse down into arrays and will try to
 * properly export bools when it can, though PHP has a hard time with
 * this since they often end up as strings or ints.
 */
function ctools_var_export($var, $prefix = '') {
  if (is_array($var)) {
    if (empty($var)) {
      $output = 'array()';
    }
    else {
      $output = "array(\n";
      foreach ($var as $key => $value) {
        $output .= $prefix . "  " . ctools_var_export($key) . " => " . ctools_var_export($value, $prefix . '  ') . ",\n";
      }
      $output .= $prefix . ')';
    }
  }
  else if (is_object($var) && get_class($var) === 'stdClass') {
    // var_export() will export stdClass objects using an undefined
    // magic method __set_state() leaving the export broken. This
    // workaround avoids this by casting the object as an array for
    // export and casting it back to an object when evaluated.
    $output = '(object) ' . ctools_var_export((array) $var, $prefix);
  }
  else if (is_bool($var)) {
    $output = $var ? 'TRUE' : 'FALSE';
  }
  else {
    $output = var_export($var, TRUE);
  }

  return $output;
}

/**
 * Export an object into code.
 */
function ctools_export_object($table, $object, $indent = '', $identifier = NULL, $additions = array(), $additions2 = array()) {
  $schema = ctools_export_get_schema($table);
  if (!isset($identifier)) {
    $identifier = $schema['export']['identifier'];
  }

  $output = $indent . '$' . $identifier . ' = new ' . get_class($object) . "();\n";

  if ($schema['export']['can disable']) {
    $output .= $indent . '$' . $identifier . '->disabled = FALSE; /* Edit this to true to make a default ' . $identifier . ' disabled initially */' . "\n";
  }
  if (!empty($schema['export']['api']['current_version'])) {
    $output .= $indent . '$' . $identifier . '->api_version = ' . $schema['export']['api']['current_version'] . ";\n";
  }

  // Put top additions here:
  foreach ($additions as $field => $value) {
    $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
  }

  $fields = $schema['fields'];
  if (!empty($schema['join'])) {
    foreach ($schema['join'] as $join) {
      if (!empty($join['load'])) {
        foreach ($join['load'] as $join_field) {
          $fields[$join_field] = $join['fields'][$join_field];
        }
      }
    }
  }

  // Go through our schema and joined tables and build correlations.
  foreach ($fields as $field => $info) {
    if (!empty($info['no export'])) {
      continue;
    }
    if (!isset($object->$field)) {
      if (isset($info['default'])) {
        $object->$field = $info['default'];
      }
      else {
        $object->$field = '';
      }
    }

    // Note: This is the *field* export callback, not the table one!
    if (!empty($info['export callback']) && function_exists($info['export callback'])) {
      $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . $info['export callback']($object, $field, $object->$field, $indent) . ";\n";
    }
    else {
      $value = $object->$field;
      if ($info['type'] == 'int') {
        $value = (isset($info['size']) && $info['size'] == 'tiny') ? (bool) $value : (int) $value;
      }

      $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
    }
  }

  // And bottom additions here
  foreach ($additions2 as $field => $value) {
    $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . ctools_var_export($value, $indent) . ";\n";
  }

  return $output;
}

/**
 * Get the schema for a given table.
 *
 * This looks for data the export subsystem needs and applies defaults so
 * that it's easily available.
 */
function ctools_export_get_schema($table) {
  $cache = &drupal_static(__FUNCTION__);
  if (empty($cache[$table])) {
    $schema = drupal_get_schema($table);

    // If our schema isn't loaded, it's possible we're in a state where it
    // simply hasn't been cached. If we've been asked, let's force the
    // issue.
    if (!$schema || empty($schema['export'])) {
      // force a schema reset:
      $schema = drupal_get_schema($table, TRUE);
    }

    if (!isset($schema['export'])) {
      return array();
    }

    if (empty($schema['module'])) {
      return array();
    }

    // Add some defaults
    $schema['export'] += array(
      'key' => 'name',
      'key name' => 'Name',
      'object' => 'stdClass',
      'status' => 'default_' . $table,
      'default hook' => 'default_' . $table,
      'can disable' => TRUE,
      'identifier' => $table,
      'primary key' => !empty($schema['primary key']) ? $schema['primary key'][0] : '',
      'bulk export' => TRUE,
      'list callback' => "$schema[module]_{$table}_list",
      'to hook code callback' => "$schema[module]_{$table}_to_hook_code",
      'cache defaults' => FALSE,
      'default cache bin' => 'cache',
      'export type string' => 'type',
    );

