<?php namespace Illuminate\Session;

use Closure;
use Carbon\Carbon;
use Symfony\Component\HttpFoundation\Cookie;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\HttpKernelInterface;

class Middleware implements HttpKernelInterface {

	/**
	 * The wrapped kernel implementation.
	 *
	 * @var \Symfony\Component\HttpKernel\HttpKernelInterface
	 */
	protected $app;

	/**
	 * The session manager.
	 *
	 * @var \Illuminate\Session\SessionManager
	 */
	protected $manager;

	/**
	 * The callback to determine to use session arrays.
	 *
	 * @var \Closure|null
	 */
	protected $reject;

	/**
	 * Create a new session middleware.
	 *
	 * @param  \Symfony\Component\HttpKernel\HttpKernelInterface  $app
	 * @param  \Illuminate\Session\SessionManager  $manager
	 * @param  \Closure|null  $reject
	 * @return void
	 */
	public function __construct(HttpKernelInterface $app, SessionManager $manager, Closure $reject = null)
	{
		$this->app = $app;
		$this->reject = $reject;
		$this->manager = $manager;
	}

	/**
	 * Handle the given request and get the response.
	 *
	 * @implements HttpKernelInterface::handle
	 *
	 * @param  \Symfony\Component\HttpFoundation\Request  $request
	 * @param  int   $type
	 * @param  bool  $catch
	 * @return \Symfony\Component\HttpFoundation\Response
	 */
	public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
	{
		$this->checkRequestForArraySessions($request);

		// If a session driver has been configured, we will need to start the session here
		// so that the data is ready for an application. Note that the Laravel sessions
		// do not make use of PHP "native" sessions in any way since they are crappy.
		if ($this->sessionConfigured())
		{
			$session = $this->startSession($request);

			$request->setSession($session);
		}

		$response = $this->app->handle($request, $type, $catch);

		// Again, if the session has been configured we will need to close out the session
		// so that the attributes may be persisted to some storage medium. We will also
		// add the session identifier cookie to the application response headers now.
		if ($this->sessionConfigured())
		{
			$this->closeSession($session);

			$this->addCookieToResponse($response, $session);
		}

		return $response;
	}

	/**
	 * Check the request and reject callback for array sessions.
	 *
	 * @param  \Symfony\Component\HttpFoundation\Request  $request
	 * @return void
	 */
	public function checkRequestForArraySessions(Request $request)
	{
		if (is_null($this->reject)) return;

		if (call_user_func($this->reject, $request))
		{
			$this->manager->setDefaultDriver('array');
		}
	}

	/**
	 * Start the session for the given request.
	 *
	 * @param  \Symfony\Component\HttpFoundation\Request  $request
	 * @return \Illuminate\Session\SessionInterface
	 */
	protected function startSession(Request $request)
	{
		with($session = $this->getSession($request))->setRequestOnHandler($request);

		$session->start();

		return $session;
	}

	/**
	 * Close the session handling for the request.
	 *
	 * @param  \Illuminate\Session\SessionInterface  $session
	 * @return void
	 */
	protected function closeSession(SessionInterface $session)
	{
		$session->save();

		$this->collectGarbage($session);
	}

	/**
	 * Get the full URL for the request.
	 *
	 * @param  \Symfony\Component\HttpFoundation\Request  $request
	 * @return string
	 */
	protected function getUrl(Request $request)
	{
		$url = rtrim(preg_replace('/\?.*/', '', $request->getUri()), '/');

		return $request->getQueryString() ? $url.'?'.$request->getQueryString() : $url;
	}

	/**
	 * Remove the garbage from the session if necessary.
	 *
	 * @param  \Illuminate\Session\SessionInterface  $session
	 * @return void
	 */
	protected function collectGarbage(SessionInterface $session)
	{
		$config = $this->manager->getSessionConfig();

		// Here we will see if this request hits the garbage collection lottery by hitting
		// the odds needed to perform garbage collection on any given request. If we do
		// hit it, we'll call this handler to let it delete all the expired sessions.
		if ($this->configHitsLottery($config))
		{
			$session->getHandler()->gc($this->getLifetimeSeconds());
		}
	}

	/**
	 * Determine if the configuration odds hit the lottery.
	 *
	 * @param  array  $config
	 * @return bool
	 */
	protected function configHitsLottery(array $config)
	{
		return mt_rand(1, $config['lottery'][1]) <= $config['lottery'][0];
	}

	/**
	 * Add the session cookie to the application response.
	 *
	 * @param  \Symfony\Component\HttpFoundation\Response  $response
	 * @param  \Symfony\Component\HttpFoundation\Session\SessionInterface  $session
	 * @return void
	 */
	protected function addCookieToResponse(Response $response, SessionInterface $session)
	{
		$s = $session;

		if ($this->sessionIsPersistent($c = $this->manager->getSessionConfig()))
		{
			$secure = array_get($c, 'secure', false);

			$response->headers->setCookie(new Cookie(
				$s->getName(), $s->getId(), $this->getCookieLifetime(), $c['path'], $c['domain'], $secure
			));
		}
	}

	/**
	 * Get the session lifetime in seconds.
	 *
	 *
	 */
	protected function getLifetimeSeconds()
	{
		return array_get($this->manager->getSessionConfig(), 'lifetime') * 60;
	}

	/**
	 * Get the cookie lifetime in seconds.
	 *
	 * @return int
	 */
	protected function getCookieLifetime()
	{
		$config = $this->manager->getSessionConfig();

		return $config['expire_on_close'] ? 0 : Carbon::now()->addMinutes($config['lifetime']);
	}

	/**
	 * Determine if a session driver has been configured.
	 *
	 * @return bool
	 */
	protected function sessionConfigured()
	{
		return ! is_null(array_get($this->manager->getSessionConfig(), 'driver'));
	}

	/**
	 * Determine if the configured session driver is persistent.
	 *
	 * @param  array|null  $config
	 * @return bool
	 */
	protected function sessionIsPersistent(array $config = null)
	{
		// Some session drivers are not persistent, such as the test array driver or even
		// when the developer don't have a session driver configured at all, which the
		// session cookies will not need to get set on any responses in those cases.
		$config = $config ?: $this->manager->getSessionConfig();

		return ! in_array($config['driver'], array(null, 'array'));
	}

	/**
	 * Get the session implementation from the manager.
	 *
	 * @return \Illuminate\Session\SessionInterface
	 */
	public function getSession(Request $request)
	{
		$session = $this->manager->driver();

		$session->setId($request->cookies->get($session->getName()));

		return $session;
	}

}