refactor(controller): base slim-http native json output

app/Controllers/BaseController.php

@@ -5,6 +5,8 @@ namespace App\Controllers;
 use App\Models\User;
 use App\Services\View;
 use App\Services\Auth;
+use Slim\Http\Response;
+use Psr\Http\Message\ResponseInterface;
 use Smarty;
 
 /**
@@ -40,13 +42,18 @@ class BaseController
     {
         return $this->view;
     }
+
+    // TODO: remove
     /**
-     * @param $response
-     * @param $res
-     * @return mixed
+     * Output JSON
+     *
+     * @param Response      $response
+     * @param array|object  $resource
+     *
+     * @return ResponseInterface
      */
-    public function echoJson($response, $res)
+    public function echoJson(Response $response, $resource)
     {
-        return $response->getBody()->write(json_encode($res));
+        return $response->withJson($resource);
     }
 }