    // If the export definition doesn't have the "primary key" then the CRUD
    // save callback won't work.
    if (empty($schema['export']['primary key']) && user_access('administer site configuration')) {
      drupal_set_message(t('The export definition of @table is missing the "primary key" property.', array('@table' => $table)), 'error');
    }

    // Notes:
    // The following callbacks may be defined to override default behavior
    // when using CRUD functions:
    //
    // create callback
    // load callback
    // load multiple callback
    // load all callback
    // save callback
    // delete callback
    // export callback
    // import callback
    //
    // See the appropriate ctools_export_crud function for details on what
    // arguments these callbacks should accept. Please do not call these
    // directly, always use the ctools_export_crud_* wrappers to ensure
    // that default implementations are honored.
    $cache[$table] = $schema;
  }

  return $cache[$table];
}

/**
 * Gets the schemas for all tables with ctools object metadata.
 */
function ctools_export_get_schemas($for_export = FALSE) {
  $export_tables = &drupal_static(__FUNCTION__);
  if (is_null($export_tables)) {
    $export_tables = array();
    $schemas = drupal_get_schema();
    foreach ($schemas as $table => $schema) {
      if (!isset($schema['export'])) {
        unset($schemas[$table]);
        continue;
      }
      $export_tables[$table] = ctools_export_get_schema($table);
    }
  }
  return $for_export ? array_filter($export_tables, '_ctools_export_filter_export_tables') : $export_tables;
}

function _ctools_export_filter_export_tables($schema) {
  return !empty($schema['export']['bulk export']);
}

function ctools_export_get_schemas_by_module($modules = array(), $for_export = FALSE) {
  $export_tables = array();
  $list = ctools_export_get_schemas($for_export);
  foreach ($list as $table => $schema) {
    $export_tables[$schema['module']][$table] = $schema;
  }
  return empty($modules) ? $export_tables : array_keys($export_tables, $modules);
}

/**
 * Set the status of a default $object as a variable.
 *
 * The status, in this case, is whether or not it is 'disabled'.
 * This function does not check to make sure $object actually
 * exists.
 */
function ctools_export_set_status($table, $name, $new_status = TRUE) {
  $schema = ctools_export_get_schema($table);
  $status = variable_get($schema['export']['status'], array());

  $status[$name] = $new_status;
  variable_set($schema['export']['status'], $status);
}

/**
 * Set the status of a default $object as a variable.
 *
 * This is more efficient than ctools_export_set_status because it
 * will actually unset the variable entirely if it's not necessary,
 * this saving a bit of space.
 */
function ctools_export_set_object_status($object, $new_status = TRUE) {
  $table = $object->table;
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];
  $status = variable_get($export['status'], array());

  // Compare
  if (!$new_status && $object->export_type & EXPORT_IN_DATABASE) {
    unset($status[$object->{$export['key']}]);
  }
  else {
    $status[$object->{$export['key']}] = $new_status;
  }

  variable_set($export['status'], $status);
}

/**
 * Provide a form for displaying an export.
 *
 * This is a simple form that should be invoked like this:
 * @code
 *   $output = drupal_get_form('ctools_export_form', $code, $object_title);
 * @endcode
 */
function ctools_export_form($form, &$form_state, $code, $title = '') {
  $lines = substr_count($code, "\n");
  $form['code'] = array(
    '#type' => 'textarea',
    '#title' => $title,
    '#default_value' => $code,
    '#rows' => $lines,
  );

  return $form;
}

/**
 * Create a new object based upon schema values.
 *
 * Because 'default' has ambiguous meaning on some fields, we will actually
 * use 'object default' to fill in default values if default is not set
 * That's a little safer to use as it won't cause weird database default
 * situations.
 */
function ctools_export_new_object($table, $set_defaults = TRUE) {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];

