Dispatcher between Symfony2 and a legacy application

app.php

<?php

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\Routing\RequestContext;
use Symfony\Component\Routing\Exception\ResourceNotFoundException;

// Hack SwiftMailer (symfony1 vs Symfony2)
define('SWIFT_REQUIRED_LOADED', true);

$loader  = require_once __DIR__.'/../app/bootstrap.php.cache';
Request::enableHttpMethodParameterOverride();
$request = Request::createFromGlobals();
$env     = 'prod';

$appUrlMatcher = sprintf(__DIR__.'/../cache/%s/app%sUrlMatcher.php', $env, ucfirst($env));
if (!file_exists($appUrlMatcher)) {
    require_once __DIR__.'/../app/AppKernel.php';
    $kernel = new AppKernel($env, true);
    $kernel->boot();
    $kernel->getContainer()->get('router')->getMatcher();
}
$classUrlMatcher = basename($appUrlMatcher, '.php');
require_once $appUrlMatcher;

$context = new RequestContext();
$context->fromRequest($request);
$matcher = new $classUrlMatcher($context);
try {
    $attributes = $matcher->match($request->getPathInfo());
} catch (ResourceNotFoundException $e) {

    // The requested route does not exist in the Symfony2 application.
    include __DIR__.'/index.php'; // Launch the legacy application.
    return;

}

foreach ($attributes AS $key=>$attribute) {
    $request->attributes->set($key, $attribute);
}

if (!isset($kernel)) {
    require_once __DIR__.'/../app/AppKernel.php';
    $kernel = new AppKernel($env, false);
    $kernel->boot();
}

// Hack SwiftMailer (symfony1 vs Symfony2) > /vendor/swiftmailer/swiftmailer/lib/swift_required.php
$path = __DIR__.'/../vendor/swiftmailer/swiftmailer/lib';
require $path . '/classes/Swift.php';
if (!function_exists('_swiftmailer_init')) {
    function _swiftmailer_init()
    {
        require $path . '/swift_init.php';
    }
}
Swift::registerAutoload('_swiftmailer_init');
// end hack

$kernel->loadClassCache();
$response = $kernel->handle($request);
$response->send();
$kernel->terminate($request, $response);

app_dev.php

<?php

use Symfony\Component\Debug\Debug;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\Routing\RequestContext;
use Symfony\Component\Routing\Exception\ResourceNotFoundException;

if (isset($_SERVER['HTTP_CLIENT_IP'])
    || isset($_SERVER['HTTP_X_FORWARDED_FOR'])
    || !in_array(@$_SERVER['REMOTE_ADDR'], array('127.0.0.1', 'fe80::1', '::1'))
    ) {
    header('HTTP/1.0 403 Forbidden');
    exit('You are not allowed to access this file. Check '.basename(__FILE__).' for more information.');
}

// Hack SwiftMailer (symfony1 vs Symfony2)
define('SWIFT_REQUIRED_LOADED', true);

$loader  = require_once __DIR__.'/../app/bootstrap.php.cache';
Debug::enable();
Request::enableHttpMethodParameterOverride();
$request = Request::createFromGlobals();
$env     = 'dev';

$appUrlMatcher = sprintf(__DIR__.'/../cache/%s/app%sUrlMatcher.php', $env, ucfirst($env));
if (!file_exists($appUrlMatcher)) {
    require_once __DIR__.'/../app/AppKernel.php';
    $kernel = new AppKernel($env, true);
    $kernel->boot();
    $kernel->getContainer()->get('router')->getMatcher();
}
$classUrlMatcher = basename($appUrlMatcher, '.php');
require_once $appUrlMatcher;

$context = new RequestContext();
$context->fromRequest($request);
$matcher = new $classUrlMatcher($context);
try {
    $attributes = $matcher->match($request->getPathInfo());
} catch (ResourceNotFoundException $e) {

    // The requested route does not exist in the Symfony2 application.
    include __DIR__.'/index.php'; // Launch the legacy application.
    return;

}

if (!array_key_exists('token', $attributes)) {
    foreach ($attributes AS $key=>$attribute) {
        $request->attributes->set($key, $attribute);
    }
}

if (!isset($kernel)) {
    require_once __DIR__.'/../app/AppKernel.php';
    $kernel = new AppKernel($env, true);
    $kernel->boot();
}

// Hack SwiftMailer (symfony1 vs Symfony2) > /vendor/swiftmailer/swiftmailer/lib/swift_required.php
$path = __DIR__.'/../vendor/swiftmailer/swiftmailer/lib';
require $path . '/classes/Swift.php';
if (!function_exists('_swiftmailer_init')) {
    function _swiftmailer_init()
    {
        require $path . '/swift_init.php';
    }
}
Swift::registerAutoload('_swiftmailer_init');
// end hack

$kernel->loadClassCache();
$response = $kernel->handle($request);
$response->send();
$kernel->terminate($request, $response);