<?php
class FAQCategory extends DataObject {

    static $db = array(
        'FAQCategory' => 'Varchar(255)'
    );

    static $has_many = array(
        'FAQSubCategories' => "FAQSubCategory"
    );

    public function getCMSFields($params = null) {
        $fields = parent::getCMSFields($params);

        $fields->removeByName("FAQSubCategories");

        $fields->addFieldToTab("Root.Main",
                $manager =new DataObjectManager(
                        $this,
                        'FAQSubCategories',
                        'FAQSubCategory',
                        array(
                                'FAQSubCategory' => 'FAQSubCategory'
                        )
                ));

        $manager->setAddTitle("FAQ Sub Categories");
        $manager->set_popup_width(900);

        return $fields;
    }
}

class FAQSubCategory extends DataObject {

    static $db = array(
        'FAQSubCategory' => 'Varchar(255)'
    );

    static $has_one = array(
        'Parent' => 'FAQCategory'
    );

    static $has_many = array(
        'FAQs' => "FAQ"
    );

    public function getCMSFields($params = null) {
        $fields = parent::getCMSFields($params);

        $fields->removeByName("FAQs");

        $fields->addFieldToTab("Root.Main",
            $manager = new DataObjectManager(
                $this,
                'FAQs',
                'FAQ',
                array(
                    'Question' => 'Question'
                )
            )
        );

        $manager->setAddTitle("FAQ");

    // This does not set the width
        $manager->set_popup_width(800);

        return $fields;
    }
}

class FAQ extends DataObject {

    static $db = array(
        'Question' => 'HTMLText',
        'Answer' => 'HTMLText'
    );
    static $has_one = array(
        'Parent' => 'FAQSubCategory',
    );

    public function getCMSFields() {
        $fields = new FieldSet();

        $fields->push(new SimpleHTMLEditorField("Question"));
        $fields->push(new SimpleHTMLEditorField("Answer"));

        return $fields;
    }

}