app.py

from langchain_openai import ChatOpenAI
from langchain.prompts import PromptTemplate
from langchain.memory import ConversationBufferMemory
from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
from langchain_core.output_parsers import StrOutputParser
from langchain_core.runnables import RunnablePassthrough
import os
import shutil


import gradio as gr
from langchain_community.document_loaders import PyPDFLoader
import os
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_community.embeddings.sentence_transformer import (
    SentenceTransformerEmbeddings,
)
from langchain_chroma import Chroma

from langchain_core.messages import AIMessage, HumanMessage
from langchain_openai import OpenAIEmbeddings

def predict(message, history):

    llm = ChatOpenAI(model_name="gpt-4o", temperature=0)
    template = """You are a general purpose chatbot. Be friendly and kind. Help people answer their questions. Use the context below to answer the questions. Even if you don't know the exact answer, feel free to give an approximate answer. Answer as if you are answering in an exam. The answer should be upto point, nothing extra. 
    {context}
    Question: {question}
    Helpful Answer:"""
    QA_CHAIN_PROMPT = PromptTemplate(input_variables=["context", "question"],template=template,)
    memory = ConversationBufferMemory(
        memory_key="chat_history",
        return_messages=True
    )

    embeddings = OpenAIEmbeddings(model="text-embedding-3-large")
    db = Chroma(persist_directory="./chroma", embedding_function=embeddings, collection_name="Autism1")
    retriever = db.as_retriever(k=10)

    contextualize_q_system_prompt = """Given a chat history and the latest user question \
    which might reference context in the chat history, formulate a standalone question \
    which can be understood without the chat history. Do NOT answer the question, \
    just reformulate it if needed and otherwise return it as is."""
    contextualize_q_prompt = ChatPromptTemplate.from_messages(
        [
            ("system", contextualize_q_system_prompt),
            MessagesPlaceholder(variable_name="chat_history"),
            ("human", "{question}"),
        ]
    )
    contextualize_q_chain = contextualize_q_prompt | llm | StrOutputParser()
    def contextualized_question(input: dict):
      if input.get("chat_history"):
          return contextualize_q_chain
      else:
          return input["question"]

    rag_chain = (
        RunnablePassthrough.assign(
            context=contextualized_question | retriever
        )
        | QA_CHAIN_PROMPT
        | llm
      )
    history = []
    ai_msg = rag_chain.invoke({"question": message, "chat_history": history})
    print(ai_msg)
    bot_response = ai_msg.content.strip()

    # Ensure history is correctly formatted as a list of tuples (user_message, bot_response)
    history.append((HumanMessage(content=message), AIMessage(content=bot_response)))

    docs = db.similarity_search(message,k=2)
    extra = "\n"*2 +"*"*100 + "\n" + "Source:" "\n" + "*"*100 + "\n"
    additional_info = []
    for d in docs:
        citations = d.metadata["source"] + " pg." + str(d.metadata["page"])
        additional_info = d.page_content
        extra += citations + "\n" + additional_info + "\n" + "*"*100 + "\n"
    # Return the bot's response and the updated history
    return bot_response + " " + extra

def upload_file(files):

    gr.Info("Wait for query Message")
    file_paths = [file.name for file in files]
    loaders = []
    for file_path in file_paths:
      if file_path.endswith(".pdf"):
        print(file_path)
        loaders.append(PyPDFLoader(file_path))

    documents = []
    for loader in loaders:
        documents.extend(loader.load())

    text_splitter = RecursiveCharacterTextSplitter(chunk_size=512, chunk_overlap=16)
    docs = text_splitter.split_documents(documents)

    collection_name = "Autism1"
    persist_directory = "./chroma"
    print(len(docs))
    embeddings = OpenAIEmbeddings(model="text-embedding-3-large")
    if os.path.isdir(persist_directory):
        shutil.rmtree(persist_directory)
    db = Chroma.from_documents(docs, embeddings, collection_name=collection_name, persist_directory=persist_directory)
    print("Done Processing, you can query")
    gr.Info("You can query now")

with gr.Blocks() as demo:
    with gr.Column():
      upload_button = gr.UploadButton("Click to Upload a File", file_types=["file"], file_count="multiple")
      upload_button.upload(upload_file, upload_button)
      chatbot = gr.Chatbot(height=500)
      gr.ChatInterface(fn = predict,chatbot=chatbot)#, fill_height=True, fill_width=True, chatbot=chatbot)

demo.launch(debug=True)