"""Пробный период подписки."""

from __future__ import annotations

import logging
from dataclasses import dataclass
from datetime import datetime, timedelta, timezone

from remnawave import RemnawaveSDK

from services.db import AuthError, Database
from services.purchase import provision_subscription
from services.tariffs import Tariff, get_tariff

logger = logging.getLogger(__name__)

DEFAULT_TRIAL_DAYS = 3


@dataclass(frozen=True, slots=True)
class TrialResult:
    ok: bool
    message: str
    expire_at: datetime | None = None


def trial_days_setting(db: Database) -> int:
    raw = (db.get_setting("trial_days") or str(DEFAULT_TRIAL_DAYS)).strip()
    try:
        days = int(raw)
    except ValueError:
        days = DEFAULT_TRIAL_DAYS
    return max(0, min(days, 30))


def trial_enabled(db: Database) -> bool:
    return trial_days_setting(db) > 0


async def grant_trial(
    *,
    db: Database,
    sdk: RemnawaveSDK,
    telegram_id: int,
    tariffs: list[Tariff],
) -> TrialResult:
    days = trial_days_setting(db)
    if days <= 0:
        return TrialResult(ok=False, message="Пробный период выключен")

    user = db.ensure_user(telegram_id)
    if user.banned:
        return TrialResult(ok=False, message="Аккаунт заблокирован")
    if user.trial_used_at:
        return TrialResult(ok=False, message="Пробный период уже использован")

    tariff_id = (db.get_setting("trial_tariff_id") or "").strip()
    tariff = get_tariff(tariffs, tariff_id) if tariff_id else None
    if tariff is None and tariffs:
        tariff = min(tariffs, key=lambda t: t.price)
    if tariff is None:
        return TrialResult(ok=False, message="Нет тарифа для пробного периода")

    trial_tariff = Tariff(
        id=tariff.id,
        title=f"Trial · {tariff.title}",
        price=0.0,
        days=days,
        traffic_gb=tariff.traffic_gb,
        device_limit=tariff.device_limit,
        squad_uuids=tariff.squad_uuids,
        description="trial",
    )

    try:
        rw_uuid, sub_url, expire_at = await provision_subscription(
            sdk,
            telegram_id=telegram_id,
            tariff=trial_tariff,
            login=user.login,
            extra_devices=user.extra_devices,
        )
    except Exception as exc:  # noqa: BLE001
        logger.exception("trial provision failed")
        return TrialResult(ok=False, message=f"Не удалось выдать пробный период: {exc}")

    db.mark_trial_used(telegram_id)
    db.record_purchase(
        telegram_id,
        tariff_id=f"trial:{tariff.id}",
        price=0.0,
        remnawave_uuid=rw_uuid,
        subscription_url=sub_url,
    )
    return TrialResult(
        ok=True,
        message=f"Пробный период на {days} дн. активен до {expire_at.strftime('%d.%m.%Y %H:%M UTC')}",
        expire_at=expire_at,
    )