"""Repository: get_or_create_user, get_duties, insert_duty, get_current_duty, group_duty_pins."""

import hashlib
import secrets
from datetime import datetime, timedelta, timezone

from sqlalchemy.orm import Session

import duty_teller.config as config
from duty_teller.db.models import User, Duty, GroupDutyPin, CalendarSubscriptionToken


def get_user_by_telegram_id(session: Session, telegram_user_id: int) -> User | None:
    """Find user by Telegram user ID.

    Args:
        session: DB session.
        telegram_user_id: Telegram user id.

    Returns:
        User or None if not found. Does not create a user.
    """
    return session.query(User).filter(User.telegram_user_id == telegram_user_id).first()


def is_admin_for_telegram_user(session: Session, telegram_user_id: int) -> bool:
    """Check if the Telegram user is admin (by username or by stored phone).

    Args:
        session: DB session.
        telegram_user_id: Telegram user id.

    Returns:
        True if user is in ADMIN_USERNAMES or their stored phone is in ADMIN_PHONES.
    """
    user = get_user_by_telegram_id(session, telegram_user_id)
    if not user:
        return False
    return config.is_admin(user.username or "") or config.is_admin_by_phone(user.phone)


def get_or_create_user(
    session: Session,
    telegram_user_id: int,
    full_name: str,
    username: str | None = None,
    first_name: str | None = None,
    last_name: str | None = None,
) -> User:
    """Get or create user by Telegram user ID.

    On create, name fields come from Telegram. On update: username is always
    synced; full_name, first_name, last_name are updated only if
    name_manually_edited is False (otherwise existing display name is kept).

    Args:
        session: DB session.
        telegram_user_id: Telegram user id.
        full_name: Display full name.
        username: Telegram username (optional).
        first_name: Telegram first name (optional).
        last_name: Telegram last name (optional).

    Returns:
        User instance (created or updated).
    """
    user = get_user_by_telegram_id(session, telegram_user_id)
    if user:
        user.username = username
        if not user.name_manually_edited:
            user.full_name = full_name
            user.first_name = first_name
            user.last_name = last_name
        session.commit()
        session.refresh(user)
        return user
    user = User(
        telegram_user_id=telegram_user_id,
        full_name=full_name,
        username=username,
        first_name=first_name,
        last_name=last_name,
        name_manually_edited=False,
    )
    session.add(user)
    session.commit()
    session.refresh(user)
    return user


def get_or_create_user_by_full_name(session: Session, full_name: str) -> User:
    """Find user by exact full_name or create one (for duty-schedule import).

    New users have telegram_user_id=None and name_manually_edited=True.

    Args:
        session: DB session.
        full_name: Exact full name to match or set.

    Returns:
        User instance (existing or newly created).
    """
    user = session.query(User).filter(User.full_name == full_name).first()
    if user:
        return user
    user = User(
        telegram_user_id=None,
        full_name=full_name,
        username=None,
        first_name=None,
        last_name=None,
        name_manually_edited=True,
    )
    session.add(user)
    session.commit()
    session.refresh(user)
    return user


def update_user_display_name(
    session: Session,
    telegram_user_id: int,
    full_name: str,
    first_name: str | None = None,
    last_name: str | None = None,
) -> User | None:
    """Update display name and set name_manually_edited=True.

    Use from API or admin when name is changed manually; subsequent
    get_or_create_user will not overwrite these fields.

    Args:
        session: DB session.
        telegram_user_id: Telegram user id.
        full_name: New full name.
        first_name: New first name (optional).
        last_name: New last name (optional).

    Returns:
        Updated User or None if not found.
    """
    user = session.query(User).filter(User.telegram_user_id == telegram_user_id).first()
    if not user:
        return None
    user.full_name = full_name
    user.first_name = first_name
    user.last_name = last_name
    user.name_manually_edited = True
    session.commit()
    session.refresh(user)
    return user


def delete_duties_in_range(
    session: Session,
    user_id: int,
    from_date: str,
    to_date: str,
) -> int:
    """Delete all duties of the user that overlap the given date range.

    Args:
        session: DB session.
        user_id: User id.
        from_date: Start date YYYY-MM-DD.
        to_date: End date YYYY-MM-DD.

