Add ActivityPub DiscoverActor util

app/Util/ActivityPub/DiscoverActor.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace App\Util\ActivityPub;
+
+use \Zttp\Zttp;
+
+class DiscoverActor {
+
+  protected $url;
+  protected $response;
+
+  public function __construct($url)
+  {
+    $this->url = $url;
+  }
+
+  public function fetch()
+  {
+    $res = Zttp::withHeaders([
+      'Accept' => 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"',
+      'User-Agent' => 'PixelFedBot - https://pixelfed.org'
+    ])->get($this->url);
+    $this->response = $res->body();
+    return $this;
+  }
+
+  public function getResponse()
+  {
+    return json_decode($this->response, true);
+  }
+
+  public function getJsonResponse()
+  {
+    return $this->response;
+  }
+
+  public function discover()
+  {
+    $this->fetch();
+    $res = $this->getResponse();
+
+    if(empty($res) || !in_array('type', $res) || $res['type'] !== 'Person') {
+      throw new \Exception('Invalid Actor Object');
+    }
+
+    return $res;
+  }
+
+}