#!/usr/bin/env python3
import fnmatch
import locale
import os
from collections import defaultdict
from dataclasses import dataclass
from datetime import datetime, timedelta
from html import escape
from itertools import groupby
from pathlib import Path
from string import Template
from textwrap import dedent
from time import perf_counter

import mistune
from jinja2 import Environment as Env
from jinja2 import FileSystemLoader
from minicli import cli, run, wrap
from mistune.directives import DirectiveInclude
from PIL import Image
from slugify import slugify

from typography import typographie

# Useful for dates rendering within Jinja2.
locale.setlocale(locale.LC_ALL, "fr_FR.UTF-8")

HERE = Path(".")
DAVID = HERE / "david"
STATIC = HERE / ".." / "larlet-fr-static"
DOMAIN = "https://larlet.fr"
LOCAL_DOMAIN = "http://larlet.test:3579"
# Hardcoding publication at 12 in Paris timezone.
NORMALIZED_STRFTIME = "%Y-%m-%dT12:00:00+01:00"
TODAY = datetime.today() + timedelta(hours=6)
PUBLICATION_BUFFER = TODAY - timedelta(days=7)
NB_ITEMS_IN_FEED = 30

all_tags = set()
pages_by_tags = defaultdict(list)
pages_by_url = {}


class MarkParser(mistune.InlineParser):
    """Parses `==foo==` as `<mark>foo</mark>`."""

    MARK = (
        r"(\={2})(?=[^\s*])("
        r"(?:\\[\\*]|[^*])*"
        r"(?:" + mistune.InlineParser.ESCAPE + r"|[^\s*]))\1"
    )

    RULE_NAMES = mistune.InlineParser.RULE_NAMES + ("mark",)

    def parse_mark(self, m, state):
        marker = m.group(1)
        text = m.group(2)
        return "mark", self.render(text, state)


class MarkRenderer(mistune.HTMLRenderer):
    """To use in conjunction with `MarkParser`."""

    def mark(self, text):
        return "<mark>" + text + "</mark>"


class TagsRenderer(mistune.HTMLRenderer):
    """Make the asumption each line starting with a `#` is a tag."""

    def paragraph(self, text):
        if text.startswith("#"):
            tags = " ".join(
                f'<a href="/david/2021/{slugify(tag.strip())}/">#{tag.strip()}</a>'
                for tag in text.split("#")
                if tag.strip()
            )
            return f"<nav><p>{tags}</p></nav>\n"
        return super().paragraph(text)


class FrenchTypographyRenderer(mistune.HTMLRenderer):
    """Apply French typographic rules to text."""

    def text(self, text):
        return typographie(super().text(text))


class InternalLinkTitleRenderer(mistune.HTMLRenderer):
    """Automatically generate the title for internal links."""

    def link(self, link, text=None, title=None):
        if text is None:
            text = link

        s = '<a href="' + self._safe_url(link) + '"'

        if not title and link.startswith("/david/2021/"):
            # It will not work for internal links referencing the future.
            page = pages_by_url.get(link)
            if page:
                title = page.title

        if title:
            s += ' title="' + mistune.escape_html(title) + '"'
        return s + ">" + (text or link) + "</a>"


class CustomAndBlockquoteLanguageRenderer(
    FrenchTypographyRenderer, InternalLinkTitleRenderer, MarkRenderer, TagsRenderer
):
    """Sets the English language attribute for blockquotes with `[en]` prefix."""

    def _get_language(self, text):
        if text.startswith("<p>[en] "):
            return "en", text.replace("<p>[en] ", "<p>")
        else:
            return None, text

    def block_quote(self, text):
        language, text = self._get_language(text)
        if language:
            return f'\n<blockquote lang="{language}">\n{text}</blockquote>\n'
        else:
            return f"\n<blockquote>\n{text}</blockquote>\n"


class ImgsWithSizesRenderer(CustomAndBlockquoteLanguageRenderer):
    """Renders images as <figure>s and add sizes."""

    def paragraph(self, text):
        # In case of a figure, we do not want the (non-standard) paragraph.
        if text.strip().startswith("<figure>"):
            return text
        return super().paragraph(text)

    def image(self, src, alt="", title=None):
        full_path = STATIC / Path(src[1:])
        image = Image.open(full_path)
        width, height = image.size
        return dedent(
            f"""\
                <figure>
                    <a href="{src}"
                        title="Cliquer pour une version haute résolution">
                        <img src="{src}" alt="{alt}"
                             width="{width}" height="{height}" />
                    </a>
                    <figcaption>{title}</figcaption>
                </figure>
            """
        )


class ImgsWithSizesAndLightboxRenderer(ImgsWithSizesRenderer):
    """Renders images as <figure>s and add sizes + lazy attribute.

