##########################################################################
#   app.py   -  Pennwick PDF Chat
#
#   HuggingFace Spaces application to anlayze uploaded PDF files
#           with open-source models ( hkunlp/instructor-xl )
#
#   Mike Pastor  February 17, 2024


import streamlit as st
from streamlit.components.v1 import html

from dotenv import load_dotenv

from PyPDF2 import PdfReader

from PIL import Image

# Local file
from htmlTemplates import css, bot_template, user_template


#  from langchain.embeddings import HuggingFaceInstructEmbeddings
from langchain_community.embeddings import HuggingFaceInstructEmbeddings

# from langchain.vectorstores import FAISS
from langchain_community.vectorstores import FAISS
from langchain.text_splitter import CharacterTextSplitter
from langchain.memory import ConversationBufferMemory
from langchain.chains import ConversationalRetrievalChain

#  from langchain.llms import HuggingFaceHub
from langchain_community.llms import HuggingFaceHub

##################################################################################
#  Admin flags
DISPLAY_DIALOG_LINES=6

SESSION_STARTED = False


##################################################################################
def extract_pdf_text(pdf_docs):
    text = ""
    for pdf in pdf_docs:
        pdf_reader = PdfReader(pdf)
        for page in pdf_reader.pages:
            text += page.extract_text()
    return text

##################################################################################
#  Chunk size and overlap must not exceed the models capacity!
#
def extract_bitesize_pieces(text):
    text_splitter = CharacterTextSplitter(
        separator="\n",
        chunk_size=800,    #  1000
        chunk_overlap=200,
        length_function=len
    )
    chunks = text_splitter.split_text(text)
    return chunks

##################################################################################
def prepare_embedding_vectors(text_chunks):

    st.write('Here in vector store....', unsafe_allow_html=True)
    # embeddings = OpenAIEmbeddings()

    #  pip install InstructorEmbedding
    #  pip install sentence-transformers==2.2.2
    embeddings = HuggingFaceInstructEmbeddings(model_name="hkunlp/instructor-xl")

    st.write('Here in vector store - got embeddings ', unsafe_allow_html=True)
    #  from InstructorEmbedding import INSTRUCTOR
    # model = INSTRUCTOR('hkunlp/instructor-xl')
    # sentence = "3D ActionSLAM: wearable person tracking in multi-floor environments"
    # instruction = "Represent the Science title:"
    # embeddings = model.encode([[instruction, sentence]])

    # embeddings = model.encode(text_chunks)
    print('have Embeddings:   ')

    # text_chunks="this is a test"
    #   FAISS,  Chroma and other vector databases
    #
    vectorstore = FAISS.from_texts(texts=text_chunks, embedding=embeddings)
    st.write('FAISS succeeds:   ')

    return vectorstore
    
##################################################################################
def prepare_conversation(vectorstore):
    # llm = ChatOpenAI()
    #  llm = HuggingFaceHub(repo_id="google/flan-t5-xxl", model_kwargs={"temperature":0.5, "max_length":512})
    #  google/bigbird-roberta-base     facebook/bart-large
    llm = HuggingFaceHub(repo_id="google/flan-t5-xxl", model_kwargs={"temperature": 0.7, "max_length": 512})

    memory = ConversationBufferMemory(
        memory_key='chat_history', return_messages=True)
    conversation_chain = ConversationalRetrievalChain.from_llm(
        llm=llm,
        retriever=vectorstore.as_retriever(),
        memory=memory,
    )
    return conversation_chain

##################################################################################
def process_user_question(user_question):

    print('process_user_question called: \n')

    # if not SESSION_STARTED:
    #     print('No Session')
    #     st.write( 'Please upload and analyze your PDF files first!')
    #     return
        
    if user_question == None :
        print('question is null')
        return
    if user_question == '' :
        print('question is blank')
        return
    if st == None :
        print('session is null')
        return
    if st.session_state == None :
        print('session STATE is null')
        return

    print('question is: ', user_question)
    print('\nsession is: ', st )

    # try:
    #     response = st.session_state.conversation({'question': user_question})
    #     # response = st.session_state.conversation({'summarization': user_question})
    #     st.session_state.chat_history = response['chat_history']
    # Exception:
    #     st.write( 'Please upload and analyze your PDF files first!')
    #     return

