part 3

WrappingHandlersLocator.php

<?php

declare(strict_types=1);

namespace App;

use Exception;
use ReflectionFunction;
use ReflectionParameter;
use Symfony\Component\Messenger\Envelope;
use Symfony\Component\Messenger\Handler\HandlerDescriptor;
use Symfony\Component\Messenger\Handler\HandlersLocatorInterface;

class WrappingHandlersLocator implements HandlersLocatorInterface
{
    private HandlersLocatorInterface $decorated;

    public function __construct(HandlersLocatorInterface $decorated)
    {
        $this->decorated = $decorated;
    }

    public function getHandlers(Envelope $envelope): iterable
    {
        /** @var iterable<int, HandlerDescriptor> $handlerDescriptors */
        $handlerDescriptors = $this->decorated->getHandlers($envelope);
        $message = $envelope->getMessage();

        foreach ($handlerDescriptors as $handlerDescriptor) {
            if ($this->shouldWrapHandler($handlerDescriptor, $message)) {
                yield $this->wrapHandler($handlerDescriptor, $message);
            } else {
                yield $handlerDescriptor;
            }
        }
    }

    private function shouldWrapHandler(HandlerDescriptor $handlerDescriptor, object $message): bool
    {
        $arguments = $this->getHandlerArguments($handlerDescriptor);

        return (count($arguments) == 0)
            || (count($arguments) > 1)
            || (!$arguments[0]->getType()->getName() == get_class($message));
    }

    /** @return array<int, ReflectionParameter> */
    private function getHandlerArguments(HandlerDescriptor $handlerDescriptor): array
    {
        $function = new ReflectionFunction($handlerDescriptor->getHandler());

        return $function->getParameters();
    }

    private function wrapHandler(HandlerDescriptor $handlerDescriptor, object $message): HandlerDescriptor
    {
        $handlerArguments = $this->getHandlerArguments($handlerDescriptor);
        $handlerArgumentValues = $this->resolveValuesForHandlerArguments($handlerArguments, $message);

        return new HandlerDescriptor(
            fn() => $handlerDescriptor->getHandler()(...$handlerArgumentValues),
            [
                'alias' => $this->generateHandlerAlias($handlerDescriptor)
            ]
        );
    }

    private function generateHandlerAlias(HandlerDescriptor $handlerDescriptor): string
    {
        $function = new ReflectionFunction($handlerDescriptor->getHandler());

        return sprintf(
            "%s::%s",
            $function->getClosureScopeClass()?->getShortName(),
            $function->getName()
        );
    }

    /**
     * @param array<int, ReflectionParameter> $arguments
     * @return array<int, mixed>
     */
    private function resolveValuesForHandlerArguments(array $arguments, object $message): array
    {
        return array_map(
            fn(ReflectionParameter $argument) => $this->resolveValueForHandlerArgument($argument, $message),
            $arguments
        );
    }

    private function resolveValueForHandlerArgument(
        ReflectionParameter $argument,
        object $message
    ): mixed {
        $attribute = $this->getAttributeForArgument($argument);

        $messagePropertyName = $attribute?->messageProperty ?? $argument->getName();

        if (property_exists($message, $messagePropertyName)) {
            return $message->{$messagePropertyName};
        }

        if ($argument->isDefaultValueAvailable()) {
            return $argument->getDefaultValue();
        }

        if ($attribute?->defaultValue) {
            return $attribute->defaultValue;
        }

        throw new Exception(sprintf(
            "Missing handler argument mapping or default value for the \"%s\" argument of \"%s::%s\".",
            $argument->getName(),
            $argument->getDeclaringClass()->getName(),
            $argument->getDeclaringFunction()->getName()
        ));
    }

    private function getAttributeForArgument(ReflectionParameter $argument): ?ExtractedValue
    {
        $attributes = $argument->getAttributes(ExtractedValue::class);

        if (!count($attributes)) {
            return null;
        }

        return $attributes[0]->newInstance();
    }
}