BasicCommandBus

BasicCommandBus.php

<?php

namespace Framework\Bus;

use Interop\Container\ContainerInterface;

final class BasicCommandBus implements CommandBusInterface
{

    /**
     * @var \Framework\Bus\Middlewares\CommandBusMiddleware
     */
    private $middlewareChain;

    /**
     * @var ContainerInterface
     */
    private $container;

    public function __construct(ContainerInterface $container, array $middlewares)
    {
        $this->middlewareChain = $this->buildMiddlewareChain($middlewares);
        $this->container       = $container;
    }

    public function execute(Command $command)
    {
        // Resolve the handler class
        $handler = $this->resolveHandlerClass($command);

        // Pass the command and its handler in the middleware chain
        return $this->middlewareChain->handle($command, $handler);
    }

    private function buildMiddlewareChain(array $middlewares = [])
    {
        if (empty($middlewares)) {
            return null;
        }

        // Fetch the first middleware
        $next = array_shift($middlewares);

        // Set its next middleware
        $next->setNext($this->buildMiddlewareChain($middlewares));

        return $next;
    }

    /**
     * Resolves an instance of the handler class
     * corresponding to $command.
     *
     * @param Command $command
     *
     * @return mixed
     * @throws \Exception
     */
    private function resolveHandlerClass(Command $command)
    {
        $reflectionObject = new \ReflectionObject($command);
        $shortName        = $reflectionObject->getShortName();
        $className        = $reflectionObject->getNamespaceName() . '\\Handlers\\' . $shortName . 'Handler';

        if (!class_exists($className)) {
            throw new \Exception("No command handler found for " . $className);
        }

        // Let the container resolve the instance and inject the
        // required dependencies.
        return $this->container->get($className);
    }
}