app.py

import os
from typing import Optional, Tuple

import gradio as gr
from langchain.chains import ConversationChain
from langchain.llms import OpenAI


def load_chain():
    """Logic for loading the chain you want to use should go here."""
    llm = OpenAI(temperature=0)
    chain = ConversationChain(llm=llm)
    return chain


def set_openai_api_key(api_key: str):
    """Set the api key and return chain.
    If no api_key, then None is returned.
    """
    if api_key:
        os.environ["OPENAI_API_KEY"] = api_key
        chain = load_chain()
        os.environ["OPENAI_API_KEY"] = ""
        return chain


def chat(
    inp: str, history: Optional[Tuple[str, str]], chain: Optional[ConversationChain]
):
    """Execute the chat functionality."""
    history = history or []
    # If chain is None, that is because no API key was provided.
    if chain is None:
        history.append((inp, "Please paste your OpenAI key to use"))
        return history, history
    # Run chain and append input.
    output = chain.run(input=inp)
    history.append((inp, output))
    return history, history


block = gr.Blocks(css=".gradio-container {background-color: lightgray}")

with block:
    with gr.Row():
        gr.Markdown("<h3><center>LangChain Demo</center></h3>")

        openai_api_key_textbox = gr.Textbox(
            placeholder="Paste your OpenAI API key (sk-...)",
            show_label=False,
            lines=1,
            type="password",
        )

    chatbot = gr.Chatbot()

    with gr.Row():
        message = gr.Textbox(
            label="What's your question?",
            placeholder="What's the answer to life, the universe, and everything?",
            lines=1,
        )
        submit = gr.Button(value="Send", variant="secondary").style(full_width=False)

    gr.Examples(
        examples=[
            "Hi! How's it going?",
            "What should I do tonight?",
            "Whats 2 + 2?",
        ],
        inputs=message,
    )

    gr.HTML("Demo application of a LangChain chain.")

    gr.HTML(
        "<center>Powered by <a href='https://github.com/hwchase17/langchain'>LangChain 🦜️🔗</a></center>"
    )

    state = gr.State()
    agent_state = gr.State()

    submit.click(chat, inputs=[message, state, agent_state], outputs=[chatbot, state])
    message.submit(chat, inputs=[message, state, agent_state], outputs=[chatbot, state])

    openai_api_key_textbox.change(
        set_openai_api_key,
        inputs=[openai_api_key_textbox],
        outputs=[agent_state],
    )

block.launch(debug=True)