import time
import streamlit as st
import torch
import string

from transformers import BertTokenizer, BertForMaskedLM

@st.cache()
def load_bert_model(model_name):
  try:
    bert_tokenizer = BertTokenizer.from_pretrained(model_name)
    bert_model = BertForMaskedLM.from_pretrained(model_name).eval()
    return bert_tokenizer,bert_model
  except Exception as e:
    pass



  
def decode(tokenizer, pred_idx, top_clean):
  ignore_tokens = string.punctuation + '[PAD]'
  tokens = []
  for w in pred_idx:
    token = ''.join(tokenizer.decode(w).split())
    if token not in ignore_tokens:
      tokens.append(token.replace('##', ''))
  return '\n'.join(tokens[:top_clean])

def encode(tokenizer, text_sentence, add_special_tokens=True):
  text_sentence = text_sentence.replace('<mask>', tokenizer.mask_token)
    # if <mask> is the last token, append a "." so that models dont predict punctuation.
  if tokenizer.mask_token == text_sentence.split()[-1]:
    text_sentence += ' .'

    input_ids = torch.tensor([tokenizer.encode(text_sentence, add_special_tokens=add_special_tokens)])
    mask_idx = torch.where(input_ids == tokenizer.mask_token_id)[1].tolist()[0]
  return input_ids, mask_idx

def get_all_predictions(text_sentence, top_clean=5):
    # ========================= BERT =================================
  input_ids, mask_idx = encode(bert_tokenizer, text_sentence)
  with torch.no_grad():
    predict = bert_model(input_ids)[0]
  bert = decode(bert_tokenizer, predict[0, mask_idx, :].topk(top_k).indices.tolist(), top_clean)
  return {'bert': bert}

def get_bert_prediction(input_text,top_k):
  try:
    input_text += ' <mask>'
    res = get_all_predictions(input_text, top_clean=int(top_k))
    return res
  except Exception as error:
    pass

try:

  st.title("Qualitative evaluation of Pretrained BERT models")
  st.markdown("""
        <a href="https://ajitrajasekharan.github.io/2021/01/02/my-first-post.html"><small style="font-size:18px; color: #8f8f8f">This app is used to qualitatively examine the performance of pretrained models to do NER , <b>with no fine tuning</b></small></a>
        """, unsafe_allow_html=True)
  st.write("Incomplete. Work in progress...")
  #st.write("https://ajitrajasekharan.github.io/2021/01/02/my-first-post.html")
  st.write("CLS vectors as well as the model prediction for a blank position are examined")

  top_k = 10
  print(top_k)


  bert_tokenizer, bert_model  = load_bert_model('ajitrajasekharan/biomedical')
  default_text = "Imatinib is used to treat"
  
 
  input_text = st.text_area(
    label="Original text",
    value=default_text,
  )

  start = None
  if st.button("Submit"):
    start = time.time()
    with st.spinner("Computing"):
    

            

            try:
                res = get_bert_prediction(default_text,top_k)
	

                st.header("JSON:")

                st.json(res)

            except Exception as e:
                st.error("Some error occured!" + str(e))
                st.stop()
	
    st.write("---")


	
    if start is not None:
        st.text(f"prediction took {time.time() - start:.2f}s")

except Exception as e:
  print("SOME PROBLEM OCCURED")