public static function adn_contributor_filter()
    {
        if (!is_admin()) {
            return;
        }
        if (!\Podlove\Modules\Base::is_module_settings_page()) {
            return;
        }
        if (!\Podlove\Modules\Base::is_active('app_dot_net')) {
            return;
        }
        $adn = \Podlove\Modules\AppDotNet\App_Dot_Net::instance();
        $roles = \Podlove\Modules\Contributors\Model\ContributorRole::all();
        $groups = \Podlove\Modules\Contributors\Model\ContributorGroup::all();
        $selected_role = $adn->get_module_option('adn_contributor_filter_role');
        $selected_group = $adn->get_module_option('adn_contributor_filter_group');
        if (count($roles) > 0 || count($groups) > 0) {
            $adn->register_option('contributor_filter', 'callback', array('label' => __('Contributor Filter', 'podlove'), 'description' => __('<br />Filter <code title="' . __('The contributors of the episode', 'podlove') . '">{episodeContributors}</code> by Group and/or role', 'podlove'), 'callback' => function () use($selected_role, $selected_group, $roles, $groups) {
                if (count($groups) > 0) {
                    ?>
						<select class="chosen" id="podlove_module_app_dot_net_adn_contributor_filter_group" name="podlove_module_app_dot_net[adn_contributor_filter_group]">
							<option value="">&nbsp;</option>
							<?php 
                    foreach ($groups as $group) {
                        echo "<option value='" . $group->id . "' " . ($selected_group == $group->id ? "selected" : "") . ">" . $group->title . "</option>";
                    }
                    ?>
						</select> Group
					<?php 
                }
                if (count($roles) > 0) {
                    ?>
						<select class="chosen" id="podlove_module_app_dot_net_adn_contributor_filter_role" name="podlove_module_app_dot_net[adn_contributor_filter_role]">
							<option value="">&nbsp;</option>
							<?php 
                    foreach ($roles as $role) {
                        echo "<option value='" . $role->id . "' " . ($selected_role == $role->id ? "selected" : "") . ">" . $role->title . "</option>";
                    }
                    ?>
						</select> Role
					<?php 
                }
            }));
        }
    }