import streamlit as st
import pandas as pd
import re

st.set_page_config(page_icon='🍃', page_title='MRC for Legal Document Dataset checker', layout='wide', initial_sidebar_state="collapsed")

# start processing events
def load_data(file_uploader):
    if file_uploader is not None:
        return pd.read_csv(file_uploader)
    else:
        return pd.DataFrame(columns=['context', 'question', 'answer'])
    
def convert_df(df):
    # IMPORTANT: Cache the conversion to prevent computation on every rerun
    return df.to_csv().encode("utf-8")
# end processing events

st.markdown("<h1 style='text-align: center;'>Investigation Legal Dataset checker for Machine Reading Comprehension</h1>", unsafe_allow_html=True)

file = st.file_uploader(label='Upload your file here:', type=['csv'], accept_multiple_files=False, label_visibility='hidden')
df = load_data(file_uploader=file)

if 'df' not in st.session_state:
    st.session_state.df = df

if 'idx' not in st.session_state:
    st.session_state.idx = 0

st.markdown(f"<h3 style='text-align: center;'>Sample {st.session_state.idx + 1}/{len(df)}</h3>", unsafe_allow_html=True)

col_1, col_2, col_3, col_4, col_5, col_6, col_7, col_8, col_9, col_10 = st.columns([1, 1, 1, 1, 1, 1, 1, 1, 1, 1])

btn_previous = col_1.button(label=':arrow_backward: Previous sample', use_container_width=True)
btn_next = col_2.button(label='Next sample :arrow_forward:', use_container_width=True)
btn_save = col_3.button(label=':heavy_check_mark: Save change', use_container_width=True)
# txt_goto = col_4.selectbox(label='None', options=[np.array(range(len(df)))], label_visibility='collapsed')

if len(df) != 0:
    index = st.session_state.idx

    txt_context = st.text_area(height=300, label='Your context:', value=st.session_state.df['context'][index])
    txt_question = st.text_area(height=100, label='Your question:', value=st.session_state.df['question'][index])
    txt_answer = st.text_area(height=100, label='Your answer:', value=st.session_state.df['answer'][index])

    if txt_answer.strip() and txt_context.strip():
        highlighted_context = re.sub(re.escape(txt_answer), "<mark>" + txt_answer + "</mark>", txt_context, flags=re.IGNORECASE)
        st.markdown(highlighted_context, unsafe_allow_html=True)


    if btn_next:
        if index < len(df) - 1:
            st.session_state.idx += 1
            st.rerun()

    if btn_save:
        st.session_state.df['context'][index] = txt_context
        st.session_state.df['question'][index] = txt_question
        st.session_state.df['answer'][index] = txt_answer
        csv_file = convert_df(df=st.session_state.df)
        btn_download = col_4.download_button(data=csv_file, label=':arrow_down_small: Download file', use_container_width=True, file_name="large_df.csv", mime="text/csv")

    if btn_previous:
        if index > 0:
            st.session_state.idx -= 1
            st.rerun()