app.py

import streamlit as st
from streamlit_chat import message
import tempfile
from langchain.document_loaders import PyPDFLoader
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.vectorstores import FAISS
from langchain.chains import ConversationalRetrievalChain
from langchain_g4f import G4FLLM
from g4f import Provider, models

# Configuration
DB_FAISS_PATH = 'vectorstore/db_faiss'
EMBEDDING_MODEL = 'sentence-transformers/all-MiniLM-L6-v2'
LLM_MODEL = models.gpt_35_long 
LLM_PROVIDER = Provider.OpenaiChat

# UI Configuration
def configure_ui():
    """Configure Streamlit UI settings"""
    st.set_page_config(page_title="Zendo AI Assistant", page_icon="📄")
    hide_streamlit_style = """
    <style>
    #MainMenu {visibility: hidden;}
    footer {visibility: hidden;}
    .stTextInput input {font-size: 16px;}
    </style>
    """
    st.markdown(hide_streamlit_style, unsafe_allow_html=True)

# Initialize session state
def init_session_state():
    """Initialize session state variables"""
    if 'history' not in st.session_state:
        st.session_state['history'] = []
    if 'generated' not in st.session_state:
        st.session_state['generated'] = ["こんにちは！Zendoアシスタントです。PDFの内容について何でも聞いてください 🤗"]
    if 'past' not in st.session_state:
        st.session_state['past'] = ["ようこそ！"]

# Load LLM model
def load_llm():
    """Load the language model"""
    return G4FLLM(
        model=LLM_MODEL,
        provider=LLM_PROVIDER,
    )

# Process uploaded PDF
def process_pdf(uploaded_file):
    """Process the uploaded PDF file"""
    with tempfile.NamedTemporaryFile(delete=False, suffix=".pdf") as tmpfile:
        tmpfile.write(uploaded_file.getvalue())
        tmpfile_path = tmpfile.name
    
    loader = PyPDFLoader(tmpfile_path)
    pdf_data = loader.load()
    
    embeddings = HuggingFaceEmbeddings(
        model_name=EMBEDDING_MODEL,
        model_kwargs={'device': 'cpu'}
    )
    
    db = FAISS.from_documents(pdf_data, embeddings)
    db.save_local(DB_FAISS_PATH)
    return db

# Chat function
def conversational_chat(query, chain):
    """Handle conversational chat with memory"""
    result = chain({
        "question": query, 
        "chat_history": st.session_state['history']
    })
    st.session_state['history'].append((query, result["answer"]))
    return result["answer"]

# Main application
def main():
    configure_ui()
    init_session_state()
    
    st.title("📄 Zendo AI Assistant - PDFチャットボット")
    
    # Language selection
    col1, col2 = st.columns([1, 3])
    with col1:
        language = st.selectbox("言語/Language", ["日本語", "English", "Tiếng Việt"])
    
    # Upload PDF
    uploaded_file = st.file_uploader(
        "PDFファイルをアップロードしてください (Upload PDF file)", 
        type="pdf",
        help="PDFをアップロードすると、その内容について質問できます"
    )
    
    if uploaded_file:
        with st.spinner("PDFを処理中...少々お待ちください"):
            db = process_pdf(uploaded_file)
            llm = load_llm()
            chain = ConversationalRetrievalChain.from_llm(
                llm=llm, 
                retriever=db.as_retriever()
            )
            st.success("PDFの処理が完了しました！質問をどうぞ")
        
        # Chat interface
        response_container = st.container()
        
        with st.form(key='chat_form', clear_on_submit=True):
            user_input = st.text_input(
                "メッセージを入力...", 
                key='input',
                placeholder="PDFについて質問してください"
            )
            submit_button = st.form_submit_button(label='送信')
            
            if submit_button and user_input:
                output = conversational_chat(user_input, chain)
                st.session_state['past'].append(user_input)
                st.session_state['generated'].append(output)
        
        # Display chat history
        if st.session_state['generated']:
            with response_container:
                for i in range(len(st.session_state['generated'])):
                    message(
                        st.session_state["past"][i], 
                        is_user=True, 
                        key=str(i) + '_user', 
                        avatar_style="big-smile"
                    )
                    message(
                        st.session_state["generated"][i], 
                        key=str(i), 
                        avatar_style="thumbs"
                    )
    else:
        st.info("PDFファイルをアップロードしてチャットを開始してください")

if __name__ == "__main__":
    main()