Router for API REST like methods

Router.php

<?php

namespace ApiModule;

use Nette,
    Nette\Application\Request;

class Router extends Nette\Object implements Nette\Application\IRouter
{

    const FORMAT_KEY = 'format';
    const METHOD_KEY = 'method';

    const FORMAT_JSON = 'json';

    private $defaults = array(
        self::FORMAT_KEY => self::FORMAT_JSON,
        'id' => NULL,
    );

    function getFormats()
    {
        return array(
            self::FORMAT_JSON
        );
    }

    function getMethods()
    {
        return array(
            'GET',
            'PUT',
            'POST',
            'PARTIAL',
            'DELETE',
        );
    }

    /**
     * /api/(<namespace>/)*resource(/<id>)?(.<format json|xml...>)
     */
    function match(Nette\Http\IRequest $httpRequest)
    {
        $presenter = NULL;
        $method = NULL;
        $id = NULL;

        $match = preg_match('~^api/(?P<resource>[a-z]+(/[a-z]+)*)(/(?P<id>[1-9][0-9]*))?(.(?P<format>json))?$~i', $httpRequest->getUrl()->getPathInfo(), $matches);
        if (!$match) {
            return NULL;
        }
        $matches += array(
            'format' => self::FORMAT_JSON,
            'user' => '',
            'id' => '',
        );

        $params = array();
        if ($matches['id'] !== '') {
            $params['id'] = $matches['id'];
        }
        if ($matches['user'] !== '') {
            $params['user'] = $matches['user'];
        }

        $slugs = explode('/', $matches['resource'], 2);
        $first = array_shift($slugs);
        if (!$slugs) {
            array_push($slugs, 'default');
        } else {
            $last = array_pop($slugs);
            $last = strtr(ucwords($last), '/', '');
            array_push($slugs, $last);
        }
        array_unshift($slugs, 'api');
        array_unshift($slugs, $first);

        $presenter = ucwords(implode(':', $slugs));
        unset($params['resource']);

        $method = $httpRequest->getMethod();
        if (in_array($method, array('POST', 'PARTIAL', 'PUT'))) {
            if ($httpRequest->getHeader('Content-Type') === 'application/json') {
                $recieved = (array) json_decode(file_get_contents('php://input'), TRUE);
            } else {
                $recieved = $httpRequest->getPost();
            }
        } else {
            $recieved = array();
        }

        $params = $params + $httpRequest->getQuery() + $recieved + $this->defaults;
        if (isset($params[self::METHOD_KEY])) {
            $method = strtoupper($params[self::METHOD_KEY]);
            $this->validateMethod($method);
            unset($params[self::METHOD_KEY]);
        }

        $params[self::FORMAT_KEY] = strtolower($params[self::FORMAT_KEY]);
        $this->validateFormat($params[self::FORMAT_KEY]);

        return new Request(
            $presenter,
            $method,
            $params,
            $httpRequest->getPost(),
            $httpRequest->getFiles(),
            array(Request::SECURED => $httpRequest->isSecured())
        );
    }

    private function validateFormat($format)
    {
        if (!in_array($format, $this->getFormats(), TRUE)) {
            throw new Nette\InvalidStateException("Invalid format '$format' supported formats: " . implode(', ', $this->getFormats()) . ".");
        }
    }

    private function validateMethod($method)
    {
        if (!in_array($method, $this->getMethods(), TRUE)) {
            throw new Nette\InvalidStateException("Invalid method '$method' supported methods: " . implode(', ', $this->getMethods()) . ".");
        }
    }

    function constructUrl(Request $appRequest, Nette\Http\Url $refUrl)
    {
        return NULL;
    }

}