app_modules/llm_chat_chain.py

from langchain import LLMChain, PromptTemplate
from langchain.chains import ConversationalRetrievalChain
from langchain.chains.base import Chain
from langchain.memory import ConversationBufferMemory

from app_modules.llm_inference import LLMInference


class ChatChain(LLMInference):
    def __init__(self, llm_loader):
        super().__init__(llm_loader)

    def create_chain(self) -> Chain:
        template = """You are a chatbot having a conversation with a human.
{chat_history}
Human: {question}
Chatbot:"""

        prompt = PromptTemplate(
            input_variables=["chat_history", "question"], template=template
        )
        memory = ConversationBufferMemory(memory_key="chat_history")

        llm_chain = LLMChain(
            llm=self.llm_loader.llm,
            prompt=prompt,
            verbose=True,
            memory=memory,
        )

        return llm_chain