from __future__ import annotations

import logging
import re
import ssl
from dataclasses import dataclass
from datetime import datetime
from typing import List, Optional

import aiohttp
import certifi
from bs4 import BeautifulSoup

logger = logging.getLogger(__name__)

DRIVE_FOLDER_EMBED = (
    "https://drive.google.com/embeddedfolderview?id={folder_id}#list"
)
DRIVE_DOWNLOAD_URL = "https://drive.google.com/uc?export=download&id={file_id}"
USER_AGENT = (
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
    "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
)


def _drive_connector() -> aiohttp.TCPConnector:
    ssl_context = ssl.create_default_context(cafile=certifi.where())
    return aiohttp.TCPConnector(ssl=ssl_context)


@dataclass(frozen=True)
class DriveScheduleFile:
    file_id: str
    name: str
    schedule_date: datetime


class DriveScheduleSource:
    def __init__(self, folder_id: str):
        self.folder_id = folder_id
        self._files_cache: Optional[List[DriveScheduleFile]] = None

    @staticmethod
    def _parse_filename_date(name: str) -> Optional[datetime]:
        match = re.match(
            r"^(\d{2})\.(\d{2})\.(\d{2})\s+по\s+учащимся\.pdf$",
            name.strip(),
            re.IGNORECASE,
        )
        if not match:
            return None
        day, month, year = map(int, match.groups())
        return datetime(2000 + year, month, day)

    async def list_student_schedules(self, force_refresh: bool = False) -> List[DriveScheduleFile]:
        if self._files_cache is not None and not force_refresh:
            return self._files_cache

        url = DRIVE_FOLDER_EMBED.format(folder_id=self.folder_id)

        async with aiohttp.ClientSession(
            headers={"User-Agent": USER_AGENT},
            connector=_drive_connector(),
        ) as session:
            async with session.get(url) as resp:
                resp.raise_for_status()
                html = await resp.text()

        soup = BeautifulSoup(html, "html.parser")
        files: List[DriveScheduleFile] = []

        for entry in soup.select("div.flip-entry"):
            entry_id = entry.get("id", "")
            if not entry_id.startswith("entry-"):
                continue
            file_id = entry_id.removeprefix("entry-")
            title_el = entry.select_one(".flip-entry-title")
            if not title_el:
                continue
            name = title_el.get_text(strip=True)
            schedule_date = self._parse_filename_date(name)
            if schedule_date is None:
                continue
            files.append(DriveScheduleFile(file_id=file_id, name=name, schedule_date=schedule_date))

        files.sort(key=lambda item: item.schedule_date)
        self._files_cache = files
        return files

    async def find_for_date(self, target: datetime) -> Optional[DriveScheduleFile]:
        files = await self.list_student_schedules()
        for item in reversed(files):
            if (
                item.schedule_date.day == target.day
                and item.schedule_date.month == target.month
                and item.schedule_date.year == target.year
            ):
                return item
        return None

    async def download_pdf(self, file_id: str) -> bytes:
        url = DRIVE_DOWNLOAD_URL.format(file_id=file_id)
        async with aiohttp.ClientSession(
            headers={"User-Agent": USER_AGENT},
            connector=_drive_connector(),
        ) as session:
            async with session.get(url) as resp:
                resp.raise_for_status()
                return await resp.read()