app.py

import urllib.request
import fitz
import re
import numpy as np
import tensorflow_hub as hub
import openai
import gradio as gr
import os
from sklearn.neighbors import NearestNeighbors


def download_pdf(url, output_path):
    urllib.request.urlretrieve(url, output_path)


def preprocess(text):
    text = text.replace('\n', ' ')
    text = re.sub('\s+', ' ', text)
    return text


def pdf_to_text(path, start_page=1, end_page=None):
    doc = fitz.open(path)
    total_pages = doc.page_count

    if end_page is None:
        end_page = total_pages

    text_list = []

    for i in range(start_page-1, end_page):
        text = doc.load_page(i).get_text("text")
        text = preprocess(text)
        text_list.append(text)

    doc.close()
    return text_list


def text_to_chunks(texts, word_length=150, start_page=1):
    text_toks = [t.split(' ') for t in texts]
    page_nums = []
    chunks = []

    for idx, words in enumerate(text_toks):
        for i in range(0, len(words), word_length):
            chunk = words[i:i+word_length]
            if (i+word_length) > len(words) and (len(chunk) < word_length) and (
                len(text_toks) != (idx+1)):
                text_toks[idx+1] = chunk + text_toks[idx+1]
                continue
            chunk = ' '.join(chunk).strip()
            chunk = f'[{idx+start_page}]' + ' ' + '"' + chunk + '"'
            chunks.append(chunk)
    return chunks


class SemanticSearch:

    def __init__(self):
        self.use = hub.load('https://tfhub.dev/google/universal-sentence-encoder/4')
        self.fitted = False

    def fit(self, data, batch=1000, n_neighbors=5):
        self.data = data
        self.embeddings = self.get_text_embedding(data, batch=batch)
        n_neighbors = min(n_neighbors, len(self.embeddings))
        self.nn = NearestNeighbors(n_neighbors=n_neighbors)
        self.nn.fit(self.embeddings)
        self.fitted = True

    def __call__(self, text, return_data=True):
        inp_emb = self.use([text])
        neighbors = self.nn.kneighbors(inp_emb, return_distance=False)[0]

        if return_data:
            return [self.data[i] for i in neighbors]
        else:
            return neighbors

    def get_text_embedding(self, texts, batch=1000):
        embeddings = []
        for i in range(0, len(texts), batch):
            text_batch = texts[i:(i+batch)]
            emb_batch = self.use(text_batch)
            embeddings.append(emb_batch)
        embeddings = np.vstack(embeddings)
        return embeddings


recommender = SemanticSearch()
pdf_paths = []  # List to store multiple PDF paths


def load_recommender(paths, start_page=1):
    global recommender, pdf_paths
    pdf_paths = paths
    texts = []
    for path in paths:
        texts.extend(pdf_to_text(path, start_page=start_page))
    chunks = text_to_chunks(texts, start_page=start_page)
    recommender.fit(chunks)
    return 'Corpus Loaded.'


def generate_text(prompt, engine="mlsgpt3"):
    completions = openai.Completion.create(
        engine=engine,
        prompt=prompt,
        max_tokens=512,
        n=1,
        stop=None,
        temperature=0.7,
    )
    message = completions.choices[0].text
    return message


def generate_answer(question):
    topn_chunks = recommender(question)
    prompt = ""
    prompt += 'search results:\n\n'
    for c in topn_chunks:
        prompt += c + '\n\n'

    prompt += "Instructions: Compose a comprehensive reply to the query using the search results given. " \
              "Cite each reference using [number] notation (every result has this number at the beginning). " \
              "Citation should be done at the end of each sentence. If the search results mention multiple subjects " \
              "with the same name, create separate answers for each. Only include information found in the results and " \
              "don't add any additional information. Make sure the answer is correct and don't output false content. " \
              "If the text does not relate to the query, simply state 'Found Nothing'. Ignore outlier " \
              "search results which have nothing to do with the question. Only answer what is asked. The " \
              "answer should be short and concise.\n\nQuery: {question}\nAnswer: "

    prompt += f"Query: {question}\nAnswer:"
    answer = generate_text(prompt)
    return answer


def question_answer(files, question, secret):
    api_key = os.environ.get('AzureKey')
    url_base = os.environ.get('AzureUrlBase')

    if api_key is None or url_base is None:
        return '[ERROR]: Please provide the Azure API Key and URL Base as environment variables.'

    openai.api_key = api_key
    openai.api_type = "azure"
    openai.api_base = url_base
    openai.api_version = "2022-12-01"

    if files == []:
        return '[ERROR]: Please provide at least one PDF.'

    if secret != os.environ.get('Secret'):
        return '[Error]: Please provide the correct secret'

    else:
        loaded_files = []
        for file in files:
            old_file_name = file.name
            file_name = file.name
            file_name = file_name[:-12] + file_name[-4:]
            os.rename(old_file_name, file_name)
            loaded_files.append(file_name)
        load_recommender(loaded_files)

    if question.strip() == '':
        return '[ERROR]: Question field is empty.'

    return generate_answer(question)


title = 'AzurePDFGPT'
description = "A test platform for indexing PDFs to in order to 'chat' with them. It is hardcoded to the Jaytest and MLSLGPT engine"

with gr.Interface(
    fn=question_answer,
    inputs=[
        gr.File(label='PDFs', file_types=['.pdf'], file_count="multiple"),
        gr.Textbox(label='Question'),
        gr.Textbox(label='Secret')
    ],
    outputs=gr.Textbox(label='Answer'),
    title=title,
    description=description
) as iface:
    iface.launch()