Provide basePath support (#309)

* Provide basePath support

To be able to serve the application via a reverse proxy in a subfolder
smarty needs to be aware of the basepath if any.

* Provide basepath support via X-Forwarded headers

* Fix warnings

* Review adjustments

* Provide support X-Forwarded-Host header

* Use $uri in view factory directly

* Use middleware to set basepath from X-Forwarded-Path header

* Fix invalid type hint in RouterPathMiddleware

* Add "X-Forwarded-Host" to README

classes/RouterPathMiddleware.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Alltube;
+
+use Psr\Container\ContainerInterface;
+use Slim\Http\Request;
+use Slim\Http\Response;
+use Slim\Router;
+
+/**
+ * Class RouterPathMiddleware
+ * @package Alltube
+ */
+class RouterPathMiddleware
+{
+    /**
+     * @var Router
+     */
+    private $router;
+
+    /**
+     * RouterPathMiddleware constructor.
+     * @param ContainerInterface $container
+     */
+    public function __construct(ContainerInterface $container)
+    {
+        $this->router = $container->get('router');
+    }
+
+    /**
+     * @param Request $request
+     * @param Response $response
+     * @param callable $next
+     * @return mixed
+     */
+    public function __invoke(Request $request, Response $response, callable $next)
+    {
+        $this->router->setBasePath(current($request->getHeader('X-Forwarded-Path')));
+
+        return $next($request, $response);
+    }
+}