Add a new extender interface for extension lifecycle hooks

src/Extension/Extension.php

@@ -12,6 +12,7 @@
 namespace Flarum\Extension;
 
 use Flarum\Extend\Compat;
+use Flarum\Extend\LifecycleInterface;
 use Illuminate\Contracts\Container\Container;
 use Illuminate\Contracts\Support\Arrayable;
 use Illuminate\Support\Arr;
@@ -223,6 +224,24 @@ class Extension implements Arrayable
         return $icon;
     }
 
+    public function enable(Container $container)
+    {
+        $this->setEnabled(true);
+
+        foreach ($this->getLifecycleExtenders() as $extender) {
+            $extender->onEnable($container, $this);
+        }
+    }
+
+    public function disable(Container $container)
+    {
+        $this->setEnabled(false);
+
+        foreach ($this->getLifecycleExtenders() as $extender) {
+            $extender->onDisable($container, $this);
+        }
+    }
+
     /**
      * @param bool $enabled
      * @return Extension
@@ -277,6 +296,19 @@ class Extension implements Arrayable
         return array_flatten($extenders);
     }
 
+    /**
+     * @return LifecycleInterface[]
+     */
+    private function getLifecycleExtenders(): array
+    {
+        return array_filter(
+            $this->getExtenders(),
+            function ($extender) {
+                return $extender instanceof LifecycleInterface;
+            }
+        );
+    }
+
     private function getExtenderFile(): ?string
     {
         $filename = "{$this->path}/extend.php";

src/Extension/ExtensionManager.php

@@ -128,7 +128,7 @@ class ExtensionManager
 
             $this->setEnabled($enabled);
 
-            $extension->setEnabled(true);
+            $extension->enable($this->app);
 
             $this->dispatcher->dispatch(new Enabled($extension));
         }
@@ -152,7 +152,7 @@ class ExtensionManager
 
             $this->setEnabled($enabled);
 
-            $extension->setEnabled(false);
+            $extension->disable($this->app);
 
             $this->dispatcher->dispatch(new Disabled($extension));
         }