from transformers import GPT2LMHeadModel, AutoTokenizer
import re

tokenizer = AutoTokenizer.from_pretrained("flax-community/gpt2-bengali")
model = GPT2LMHeadModel.from_pretrained("./350")

model.to("cuda")

print(model)

BEGIN_TOKEN = "<।summary_begin।>"
END_TOKEN = "<।summary_end।>"
SUMMARY_TOKEN = "<।summary।>"


def processTxt(txt):
    txt = re.sub(r"।", "। ", txt)
    txt = re.sub(r",", ", ", txt)
    txt = re.sub(r"!", "। ", txt)
    txt = re.sub(r"\?", "। ", txt)
    txt = re.sub(r"\"", "", txt)
    txt = re.sub(r"'", "", txt)
    txt = re.sub(r"’", "", txt)
    txt = re.sub(r"’", "", txt)
    txt = re.sub(r"‘", "", txt)
    txt = re.sub(r";", "। ", txt)

    txt = re.sub(r"\s+", " ", txt)

    return txt


def index_of(val, in_text, after=0):
    try:
        return in_text.index(val, after)
    except ValueError:
        return -1


def summarize(txt):
    txt = processTxt(txt.strip())
    txt = "<|SUMMARY_BEGIN|>" + txt + "<|SUMMARY|>"

    inputs = tokenizer(txt, max_length=800, truncation=True, return_tensors="pt")
    inputs.to("cuda")
    output = model.generate(inputs["input_ids"], max_length=len(txt) + 120)

    txt = tokenizer.batch_decode(output, skip_special_tokens=True)[0]

    start = index_of(SUMMARY_TOKEN, txt) + len(SUMMARY_TOKEN)

    print(txt)
    if start == len(SUMMARY_TOKEN) - 1:
        return "No Summary!"

    end = index_of(END_TOKEN, txt, start)

    if end == -1:
        end = index_of(SUMMARY_TOKEN, txt, start)

    if end == -1:
        end = index_of(BEGIN_TOKEN, txt, start)

    if end == -1:
        return txt[start:].strip()

    txt = txt[start:end].strip()

    end = index_of(SUMMARY_TOKEN, txt)

    if end == -1:
        return txt
    else:
        return txt[:end].strip()