    # st.empty()

    # try:
    #     st.session_state.conversation({'question': "Summarize the document"})
    #     # if "key" not in st.session_state:
    #     #     st.write('Good')
    # except:
    #     st.error("Please upload and analyze your PDF files first!")
    #     return

    if st.session_state.conversation == None:
        st.error("Please upload and analyze your PDF files first!")
        return
            
    response = st.session_state.conversation({'question': user_question})
    st.session_state.chat_history = response['chat_history']
    results_size = len(response['chat_history'])
    
    results_string  = ""

    print('results_size is: ', results_size )

    for i, message in enumerate(st.session_state.chat_history):

        #  Scrolling does not display the last printed line, 
        #    so only print the last 6 lines
        #
        print('results_size on msg: ', results_size, i, ( results_size - DISPLAY_DIALOG_LINES ) )
        if results_size > DISPLAY_DIALOG_LINES:
            if i < ( results_size - DISPLAY_DIALOG_LINES ):
                continue
                
        if i % 2 == 0:
            # st.write(user_template.replace(
            #     "{{MSG}}", message.content), unsafe_allow_html=True)

            results_string += ( "<p>" + message.content + "</p>" )

        else:
            # st.write(bot_template.replace(
            #     "{{MSG}}", message.content), unsafe_allow_html=True)

            results_string += ( "<p>" + "-- " + message.content + "</p>" )


    html(results_string, height=300, scrolling=True)
    
    
###################################################################################
def main():

    print( 'Pennwick Starting up...\n')
    # Load the environment variables - if any
    load_dotenv()

    ##################################################################################
    #  st.set_page_config(page_title="Pennwick PDF Analyzer", page_icon=":books:")
    # im = Image.open("robot_icon.ico")
    # st.set_page_config(page_title="Pennwick PDF Analyzer", page_icon=im )
    # st.set_page_config(page_title="Pennwick PDF Analyzer")

    # import base64
    # from PIL import Image
    
    # # Open your image
    # image = Image.open("robot_icon.ico")
    
    # # Convert image to base64 string
    # with open("robot_icon.ico", "rb") as f:
    #     encoded_string = base64.b64encode(f.read()).decode()
    
    # # Set page config with base64 string
    # st.set_page_config(page_title="Pennwick File Analyzer 2", page_icon=f"data:image/ico;base64,{encoded_string}")


    st.set_page_config(page_title="Pennwick File Analyzer", page_icon="./robot_icon.ico")
    
    print( 'prepared page...\n')


    ###################

    st.write(css, unsafe_allow_html=True)

    if "conversation" not in st.session_state:
        st.session_state.conversation = None
    if "chat_history" not in st.session_state:
        st.session_state.chat_history = None

    # st.header("Pennwick File Analyzer :shark:")
    # st.header("Pennwick File Analyzer 2")
        
    st.image("robot_icon.png", width=96 )
    st.header(f"Pennwick File Analyzer")

    user_question = None
    user_question = st.text_input("Ask the  Open Source - Flan-T5 Model  a question about your uploaded documents:")
    if user_question != None:
        print( 'calling process question', user_question)
        process_user_question(user_question)

    # st.write( user_template, unsafe_allow_html=True)
    # st.write(user_template.replace( "{{MSG}}", "Hello robot!"), unsafe_allow_html=True)
    # st.write(bot_template.replace( "{{MSG}}", "Hello human!"), unsafe_allow_html=True)


    with st.sidebar:

        st.subheader("Which documents would you like to analyze?")
        st.subheader("(no data is saved beyond the session)")
        
        pdf_docs = st.file_uploader(
            "Upload your PDF documents here and click on 'Analyze'", accept_multiple_files=True)

        # Upon button press
        if st.button("Analyze these files"):
            with st.spinner("Processing..."):

                #################################################################
                #  Track the overall time for file processing into Vectors
                # #
                from datetime import datetime
                global_now = datetime.now()
                global_current_time = global_now.strftime("%H:%M:%S")
                st.write("Vectorizing Files - Current Time =", global_current_time)

                # get pdf text
                raw_text = extract_pdf_text(pdf_docs)
                #  st.write(raw_text)

                # # get the text chunks
                text_chunks = extract_bitesize_pieces(raw_text)
                # st.write(text_chunks)

                # # create vector store
                vectorstore = prepare_embedding_vectors(text_chunks)

                # # create conversation chain
                st.session_state.conversation = prepare_conversation(vectorstore)

                SESSION_STARTED = True
                
                # Mission Complete!
                global_later = datetime.now()
                st.write("Files Vectorized - Total EXECUTION Time =",
                         (global_later - global_now), global_later)


if __name__ == '__main__':
    main()