# 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.


import dataclasses
import itertools
from urllib.parse import parse_qsl, urlencode, urljoin, urlparse, urlunparse

from typing import Any, Iterable

from bs4 import BeautifulSoup
from bs4.element import Tag

from images import ImageStore
from spec import Spec
from texify import Texifier


def ilen(it: Iterable[Any]) -> int:
    return sum(1 for _ in it)


def _removeViewFromURL(url: str) -> str:
    u = urlparse(url)
    old_qs = parse_qsl(u.query)
    new_qs = [(k, v) for k, v in old_qs if k != 'view']
    return urlunparse(u._replace(query=urlencode(new_qs)))


def nonFlatURL(url: str) -> str:
    return _removeViewFromURL(url)


def flatURL(url: str) -> str:
    u = urlparse(_removeViewFromURL(url))
    qs = parse_qsl(u.query) + [('view', 'flat')]
    return urlunparse(u._replace(query=urlencode(qs)))


@dataclasses.dataclass(frozen=True)
class Chunk:
    icon: str | None
    character: Tag | None
    screen_name: Tag | None
    author: Tag | None
    content: Tag

# We avoid the name "post" because the Glowfic community uses the term
# inconsistently:
#  * The Glowfic software sometimes uses "post" to refer to a whole thread
#    (in the URL), sometimes uses "post" to refer to chunks (in the CSS),
#    but mostly uses "post" to refer to just the first chunk in a thread
#    (in the HTML and UI).  The non-first chunks are "replies".
#  * Readers and this software don't need to distinguish first-chunks and
#    non-first-chunks.
#  * Humans in the community tend to use "posts" to mean chunks.


class Thread:

    def __init__(self, spec: Spec) -> None:
        def find_next_thread(dom: BeautifulSoup) -> str | None:
            for c in dom.findChildren('div', class_='post-navheader'):
                for a in c.findChildren('a'):
                    if 'Next Post' in a.text and 'href' in a.attrs and isinstance(
                            a.attrs['href'], str):
                        return urljoin(spec.url, a.attrs['href'])
            return None

        spec.log('Fetching HTML...\r')
        html = spec.fetcher.fetch(spec.url)
        flat_html = spec.fetcher.fetch(flatURL(spec.url))
        spec.log('Parsing HTML...\r')
        self._next_thread = find_next_thread(
            BeautifulSoup(spec.htmlfilter(html), 'html.parser'))
        self._dom = BeautifulSoup(spec.htmlfilter(flat_html), 'html.parser')
        self._spec = spec

    def title(self) -> str | None:
        span = self._dom.findChild("span", id="post-title")
        if not isinstance(span, Tag):
            return None
        return span.text.strip()

    def next_thread(self) -> str | None:
        return self._next_thread

    def chunkDOMs(self) -> Iterable[Tag]:
        def text() -> Tag:
            body = self._dom.body
            assert body
            text = body.find_next("div", class_="post-post")
            assert isinstance(text, Tag)
            return text

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

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

    def emit(self) -> None:
        self._spec.log('Counting chunks...\r')
        num_chunks = ilen(self.chunkDOMs())
        title = self.title() or "chunk"
        for i, r in enumerate(self.chunkDOMs()):
            percent = 100.0 * (i + 1) / num_chunks
            self._spec.log(
                f'Processing {title} {i+1} of {num_chunks} ({percent:.1f}%)\r')
            self._spec.domfilter(r)
            chunk = makeChunk(r, self._spec.images)
            self._spec.texout.write(
                self._spec.texfilter(renderChunk(self._spec.texifier, chunk)))
        self._spec.log('')
        next_url = self.next_thread()
        if next_url is not None:
            Thread(dataclasses.replace(self._spec, url=next_url)).emit()


def makeChunk(chunk_dom: Tag, image_store: ImageStore) -> Chunk:

    def getIcon() -> str | None:
        icon_div = chunk_dom.findChild('div', class_='post-icon')
        if icon_div is None:
            return None
        assert isinstance(icon_div, Tag)
        icon_img = icon_div.findChild('img')
        if icon_img is None:
            return None
        assert isinstance(icon_img, Tag)
        return image_store.get_image(icon_img.attrs['src'])

    def getByClass(css_class: str) -> Tag | None:
        tag = chunk_dom.findChild('div', class_=css_class)
        assert tag is None or isinstance(tag, Tag)
        return tag

    def stripHREF(tag: Tag) -> None:
        for c in tag.findChildren("a"):
            if "href" in c.attrs:
                del c.attrs["href"]

    def getMeta(css_class: str) -> Tag | None:
        tag = getByClass(css_class)
        if tag is None:
            return None
        stripHREF(tag)
        return tag

    content = chunk_dom.findChild('div', class_='post-content')
    assert isinstance(content, Tag)

    return Chunk(getIcon(),
                 getMeta('post-character'),
                 getMeta('post-screenname'),
                 getMeta('post-author'),
                 content)


def renderChunk(texifier: Texifier, chunk: Chunk) -> bytes:
    return b''.join([
        br'\glowhead{',
        br'\glowicon{%s}' % chunk.icon.encode('UTF-8') if chunk.icon else b'',
        b'}{',
        texifier.texify(chunk.character) if chunk.character else b'',
        b'}{',
        texifier.texify(chunk.screen_name) if chunk.screen_name else b'',
        b'}{',
        texifier.texify(chunk.author) if chunk.author else b'',
        b'}',
        texifier.texify(chunk.content)])


ContentOnlyLayout = br'''
\newcommand{\glowhead}[4]{}
'''


BelowIconLayout = br'''
\newcommand{\glowhead}[4]{\wrapstuffclear
\begin{wrapstuff}[l]
\fbox{
\begin{varwidth}{0.5\textwidth}
  \smash{\parbox[t][0pt]{0pt}{
    \setlength{\fboxrule}{0.2pt}
    \setlength{\fboxsep}{0pt}
    \vspace{-3.4pt}
    \fbox{\hspace{107mm}}
  }\\*}
  \vspace{-1em}
\begin{center}
#1\ifnotempty
{#1}{\\*}#2\ifnotempty
{#2}{\\*}#3\ifnotempty
{#3}{\\*}#4
\end{center}
\end{varwidth}
}
\end{wrapstuff}

\strut

\noindent}'''


# Why is \textwidth not the width of the text?
# Why is the width of the text .765\textwidth?
BesideIconLayout = br'''
\newcommand{\glowhead}[4]{

\strut

\noindent\fbox{
#1
\parbox[b]{.765\textwidth}{
\begin{center}
#2\ifnotempty
{#2}{\\*}#3\ifnotempty
{#3}{\\*}#4
\end{center}
}
}\\*
\vspace{-0.75em}\\*
\noindent}'''