# paperdoorknob: Print glowfic
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, version 3.


from argparse import ArgumentParser
import itertools
import os.path
import subprocess

from typing import IO, Iterable

from bs4 import BeautifulSoup
from bs4.element import Tag
from xdg_base_dirs import xdg_cache_home

from fetch import CachingFetcher, Fetcher


def command_line_parser() -> ArgumentParser:
    parser = ArgumentParser(prog='paperdoorknob', description='Print glowfic')
    parser.add_argument(
        '--cache_path',
        metavar='PATH',
        help='Where to keep the http cache (instead of %(default)s)',
        default=os.path.join(xdg_cache_home(), "paperdoorknob"))
    parser.add_argument(
        '--out',
        help='The filename stem at which to write output ' +
             '(eg: "%(default)s" produces %(default)s.text, %(default)s.pdf, etc.)',
        default='book')
    parser.add_argument('--pandoc', help='Location of the pandoc executable')
    parser.add_argument(
        '--timeout',
        help='How long to wait for HTTP requests, in seconds',
        default=30)
    parser.add_argument('url', help='URL to retrieve')
    return parser


def fetch(url: str, fetcher: Fetcher) -> BeautifulSoup:
    return BeautifulSoup(fetcher.fetch(url), 'html.parser')


def clean(html: BeautifulSoup) -> BeautifulSoup:
    for eb in html.find_all("div", class_="post-edit-box"):
        eb.decompose()
    for footer in html.find_all("div", class_="post-footer"):
        footer.decompose()
    return html


def replies(html: BeautifulSoup) -> Iterable[Tag]:
    def text() -> Tag:
        body = html.body
        assert body
        text = body.find_next("div", class_="post-post")
        assert isinstance(text, Tag)
        return text

    def the_replies() -> Iterable[Tag]:
        rs = html.find_all("div", class_="post-reply")
        assert all(isinstance(r, Tag) for r in rs)
        return rs

    return itertools.chain([text()], the_replies())


def html_to_tex(pandoc: str, tag: Tag) -> bytes:
    return subprocess.run([pandoc, '--from=html', '--to=latex'],
                          input=tag.encode(),
                          stdout=subprocess.PIPE,
                          check=True).stdout


def process(
        url: str,
        fetcher: Fetcher,
        texout: IO[bytes],
        pandoc: str) -> None:
    texout.write(b'\\documentclass{article}\n\\begin{document}\n')
    html = clean(fetch(url, fetcher))
    for r in replies(html):
        texout.write(html_to_tex(pandoc, r))
    texout.write(b'\\end{document}\n')


def main() -> None:
    args = command_line_parser().parse_args()
    with CachingFetcher(args.cache_path, args.timeout) as fetcher:
        with open(args.out + '.tex', 'wb') as texout:
            process(args.url, fetcher, texout, args.pandoc or 'pandoc')


if __name__ == '__main__':
    main()