✨ Refactor chat handler creation

src/funcchain/syntax/components/handler.py

@@ -1,63 +1,48 @@
-from typing import Union
-
-from langchain_core.chat_history import BaseChatMessageHistory
 from langchain_core.language_models import BaseChatModel
-from langchain_core.messages import AIMessage, HumanMessage
 from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
-from langchain_core.runnables import Runnable
 from langchain_core.runnables.history import RunnableWithMessageHistory
 
-from ...backend.settings import settings
+from ...backend.settings import create_local_settings
 from ...model.defaults import univeral_model_selector
+from ...schema.types import ChatHandler, OptionalChatHistoryFactory, UniversalChatModel
+from ...utils.memory import InMemoryChatMessageHistory, create_history_factory
 from ...utils.msg_tools import msg_to_str
 
-UniversalLLM = Union[BaseChatModel, str, None]
-
 
-def load_universal_llm(llm: UniversalLLM) -> BaseChatModel:
+def load_universal_llm(llm: UniversalChatModel) -> BaseChatModel:
     if isinstance(llm, str):
-        settings.llm = llm
+        settings = create_local_settings({"llm": llm})
         llm = None
     if not llm:
         llm = univeral_model_selector(settings)
     return llm
 
 
-# def history_handler(input: Iterator[Any]) -> Iterator[Any]:
-
-#     for chunk in input:
-#         yield chunk
-
-
-def BasicChatHandler(
+def create_chat_handler(
     *,
-    llm: UniversalLLM = None,
-    chat_history: BaseChatMessageHistory | None = None,
+    llm: UniversalChatModel = None,
+    history_factory: OptionalChatHistoryFactory = None,
     system_message: str = "",
-) -> Runnable[HumanMessage, AIMessage]:
-    if chat_history is None:
-        from ...utils.memory import ChatMessageHistory
-
-        chat_history = ChatMessageHistory()
-
+) -> ChatHandler:
+    history_factory = history_factory or create_history_factory(InMemoryChatMessageHistory)
     llm = load_universal_llm(llm)
 
-    handler_chain = (
+    chat_handler_chain = (
         ChatPromptTemplate.from_messages(
             [
-                *(("system", system_message) if system_message else []),
+                *([("system", system_message)] if system_message else []),  # todo test this
                 MessagesPlaceholder(variable_name="history"),
-                ("human", "{user_msg}"),
+                ("human", "{message}"),
             ]
         )
         | llm
     )
     return {
         # todo handle images
-        "user_msg": lambda x: msg_to_str(x),
+        "message": lambda x: msg_to_str(x),
     } | RunnableWithMessageHistory(
-        handler_chain,  # type: ignore
-        get_session_history=lambda _: chat_history,
-        input_messages_key="user_msg",
+        chat_handler_chain,  # type: ignore
+        get_session_history=history_factory,
+        input_messages_key="message",
         history_messages_key="history",
     )