MiddlewareChain.php

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<?php
namespace MediaWiki\Notification;
 
use Wikimedia\ObjectFactory\ObjectFactory;
 
class MiddlewareChain {
    private array $middleware = [];
 
    private ObjectFactory $objectFactory;
    private array $middlewareSpecs;
    private bool $loadedFromSpecs = false;
 
    private bool $isProcessing = false;
 
    public function __construct( ObjectFactory $objectFactory, array $specs ) {
        $this->objectFactory = $objectFactory;
        $this->middlewareSpecs = $specs;
    }
 
    public function process( NotificationsBatch $batch ): NotificationsBatch {
        if ( $this->isProcessing ) {
            // If you need to send an additional notification from middleware,
            // use NotificationBatch::add() instead of calling NotificationService from middleware
            throw new MiddlewareException(
                "Middleware cannot re-trigger the notification processing while it is already in progress. "
            );
        }
        $this->isProcessing = true;
 
        if ( !$this->loadedFromSpecs ) {
            foreach ( $this->middlewareSpecs as $spec ) {
                $this->middleware[] = $this->objectFactory->createObject( $spec, [
                    'assertClass' => NotificationMiddlewareInterface::class
                ] );
            }
            $this->loadedFromSpecs = true;
        }
 
        $this->callNext( $batch, 0 );
        $this->isProcessing = false;
        return $batch;
    }
 
    private function callNext( NotificationsBatch $batch, int $index ): void {
        if ( $index < count( $this->middleware ) ) {
            $this->middleware[$index]->handle(
                $batch,
                function () use ( $batch, $index ) {
                    $this->callNext( $batch, $index + 1 );
                }
            );
        }
    }
}