private function setup_plugin($comment) {
        global $DB;
        $this->context = context::instance_by_id($comment->contextid, IGNORE_MISSING);
        if (!$this->context) {
            return false;
        }
        switch ($this->context->contextlevel) {
            case CONTEXT_BLOCK:
                if ($block = $DB->get_record('block_instances', array('id' => $this->context->instanceid))) {
                    $this->plugintype = 'block';
                    $this->pluginname = $block->blockname;
                } else {
                    return false;
                }
                break;
            case CONTEXT_MODULE:
                $this->plugintype = 'mod';
                $this->cm = get_coursemodule_from_id('', $this->context->instanceid);
                $this->setup_course($this->cm->course);
                $this->modinfo = get_fast_modinfo($this->course);
                $this->pluginname = $this->modinfo->cms[$this->cm->id]->modname;
                break;
        }
        return true;
    }