import nltk
from summarizer import Summarizer
from sumy.nlp.tokenizers import Tokenizer
from sumy.summarizers.lsa import LsaSummarizer
from sumy.parsers.plaintext import PlaintextParser
from sumy.summarizers.lex_rank import LexRankSummarizer
from sumy.summarizers.sum_basic import SumBasicSummarizer
from transformers import AutoTokenizer, AutoModelForSeq2SeqLM

nltk.download('punkt')

def extractive(method, file):
  sumarizer = method
  sentences_ = []
  doc_ = PlaintextParser(file, Tokenizer("en")).document
  for sentence in sumarizer(doc_, 5):
    sentences_.append(str(sentence))
    summm_ = " ".join(sentences_)
  return summm_

def summarize(file, model):
  
  with open(file.name) as f:
    doc = f.read()

  if model == "Pegasus":
    checkpoint = "google/pegasus-billsum"
    tokenizer = AutoTokenizer.from_pretrained(checkpoint)
    model = AutoModelForSeq2SeqLM.from_pretrained(checkpoint)
    inputs = tokenizer(doc, 
                    max_length=1024, 
                    truncation=True,
                    return_tensors="pt")
    
    summary_ids = model.generate(inputs["input_ids"])
    summary = tokenizer.batch_decode(summary_ids, 
                                  skip_special_tokens=True, 
                                  clean_up_tokenization_spaces=False)    
    summary =  summary[0]

  elif model == "TextRank":
    summary = extractive(LexRankSummarizer(), doc)

  elif model == "SumBasic":
    summary = extractive(SumBasicSummarizer(), doc)

  elif model == "Lsa":
    summary = extractive(LsaSummarizer(), doc)

  elif model == "BERT":
    modelbert = Summarizer('distilbert-base-uncased', hidden=[-1,-2], hidden_concat=True)
    result = modelbert(doc)
    summary = ''.join(result)
    
  return summary