app.py

from dotenv import load_dotenv
import os
import streamlit as st
from langchain_aws import BedrockEmbeddings
from langchain_core.vectorstores import InMemoryVectorStore
from langchain.chat_models import init_chat_model
from langchain_core.documents import Document
from typing_extensions import List, Dict

from langchain_text_splitters import RecursiveCharacterTextSplitter
from langgraph.graph import START, StateGraph, END

from langchain_community.document_loaders import DirectoryLoader, PyPDFLoader
from langgraph.graph import MessagesState
from langchain_core.tools import tool
from langchain_core.messages import SystemMessage
from langgraph.prebuilt import ToolNode, tools_condition
from langchain_milvus import Milvus
from utils import extract_text_from_content
from logging_config import setup_logger
from load_vector_db import init_vector_db
from graph_question_validation import init_graph
import time

logger = setup_logger(__name__)


# Load environment variables
load_dotenv(override=True)

# Set AWS credentials from environment variables
os.environ["AWS_ACCESS_KEY_ID"] = os.environ.get("aws_access_key_id")
os.environ["AWS_SECRET_ACCESS_KEY"] = os.environ.get("aws_secret_access_key")
os.environ["AWS_SESSION_TOKEN"] = os.environ.get("aws_session_token")
os.environ["AWS_DEFAULT_REGION"] = os.environ.get("AWS_DEFAULT_REGION")
print(os.environ["AWS_ACCESS_KEY_ID"])


# Initialize session state variables if they don't exist
if "messages" not in st.session_state:
    st.session_state.messages = []
if "initialized" not in st.session_state:
    st.session_state.initialized = False



def run_graph(graph, input_message: str):
    """Run the graph with the input message."""
    # Create a new state


    st.conversation_history.append(
        {
            "role": "user", 
            "content": input_message
        }
    )

    input_message_formatted = {
            "messages": st.conversation_history
        }

        

    # Stream responses
    full_response = ""
    response_chunks = []
    values = []
    
    start = time.time()
    time_to_start_streaming = None
    for mode, mode_chunk in graph.stream(
        input_message_formatted,
        stream_mode=["messages", "values"],
    ):
        if mode == "values":
            values.append(mode_chunk)
        elif mode == "messages":
            message, metadata = mode_chunk

            if metadata["langgraph_node"] in ["generate_questions", "generate_answer_to_query"]:

                if hasattr(message, 'content'):
                    if time_to_start_streaming is None:
                        time_to_start_streaming = time.time() - start
                        logger.info(f"Time taken to start streaming: {time_to_start_streaming} seconds")
                    content = message.content

                    chunk_text = extract_text_from_content(content)

                    if chunk_text:
                        response_chunks.append(chunk_text)
                        yield chunk_text, values
        full_response = ''.join(response_chunks)

    logger.info(f"Time taken for complete generation: {time.time() - start} seconds")
                    

    # print(f"Full text: {full_response}")
    # print(f"full values: {values}")
    st.conversation_history.append({
        "role": "assistant",
        "content": full_response
    })
    return full_response, values

# Main Streamlit UI
st.title("PDF Question-Answering Chat")

# Initialize the app if not already done
if not st.session_state.initialized:
    try:
        app_components = init_graph()
        st.session_state.app_components = app_components
        st.session_state.initialized = True
        st.conversation_history = []
    except Exception as e:
        st.error(f"Error initializing app: {e}")
        st.stop()

# Display chat messages from history
for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        st.markdown(message["content"])

# Accept user input
if prompt := st.chat_input("Ask a question about your PDFs"):
    # Add user message to chat history
    st.session_state.messages.append({"role": "user", "content": prompt})
    
    # Display user message in chat message container
    with st.chat_message("user"):
        st.markdown(prompt)

    # Display assistant response in chat message container
    with st.chat_message("assistant"):
        message_placeholder = st.empty()
        
        try:
            # Stream the response
            full_response = ""
            sources_text = "\n\n"
            values = {}
            for chunk, values in run_graph(st.session_state.app_components["graph"], prompt):
                if chunk:  # Only process non-empty chunks
                    # print(f"Chunk: {chunk}")
                    full_response += chunk
                    message_placeholder.markdown(full_response + "▌")

            
            try:
                values = values[-1]
                logger.info(f"values keys: {values.keys()}")
                logger.info(f"'retrieved_docs' in values: { 'retrieved_docs' in values }")

                # print(f"values: {values}")
                if 'retrieved_docs' in values:
                    pages_dict = {}

                    for i in values['retrieved_docs']:
                        doc_metadata = i.metadata
                        key = (doc_metadata['source'], doc_metadata['page'])
                        if key not in pages_dict:
                            pages_dict[key] = {
                                "source": doc_metadata['source'],
                                "page": doc_metadata['page'],
                                "page_label": doc_metadata['page_label'],
                                "relevance_score" : doc_metadata["relevance_score"],
                            }
                            sources_text += f"Source: {doc_metadata['source']}, Page: {doc_metadata['page']}, Page Label: {doc_metadata['page_label']}, Relevance Score : {doc_metadata["relevance_score"]}\n\n"
            except Exception as e:
                logger.error(f"Error processing values: {e}")
                sources_text = "No sources found for the response."        
            
            if full_response == "":
                full_response = "Could not find any relevant information in the documents."

                st.conversation_history.append(
                    {
                        "role": "assistant", 
                        "content": full_response
                    }
                )
            else:
                full_response += "\n\n" + sources_text
            

            message_placeholder.markdown(full_response)
            logger.info(f"Full response: {full_response}")
            
            # Add assistant response to chat history
            st.session_state.messages.append({"role": "assistant", "content": full_response})
        except Exception as e:
            import traceback
            error_msg = f"Error processing your query: {str(e)}\n\n```\n{traceback.format_exc()}\n```"
            message_placeholder.error(error_msg)
            st.session_state.messages.append({"role": "assistant", "content": error_msg})