    Returns:
        Number of duties deleted.
    """
    to_next = (
        datetime.fromisoformat(to_date + "T00:00:00") + timedelta(days=1)
    ).strftime("%Y-%m-%d")
    q = session.query(Duty).filter(
        Duty.user_id == user_id,
        Duty.start_at < to_next,
        Duty.end_at >= from_date,
    )
    count = q.count()
    q.delete(synchronize_session=False)
    session.commit()
    return count


def get_duties(
    session: Session,
    from_date: str,
    to_date: str,
) -> list[tuple[Duty, str]]:
    """Return duties overlapping the given date range with user full_name.

    Args:
        session: DB session.
        from_date: Start date YYYY-MM-DD.
        to_date: End date YYYY-MM-DD.

    Returns:
        List of (Duty, full_name) tuples.
    """
    to_date_next = (
        datetime.fromisoformat(to_date + "T00:00:00") + timedelta(days=1)
    ).strftime("%Y-%m-%d")
    q = (
        session.query(Duty, User.full_name)
        .join(User, Duty.user_id == User.id)
        .filter(Duty.start_at < to_date_next, Duty.end_at >= from_date)
    )
    return list(q.all())


def get_duties_for_user(
    session: Session,
    user_id: int,
    from_date: str,
    to_date: str,
) -> list[tuple[Duty, str]]:
    """Return duties for one user overlapping the date range.

    Args:
        session: DB session.
        user_id: User id.
        from_date: Start date YYYY-MM-DD.
        to_date: End date YYYY-MM-DD.

    Returns:
        List of (Duty, full_name) tuples.
    """
    to_date_next = (
        datetime.fromisoformat(to_date + "T00:00:00") + timedelta(days=1)
    ).strftime("%Y-%m-%d")
    q = (
        session.query(Duty, User.full_name)
        .join(User, Duty.user_id == User.id)
        .filter(
            Duty.user_id == user_id,
            Duty.start_at < to_date_next,
            Duty.end_at >= from_date,
        )
    )
    return list(q.all())


def _token_hash(token: str) -> str:
    """Return SHA256 hex digest of the token (constant-time comparison via hmac)."""
    return hashlib.sha256(token.encode()).hexdigest()


def create_calendar_token(session: Session, user_id: int) -> str:
    """Create a new calendar subscription token for the user.

    Any existing tokens for this user are removed. The raw token is returned
    only once (not stored in plain text).

    Args:
        session: DB session.
        user_id: User id.

    Returns:
        Raw token string (e.g. for URL /api/calendar/ical/{token}.ics).
    """
    session.query(CalendarSubscriptionToken).filter(
        CalendarSubscriptionToken.user_id == user_id
    ).delete(synchronize_session=False)
    raw_token = secrets.token_urlsafe(32)
    token_hash_val = _token_hash(raw_token)
    now_iso = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
    record = CalendarSubscriptionToken(
        user_id=user_id,
        token_hash=token_hash_val,
        created_at=now_iso,
    )
    session.add(record)
    session.commit()
    return raw_token


def get_user_by_calendar_token(session: Session, token: str) -> User | None:
    """Find user by calendar subscription token.

    Uses constant-time comparison to avoid timing leaks.

    Args:
        session: DB session.
        token: Raw token from URL.

    Returns:
        User or None if token is invalid or not found.
    """
    token_hash_val = _token_hash(token)
    row = (
        session.query(CalendarSubscriptionToken, User)
        .join(User, CalendarSubscriptionToken.user_id == User.id)
        .filter(CalendarSubscriptionToken.token_hash == token_hash_val)
        .first()
    )
    if row is None:
        return None
    return row[1]


def insert_duty(
    session: Session,
    user_id: int,
    start_at: str,
    end_at: str,
    event_type: str = "duty",
) -> Duty:
    """Create a duty record.

    Args:
        session: DB session.
        user_id: User id.
        start_at: Start time UTC, ISO 8601 with Z (e.g. 2025-01-15T09:00:00Z).
        end_at: End time UTC, ISO 8601 with Z.
        event_type: One of "duty", "unavailable", "vacation". Default "duty".

    Returns:
        Created Duty instance.
    """
    duty = Duty(
        user_id=user_id,
        start_at=start_at,
        end_at=end_at,
        event_type=event_type,
    )
    session.add(duty)
    session.commit()
    session.refresh(duty)
    return duty


def get_current_duty(session: Session, at_utc: datetime) -> tuple[Duty, User] | None:
    """Return the duty and user active at the given UTC time (event_type='duty').