    Also, implement a lightbox markup. See:
    https://www.sylvaindurand.org/overlay-image-in-pure-css/
    """

    def image(self, src, alt="", title=None):
        file_name = Path(src).stem
        full_path = STATIC / Path(src[1:])
        image = Image.open(full_path)
        width, height = image.size
        return dedent(
            f"""\
                <figure>
                    <a href="#{file_name}"
                        title="Cliquer pour une version haute résolution">
                        <img src="{src}" alt="{alt}"
                             loading="lazy" width="{width}" height="{height}" />
                    </a>
                    <a href="#_" class="lightbox" id="{file_name}">
                        <img src="{src}" alt="{alt}"
                             loading="lazy" width="{width}" height="{height}" />
                    </a>
                    <figcaption>{title}</figcaption>
                </figure>
            """
        )


class H2AnchorsRenderer(ImgsWithSizesAndLightboxRenderer):
    """Custom renderer for H2 titles with anchors."""

    def heading(self, text, level):
        if level == 2:
            slug = slugify(text)
            return (
                f'<h2 id="{slug}">'
                f"{text} "
                f'<a href="#{slug}" title="Ancre vers cette partie">#</a>'
                f"</h2>"
            )
        else:
            return super().heading(text, level)


# We want a custom renderer to create a hash/link for each H2 headings.
markdown_with_h2_anchors = mistune.Markdown(
    renderer=H2AnchorsRenderer(escape=False),
    inline=MarkParser(H2AnchorsRenderer(escape=False)),
    plugins=[DirectiveInclude()],
)
# The second markdown is pertinent to generate articles for the feed,
# we do not need anchors in that case.
markdown_with_img_sizes = mistune.Markdown(
    renderer=ImgsWithSizesRenderer(escape=False),
    inline=MarkParser(ImgsWithSizesRenderer(escape=False)),
    plugins=[DirectiveInclude()],
)

# This is the jinja2 configuration to locate templates.
environment = Env(loader=FileSystemLoader(str(DAVID / "templates")))


def neighborhood(iterable, first=None, last=None):
    """
    Yield the (previous, current, next) items given an iterable.

    You can specify a `first` and/or `last` item for bounds.
    """
    iterator = iter(iterable)
    previous = first
    current = next(iterator)  # Throws StopIteration if empty.
    for next_ in iterator:
        yield (previous, current, next_)
        previous = current
        current = next_
    yield (previous, current, last)


def each_markdown_from(source_dir, file_name="*.md"):
    """Walk across the `source_dir` and return the md file paths."""
    for filename in fnmatch.filter(os.listdir(source_dir), file_name):
        yield filename


@dataclass
class Page:
    title: str
    content: str
    tags: list
    file_path: str
    lang: str = "fr"

    def __post_init__(self):
        date_str, _ = self.file_path.split(" - ", 1)
        self.url = f"/david/{date_str.replace('-', '/')}/"
        self.date = datetime.strptime(date_str, "%Y-%m-%d").date()
        self.full_url = f"{DOMAIN}{self.url}"
        self.normalized_date = self.date.strftime(NORMALIZED_STRFTIME)
        self.escaped_title = escape(self.title)
        tag_template = Template(
            f'<a href="{DOMAIN}/david/2021/$tag_slug/">#$tag_name</a>'
        )
        tag_links = " ".join(
            tag_template.substitute(tag_slug=slugify(tag), tag_name=tag)
            for tag in self.tags
        )
        self.escaped_content = escape(
            self.content.replace('href="/', f'href="{DOMAIN}/')
            .replace('src="/', f'src="{DOMAIN}/')
            .replace('href="#', f'href="{self.full_url}#')
            + f"<nav><p>{tag_links}</p></nav>"
            + '<hr/><p><a href="mailto:david@larlet.fr">Réagir ?</a></p>'
        )
        # Extract first paragraph.
        self.extract = self.content.split("</p>", 1)[0] + "</p>"

    def __eq__(self, other):
        return self.url == other.url

    def __lt__(self, other: "Page"):
        if not isinstance(other, Page):
            return NotImplemented
        return self.date < other.date

