Move the functionality to a plugin

Use an associated model to prevent race conditions on creating the
profile object.

plugins/MentionURL/lib/util.php

@@ -0,0 +1,57 @@
+<?php
+
+function mention_url_representative_hcard($url, $fn=null, $mf2=null) {
+   if(!$mf2) {
+       $request = HTTPClient::start();
+
+        try {
+            $response = $request->get($url);
+        } catch(Exception $ex) {
+            return null;
+        }
+
+        $url = $response->getEffectiveUrl();
+        $mf2 = new Mf2\Parser($response->getBody(), $url);
+        $mf2 = $mf2->parse();
+    }
+
+    $hcard = null;
+
+    if(!empty($mf2['items'])) {
+        $hcards = array();
+        foreach($mf2['items'] as $item) {
+            if(!in_array('h-card', $item['type'])) {
+                continue;
+            }
+
+            // We found a match, return it immediately
+            if(isset($item['properties']['url']) && in_array($url, $item['properties']['url'])) {
+                $hcard = $item['properties'];
+                break;
+            }
+
+            // Let's keep all the hcards for later, to return one of them at least
+            $hcards[] = $item['properties'];
+        }
+
+        // No match immediately for the url we expected, but there were h-cards found
+        if (count($hcards) > 0) {
+            $hcard = $hcards[0];
+        }
+    }
+
+    if(!$hcard && $fn) {
+        $hcard = array('name' => array($fn));
+    }
+
+    if(!$hcard && $response) {
+        preg_match('/<title>([^<]+)/', $response->getBody(), $match);
+        $hcard = array('name' => array($match[1]));
+    }
+
+    if($hcard && !$hcard['url']) {
+        $hcard['url'] = array($url);
+    }
+
+    return $hcard;
+}