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/*
* This file is part of the ICanBoogie package.
*
* (c) Olivier Laviale <olivier.laviale@gmail.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace ICanBoogie\HTTP;
use ICanBoogie\Exception\RescueEvent;
use ICanBoogie\HTTP\RequestDispatcher\BeforeDispatchEvent;
use ICanBoogie\HTTP\RequestDispatcher\DispatchEvent;
/**
* Dispatches HTTP requests.
*
* ## Events
*
* - `ICanBoogie\HTTP\RequestDispatcher::dispatch:before` of class {@link BeforeDispatchEvent}.
* - `ICanBoogie\HTTP\RequestDispatcher::dispatch` of class {@link DispatchEvent}.
* - `ICanBoogie\HTTP\RequestDispatcher::rescue` of class {@link ICanBoogie\Exception\RescueEvent}.
*/
class RequestDispatcher implements \ArrayAccess, \IteratorAggregate, Dispatcher
{
/**
* The dispatchers called during the dispatching of the request.
*
* @var array
*/
protected $dispatchers = [];
/**
* The weights of the dispatchers.
*
* @var array
*/
protected $dispatchers_weight = [];
protected $dispatchers_order;
/**
* Initializes the {@link $dispatchers} property.
*
* Dispatchers can be defined as callable or class name. If a dispatcher definition is not a
* callable it is used as class name to instantiate a dispatcher.
*
* @param array $dispatchers
*/
public function __construct(array $dispatchers = [])
{
foreach ($dispatchers as $dispatcher_id => $dispatcher)
{
$this[$dispatcher_id] = $dispatcher;
}
}
/**
* Dispatches the request to retrieve a {@link Response}.
*
* The request is dispatched by the {@link dispatch()} method. If an exception is thrown
* during the dispatch the {@link rescue()} method is used to rescue the exception and
* retrieve a {@link Response}.
*
* ## HEAD requests
*
* If a {@link NotFound} exception is caught during the dispatching of a request with a
* {@link Request::METHOD_HEAD} method the following happens:
*
* 1. The request is cloned and the method of the cloned request is changed to
* {@link Request::METHOD_GET}.
* 2. The cloned method is dispatched.
* 3. If the result is *not* a {@link Response} instance, the result is returned.
* 4. Otherwise, a new {@link Response} instance is created with a `null` body, but the status
* code and headers of the original response.
* 5. The new response is returned.
*
* @param Request $request
*
* @return Response
*/
public function __invoke(Request $request)
{
$response = $this->handle($request);
if ($request->is_head && $response->body)
{
return new Response(null, $response->status, $response->headers);
}
return $response;
}
/**
* Dispatches the request and try to rescue it if it fails.
*
* If a {@link NotFound} exception is caught and the request method is `HEAD`, the request
* is passed to {@link handle_head()}.
*
* @param Request $request
*
* @return Response
* @throws \Exception
*/
private function handle(Request $request)
{
try
{
return $this->dispatch($request);
}
catch (\Exception $e)
{
if ($e instanceof NotFound && $request->is_head)
{
try
{
return $this->handle_head($request);
}
catch (\Exception $head_exception)
{
#
# We don't care about this one, let's rescue the original exception.
#
}
}
return $this->rescue($e, $request);
}
}
/**
* Trying to rescue a NotFound HEAD request using GET instead.
*
* @param Request $request
*
* @return Response
*/
private function handle_head(Request $request)
{
$response = $this->handle($request->with([ 'is_get' => true ]));
if ($response->content_length === null && !$response->body instanceof \Closure)
{
try
{
$response->content_length = strlen((string) $response->body);
}
catch (\Exception $e)
{
#
# It's not that bad if we can't obtain the length of the body.
#
}
}
return $response;
}
/**
* Checks if the dispatcher is defined.
*
* @param string $dispatcher_id The identifier of the dispatcher.
*
* @return bool `true` if the dispatcher is defined, `false` otherwise.
*/
public function offsetExists($dispatcher_id)
{
return isset($this->dispatchers[$dispatcher_id]);
}
/**
* Returns a dispatcher.
*
* @param string $dispatcher_id The identifier of the dispatcher.
*
* @return mixed
*/
public function offsetGet($dispatcher_id)
{
if (!$this->offsetExists($dispatcher_id))
{
throw new DispatcherNotDefined($dispatcher_id);
}
return $this->dispatchers[$dispatcher_id];
}
/**
* Defines a dispatcher.
*
* @param string $dispatcher_id The identifier of the dispatcher.
* @param mixed $dispatcher The dispatcher class or callback.
