feat: universal chat in explore (#649)

Co-authored-by: StyleZhang <jasonapring2015@outlook.com>

api/core/agent/agent/output_parser/structured_chat.py

@@ -0,0 +1,29 @@
+import json
+import re
+from typing import Union
+
+from langchain.agents.structured_chat.output_parser import StructuredChatOutputParser as LCStructuredChatOutputParser, \
+    logger
+from langchain.schema import AgentAction, AgentFinish, OutputParserException
+
+
+class StructuredChatOutputParser(LCStructuredChatOutputParser):
+    def parse(self, text: str) -> Union[AgentAction, AgentFinish]:
+        try:
+            action_match = re.search(r"```(.*?)\n(.*?)```?", text, re.DOTALL)
+            if action_match is not None:
+                response = json.loads(action_match.group(2).strip(), strict=False)
+                if isinstance(response, list):
+                    # gpt turbo frequently ignores the directive to emit a single action
+                    logger.warning("Got multiple action responses: %s", response)
+                    response = response[0]
+                if response["action"] == "Final Answer":
+                    return AgentFinish({"output": response["action_input"]}, text)
+                else:
+                    return AgentAction(
+                        response["action"], response.get("action_input", {}), text
+                    )
+            else:
+                return AgentFinish({"output": text}, text)
+        except Exception as e:
+            raise OutputParserException(f"Could not parse LLM output: {text}") from e