+
+ // If this notice is out of scope, no root for you!
+
+ if (!$this->inScope($profile)) {
+ return null;
+ }
+
+ // If this isn't a reply to anything, then it's its own
+ // root.
+
+ if (empty($this->reply_to)) {
+ return $this;
+ }
+
+ if (is_null($profile)) {
+ $keypart = sprintf('notice:conversation_root:%d:null', $this->id);
+ } else {
+ $keypart = sprintf('notice:conversation_root:%d:%d',
+ $this->id,
+ $profile->id);
+ }
+
+ $root = self::cacheGet($keypart);
+
+ if ($root !== false && $root->inScope($profile)) {
+ return $root;
+ } else {
+ $last = $this;
+
+ do {
+ $parent = $last->getOriginal();
+ if (!empty($parent) && $parent->inScope($profile)) {
+ $last = $parent;
+ continue;
+ } else {
+ $root = $last;
+ break;
+ }
+ } while (!empty($parent));
+
+ self::cacheSet($keypart, $root);
+ }
+
+ return $root;