readfstr.py

# python3 readfstr.py input.epub output.epub

import argparse
from ebooklib import epub                      # pip install ebooklib
from bs4 import BeautifulSoup, NavigableString # pip install bs4

def make_half_word_bold(soup, text):
    new_elements = []
    for word in text.split():
        n = len(word)
        half = n // 2
        new_element = soup.new_tag("span")
        b_tag = soup.new_tag("b")
        b_tag.string = word[:half]
        new_element.append(b_tag)
        new_element.append(word[half:])
        new_elements.append(new_element)
    return new_elements

def style_epub(input_file, output_file):
    # Load ePub book
    book = epub.read_epub(input_file)
    
    # Iterate through items in the ePub
    for item in book.get_items_of_type(9):  # 9 is the constant for XHTML
        # Parse with BeautifulSoup
        soup = BeautifulSoup(item.content, 'html.parser')
        
        # Modify text within tags
        for tag in soup.find_all(string=True):
            parent = tag.parent
            if parent is not None:
                modified_elements = make_half_word_bold(soup, tag)
                tag.extract()
                for elem in modified_elements:
                    parent.append(elem)
                    parent.append(' ')


        # Update the item content
        item.content = str(soup).encode('utf-8')
    
    # Write out modified ePub
    epub.write_epub(output_file, book)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Style an ePub file.')
    parser.add_argument('input_file', type=str, help='Path to the input ePub file')
    parser.add_argument('output_file', type=str, help='Path for the styled output ePub file')

    args = parser.parse_args()
    style_epub(args.input_file, args.output_file)