    Args:
        session: DB session.
        at_utc: Point in time (timezone-aware or naive UTC).

    Returns:
        (Duty, User) or None if no duty at that time.
    """
    from datetime import timezone

    if at_utc.tzinfo is not None:
        at_utc = at_utc.astimezone(timezone.utc)
    now_iso = at_utc.strftime("%Y-%m-%dT%H:%M:%S") + "Z"
    row = (
        session.query(Duty, User)
        .join(User, Duty.user_id == User.id)
        .filter(
            Duty.event_type == "duty",
            Duty.start_at <= now_iso,
            Duty.end_at > now_iso,
        )
        .first()
    )
    if row is None:
        return None
    return (row[0], row[1])


def get_next_shift_end(session: Session, after_utc: datetime) -> datetime | None:
    """Return the end_at of the current or next duty (event_type='duty').

    Args:
        session: DB session.
        after_utc: Point in time (timezone-aware or naive UTC).

    Returns:
        End datetime (naive UTC) or None if no current or future duty.
    """
    from datetime import timezone

    if after_utc.tzinfo is not None:
        after_utc = after_utc.astimezone(timezone.utc)
    after_iso = after_utc.strftime("%Y-%m-%dT%H:%M:%S") + "Z"
    current = (
        session.query(Duty)
        .filter(
            Duty.event_type == "duty",
            Duty.start_at <= after_iso,
            Duty.end_at > after_iso,
        )
        .first()
    )
    if current:
        return datetime.fromisoformat(current.end_at.replace("Z", "+00:00")).replace(
            tzinfo=None
        )
    next_duty = (
        session.query(Duty)
        .filter(Duty.event_type == "duty", Duty.start_at > after_iso)
        .order_by(Duty.start_at)
        .first()
    )
    if next_duty:
        return datetime.fromisoformat(next_duty.end_at.replace("Z", "+00:00")).replace(
            tzinfo=None
        )
    return None


def get_group_duty_pin(session: Session, chat_id: int) -> GroupDutyPin | None:
    """Get the pinned duty message record for a chat.

    Args:
        session: DB session.
        chat_id: Telegram chat id.

    Returns:
        GroupDutyPin or None.
    """
    return session.query(GroupDutyPin).filter(GroupDutyPin.chat_id == chat_id).first()


def save_group_duty_pin(
    session: Session, chat_id: int, message_id: int
) -> GroupDutyPin:
    """Save or update the pinned duty message for a chat.

    Args:
        session: DB session.
        chat_id: Telegram chat id.
        message_id: Message id to pin/update.

    Returns:
        GroupDutyPin instance (created or updated).
    """
    pin = session.query(GroupDutyPin).filter(GroupDutyPin.chat_id == chat_id).first()
    if pin:
        pin.message_id = message_id
    else:
        pin = GroupDutyPin(chat_id=chat_id, message_id=message_id)
        session.add(pin)
    session.commit()
    session.refresh(pin)
    return pin


def delete_group_duty_pin(session: Session, chat_id: int) -> None:
    """Remove the pinned duty message record for the chat (e.g. when bot leaves group).

    Args:
        session: DB session.
        chat_id: Telegram chat id.
    """
    session.query(GroupDutyPin).filter(GroupDutyPin.chat_id == chat_id).delete()
    session.commit()


def get_all_group_duty_pin_chat_ids(session: Session) -> list[int]:
    """Return all chat_ids that have a pinned duty message.

    Used to restore update jobs on bot startup.

    Args:
        session: DB session.

    Returns:
        List of chat ids.
    """
    rows = session.query(GroupDutyPin.chat_id).all()
    return [r[0] for r in rows]


def set_user_phone(
    session: Session, telegram_user_id: int, phone: str | None
) -> User | None:
    """Set or clear phone for user by Telegram user id.

    Args:
        session: DB session.
        telegram_user_id: Telegram user id.
        phone: Phone string or None to clear.

    Returns:
        Updated User or None if not found.
    """
    user = session.query(User).filter(User.telegram_user_id == telegram_user_id).first()
    if not user:
        return None
    if phone is None or (isinstance(phone, str) and not phone.strip()):
        user.phone = None
    else:
        user.phone = config.normalize_phone(phone)
    session.commit()
    session.refresh(user)
    return user