from __future__ import annotations

import json
import logging
import re
from datetime import UTC, datetime
from pathlib import Path
from threading import Thread
from typing import Any

import telebot
from telebot import types

from app.config import Settings
from app.db import Database, TransactionInput, amount_to_cents

logger = logging.getLogger(__name__)

CATEGORY_PATTERN = re.compile(r"^[^\x00-\x1f]{1,40}$")


def parse_transaction(raw: str) -> TransactionInput:
    try:
        payload: dict[str, Any] = json.loads(raw)
    except (json.JSONDecodeError, TypeError) as exc:
        raise ValueError("Не удалось прочитать данные") from exc

    if payload.get("type") != "transaction" or payload.get("v") != 1:
        raise ValueError("Неизвестный формат данных")

    kind = payload.get("kind")
    if kind not in {"income", "expense"}:
        raise ValueError("Некорректный тип операции")

    category = str(payload.get("category", "")).strip()
    if not CATEGORY_PATTERN.fullmatch(category):
        raise ValueError("Категория должна содержать от 1 до 40 символов")

    note = str(payload.get("note", "")).strip() or None
    if note and len(note) > 160:
        raise ValueError("Комментарий слишком длинный")

    occurred_at_raw = str(payload.get("occurred_at", "")).strip()
    try:
        occurred_at = datetime.fromisoformat(occurred_at_raw.replace("Z", "+00:00"))
    except ValueError:
        occurred_at = datetime.now(UTC)
    if occurred_at.tzinfo is None:
        occurred_at = occurred_at.replace(tzinfo=UTC)

    return TransactionInput(
        kind=kind,
        amount_cents=amount_to_cents(payload.get("amount")),
        category=category,
        note=note,
        occurred_at=occurred_at.astimezone(UTC).isoformat(),
    )


class TelegramBotService:
    def __init__(self, settings: Settings, database: Database):
        self.settings = settings
        self.database = database
        self.bot = telebot.TeleBot(settings.telegram_token, threaded=True)
        self.thread: Thread | None = None
        self._register_handlers()

    def _keyboard(self) -> types.ReplyKeyboardMarkup:
        keyboard = types.ReplyKeyboardMarkup(resize_keyboard=True)
        keyboard.add(
            types.KeyboardButton(
                text="Открыть Пожитки",
                web_app=types.WebAppInfo(url=self.settings.webapp_url),
            )
        )
        return keyboard

    def _register_handlers(self) -> None:
        @self.bot.message_handler(commands=["start"])
        def start(message: types.Message) -> None:
            user = message.from_user
            if user is None:
                return
            self._save_user(user)

            parts = (message.text or "").split(maxsplit=1)
            friend_added = False
            if len(parts) == 2 and parts[1].startswith("friend_"):
                try:
                    inviter_id = int(parts[1].removeprefix("friend_"))
                except ValueError:
                    inviter_id = 0
                if inviter_id > 0:
                    friend_added = self.database.add_friendship(user.id, inviter_id)

            prefix = "Теперь вы друзья!\n\n" if friend_added else ""
            self.bot.send_message(
                message.chat.id,
                prefix
                + "Пожитки считают доходы, расходы и процент накоплений. "
                "Нажмите кнопку ниже, чтобы открыть приложение.",
                reply_markup=self._keyboard(),
            )

        @self.bot.message_handler(content_types=["web_app_data"])
        def web_app_data(message: types.Message) -> None:
            user = message.from_user
            if user is None or message.web_app_data is None:
                return
            self._save_user(user)
            try:
                item = parse_transaction(message.web_app_data.data)
                self.database.add_transaction(user.id, item)
            except ValueError as exc:
                self.bot.send_message(
                    message.chat.id,
                    f"Не получилось сохранить операцию: {exc}",
                    reply_markup=self._keyboard(),
                )
                return

            operation = "Доход" if item.kind == "income" else "Расход"
            self.bot.send_message(
                message.chat.id,
                f"{operation} сохранён в категории «{item.category}». Откройте приложение снова, чтобы увидеть обновлённую статистику.",
                reply_markup=self._keyboard(),
            )

        @self.bot.message_handler(commands=["help"])
        def help_message(message: types.Message) -> None:
            self.bot.send_message(
                message.chat.id,
                "Добавляйте операции через WebApp. Ссылка «Стать друзьями» находится на вкладке рейтинга.",
                reply_markup=self._keyboard(),
            )

    def _save_user(self, user: types.User) -> None:
        self.database.upsert_user(
            user_id=user.id,
            first_name=user.first_name or "Пользователь",
            last_name=user.last_name,
            username=user.username,
        )
        try:
            photos = self.bot.get_user_profile_photos(user.id, limit=1)
            if not photos.photos:
                return
            photo = photos.photos[0][-1]
            if self.database.get_avatar_file_id(user.id) == photo.file_id:
                return
            file_info = self.bot.get_file(photo.file_id)
            content = self.bot.download_file(file_info.file_path)
            suffix = Path(file_info.file_path).suffix or ".jpg"
            filename = f"{user.id}{suffix}"
            target = self.settings.avatars_dir / filename
            self.settings.avatars_dir.mkdir(parents=True, exist_ok=True)
            target.write_bytes(content)
            self.database.upsert_user(
                user_id=user.id,
                first_name=user.first_name or "Пользователь",
                last_name=user.last_name,
                username=user.username,
                avatar_file_id=photo.file_id,
                avatar_path=filename,
            )
        except Exception:
            logger.exception("Could not update avatar for Telegram user %s", user.id)

    def start(self) -> None:
        me = self.bot.get_me()
        if me.username:
            self.database.set_meta("bot_username", me.username)
        self.bot.set_my_commands(
            [
                types.BotCommand("start", "Открыть приложение"),
                types.BotCommand("help", "Как пользоваться"),
            ]
        )
        self.thread = Thread(
            target=self.bot.infinity_polling,
            kwargs={"skip_pending": True, "timeout": 30, "long_polling_timeout": 30},
            name="telegram-polling",
            daemon=True,
        )
        self.thread.start()
        logger.info("Telegram bot @%s started", me.username)

    def stop(self) -> None:
        self.bot.stop_polling()