import tempfile
import subprocess
import os.path

def extract_pages(source, bookmark, start=None, end=None):

    return extract_and_concat([(source, bookmark, start, end)])

def extract_and_concat(items):
    
    # create a temporary directory for our sections
    d = tempfile.TemporaryDirectory(prefix="polyphonic_")

    sections = []

    for i, (source, bookmark, start, end) in enumerate(items):

        if start is None:
            sections.append(source)

        else:

            if end is None:
                end = start

            dest = os.path.join(d.name, f'section_{i}.pdf')

            cmd = ['gs', '-sDEVICE=pdfwrite', '-q', '-dBATCH', '-dNOPAUSE', 
                f'-dFirstPage={start}', f'-dLastPage={end}', 
                f'-sOutputFile={dest}',
                source]

            subprocess.run(cmd, check=True)
            sections.append(dest)

    # concat the items
    output = tempfile.NamedTemporaryFile(prefix="polyphonic_", suffix='.pdf')

    cmd = ['gs', '-sDEVICE=pdfwrite', '-q', '-dBATCH', '-dNOPAUSE',
           '-sOutputFile=-']
    cmd.extend(sections)

    subprocess.run(cmd, stdout=output)

    output.seek(0)
    return output