    @staticmethod
    def all(source: Path, only_published=True, with_h2_anchors=True):
        """Retrieve all pages sorted by desc."""
        page_list = []
        md = markdown_with_h2_anchors if with_h2_anchors else markdown_with_img_sizes
        for file_name in sorted(each_markdown_from(source)):
            result = md.read(source / file_name)
            # Extract (and remove) the title from the generated page.
            title, content = result.split("</h1>", 1)
            h1_opening_size = len("<h1>")
            title = title[h1_opening_size:]
            tags = {}
            if "<nav><p>" in content:
                # Extract the tags from the generated page.
                content, tags_links = content.split("<nav><p>", 1)
                nav_closing_size = len("</p></nav>\n")
                tags_links = tags_links[:-nav_closing_size]
                tags = sorted(
                    {
                        tag.strip().split("#", 1)[1]
                        for tag in tags_links.split("</a>")
                        if tag.strip()
                    },
                    key=lambda tag: slugify(tag),
                )
            page = Page(title, content, tags, file_name)
            pages_by_url[page.url] = page
            if not page.is_draft:
                all_tags.update(tags)
                for tag in tags:
                    if page not in pages_by_tags[tag]:
                        pages_by_tags[tag].append(page)
            if only_published and page.is_draft:
                continue
            page_list.append(page)
        return sorted(page_list, reverse=True)

    @property
    def is_draft(self):
        return (
            datetime(year=self.date.year, month=self.date.month, day=self.date.day)
            > PUBLICATION_BUFFER
        )


@cli
def pages():
    """Build article pages."""
    root_path = DAVID / "2021"
    source_path = root_path / "sources"
    for previous, page, next_ in neighborhood(
        reversed(Page.all(source=source_path, only_published=False)),
        first={
            "url": "/david/2020/",
            "title": "Publications 2020",
            "is_draft": False,
        },
    ):
        template = environment.get_template("article_2020.html")
        content = template.render(page=page, prev=previous, next=next_, slugify=slugify)
        target_path = Path(page.url[1:])
        target_path.mkdir(parents=True, exist_ok=True)
        open(target_path / "index.html", "w").write(content)
        if page.is_draft:
            print(f"Draft: {LOCAL_DOMAIN}{page.url} ({page.title})")
    template = environment.get_template("archives_2020.html")
    content = template.render(page_list=reversed(Page.all(source=source_path)))
    open(root_path / "index.html", "w").write(content)


@cli
def tags():
    """Build tags pages."""
    root_path = DAVID / "2021"
    source_path = root_path / "sources"
    # Parse all pages to collect tags.
    Page.all(source=source_path, only_published=True)
    for tag in all_tags:
        template = environment.get_template("tag_2021.html")
        content = template.render(
            page_list=pages_by_tags[tag],
            tag_name=tag,
        )
        target_path = DAVID / "2021" / slugify(tag)
        target_path.mkdir(parents=True, exist_ok=True)
        open(target_path / "index.html", "w").write(content)


@cli
def home():
    """Build the home page with last published items."""

    def group_by_month_year(item):
        return item.date.strftime("%B %Y").title()

    template = environment.get_template("profil.html")
    page_list = Page.all(source=DAVID / "2021" / "sources")
    tags = sorted((slugify(tag), tag, len(pages_by_tags[tag])) for tag in all_tags)
    content = template.render(
        page_list=groupby(page_list, key=group_by_month_year), tags=tags
    )
    open(DAVID / "index.html", "w").write(content)


@cli
def feed():
    """Generate a feed from last published items."""
    template = environment.get_template("feed.xml")
    page_list = Page.all(source=DAVID / "2021" / "sources", with_h2_anchors=False)
    content = template.render(
        page_list=page_list[:NB_ITEMS_IN_FEED],
        current_dt=TODAY.strftime(NORMALIZED_STRFTIME),
        BASE_URL=f"{DOMAIN}/david/",
    )
    open(DAVID / "log" / "index.xml", "w").write(content)


@wrap
def perf_wrapper():
    start = perf_counter()
    yield
    elapsed = perf_counter() - start
    print(f"Done in {elapsed:.5f} seconds.")


if __name__ == "__main__":
    run()