Bidirectional save & remove of products & groups (Fieltype pages)

bidirectional

<?php

/**
 * Groups & Products references guard.
 *
 * Bidirectional save & remove of products & groups
 *
 * templates:
 *      - 'group', pagefield: page_products
 *      - 'product', pagefield: page_groups
 */

class GroupAndProducts extends WireData implements Module {

    public static function getModuleInfo() {
        return array(
            'title' => 'Group And Products',
            'summary' => 'Bidirectional save & remove of products & groups',
            'version' => 1,
            'autoload' => true,
        );
    }

    public function init() {
        $this->addHookAfter('Pages::saveReady', $this, 'hookPagesSave');
    }

    /**
     * Hook called when a page is saved
     *
     * Used to delete references to the page in any PageTable tables
     *
     */
    public function hookPagesSave(HookEvent $event) {
        $page = $event->arguments('page');

        $template = ($page->template != 'group' && $page->template != 'product') ? false :  $page->template->name;
        // False template, no glory
        if ($template === false) return;
        if ($template === 'product') {
            $this->productSave($page);
        } else if ($template === 'group') {
            $this->groupSave($page);
        }
    }

    /**
     * Group page is saved so check the product references
     *
     */
    protected function groupSave(Page $group) {

        // $this->log->save('changes', json_encode($group->getChanges()));

        if (in_array('page_products', $group->getChanges())) {
            // Assign group to a product
            foreach($group->page_products as $product) {
                if (!$product->page_groups->has($group)) {
                    $product->page_groups->add($group);
                    $product->save('page_groups');
                    //$product->setTrackChanges(false);
                    $message = sprintf($this->_('“%1$s” is added to the group: %2$s'), $product->title, $group->title);
                    $this->message($message);
                }
            }

            // Remove group from a product
            $products = $this->pages->find("template=product, page_groups=$group");
            foreach($products as $product) {
                if (!$group->page_products->has($product)) {
                    $product->page_groups->remove($group);
                    $product->save('page_groups');
                    //$product->setTrackChanges(false);
                    $message = sprintf($this->_('“%1$s” is removed from the group: %2$s'), $product->title, $group->title);
                    $this->message($message);
                }
            }
        }
    }

    /**
     * Product page is saved so check check references
     *
     */
    protected function productSave(Page $product) {

        // $this->log->save('changes', json_encode($product->getChanges()));

        if (in_array('page_groups', $product->getChanges())) {
            foreach($product->page_groups as $group) {
                if (!$group->page_products->has($product)) {
                    $group->page_products->add($product);
                    $group->save('page_products');
                    //$product->setTrackChanges(false);
                    $message = sprintf($this->_('“%1$s” is added to the group: %2$s'), $product->title, $group->title);
                    $this->message($message);
                }
            }

            // Remove group from a product
            $groups = $this->pages->find("template=group, page_products=$product");
            foreach($groups as $group) {
                if (!$product->page_groups->has($group)) {
                    $group->page_products->remove($product);
                    $group->save('page_products');
                    //$product->setTrackChanges(false);
                    $message = sprintf($this->_('“%1$s” is removed from the group: %2$s'), $product->title, $group->title);
                    $this->message($message);
                }
            }
        }
    }
}