import streamlit as st
from docx import Document
import PyPDF2
import pdfplumber
import pytesseract
import difflib
import base64

def read_pdf(file):
    try:
        pdf_reader = PyPDF2.PdfFileReader(file)
        total_pages = pdf_reader.numPages
        text = []
        for page_num in range(total_pages):
            page = pdf_reader.getPage(page_num)
            text.append(page.extract_text())
        return "\n".join(text)
    except:
        st.warning('Failed to directly read PDF, trying OCR...')
        try:
            with pdfplumber.open(file) as pdf:
                text = "\n".join([page.extract_text() for page in pdf.pages])
            return text
        except Exception as e:
            st.error(f"Error in OCR: {str(e)}")
            return None

def read_docx(file):
    doc = Document(file)
    return "\n".join([p.text for p in doc.paragraphs])

def compare_texts(text1, text2):
    d = difflib.Differ()
    diff = list(d.compare(text1.splitlines(), text2.splitlines()))
    
    result = []
    page_no = 1
    for line in diff:
        if 'Page' in line:  # if a new page starts
            page_no += 1
        elif line.startswith('+ '):  # text present in text2 but not in text1
            result.append(f'Additional text detected on page {page_no}')
        elif line.startswith('- '):  # text present in text1 but not in text2
            result.append(f'Less text detected on page {page_no}')
    
    return "\n".join(set(result))  # using set to remove duplicates

st.title('PDF and DOCX Comparison Tool')

pdf_file = st.file_uploader('Upload a PDF file', type=['pdf'])
docx_file = st.file_uploader('Upload a DOCX file', type=['docx'])

if pdf_file and docx_file:
    pdf_text = read_pdf(pdf_file)
    docx_text = read_docx(docx_file)

    b64_pdf = base64.b64encode(pdf_file.read()).decode()  # some strings <-> bytes conversions necessary here
    href = f'<a href="data:file/pdf;base64,{b64_pdf}" download="file.pdf">Download PDF File</a> (right-click and save as &lt;some_name&gt;.pdf)'
    st.markdown(href, unsafe_allow_html=True)

    st.markdown(f'<iframe src="data:application/pdf;base64,{b64_pdf}" width="50%" height="600px" type="application/pdf"></iframe>', unsafe_allow_html=True)
    st.markdown("### DOCX Content:")
    st.text(docx_text)

    if pdf_text and docx_text:
        comparison_result = compare_texts(pdf_text, docx_text)
        st.text(comparison_result)
    else:
        st.error('Failed to read text from one or both files.')