csfr_protection();
$action = NULL;
if (isset($_POST['action'])) {
    $action = trim($_POST['action']);
}
if (isset($action)) {
    switch ($action) {
        case "list_subject_types":
            $current_taxonomy = new Taxonomy();
            if (isset($_POST['id'])) {
                $current_taxonomy->load((int) $_POST['id']);
            } else {
                $current_taxonomy->load();
            }
            echo '<p><a href="index.php?p=form_add_subject_type">Add a new subject type</a></p>';
            echo $current_taxonomy->get_taxonomy();
            break;
        case "list_subject_types_DEPRECATED":
            // might have an ID value passed as well.
            $db = Database::get_instance();
            $query = $db->prepare("SELECT id FROM subject_types");
            if ($query->execute()) {
                $subjects_collection = array();
                while ($row = $query->fetch()) {
                    $new_subject = new SubjectType();
                    $new_subject->load($row['id']);
                    $subjects_collection[] = $new_subject;
                }
                $output = '<table class="table table-striped table-bordered">';
                $output .= '<thead><tr><td><strong>Subject types</strong></td><td><strong>Description</strong></td></tr></thead>';
                foreach ($subjects_collection as $subject) {