Merges several input PDFs into a single, large, PDF with bookmarks for each individual PDF.

pdf_merge.py

import os
import re
import sys

import PyPDF2

MIN_PYTHON = (3, 0)


"""
Usage: python pdf_merge.py [inputs] <output>
Example: python pdf_merge.py *.pdf merged.pdf
"""


def natural_sort_key(s: str):
    """
    Function to convert a string into a sortable entry that respects natural ordering.
    I.e.: 1 comes before 10
    """
    return [int(text) if text.isdigit() else text.lower() for text in re.compile('([0-9]+)').split(s)]


def get_pdf_title(pdf_file_path: str) -> str:
    pdf_reader = PyPDF2.PdfFileReader(open(pdf_file_path, 'rb'))
    pdf_title = pdf_reader.getDocumentInfo().title
    if pdf_title is None:
        pdf_title = os.path.basename(pdf_file_path) \
            .replace("_", " ") \
            .replace(".pdf", "")
    return pdf_title


def merge_pdfs(pdfs: [str], target_file: str) -> None:
    merger = PyPDF2.PdfFileMerger()

    if os.path.exists(target_file):
        os.remove(target_file)

    pdfs.sort(key=natural_sort_key)

    titles = [get_pdf_title(pdf) for pdf in pdfs]
    for pdf, title in zip(pdfs, titles):
        merger.append(open(pdf, 'rb'), bookmark=title)

    with open(target_file, 'wb') as out:
        merger.write(out)
    merger.close()


if __name__ == '__main__':
    if sys.version_info < MIN_PYTHON:
        sys.exit('Python %s.%s or later is required.' % MIN_PYTHON)

    if len(sys.argv) < 3:
        print('Usage: %s [sources] <target>' % sys.argv[0])
        exit(1)

    sources = sys.argv[1:-1]
    non_pdfs = [pdf for pdf in sources if not pdf.endswith('.pdf')]
    if len(non_pdfs) != 0:
        print('One or more input files are not a PDF:', non_pdfs)
        exit(1)

    not_exists = [pdf for pdf in sources if not os.path.exists(pdf)]
    if len(not_exists) != 0:
        print('One or more input files do not exist:', not_exists)
        exit(1)

    target_file = sys.argv[-1]
    if not target_file.endswith('.pdf'):
        print('Target file must have a .pdf extension')
        exit(1)

    merge_pdfs(sources, target_file)
    print('Wrote to', target_file)
    exit(0)