refac

backend/open_webui/utils/chat_fork.py

@@ -0,0 +1,41 @@
+from copy import deepcopy
+
+
+def build_fork_history(messages_map: dict, source_message_id: str) -> tuple[dict, list[dict]]:
+    if not messages_map:
+        raise ValueError('chat has no messages to fork')
+
+    branch: list[tuple[str, dict]] = []
+    seen: set[str] = set()
+    message_id = source_message_id
+
+    while message_id:
+        if message_id in seen:
+            raise ValueError('message branch contains a cycle')
+        seen.add(message_id)
+
+        message = messages_map.get(message_id)
+        if not isinstance(message, dict):
+            raise ValueError('message not found')
+
+        branch.append((message_id, message))
+        message_id = message.get('parentId')
+
+    fork_messages: dict[str, dict] = {}
+    ordered_messages: list[dict] = []
+    parent_id = None
+
+    for message_id, message in reversed(branch):
+        copied = deepcopy(message)
+        copied['id'] = message_id
+        copied['parentId'] = parent_id
+        copied['childrenIds'] = []
+
+        if parent_id:
+            fork_messages[parent_id]['childrenIds'] = [message_id]
+
+        fork_messages[message_id] = copied
+        ordered_messages.append(copied)
+        parent_id = message_id
+
+    return {'messages': fork_messages, 'currentId': source_message_id}, ordered_messages