*/
public function offsetSet($dispatcher_id, $dispatcher)
{
$weight = 0;
if ($dispatcher instanceof WeightedDispatcher)
{
$weight = $dispatcher->weight;
$dispatcher = $dispatcher->dispatcher;
}
$this->dispatchers[$dispatcher_id] = $dispatcher;
$this->dispatchers_weight[$dispatcher_id] = $weight;
$this->dispatchers_order = null;
}
/**
* Removes a dispatcher.
*
* @param string $dispatcher_id The identifier of the dispatcher.
*/
public function offsetUnset($dispatcher_id)
{
unset($this->dispatchers[$dispatcher_id]);
}
/**
* @inheritdoc
*/
public function getIterator()
{
if (!$this->dispatchers_order)
{
$weights = $this->dispatchers_weight;
$this->dispatchers_order = \ICanBoogie\sort_by_weight($this->dispatchers, function($v, $k) use ($weights) {
return $weights[$k];
});
}
return new \ArrayIterator($this->dispatchers_order);
}
/**
* Dispatches a request using the defined dispatchers.
*
* The method iterates over the defined dispatchers until one of them returns a
* {@link Response} instance. If an exception is throw during the dispatcher execution and
* the dispatcher implements the {@link Dispatcher} interface then its
* {@link Dispatcher::rescue} method is invoked to rescue the exception, otherwise the
* exception is just re-thrown.
*
* {@link BeforeDispatchEvent} is fired before dispatchers are traversed. If a
* response is provided the dispatchers are skipped.
*
* {@link DispatchEvent} is fired before the response is returned. The event is
* fired event if the dispatchers did'nt return a response. It's the last chance to get one.
*
* @param Request $request
*
* @return Response
*
* @throws \Exception If the dispatcher that raised an exception during dispatch doesn't implement
* {@link Dispatcher}.
* @throws NotFound when neither the events nor the dispatchers were able to provide
* a {@link Response}.
*/
protected function dispatch(Request $request)
{
$response = null;
new BeforeDispatchEvent($this, $request, $response);
if (!$response)
{
foreach ($this as $id => $dispatcher)
{
if (!$dispatcher instanceof Dispatcher)
{
#
# If the dispatcher is not a callable then it is considered as a class name, which
# is used to instantiate a dispatcher.
#
$this->dispatchers[$id] = $dispatcher = is_callable($dispatcher)
? new CallableDispatcher($dispatcher)
: new $dispatcher;
}
$response = $this->dispatch_with_dispatcher($dispatcher, $request);
if ($response) break;
}
}
new DispatchEvent($this, $request, $response);
if (!$response)
{
throw new NotFound;
}
return $response;
}
/**
* Dispatches the request using a dispatcher.
*
* @param Dispatcher $dispatcher
* @param Request $request
*
* @return Response
*
* @throws \Exception
*/
protected function dispatch_with_dispatcher(Dispatcher $dispatcher, Request $request)
{
try
{
$request->context->dispatcher = $dispatcher;
$response = $dispatcher($request);
}
catch (\Exception $e)
{
$response = $dispatcher->rescue($e, $request);
}
$request->context->dispatcher = null;
return $response;
}
/**
* Tries to get a {@link Response} object from an exception.
*
* {@link \ICanBoogie\Exception\RescueEvent} is fired with the exception as target.
* The response provided by one of the event hooks is returned. If there is no response the
* exception is thrown again.
*
* If a response is finally obtained, the `X-ICanBoogie-Rescued-Exception` header is added to
* indicate where the exception was thrown from.
*
* @param \Exception $exception The exception to rescue.
* @param Request $request The current request.
*
* @return Response
*
* @throws \Exception The exception is re-thrown if it could not be rescued.
*/
public function rescue(\Exception $exception, Request $request)
{
/* @var $response Response */
$response = null;
new RescueEvent($exception, $request, $response);
if (!$response)
{
if ($exception instanceof ForceRedirect)
{
return new RedirectResponse($exception->location, $exception->getCode());
}
throw $exception;
}
$this->alter_response_with_exception($response, $exception);
return $response;
}
/**
* Alters a response with an exception.
*
* The methods adds the `X-ICanBoogie-Rescued-Exception` header to the response, which
* describes the filename and the line where the exception occurred.
*
* @param Response $response
* @param \Exception $exception
*/
protected function alter_response_with_exception(Response $response, \Exception $exception)
{
$pathname = $exception->getFile();
$root = $_SERVER['DOCUMENT_ROOT'];
if ($root && strpos($pathname, $root) === 0)
{
$pathname = substr($pathname, strlen($root));
}
$response->headers['X-ICanBoogie-Rescued-Exception'] = $pathname . '@' . $exception->getLine();
}
}