set language more reliable and readme

readme.md

@@ -1,9 +1,32 @@
+# Contao Content API
+
+We at [Die Schittigs](http://www.dieschittigs.de) love
+[Contao](https://contao.org/de/), but the web moves
+forward and static HTML templating just doesn't cut it anymore. Thus we came up
+with an easily digestible JSON-API to access Contao content via JavaScript
+(or anything else that can handle JSON).
+
+With the Contao Content API it is possible to write the entire Frontend of your
+website in [React.js](https://facebook.github.io/react/), [Angular](https://angular.io/), [vue](https://vuejs.org/), or any other
+JS-framework. All while still using the great Contao Backend.
+
+Now that Contao 4 matures, we decided to Open Source our efforts. Mainly to get
+feedback and maybe even contribution from the community.
+
+## Requirements
+
+You'll need an up-and-running **Contao 4.3.x** installation.
+Please note that the API is **not compatible with Contao 3.x**.
+
 ## Installation
 
+Install [composer](https://getcomposer.org) if you haven't already,
+enter this command in the main directory of your Contao installation:
+
     composer require dieschittigs/contao-content-api
 
-Put a file called "api.php" into your /web folder.
-Paste the following contents into it:
+Contao Content API is now installed. Next, put a file called `api.php` into your
+`/web` folder. Paste the following contents into it:
 
     <?php
 
@@ -18,7 +41,71 @@ Paste the following contents into it:
     $response = $api->handle($request);
     $response->send();
 
+Alternatively copy the file `api.php` from
+`vendor/dieschittigs/contao-content-api/` into your `/web` folder.
 
 ## Usage
 
-TODO
+Once setup, the following routes are available:
+
+##### /api.php/sitemap
+
+Gets the sitemap (=all pages below root) for the given language.
+
+##### /api.php/page?url=/en/about/team.html
+
+Gets the page, including all articles and contents at this URL.
+
+##### /api.php/news?url=/en/news/new-website.html
+
+Gets the news reader content from the URL
+
+##### /api.php/?url=/page/or/newsarticle.html
+
+Tries to get the page at this URL, or content from a reader
+
+##### /api.php/user
+
+Gets the logged-in frontend user, if available.
+
+## Custom readers
+
+Contao has the concept of Reader Module (e.g. News Reader). These can be
+inserted anywhere inside of an article where they read the URL to display
+their contents. If you want to add additional Reader Modules, you can do
+so by adding them in your `api.php`.
+
+    ...
+    $api = new FrontendApi($loader);
+    $api->addReader('blog', 'BlogModel');
+    ...
+
+Please note that the second parameter is the **model** class, **not the module**
+class. The new reader is now available at
+
+##### /api.php/blog?url=/en/blog/detail/on-the-topic.html
+
+or, even more convenient, at
+
+##### /api.php/url=/en/blog/detail/on-the-topic.html
+
+Internally the API tries to instantiate the model with the alias found in the url.
+It also tries to add all `ContentModels` it can find.
+
+## Tips and tricks
+
+If you are using a router in JavaScript (e.g. react-router) you may want to redirect
+all frontend traffic to a single file. We found the easiest way to do so is to
+create a new `app.html` in the `/web` folder and change the redirect in `.htaccess`
+like so:
+
+    ...
+    RewriteRule ^contao %{ENV:BASE}/app.php [L]
+    RewriteRule ^ %{ENV:BASE}/app.html [L]
+    ...
+
+This way all the traffic goes to your JS App, while `/contao` still works.
+
+## Contribution
+
+Bug reports and pull requests are very welcome :)

src/FrontendApi.php

@@ -5,6 +5,8 @@
 use Contao\ManagerBundle\ContaoManager\Plugin as ManagerBundlePlugin;
 use Contao\ManagerBundle\HttpKernel\ContaoCache;
 use Contao\ManagerBundle\HttpKernel\ContaoKernel;
+use Contao\Environment;
+use Contao\System;
 use Doctrine\Common\Annotations\AnnotationRegistry;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
@@ -34,11 +36,22 @@ public function addReader($reader, $class)
         $this->readers[$reader] = $class;
     }
 
+    private function setLang(Request $request){
+        $globalLang = $request->query->get('lang', Helper::defaultLang());
+        $GLOBALS['TL_LANGUAGE'] = $globalLang;
+        $_SESSION['TL_LANGUAGE'] = $globalLang;
+        System::loadLanguageFile('default', $globalLang);
+    }
+
+    private function overrideRequestUri(Request $request){
+        $_SERVER["REQUEST_URI"] = $request->query->get('url', $_SERVER["REQUEST_URI"]);
+    }
+
     public function handle(Request $request)
     {
-        if ($request->query->get('url')) {
-            $_SERVER["REQUEST_URI"] = $request->query->get('url');
-        }
+        $this->overrideRequestUri($request);
+        $this->setLang($request);
+
         $result = null;
         switch ($request->getPathInfo()) {
             case '/sitemap':

src/PageHelper.php

@@ -66,7 +66,6 @@ public static function getPage($url)
             return;
         }
         Controller::setStaticUrls($page);
-        $pageUrl = Controller::generateFrontendUrl($page->row());
         $_page = self::parsePage($page);
         $_page->articles = ArticleHelper::pageArticles($page->id);
         return $_page;

src/ReaderHelper.php

@@ -10,6 +10,7 @@
 use Symfony\Component\HttpFoundation\Response;
 use Contao\ContentModel;
 use Contao\Controller;
+use Contao\ModuleNewsReader;
 
 class ReaderHelper
 {