import re
from dataclasses import dataclass, field
from datetime import datetime
from typing import Optional
from zoneinfo import ZoneInfo

import async_timeout
import discord
import feedparser
from aiohttp import ClientSession
from markdownify import markdownify as md
from sqlalchemy.ext.asyncio import AsyncSession

import settings
from database.crud import ufora_announcements as crud
from database.schemas import UforaCourse
from didier.data.embeds.base import EmbedBaseModel
from didier.utils.discord.colours import ghent_university_blue
from didier.utils.types.datetime import LOCAL_TIMEZONE, int_to_weekday
from didier.utils.types.string import leading

__all__ = [
    "fetch_ufora_announcements",
    "parse_ids",
    "UforaNotification",
]


@dataclass
class UforaNotification(EmbedBaseModel):
    """A single notification from Ufora"""

    content: dict
    course: UforaCourse
    notification_id: Optional[int] = None
    course_id: Optional[int] = None

    _view_url: str = field(init=False)
    _title: str = field(init=False)
    _description: str = field(init=False)
    published_dt: datetime = field(init=False)
    _published: str = field(init=False)

    def __post_init__(self):
        self._view_url = self._create_url()
        self._title = self._clean_content(self.content["title"])
        self._description = self._get_description()
        self.published_dt = self._published_datetime()
        self._published = self._get_published()

    def to_embed(self, **kwargs) -> discord.Embed:
        """Turn the notification into an embed"""
        embed = discord.Embed(title=self._title, colour=ghent_university_blue())

        embed.set_author(name=self.course.name)
        embed.title = self._title
        embed.url = self._view_url
        embed.description = self._description
        embed.set_footer(text=self._published)

        return embed

    def get_id(self) -> int:
        """Parse the id out of the notification"""
        return int(self.notification_id) if self.notification_id is not None else self.content["id"]

    def _create_url(self):
        if self.notification_id is None or self.course_id is None:
            return self.content["link"]

        return f"https://ufora.ugent.be/d2l/le/news/{self.course_id}/{self.notification_id}/view?ou={self.course_id}"

    def _get_description(self):
        desc = self._clean_content(self.content["summary"])

        if len(desc) > 4096:
            return desc[:4093] + "..."

        return desc

    def _clean_content(self, text: str):
        # Escape *-characters because they mess up the layout
        text = text.replace("*", "\\*")
        return md(text)

    def _published_datetime(self) -> datetime:
        """Get a datetime instance of the publication date"""
        # Datetime is unable to parse the timezone because it's useless
        # We will hereby cut it out and pray the timezone will always be UTC+0
        published = self.content["published"].rsplit(" ", 1)[0]
        time_string = "%a, %d %b %Y %H:%M:%S"
        dt = datetime.strptime(published, time_string).replace(tzinfo=ZoneInfo("GMT")).astimezone(LOCAL_TIMEZONE)
        return dt

    def _get_published(self) -> str:
        """Get a formatted string that represents when this announcement was published"""
        return (
            f"{int_to_weekday(self.published_dt.weekday())} "
            f"{leading('0', str(self.published_dt.day))}"
            "/"
            f"{leading('0', str(self.published_dt.month))}"
            "/"
            f"{self.published_dt.year} "
            f"{leading('0', str(self.published_dt.hour))}"
            ":"
            f"{leading('0', str(self.published_dt.minute))}"
            ":"
            f"{leading('0', str(self.published_dt.second))}"
        )


def parse_ids(url: str) -> Optional[tuple[int, int]]:
    """Parse the notification & course id out of a notification url"""
    match = re.search(r"\d+-\d+$", url)

    if not match:
        return None

    spl = match[0].split("-")
    return int(spl[0]), int(spl[1])


async def fetch_ufora_announcements(
    http_session: ClientSession, database_session: AsyncSession
) -> list[UforaNotification]:
    """Fetch all new announcements"""
    notifications: list[UforaNotification] = []

    # No token provided, don't fetch announcements
    if settings.UFORA_RSS_TOKEN is None:
        return notifications

    courses = await crud.get_courses_with_announcements(database_session)

    for course in courses:
        course_announcement_ids = list(map(lambda announcement: announcement.announcement_id, course.announcements))

        course_url = (
            f"https://ufora.ugent.be/d2l/le/news/rss/{course.course_id}/course?token={settings.UFORA_RSS_TOKEN}"
        )

        # Get the updated feed
        with async_timeout.timeout(10):
            async with http_session.get(course_url) as response:
                feed = feedparser.parse(await response.text())

        # Remove old notifications
        fresh_feed: list[dict] = []
        for entry in feed["entries"]:
            parsed = parse_ids(entry["id"])
            if parsed is None:
                continue

            if parsed[0] not in course_announcement_ids:
                fresh_feed.append(entry)

        if fresh_feed:
            for item in fresh_feed:
                # Parse id's out
                # Technically this can't happen but Mypy angry
                parsed = parse_ids(item["id"])

                if parsed is None:
                    continue

                # Create a new notification
                notification_id, course_id = parsed
                notification = UforaNotification(item, course, notification_id, course_id)
                notifications.append(notification)

                # Create new db entry
                await crud.create_new_announcement(database_session, notification_id, course, notification.published_dt)

    return notifications