  $object = new $export['object'];
  foreach ($schema['fields'] as $field => $info) {
    if (isset($info['object default'])) {
      $object->$field = $info['object default'];
    }
    else if (isset($info['default'])) {
      $object->$field = $info['default'];
    }
    else {
      $object->$field = NULL;
    }
  }

  if ($set_defaults) {
    // Set some defaults so this data always exists.
    // We don't set the export_type property here, as this object is not saved
    // yet. We do give it NULL so we don't generate notices trying to read it.
    $object->export_type = NULL;
    $object->{$export['export type string']} = t('Local');
  }
  return $object;
}

/**
 * Convert a group of objects to code based upon input and return this as a larger
 * export.
 */
function ctools_export_to_hook_code(&$code, $table, $names = array(), $name = 'foo') {
  $schema = ctools_export_get_schema($table);
  $export = $schema['export'];
  // Use the schema-specified function for generating hook code, if one exists
  if (function_exists($export['to hook code callback'])) {
    $output = $export['to hook code callback']($names, $name);
  }
  // Otherwise, the following code generates basic hook code
  else {
    $output = ctools_export_default_to_hook_code($schema, $table, $names, $name);
  }

  if (!empty($output)) {
    if (isset($export['api'])) {
      if (isset($code[$export['api']['owner']][$export['api']['api']]['version'])) {
        $code[$export['api']['owner']][$export['api']['api']]['version'] = max($code[$export['api']['owner']][$export['api']['api']]['version'], $export['api']['minimum_version']);
      }
      else {
        $code[$export['api']['owner']][$export['api']['api']]['version'] = $export['api']['minimum_version'];
        $code[$export['api']['owner']][$export['api']['api']]['code'] = '';
      }
      $code[$export['api']['owner']][$export['api']['api']]['code'] .= $output;
    }
    else {
      if (empty($code['general'])) {
        $code['general'] = '';
      }
      $code['general'] .= $output;
    }
  }
}

/**
 * Default function to export objects to code.
 *
 * Note that if your module provides a 'to hook code callback' then it will
 * receive only $names and $name as arguments. Your module is presumed to
 * already know the rest.
 */
function ctools_export_default_to_hook_code($schema, $table, $names, $name) {
  $export = $schema['export'];
  $output = '';
  $objects = ctools_export_crud_load_multiple($table, $names);
  if ($objects) {
    $output = "/**\n";
    $output .= " * Implements hook_{$export['default hook']}().\n";
    $output .= " */\n";
    $output .= "function " . $name . "_{$export['default hook']}() {\n";
    $output .= "  \${$export['identifier']}s = array();\n\n";
    foreach ($objects as $object) {
      $output .= ctools_export_crud_export($table, $object, '  ');
      $output .= "  \${$export['identifier']}s['" . check_plain($object->$export['key']) . "'] = \${$export['identifier']};\n\n";
    }
    $output .= "  return \${$export['identifier']}s;\n";
    $output .= "}\n";
  }

  return $output;
}
/**
 * Default function for listing bulk exportable objects.
 */
function ctools_export_default_list($table, $schema) {
  $list = array();

  $items = ctools_export_crud_load_all($table);
  $export_key = $schema['export']['key'];
  foreach ($items as $item) {
    // Try a couple of possible obvious title keys:
    $keys = array('admin_title', 'title');
    if (isset($schema['export']['admin_title'])) {
      array_unshift($keys, $schema['export']['admin_title']);
    }

    $string = '';
    foreach ($keys as $key) {
      if (!empty($item->$key)) {
        $string = $item->$key . " (" . $item->$export_key . ")";
        break;
      }
    }

    if (empty($string)) {
      $string = $item->$export_key;
    }
    $list[$item->$export_key] = check_plain($string);
  }
  return $list;
}
