Improved detection in accept-language iRail#242

Added tests for language, special cases.
Fixed broken tests iRail#253

app/Http/Controllers/Welcome.php

@@ -14,7 +14,7 @@ public function __construct()
 
     public function index()
     {
-        if (! Session::get('lang')) {
+        if (Session::get('lang') == null || empty(Session::get('lang'))) {
             return View('language');
         } else {
             return Redirect::to('route');

app/Http/Middleware/Language.php

@@ -7,6 +7,7 @@
 use Illuminate\Support\Facades\Input;
 use Illuminate\Support\Facades\Request;
 use Illuminate\Support\Facades\Session;
+use Locale;
 
 class Language
 {
@@ -29,13 +30,16 @@ class Language
      */
     public function handle($request, Closure $next)
     {
-        $browserLanguage = \Locale::lookup(['nl', 'fr', 'en'], $request->server('HTTP_ACCEPT_LANGUAGE'));
+        $browserLanguage = $this->matchAcceptLanguage($request->server('HTTP_ACCEPT_LANGUAGE'), ['nl', 'fr', 'en']);
 
-        // if the user didn't set a language in the cookie, and a browser language is available, use browser language.
-        if (empty(Session::get('lang') && ! empty($browserLanguage))) {
+        if (!empty(Input::get('lang'))) {
+            // if a language is set in the browser, we need to update the language. User may have requested a switch.
+            $language = Input::get('lang');
+        } elseif (empty(Session::get('lang')) && !empty($browserLanguage)) {
+            // if the user didn't set a language in the cookie, and a browser language is available, use browser language.
             $language = $browserLanguage;
         } else {
-            $language = (Input::get('lang')) ?: Session::get('lang');
+            $language = Session::get('lang');
         }
 
         $this->setSupportedLanguage($language);
@@ -63,4 +67,51 @@ private function setSupportedLanguage($lang)
             Session::put('lang', $lang);
         }
     }
+
+    /**
+     * Search a HTTP accept-header for a supported language. Take order (weight, q=) into account. Skip unsupported
+     * languages.
+     *
+     * This method has a big avantage over locale_lookup, as locale_lookup will only look at the first language in accept-language.
+     * This method will skip unsupported languages and keep searching for a supported, meaning that if only NL and EN are supported,
+     * da, nl;q=0.5, en;q=0.2 will result in nl being chosen. (vs null return from locale_lookup)
+     *
+     * @param string $header the HTTP accept-language header to search
+     * @param array  $supported the list of supported languages
+     * @return string|null if a language matches, a value from the supported array is returned. If not, null is
+     *     returned.
+     */
+    private function matchAcceptLanguage($header, $supported)
+    {
+
+        // step 1: transform header into array
+        // source for step 1: http://stackoverflow.com/questions/6168519/transform-accept-language-output-in-array
+
+        $values = explode(',', $header);
+
+        $accept_language = array();
+
+        foreach ($values AS $lang) {
+            $cnt = preg_match('/([-a-zA-Z]+)\s*;\s*q=([0-9\.]+)/', $lang, $matches);
+            if ($cnt === 0) {
+                $accept_language[$lang] = 1;
+            } else {
+                $accept_language[$matches[1]] = $matches[2];
+            }
+        }
+
+        // step 2: match array with supported languages
+
+        foreach ($accept_language as $accept_lang => $accept_lang_q) {
+            foreach ($supported as $supported_lang) {
+                // use filterMatches to ensure nl-be, nl, nl-nl all match nl, etc..
+                if (Locale::filterMatches($accept_lang, $supported_lang)) {
+                    return $supported_lang;
+                };
+            }
+        }
+
+        // no match found
+        return null;
+    }
 }

tests/App/Http/Middleware/LanguageMiddlewareTest.php

@@ -17,6 +17,39 @@ public function testSetLanguageToFrench()
         $this->setAssertLanguageTest('fr', 'fr');
     }
 
+    public function testSetLanguageToFrenchWhileBrowserDutch()
+    {
+        // GET parameters should have priority over browser language.
+        $response = $this->get('/?lang=fr', ['accept-language' => 'nl-be']);
+        $this->assertEquals('fr', $this->getApplicationLanguage());
+    }
+
+    public function testSetLanguageFromBrowser()
+    {
+        $response = $this->get('/', ['accept-language' => 'nl-be']);
+        $this->assertEquals('nl', $this->getApplicationLanguage());
+    }
+
+    public function testSetLanguageFromBrowser2()
+    {
+        $response = $this->get('/', ['accept-language' => 'nl']);
+        $this->assertEquals('nl', $this->getApplicationLanguage());
+    }
+
+    public function testSetLanguageFromBrowser3()
+    {
+        // unsupported languages mixed with supported. Should pick first supported.
+        $response = $this->get('/', ['accept-language' => 'da, nl;q=0.9, en;q=0.5']);
+        $this->assertEquals('nl', $this->getApplicationLanguage());
+    }
+
+    public function testSetLanguageFromBrowser4()
+    {
+        // unsupported languages. Should fall back to en.
+        $response = $this->get('/', ['accept-language' => 'da, se;q=0.9, no;q=0.5']);
+        $this->assertEquals('en', $this->getApplicationLanguage());
+    }
+
     public function testFallbackToDefaultLanguageWhenLanguageDoesNotExist()
     {
         $this->setAssertLanguageTest('en', 'NotALanguage');

tests/VariousTest.php

@@ -5,8 +5,9 @@ class VariousTest extends TestCase
 {
     public function testHome()
     {
+        // expect redirect, since call includes "accept-language" header
         $response = $this->call('GET', '/');
-        $this->assertEquals(200, $response->status());
+        $this->assertEquals(302, $response->status());
     }
 
     public function testContributors()