import re
import typing

from mistletoe import Document  # type: ignore
from mistletoe.html_renderer import HTMLRenderer  # type: ignore
from mistletoe.span_token import SpanToken  # type: ignore
from pygments import highlight  # type: ignore
from pygments.formatters import HtmlFormatter  # type: ignore
from pygments.lexers import get_lexer_by_name as get_lexer  # type: ignore
from pygments.lexers import guess_lexer  # type: ignore
from sqlalchemy import select

from app import webfinger
from app.config import BASE_URL
from app.config import CODE_HIGHLIGHTING_THEME
from app.database import AsyncSession
from app.utils import emoji

if typing.TYPE_CHECKING:
    from app.actor import Actor

_FORMATTER = HtmlFormatter(style=CODE_HIGHLIGHTING_THEME)
_HASHTAG_REGEX = re.compile(r"(#[\d\w]+)")
_MENTION_REGEX = re.compile(r"@[\d\w_.+-]+@[\d\w-]+\.[\d\w\-.]+")


class AutoLink(SpanToken):
    parse_inner = False
    precedence = 10
    pattern = re.compile(
        "(https?:\\/\\/(?:www\\.)?[-a-zA-Z0-9@:%._\\+~#=]{1,256}\\.[a-zA-Z0-9()]{1,6}\\b(?:[-a-zA-Z0-9()@:%_\\+.~#?&\\/=]*))"  # noqa: E501
    )

    def __init__(self, match_obj: re.Match) -> None:
        self.target = match_obj.group()


class Mention(SpanToken):
    parse_inner = False
    precedence = 10
    pattern = re.compile(r"(@[\d\w_.+-]+@[\d\w-]+\.[\d\w\-.]+)")

    def __init__(self, match_obj: re.Match) -> None:
        self.target = match_obj.group()


class Hashtag(SpanToken):
    parse_inner = False
    precedence = 10
    pattern = re.compile(r"(#[\d\w]+)")

    def __init__(self, match_obj: re.Match) -> None:
        self.target = match_obj.group()


class CustomRenderer(HTMLRenderer):
    def __init__(
        self,
        mentioned_actors: dict[str, "Actor"] = {},
        enable_mentionify: bool = True,
        enable_hashtagify: bool = True,
    ) -> None:
        extra_tokens = []
        if enable_mentionify:
            extra_tokens.append(Mention)
        if enable_hashtagify:
            extra_tokens.append(Hashtag)
        super().__init__(AutoLink, *extra_tokens)

        self.tags: list[dict[str, str]] = []
        self.mentioned_actors = mentioned_actors

    def render_auto_link(self, token: AutoLink) -> str:
        template = '<a href="{target}" rel="noopener">{inner}</a>'
        target = self.escape_url(token.target)
        return template.format(target=target, inner=target)

    def render_mention(self, token: Mention) -> str:
        mention = token.target
        actor = self.mentioned_actors.get(mention)
        if not actor:
            return mention

        self.tags.append(dict(type="Mention", href=actor.ap_id, name=mention))

        link = f'<span class="h-card"><a href="{actor.url}" class="u-url mention">{actor.handle}</a></span>'  # noqa: E501
        return link

    def render_hashtag(self, token: Hashtag) -> str:
        tag = token.target[1:]
        link = f'<a href="{BASE_URL}/t/{tag}" class="mention hashtag" rel="tag">#<span>{tag}</span></a>'  # noqa: E501
        self.tags.append(
            dict(href=f"{BASE_URL}/t/{tag}", name=token.target, type="Hashtag")
        )
        return link

    def render_block_code(self, token: typing.Any) -> str:
        code = token.children[0].content
        lexer = get_lexer(token.language) if token.language else guess_lexer(code)
        return highlight(code, lexer, _FORMATTER)


async def _prefetch_mentioned_actors(
    db_session: AsyncSession,
    content: str,
) -> dict[str, "Actor"]:
    from app import models
    from app.actor import fetch_actor

    actors = {}

    for mention in re.findall(_MENTION_REGEX, content):
        if mention in actors:
            continue

        _, username, domain = mention.split("@")
        actor = (
            await db_session.execute(
                select(models.Actor).where(
                    models.Actor.handle == mention,
                    models.Actor.is_deleted.is_(False),
                )
            )
        ).scalar_one_or_none()
        if not actor:
            actor_url = await webfinger.get_actor_url(mention)
            if not actor_url:
                # FIXME(ts): raise an error?
                continue
            actor = await fetch_actor(db_session, actor_url)

        actors[mention] = actor

    return actors


def hashtagify(content: str) -> tuple[str, list[dict[str, str]]]:
    # TODO: fix this, switch to mistletoe?
    tags = []
    hashtags = re.findall(_HASHTAG_REGEX, content)
    hashtags = sorted(set(hashtags), reverse=True)  # unique tags, longest first
    for hashtag in hashtags:
        tag = hashtag[1:]
        link = f'<a href="{BASE_URL}/t/{tag}" class="mention hashtag" rel="tag">#<span>{tag}</span></a>'  # noqa: E501
        tags.append(dict(href=f"{BASE_URL}/t/{tag}", name=hashtag, type="Hashtag"))
        content = content.replace(hashtag, link)
    return content, tags


async def markdownify(
    db_session: AsyncSession,
    content: str,
    enable_mentionify: bool = True,
    enable_hashtagify: bool = True,
) -> tuple[str, list[dict[str, str]], list["Actor"]]:
    """
    >>> content, tags = markdownify("Hello")

    """
    tags = []
    mentioned_actors: dict[str, "Actor"] = {}
    if enable_mentionify:
        mentioned_actors = await _prefetch_mentioned_actors(db_session, content)

    with CustomRenderer(
        mentioned_actors=mentioned_actors,
        enable_mentionify=enable_mentionify,
        enable_hashtagify=enable_hashtagify,
    ) as renderer:
        rendered_content = renderer.render(Document(content))
        tags.extend(renderer.tags)

    # Handle custom emoji
    tags.extend(emoji.tags(content))

    return rendered_content, tags, list(mentioned_actors.values())