#!/usr/bin/python

import argparse
import sys

import docx


def filter_chapters(document, chapter_numbers):
    if not chapter_numbers:
        return

    chapter_number = 0

    for paragraph in document.paragraphs:
        if paragraph.style.name == 'Heading 2':
            chapter_number += 1

        if chapter_number not in chapter_numbers:
            element = paragraph._element
            element.getparent().remove(element)


def set_default_font(document):
    document.styles['Normal'].font.name = 'Times New Roman'


def add_header_text(document, text):
    document.sections[0].header.paragraphs[0].text = text


def create_element(name):
    return docx.oxml.OxmlElement(name)


def create_attribute(element, name, value):
    element.set(docx.oxml.ns.qn(name), value)


def add_header_page_number(document):
    run = document.sections[0].header.paragraphs[0].add_run()

    fldChar1 = create_element('w:fldChar')
    create_attribute(fldChar1, 'w:fldCharType', 'begin')

    instrText = create_element('w:instrText')
    create_attribute(instrText, 'xml:space', 'preserve')
    instrText.text = "PAGE"

    fldChar2 = create_element('w:fldChar')
    create_attribute(fldChar2, 'w:fldCharType', 'end')

    run._r.append(fldChar1)
    run._r.append(instrText)
    run._r.append(fldChar2)


def skip_page_number_on_first_page(document):
    document.sections[0].different_first_page_header_footer = True
    page_number_type = docx.oxml.OxmlElement('w:pgNumType')
    page_number_type.set(docx.oxml.ns.qn('w:start'), "0")
    document.sections[0]._sectPr.append(page_number_type)


def right_align_header(document):
    header_paragraph = document.sections[0].header.paragraphs[0]
    header_paragraph.paragraph_format.alignment = docx.enum.text.WD_ALIGN_PARAGRAPH.RIGHT


def double_space_and_indent(paragraphs):
    this_paragraph_plaintext = False
    previous_paragraph_plaintext = False

    for paragraph in paragraphs:
        paragraph.paragraph_format.line_spacing = 2
        paragraph.paragraph_format.space_before = docx.shared.Inches(0)
        paragraph.paragraph_format.space_after = docx.shared.Inches(0)

        # To reduce page count, allow splitting paragraphs across pages.
        paragraph.paragraph_format.widow_control = False

        this_paragraph_plaintext = not paragraph.style.name.startswith('Heading')

        # Indent first lines of paragraphs except for styled ones (headings, etc.) and initial
        # paragraphs.
        if this_paragraph_plaintext and previous_paragraph_plaintext:
            paragraph.paragraph_format.first_line_indent = docx.shared.Inches(0.5)

        previous_paragraph_plaintext = this_paragraph_plaintext


def parse_arguments(unparsed_arguments):
    parser = argparse.ArgumentParser(add_help=True)
    parser.add_argument(
        metavar='FILENAME', dest='document_filename', help='Novel document to format',
    )
    parser.add_argument(
        '-c',
        '--chapters',
        metavar='CHAPTER',
        nargs='+',
        type=int,
        help='Numbers of chapters to include in output',
    )

    return parser.parse_args(unparsed_arguments)


def main():
    arguments = parse_arguments(sys.argv[1:])
    document = docx.Document(arguments.document_filename)

    filter_chapters(document, arguments.chapters)
    set_default_font(document)
    # add_header_text(document, 'Author / Project Title / ')
    add_header_page_number(document)

    if not arguments.chapters:
        skip_page_number_on_first_page(document)

    right_align_header(document)
    double_space_and_indent(document.paragraphs)

    document.save(arguments.document_filename)


if __name__ == '__main__':
    main()