import re
from typing import cast

import mistune
from django.utils.html import escape

_mistune_plugins = [
    "url",
    "strikethrough",
    "footnotes",
    "table",
    "mark",
    "superscript",
    "subscript",
    "math",
    "spoiler",
    "ruby",
]
_markdown = mistune.create_markdown(plugins=_mistune_plugins)


def convert_leading_space_in_md(body: str) -> str:
    body = re.sub(r"^\s+$", "", body, flags=re.MULTILINE)
    body = re.sub(
        r"^(\u2003*)( +)",
        lambda s: "\u2003" * ((len(s[2]) + 1) // 2 + len(s[1])),
        body,
        flags=re.MULTILINE,
    )
    return body


def render_md(s: str) -> str:
    return cast(str, _markdown(s))


def _spolier(s: str) -> str:
    l = s.split(">!", 1)
    if len(l) == 1:
        return escape(s)
    r = l[1].split("!<", 1)
    return (
        escape(l[0])
        + '<span class="spoiler" _="on click toggle .revealed on me">'
        + escape(r[0])
        + "</span>"
        + (_spolier(r[1]) if len(r) == 2 else "")
    )


def render_text(s: str) -> str:
    return _spolier(s)