module-vendor-notes/Block/Adminhtml/Order/View/VendorNotes.php

<?php
namespace Shopkeeper\VendorNotes\Block\Adminhtml\Order\View;

use Magento\Backend\Block\Template;
use Magento\Sales\Model\Order;
use Magento\Framework\App\Config\ScopeConfigInterface;
use Magento\Store\Model\ScopeInterface;
use Magento\Framework\Serialize\Serializer\Json;

class VendorNotes extends Template
{
    protected $_order;
    protected $_scopeConfig;
    protected $json;

    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        \Magento\Sales\Model\Order $order,
        ScopeConfigInterface $scopeConfig,
        Json $json,
        array $data = []
    ) {
        $this->_order = $order;
        $this->_scopeConfig = $scopeConfig;
        $this->json = $json;
        parent::__construct($context, $data);
    }

    public function getOrder()
    {
        return $this->_order->load($this->getRequest()->getParam('order_id'));
    }

    public function getVendorNotes()
    {
        $order = $this->getOrder();
        $notes = [];
        
        // Get the vendor mapping configuration
        $vendorMapping = $this->getVendorMapping();
        
        if (empty($vendorMapping)) {
            return $notes;
        }

        foreach ($order->getAllItems() as $item) {
            $product = $item->getProduct();
            $vendorId = $product->getData('vendor');
            
            if ($vendorId) {
                $vendorLabel = $product->getAttributeText('vendor');
                
                // Look for matching vendor in the mapping
                foreach ($vendorMapping as $mapping) {
                    if (isset($mapping['vendor_name']) && 
                        isset($mapping['note']) && 
                        $mapping['vendor_name'] === $vendorLabel) {
                        
                        $note = $mapping['note'];
                        
                        // Avoid duplicate notes
                        if ($note && !in_array($note, $notes)) {
                            $notes[] = $note;
                        }
                        break;
                    }
                }
            }
        }

        return $notes;
    }

    /**
     * Get vendor mapping from configuration
     *
     * @return array
     */
    protected function getVendorMapping()
    {
        $config = $this->_scopeConfig->getValue(
            'vendor_notes/general/vendor_mapping',
            ScopeInterface::SCOPE_STORE
        );

        if (!$config) {
            return [];
        }

        try {
            $mapping = $this->json->unserialize($config);
            return is_array($mapping) ? $mapping : [];
        } catch (\Exception $e) {
            return [];
        }
    }

    /**
     * Filter output to allow safe HTML tags
     *
     * @param string $content
     * @return string
     */
    public function filterOutputHtml($content)
    {
        // Decode HTML entities first in case the content was double-encoded
        $content = html_entity_decode($content, ENT_QUOTES, 'UTF-8');
        
        // Use Magento's filter to allow specific HTML tags
        // This is safer than just echoing raw HTML
        return $this->filterTemplate->filter($content);
    }
}