import nltk
import validators
import streamlit as st
from transformers import AutoTokenizer, pipeline

# local modules
from summarizer import Summarizer
from utils import (
    clean_text,
    fetch_article_text,
    preprocess_text_for_abstractive_summarization,
    read_text_from_file,
)

if __name__ == "__main__":
    # ---------------------------------
    # Main Application
    # ---------------------------------
    st.title("Text Summarization Tool 📝")

    st.markdown("---")
    summarize_type = st.sidebar.selectbox(
        "Summarization Type", options=["Extractive", "Abstractive"]
    )
    st.markdown(
        """This app supports two type of summarization:

1. **Extractive Summarization**: The extractive approach involves picking up the most important phrases and lines from the documents. It then combines all the important lines to create the summary. So, in this case, every line and word of the summary actually belongs to the original document which is summarized.
2. **Abstractive Summarization**: The abstractive approach involves rephrasing the complete document while capturing the complete meaning of the document. This type of summarization provides more human-like summary"""
    )
    # ---------------------------
    # SETUP & Constants
    nltk.download("punkt")
    abs_tokenizer_name = "facebook/bart-large-cnn"
    abs_model_name = "facebook/bart-large-cnn"
    abs_tokenizer = AutoTokenizer.from_pretrained(abs_tokenizer_name)
    abs_max_length = 130
    abs_min_length = 30
    # ---------------------------

    inp_text = st.text_input("Enter Text or a URL here")
    st.markdown(
        "<h3 style='text-align: center;'>OR</h3>",
        unsafe_allow_html=True,
    )
    uploaded_file = st.file_uploader(
        "Upload a .txt, .pdf, .docx file for summarization"
    )

    is_url = validators.url(inp_text)
    if is_url:
        # complete text, chunks to summarize (list of sentences for long docs)
        text, clean_txt = fetch_article_text(url=inp_text)
    elif uploaded_file:
        clean_txt = read_text_from_file(uploaded_file)
        clean_txt = clean_text(clean_txt)
    else:
        clean_txt = clean_text(inp_text)

    # view summarized text (expander)
    with st.expander("View Input Text"):
        if is_url:
            st.write(clean_txt[0])
        else:
            st.write(clean_txt)
    summarize = st.button("Summarize")

    # called on toggle button [summarize]
    if summarize:
        if summarize_type == "Extractive":
            if is_url:
                text_to_summarize = " ".join([txt for txt in clean_txt])
            else:
                text_to_summarize = clean_txt
            # extractive summarizer

            with st.spinner(
                text="Creating extractive summary. This might take a few seconds ..."
            ):
                ext_model = Summarizer()
                summarized_text = ext_model(text_to_summarize)

        elif summarize_type == "Abstractive":
            with st.spinner(
                text="Creating abstractive summary. This might take a few seconds ..."
            ):
                text_to_summarize = clean_txt
                abs_summarizer = pipeline(
                    "summarization", model=abs_model_name, tokenizer=abs_tokenizer_name
                )

                if is_url is False:
                    # list of chunks
                    text_to_summarize = preprocess_text_for_abstractive_summarization(
                        tokenizer=abs_tokenizer, text=clean_txt
                    )
                tmp_sum = abs_summarizer(
                    text_to_summarize,
                    max_length=len(text_to_summarize),
                    min_length=abs_min_length,
                    do_sample=False,
                )

                summarized_text = " ".join([summ["summary_text"] for summ in tmp_sum])

        # final summarized output
        st.subheader("Summarized text")
        st.info(summarized_text)