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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'[Page no. {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  

def load_recommender(path, start_page=1):  
  global recommender  
  texts = 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(openAI_key,prompt, engine="text-davinci-003"):  
  openai.api_key = openAI_key  
  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,openAI_key):  
  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 [ Page 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 'Text Not Found in PDF'. Ignore outlier "\  
  "search results which has nothing to do with the question. Only answer what is asked. The "\  
  "answer should be short and concise. Answer step-by-step. \n\nQuery: {question}\nAnswer: "  

  prompt += f"Query: {question}\nAnswer:"  
  answer = generate_text(openAI_key, prompt,"text-davinci-003")  
  return answer  

def question_answer(url, file, question,openAI_key):  
  if openAI_key.strip()=='':  
    return '[ERROR]: Please enter you Open AI Key. Get your key here : https://platform.openai.com/account/api-keys'  
  if url.strip() == '' and file == None:  
    return '[ERROR]: Both URL and PDF is empty. Provide atleast one.'  

  if url.strip() != '' and file != None:  
    return '[ERROR]: Both URL and PDF is provided. Please provide only one (eiter URL or PDF).'  

  if url.strip() != '':  
    glob_url = url  
    download_pdf(glob_url, 'corpus.pdf')  
    load_recommender('corpus.pdf')  

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

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

  return generate_answer(question,openAI_key)  

recommender = SemanticSearch()  

title = 'PDF GPT'  
description = """ PDF GPT allows you to chat with your PDF file using Universal Sentence Encoder and Open AI. It gives hallucination free response than other tools as the embeddings are better than OpenAI. Thequote("def load_recommender(path, start_page=1):", "return generate_answer(question,openAI_key)")