Use slug driver system properly (#31)

Closes #30

src/Resources/Discussion.php

@@ -28,7 +28,7 @@ public function query(): Builder
     public function url($model): string
     {
         return $this->generateRouteUrl('discussion', [
-            'id' => $model->id.(trim($model->slug) ? '-'.$model->slug : ''),
+            'id' => $this->generateModelSlug(Model::class, $model),
         ]);
     }
 

src/Resources/Resource.php

@@ -13,7 +13,9 @@
 namespace FoF\Sitemap\Resources;
 
 use Carbon\Carbon;
+use Flarum\Database\AbstractModel;
 use Flarum\Foundation\Config;
+use Flarum\Http\SlugManager;
 use Flarum\Http\UrlGenerator;
 use Illuminate\Database\Eloquent\Builder;
 
@@ -64,4 +66,14 @@ protected function generateRouteUrl($name, $parameters = []): string
 
         return $generator->to('forum')->route($name, $parameters);
     }
+
+    protected function generateModelSlug(string $modelClass, AbstractModel $model): string
+    {
+        /**
+         * @var SlugManager
+         */
+        $slugManager = resolve(SlugManager::class);
+
+        return $slugManager->forResource($modelClass)->toSlug($model);
+    }
 }

src/Resources/User.php

@@ -27,7 +27,7 @@ public function query(): Builder
     public function url($model): string
     {
         return $this->generateRouteUrl('user', [
-            'username' => $model->username,
+            'username' => $this->generateModelSlug(Model::class, $model),
         ]);
     }