Make EPUB e-book file from a given directory. The directory must be a valid EPUB ebook source.

make-epub.py

import sys
from pathlib import Path
from zipfile import ZipFile, ZIP_DEFLATED, ZIP_STORED

def main():
    usage = f'{sys.argv[0]} source_dir [destination_file]'
    if len(sys.argv) > 1:
        src = Path(sys.argv[1])
        dst = Path(sys.argv[2]) if len(sys.argv) > 2 else Path(src.name + ".epub")
        validate(src, dst)
        build_epub(src, dst)
        print(f'File: {dst}')
        print(f'Size: {sizeof(dst)}')
    else:
        print('Input directory not specified.')
        print(usage)

def sizeof(path):
    num = path.stat().st_size
    for unit in ['', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB']:
        if abs(num) < 1024.0:
            return f'{num:.1f} {unit}'
        num /= 1024.0
    return f'{num:.1f} YiB'

def validate(src, dst):
    container = 'META-INF/container.xml'
    if not src.exists():
        raise FileNotFoundError(f'Source directory "{src}" does not exist.')
    elif not src.is_dir():
        raise NotADirectoryError(f'Source "{src}" is not a directory.')
    elif not (src / container).is_file():
        raise FileNotFoundError(f'Source lacks "{container}" file.')
    if dst.exists():
        raise FileExistsError(f'File "{dst}" already exists.')

def build_epub(src, dst):
    mimetype = b'application/epub+zip'
    src_mimetype = src / 'mimetype'
    if src_mimetype.is_file():
        mimetype = src_mimetype.read_bytes().strip()
    with ZipFile(dst, 'w', compression=ZIP_DEFLATED, compresslevel=4) as epub:
        epub.writestr('mimetype', mimetype, compress_type=ZIP_STORED)
        for file in (f for f in src.rglob('*') if f != src_mimetype):
            epub.write(file, file.relative_to(src))

if __name__ == '__main__':
    main()