app.py

import os
from langchain_community.llms import HuggingFaceEndpoint
from langchain.chains import LLMChain
from langchain_core.prompts import PromptTemplate
import gradio as gr
from langchain_community.chat_message_histories import ChatMessageHistory
from langchain_core.chat_history import BaseChatMessageHistory
from langchain_core.runnables.history import RunnableWithMessageHistory
from langchain_core.messages import HumanMessage
from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder


repo_id = "mistralai/Mistral-7B-Instruct-v0.3"  
llm = HuggingFaceEndpoint(
      repo_id=repo_id, max_length=128, temperature=0.2
  )

store = {}

def llm_chain(question, chat_history):  

  def get_session_history(session_id: str) -> BaseChatMessageHistory:
    if session_id not in store:
        store[session_id] = ChatMessageHistory()
    return store[session_id]



  template = """Question: {question}

  """

  prompt = PromptTemplate.from_template(template)

  chain = prompt | llm

  with_message_history = RunnableWithMessageHistory(chain, get_session_history)
  config = {"configurable": {"session_id": "abc1"}}
  response = with_message_history.invoke(
      [HumanMessage(content=question)],
      config=config,
  )
  chat_history.append((question, response))

  return "", chat_history



with gr.Blocks() as demo:
  with gr.Row():
    with gr.Column():
      chatbot = gr.Chatbot()
      msg =  gr.Textbox(interactive=True, )
      with gr.Row():
        clear = gr.ClearButton([msg, chatbot], icon="https://img.icons8.com/?size=100&id=Xnx8cxDef16O&format=png&color=000000")
        send_btn = gr.Button("Send", variant='primary', icon="https://img.icons8.com/?size=100&id=g8ltXTwIfJ1n&format=png&color=000000")        
      msg.submit(fn=llm_chain, inputs=[msg, chatbot], outputs=[msg, chatbot])
      send_btn.click(fn=llm_chain, inputs=[msg, chatbot], outputs=[msg, chatbot])
      


if __name__ == "__main__":
    demo.launch()