[ATTACHMENTS][EVENT] Add onHashFile event, which can be used to deduplicate files

Currently, we simply hash the contents of the file with sha256, but in the future we can use something smarter,
which could find visual feature similarity between images

components/Posting/Posting.php

@@ -29,6 +29,7 @@ use App\Core\GSFile;
 use function App\Core\I18n\_m;
 use App\Core\Modules\Component;
 use App\Core\Security;
+use App\Entity\Attachment;
 use App\Entity\AttachmentToNote;
 use App\Entity\Note;
 use App\Util\Common;
@@ -124,7 +125,7 @@ END;
         $matched_urls = [];
         preg_match_all(self::URL_REGEX, $content, $matched_urls, PREG_SET_ORDER);
         foreach ($matched_urls as $match) {
-            $processed_attachments[] = GSFile::validateAndStoreURL($url);
+            $processed_attachments[] = GSFile::validateAndStoreURL($match[0]);
         }
 
         DB::persist($note);
@@ -138,4 +139,15 @@ END;
             DB::flush();
         }
     }
+
+    /**
+     * Get a unique representation of a file on disk
+     *
+     * This can be used in the future to deduplicate images by visual content
+     */
+    public static function onHashFile(string $filename, ?string &$out_hash)
+    {
+        $out_hash = hash_file(Attachment::FILEHASH_ALGO, $filename);
+        return Event::stop;
+    }
 }