function getHookPresets() {
    // TODO: read user file preferentially.
    $presets_template = $this->loadPresetsFile('hook_groups.template');
    $hook_presets = json_decode(preg_replace("@//.*@", '', $presets_template), TRUE);
    if (is_null($hook_presets)) {
      // @TODO: do something here to say its gone wrong. Throw Exception?
      drupal_set_message(t('Problem reading json file.'), 'error');
    }
    return $hook_presets;
  }