Configurable recursion depth when fetching replies

src/Protocol/ActivityPub/Processor.php

@@ -267,6 +267,7 @@ class Processor
 				self::updateEvent($post['event-id'], $activity);
 			}
 		}
+		self::processReplies($activity, $item);
 	}
 
 	/**
@@ -524,7 +525,16 @@ class Processor
 			}
 		}
 
-		if (DI::config()->get('system', 'decoupled_receiver') && ($activity['completion-mode'] ?? Receiver::COMPLETION_NONE != Receiver::COMPLETION_REPLIES)) {
+		return $item;
+	}
+
+	private static function processReplies(array $activity, array $item)
+	{
+		// @todo fetch replies not only in the decoupled mode
+		if (!DI::config()->get('system', 'decoupled_receiver')) {
+			return;
+		}
+		
 		$replies = [$item['thr-parent']];
 		if (!empty($item['parent-uri'])) {
 			$replies[] = $item['parent-uri'];
@@ -545,9 +555,6 @@ class Processor
 		}
 	}
 
-		return $item;
-	}
-
 	/**
 	 * Fetch and process parent posts for the given activity
 	 *
@@ -1247,7 +1254,7 @@ class Processor
 		Queue::remove($activity);
 
 		if ($success && Queue::hasChildren($item['uri']) && Post::exists(['uri' => $item['uri']])) {
-			Queue::processReplyByUri($item['uri']);
+			Queue::processReplyByUri($item['uri'], $activity);
 		}
 
 		// Store send a follow request for every reshare - but only when the item had been stored
@@ -1259,6 +1266,10 @@ class Processor
 				ActivityPub\Transmitter::sendFollowObject($item['uri'], $item['author-link']);
 			}
 		}
+
+		if ($success) {
+			self::processReplies($activity, $item);
+		}
 	}
 
 	/**
@@ -1794,10 +1805,27 @@ class Processor
 
 	private static function fetchReplies(string $url, array $child)
 	{
-		if (in_array(__FUNCTION__, $child['callstack'] ?? [])) {
+		$callstack_count = 0;
-			Logger::notice('Callstack already contains "' . __FUNCTION__ . '"', ['callstack' => $child['callstack']]);
+		foreach ($child['callstack'] ?? [] as $function) {
+			if ($function == __FUNCTION__) {
+				++$callstack_count;
+			}
+		}
+
+		$callstack = array_slice(array_column(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS), 'function'), 1);
+		$system_count = 0;
+		foreach ($callstack as $function) {
+			if ($function == __FUNCTION__) {
+				++$system_count;
+			}
+		}
+
+		$maximum_fetchreplies_depth = DI::config()->get('system', 'max_fetchreplies_depth');
+		if (max($callstack_count, $system_count) == $maximum_fetchreplies_depth) {
+			Logger::notice('Maximum callstack depth reached', ['max' => $maximum_fetchreplies_depth, 'count' => $callstack_count, 'system-count' => $system_count, 'replies' => $url, 'callstack' => $child['callstack'] ?? [], 'system' => $callstack]);
 			return;
 		}
+
 		$child['callstack'] = self::addToCallstack($child['callstack'] ?? []);
 
 		$replies = ActivityPub::fetchItems($url);
@@ -1805,7 +1833,7 @@ class Processor
 			Logger::notice('No replies', ['replies' => $url]);
 			return;
 		}
-		Logger::notice('Fetch replies - start', ['replies' => $url]);
+		Logger::notice('Fetch replies - start', ['replies' => $url, 'callstack' => $child['callstack'], 'system' => $callstack]);
 		$fetched = 0;
 		foreach ($replies as $reply) {
 			if (is_array($reply)) {

static/defaults.config.php

@@ -388,6 +388,10 @@ return [
 		// Maximum number of feed items that are fetched and processed. For unlimited items set to 0.
 		'max_feed_items' => 20,
 
+		// max_fetchreplies_depth (Integer)
+		// Maximum number of "fetchreplies" activities in the callstack. The higher, the more complete a thread will be.
+		'max_fetchreplies_depth' => 2,
+
 		// max_image_length (Integer)
 		// An alternate way of limiting picture upload sizes.
 		// Specify the maximum pixel length that pictures are allowed to be (for non-square pictures, it will apply to the longest side).