/**
  * Caution: Only call on instances, not through a singleton.
  * The "root group" fields will be created through {@link SecurityAdmin->EditForm()}.
  *
  * @return FieldList
  */
 public function getCMSFields()
 {
     Requirements::javascript(FRAMEWORK_DIR . '/javascript/PermissionCheckboxSetField.js');
     $fields = new FieldList(new TabSet("Root", new Tab('Members', _t('SecurityAdmin.MEMBERS', 'Members'), new TextField("Title", $this->fieldLabel('Title')), $parentidfield = DropdownField::create('ParentID', $this->fieldLabel('Parent'), Group::get()->exclude('ID', $this->ID)->map('ID', 'Breadcrumbs'))->setEmptyString(' '), new TextareaField('Description', $this->fieldLabel('Description'))), $permissionsTab = new Tab('Permissions', _t('SecurityAdmin.PERMISSIONS', 'Permissions'), $permissionsField = new PermissionCheckboxSetField('Permissions', false, 'Permission', 'GroupID', $this))));
     $parentidfield->setDescription(_t('Group.GroupReminder', 'If you choose a parent group, this group will take all it\'s roles'));
     // Filter permissions
     // TODO SecurityAdmin coupling, not easy to get to the form fields through GridFieldDetailForm
     $permissionsField->setHiddenPermissions((array) Config::inst()->get('SecurityAdmin', 'hidden_permissions'));
     if ($this->ID) {
         $group = $this;
         $config = new GridFieldConfig_RelationEditor();
         $config->addComponent(new GridFieldButtonRow('after'));
         $config->addComponents(new GridFieldExportButton('buttons-after-left'));
         $config->addComponents(new GridFieldPrintButton('buttons-after-left'));
         $config->getComponentByType('GridFieldAddExistingAutocompleter')->setResultsFormat('$Title ($Email)')->setSearchFields(array('FirstName', 'Surname', 'Email'));
         $config->getComponentByType('GridFieldDetailForm')->setValidator(new Member_Validator())->setItemEditFormCallback(function ($form, $component) use($group) {
             $record = $form->getRecord();
             $groupsField = $form->Fields()->dataFieldByName('DirectGroups');
             if ($groupsField) {
                 // If new records are created in a group context,
                 // set this group by default.
                 if ($record && !$record->ID) {
                     $groupsField->setValue($group->ID);
                 } elseif ($record && $record->ID) {
                     // TODO Mark disabled once chosen.js supports it
                     // $groupsField->setDisabledItems(array($group->ID));
                     $form->Fields()->replaceField('DirectGroups', $groupsField->performReadonlyTransformation());
                 }
             }
         });
         $memberList = GridField::create('Members', false, $this->DirectMembers(), $config)->addExtraClass('members_grid');
         // @todo Implement permission checking on GridField
         //$memberList->setPermissions(array('edit', 'delete', 'export', 'add', 'inlineadd'));
         $fields->addFieldToTab('Root.Members', $memberList);
     }
     // Only add a dropdown for HTML editor configurations if more than one is available.
     // Otherwise Member->getHtmlEditorConfigForCMS() will default to the 'cms' configuration.
     $editorConfigMap = HtmlEditorConfig::get_available_configs_map();
     if (count($editorConfigMap) > 1) {
         $fields->addFieldToTab('Root.Permissions', new DropdownField('HtmlEditorConfig', 'HTML Editor Configuration', $editorConfigMap), 'Permissions');
     }
     if (!Permission::check('EDIT_PERMISSIONS')) {
         $fields->removeFieldFromTab('Root', 'Permissions');
     }
     // Only show the "Roles" tab if permissions are granted to edit them,
     // and at least one role exists
     if (Permission::check('APPLY_ROLES') && DataObject::get('PermissionRole')) {
         $fields->findOrMakeTab('Root.Roles', _t('SecurityAdmin.ROLES', 'Roles'));
         $fields->addFieldToTab('Root.Roles', new LiteralField("", "<p>" . _t('SecurityAdmin.ROLESDESCRIPTION', "Roles are predefined sets of permissions, and can be assigned to groups.<br />" . "They are inherited from parent groups if required.") . '<br />' . sprintf('<a href="%s" class="add-role">%s</a>', singleton('SecurityAdmin')->Link('show/root#Root_Roles'), _t('Group.RolesAddEditLink', 'Manage roles')) . "</p>"));
         // Add roles (and disable all checkboxes for inherited roles)
         $allRoles = PermissionRole::get();
         if (Permission::check('ADMIN')) {
             $allRoles = $allRoles->filter("OnlyAdminCanApply", 0);
         }
         if ($this->ID) {
             $groupRoles = $this->Roles();
             $inheritedRoles = new ArrayList();
             $ancestors = $this->getAncestors();
             foreach ($ancestors as $ancestor) {
                 $ancestorRoles = $ancestor->Roles();
                 if ($ancestorRoles) {
                     $inheritedRoles->merge($ancestorRoles);
                 }
             }
             $groupRoleIDs = $groupRoles->column('ID') + $inheritedRoles->column('ID');
             $inheritedRoleIDs = $inheritedRoles->column('ID');
         } else {
             $groupRoleIDs = array();
             $inheritedRoleIDs = array();
         }
         $rolesField = ListboxField::create('Roles', false, $allRoles->map()->toArray())->setMultiple(true)->setDefaultItems($groupRoleIDs)->setAttribute('data-placeholder', _t('Group.AddRole', 'Add a role for this group'))->setDisabledItems($inheritedRoleIDs);
         if (!$allRoles->Count()) {
             $rolesField->setAttribute('data-placeholder', _t('Group.NoRoles', 'No roles found'));
         }
         $fields->addFieldToTab('Root.Roles', $rolesField);
     }
     $fields->push($idField = new HiddenField("ID"));
     $this->extend('updateCMSFields', $fields);
     return $fields;
 }