Allow to pass options so that one can configure priorities

Fix #1

README.md

@@ -15,18 +15,10 @@ Installation
 The recommended way to install StackNegotiation is through
 [Composer](http://getcomposer.org/):
 
-``` json
-{
-    "require": {
-        "willdurand/stack-negotiation": "@stable"
-    }
-}
+``` bash
+$ composer require "willdurand/stack-negotiation"
 ```
 
-**Protip:** you should browse the
-[`willdurand/stack-negotiation`](https://packagist.org/packages/willdurand/stack-negotiation)
-page to choose a stable version to use, avoid the `@stable` meta constraint.
-
 
 Usage
 -----
@@ -62,6 +54,16 @@ Body](http://silex.sensiolabs.org/doc/cookbook/json_request_body.html) and
 [FOSRestBundle Body
 Listener](https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/Resources/doc/3-listener-support.md#body-listener).
 
+### Options
+
+You can pass an array of _options_ to the middleware:
+
+```php
+$app = new Negotiation($app, null, null, null, [
+    'language_priorities' => [ '... '],
+    'format_priorities'   => [ '... '],
+]);
+```
 
 Unit Tests
 ----------

src/Negotiation/Stack/Negotiation.php

@@ -40,26 +40,43 @@ class Negotiation implements HttpKernelInterface
      */
     private $decoderProvider;
 
+    /**
+     * @var array
+     */
+    private $defaultOptions = [
+        'format_priorities'   => [],
+        'language_priorities' => [],
+    ];
+
+    /**
+     * @var array
+     */
+    private $options;
+
     public function __construct(
         HttpKernelInterface $app,
         FormatNegotiatorInterface $formatNegotiator = null,
-        NegotiatorInterface $languageNegotiator = null,
-        DecoderProviderInterface $decoderProvider = null
+        NegotiatorInterface $languageNegotiator     = null,
+        DecoderProviderInterface $decoderProvider   = null,
+        array $options = []
     ) {
         $this->app                = $app;
-        $this->formatNegotiator   = $formatNegotiator ?: new FormatNegotiator();
+        $this->formatNegotiator   = $formatNegotiator   ?: new FormatNegotiator();
         $this->languageNegotiator = $languageNegotiator ?: new LanguageNegotiator();
-        $this->decoderProvider    = $decoderProvider ?: new DecoderProvider([
+        $this->decoderProvider    = $decoderProvider    ?: new DecoderProvider([
             'json' => new JsonEncoder(),
             'xml'  => new XmlEncoder(),
         ]);
+        $this->options = array_merge($this->defaultOptions, $options);
     }
 
     public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQUEST, $catch = true)
     {
         // `Accept` header
         if (null !== $accept = $request->headers->get('Accept')) {
-            $accept = $this->formatNegotiator->getBest($accept);
+            $priorities = $this->formatNegotiator->normalizePriorities($this->options['format_priorities']);
+            $accept     = $this->formatNegotiator->getBest($accept, $priorities);
+
             $request->attributes->set('_accept', $accept);
 
             if (null !== $accept && !$accept->isMediaRange()) {
@@ -70,7 +87,7 @@ public function handle(Request $request, $type = HttpKernelInterface::MASTER_REQ
 
         // `Accept-Language` header
         if (null !== $accept = $request->headers->get('Accept-Language')) {
-            $accept = $this->languageNegotiator->getBest($accept);
+            $accept = $this->languageNegotiator->getBest($accept, $this->options['language_priorities']);
             $request->attributes->set('_accept_language', $accept);
 
             if (null !== $accept) {

tests/Negotiation/Tests/Stack/NegotiationTest.php

@@ -26,6 +26,22 @@ public function testAcceptHeader()
         $this->assertEquals('json', $req->attributes->get('_format'));
     }
 
+    public function testAcceptHeaderWithPriorities()
+    {
+        $app = $this->createStackedApp([], [ 'format_priorities' => [ 'json', 'xml' ] ]);
+        $req = $this->createRequest(null, [
+            'Accept' => 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
+        ]);
+
+        $app->handle($req);
+
+        $header = $req->attributes->get('_accept');
+        $this->assertInstanceOf('Negotiation\AcceptHeader', $header);
+        $this->assertEquals('application/xml', $header->getValue());
+        $this->assertEquals('application/xml', $req->attributes->get('_mime_type'));
+        $this->assertEquals('xml', $req->attributes->get('_format'));
+    }
+
     public function testAcceptLanguageHeader()
     {
         $app = $this->createStackedApp();
@@ -41,6 +57,21 @@ public function testAcceptLanguageHeader()
         $this->assertEquals('fu', $req->attributes->get('_language'));
     }
 
+    public function testAcceptLanguageHeaderWithPriorities()
+    {
+        $app = $this->createStackedApp([], [ 'language_priorities' => [ 'fr' ] ]);
+        $req = $this->createRequest(null, [
+            'Accept-Language' => 'en, fr, de',
+        ]);
+
+        $app->handle($req);
+
+        $header = $req->attributes->get('_accept_language');
+        $this->assertInstanceOf('Negotiation\AcceptHeader', $header);
+        $this->assertEquals('fr', $header->getValue());
+        $this->assertEquals('fr', $req->attributes->get('_language'));
+    }
+
     /**
      * @dataProvider dataProviderForTestDecodeBody
      */
@@ -69,9 +100,15 @@ public function dataProviderForTestDecodeBody()
         ];
     }
 
-    private function createStackedApp(array $responseHeaders = [])
+    private function createStackedApp(array $responseHeaders = [], array $options = [])
     {
-        return new Negotiation(new MockApp($responseHeaders));
+        return new Negotiation(
+            new MockApp($responseHeaders),
+            null,
+            null,
+            null,
+            $options
+        );
     }
 
     private function createRequest($content = null, array $requestHeaders = [])