app.py

from typing import Any
import gradio as gr
from langchain_openai import OpenAIEmbeddings
from langchain_community.vectorstores import Chroma

from langchain.chains import ConversationalRetrievalChain
from langchain_openai import ChatOpenAI

from langchain_community.document_loaders import PyMuPDFLoader

import fitz
from PIL import Image
import os
import re
import openai

openai.api_key = "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"


def add_text(history, text: str):
    if not text:
        raise gr.Error("Enter text")
    history = history + [(text, "")]
    return history


class MyApp:
    def __init__(self) -> None:
        self.OPENAI_API_KEY: str = openai.api_key
        self.chain = None
        self.chat_history: list = []
        self.N: int = 0
        self.count: int = 0

    def __call__(self, file: str) -> Any:
        if self.count == 0:
            self.chain = self.build_chain(file)
            self.count += 1
        return self.chain

    def process_file(self, file: str):
        loader = PyMuPDFLoader(file.name)
        documents = loader.load()
        pattern = r"/([^/]+)$"
        match = re.search(pattern, file.name)
        try:
            file_name = match.group(1)
        except:
            file_name = os.path.basename(file)

        return documents, file_name

    def build_chain(self, file: str):
        documents, file_name = self.process_file(file)
        # Load embeddings model
        embeddings = OpenAIEmbeddings(openai_api_key=self.OPENAI_API_KEY)
        pdfsearch = Chroma.from_documents(
            documents,
            embeddings,
            collection_name=file_name,
        )
        chain = ConversationalRetrievalChain.from_llm(
            ChatOpenAI(temperature=0.0, openai_api_key=self.OPENAI_API_KEY),
            retriever=pdfsearch.as_retriever(search_kwargs={"k": 1}),
            return_source_documents=True,
        )
        return chain


def get_response(history, query, file):
    if not file:
        raise gr.Error(message="Upload a PDF")
    chain = app(file)
    result = chain(
        {"question": query, "chat_history": app.chat_history}, return_only_outputs=True
    )
    app.chat_history += [(query, result["answer"])]
    app.N = list(result["source_documents"][0])[1][1]["page"]
    for char in result["answer"]:
        history[-1][-1] += char
        yield history, ""


def render_file(file):
    doc = fitz.open(file.name)
    page = doc[app.N]
    # Render the page as a PNG image with a resolution of 150 DPI
    pix = page.get_pixmap(dpi=150)
    image = Image.frombytes("RGB", [pix.width, pix.height], pix.samples)
    return image


def purge_chat_and_render_first(file):
    print("purge_chat_and_render_first")
    # Purges the previous chat session so that the bot has no concept of previous documents
    app.chat_history = []
    app.count = 0

    # Use PyMuPDF to render the first page of the uploaded document
    doc = fitz.open(file.name)
    page = doc[0]
    # Render the page as a PNG image with a resolution of 150 DPI
    pix = page.get_pixmap(dpi=150)
    image = Image.frombytes("RGB", [pix.width, pix.height], pix.samples)
    return image, []


app = MyApp()

with gr.Blocks() as demo:
    with gr.Column():
        with gr.Row():
            with gr.Column(scale=2):
                with gr.Row():
                    chatbot = gr.Chatbot(value=[], elem_id="chatbot")
                with gr.Row():
                    txt = gr.Textbox(
                        show_label=False,
                        placeholder="Enter text and press submit",
                        scale=2
                    )
                    submit_btn = gr.Button("Submit", scale=1)

            with gr.Column(scale=1):
                with gr.Row():
                    show_img = gr.Image(label="Upload PDF")
                with gr.Row():
                    btn = gr.UploadButton("📁 Upload a PDF", file_types=[".pdf"])

    btn.upload(
        fn=purge_chat_and_render_first,
        inputs=[btn],
        outputs=[show_img, chatbot],
    )

    submit_btn.click(
        fn=add_text,
        inputs=[chatbot, txt],
        outputs=[
            chatbot,
        ],
        queue=False,
    ).success(
        fn=get_response, inputs=[chatbot, txt, btn], outputs=[chatbot, txt]
    ).success(
        fn=render_file, inputs=[btn], outputs=[show_img]
    )

demo.queue()
demo.launch()